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apache/cloudberry/refs/heads/main/./src/backend/replication/logical/reorderbuffer.c
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/*-------------------------------------------------------------------------
*
* reorderbuffer.c
* PostgreSQL logical replay/reorder buffer management
*
*
* Copyright (c) 2012-2021, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* src/backend/replication/reorderbuffer.c
*
* NOTES
* This module gets handed individual pieces of transactions in the order
* they are written to the WAL and is responsible to reassemble them into
* toplevel transaction sized pieces. When a transaction is completely
* reassembled - signaled by reading the transaction commit record - it
* will then call the output plugin (cf. ReorderBufferCommit()) with the
* individual changes. The output plugins rely on snapshots built by
* snapbuild.c which hands them to us.
*
* Transactions and subtransactions/savepoints in postgres are not
* immediately linked to each other from outside the performing
* backend. Only at commit/abort (or special xact_assignment records) they
* are linked together. Which means that we will have to splice together a
* toplevel transaction from its subtransactions. To do that efficiently we
* build a binary heap indexed by the smallest current lsn of the individual
* subtransactions' changestreams. As the individual streams are inherently
* ordered by LSN - since that is where we build them from - the transaction
* can easily be reassembled by always using the subtransaction with the
* smallest current LSN from the heap.
*
* In order to cope with large transactions - which can be several times as
* big as the available memory - this module supports spooling the contents
* of a large transactions to disk. When the transaction is replayed the
* contents of individual (sub-)transactions will be read from disk in
* chunks.
*
* This module also has to deal with reassembling toast records from the
* individual chunks stored in WAL. When a new (or initial) version of a
* tuple is stored in WAL it will always be preceded by the toast chunks
* emitted for the columns stored out of line. Within a single toplevel
* transaction there will be no other data carrying records between a row's
* toast chunks and the row data itself. See ReorderBufferToast* for
* details.
*
* ReorderBuffer uses two special memory context types - SlabContext for
* allocations of fixed-length structures (changes and transactions), and
* GenerationContext for the variable-length transaction data (allocated
* and freed in groups with similar lifespans).
*
* To limit the amount of memory used by decoded changes, we track memory
* used at the reorder buffer level (i.e. total amount of memory), and for
* each transaction. When the total amount of used memory exceeds the
* limit, the transaction consuming the most memory is then serialized to
* disk.
*
* Only decoded changes are evicted from memory (spilled to disk), not the
* transaction records. The number of toplevel transactions is limited,
* but a transaction with many subtransactions may still consume significant
* amounts of memory. However, the transaction records are fairly small and
* are not included in the memory limit.
*
* The current eviction algorithm is very simple - the transaction is
* picked merely by size, while it might be useful to also consider age
* (LSN) of the changes for example. With the new Generational memory
* allocator, evicting the oldest changes would make it more likely the
* memory gets actually freed.
*
* We still rely on max_changes_in_memory when loading serialized changes
* back into memory. At that point we can't use the memory limit directly
* as we load the subxacts independently. One option to deal with this
* would be to count the subxacts, and allow each to allocate 1/N of the
* memory limit. That however does not seem very appealing, because with
* many subtransactions it may easily cause thrashing (short cycles of
* deserializing and applying very few changes). We probably should give
* a bit more memory to the oldest subtransactions, because it's likely
* they are the source for the next sequence of changes.
*
* -------------------------------------------------------------------------
*/
#include "postgres.h"
#include <unistd.h>
#include <sys/stat.h>
#include "access/detoast.h"
#include "access/heapam.h"
#include "access/rewriteheap.h"
#include "access/transam.h"
#include "access/xact.h"
#include "access/xlog_internal.h"
#include "catalog/catalog.h"
#include "lib/binaryheap.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "replication/logical.h"
#include "replication/reorderbuffer.h"
#include "replication/slot.h"
#include "replication/snapbuild.h" /* just for SnapBuildSnapDecRefcount */
#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "storage/sinval.h"
#include "utils/builtins.h"
#include "utils/combocid.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/relfilenodemap.h"
/* entry for a hash table we use to map from xid to our transaction state */
typedef struct ReorderBufferTXNByIdEnt
{
TransactionId xid;
ReorderBufferTXN *txn;
} ReorderBufferTXNByIdEnt;
/* data structures for (relfilenode, ctid) => (cmin, cmax) mapping */
typedef struct ReorderBufferTupleCidKey
{
RelFileNode relnode;
ItemPointerData tid;
} ReorderBufferTupleCidKey;
typedef struct ReorderBufferTupleCidEnt
{
ReorderBufferTupleCidKey key;
CommandId cmin;
CommandId cmax;
CommandId combocid; /* just for debugging */
} ReorderBufferTupleCidEnt;
/* Virtual file descriptor with file offset tracking */
typedef struct TXNEntryFile
{
File vfd; /* -1 when the file is closed */
off_t curOffset; /* offset for next write or read. Reset to 0
* when vfd is opened. */
} TXNEntryFile;
/* k-way in-order change iteration support structures */
typedef struct ReorderBufferIterTXNEntry
{
XLogRecPtr lsn;
ReorderBufferChange *change;
ReorderBufferTXN *txn;
TXNEntryFile file;
XLogSegNo segno;
} ReorderBufferIterTXNEntry;
typedef struct ReorderBufferIterTXNState
{
binaryheap *heap;
Size nr_txns;
dlist_head old_change;
ReorderBufferIterTXNEntry entries[FLEXIBLE_ARRAY_MEMBER];
} ReorderBufferIterTXNState;
/* toast datastructures */
typedef struct ReorderBufferToastEnt
{
Oid chunk_id; /* toast_table.chunk_id */
int32 last_chunk_seq; /* toast_table.chunk_seq of the last chunk we
* have seen */
Size num_chunks; /* number of chunks we've already seen */
Size size; /* combined size of chunks seen */
dlist_head chunks; /* linked list of chunks */
struct varlena *reconstructed; /* reconstructed varlena now pointed to in
* main tup */
} ReorderBufferToastEnt;
/* Disk serialization support datastructures */
typedef struct ReorderBufferDiskChange
{
Size size;
ReorderBufferChange change;
/* data follows */
} ReorderBufferDiskChange;
#define IsSpecInsert(action) \
( \
((action) == REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT) \
)
#define IsSpecConfirmOrAbort(action) \
( \
(((action) == REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM) || \
((action) == REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT)) \
)
#define IsInsertOrUpdate(action) \
( \
(((action) == REORDER_BUFFER_CHANGE_INSERT) || \
((action) == REORDER_BUFFER_CHANGE_UPDATE) || \
((action) == REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT)) \
)
/*
* Maximum number of changes kept in memory, per transaction. After that,
* changes are spooled to disk.
*
* The current value should be sufficient to decode the entire transaction
* without hitting disk in OLTP workloads, while starting to spool to disk in
* other workloads reasonably fast.
*
* At some point in the future it probably makes sense to have a more elaborate
* resource management here, but it's not entirely clear what that would look
* like.
*/
int logical_decoding_work_mem;
static const Size max_changes_in_memory = 4096; /* XXX for restore only */
/* ---------------------------------------
* primary reorderbuffer support routines
* ---------------------------------------
*/
static ReorderBufferTXN *ReorderBufferGetTXN(ReorderBuffer *rb);
static void ReorderBufferReturnTXN(ReorderBuffer *rb, ReorderBufferTXN *txn);
static ReorderBufferTXN *ReorderBufferTXNByXid(ReorderBuffer *rb,
TransactionId xid, bool create, bool *is_new,
XLogRecPtr lsn, bool create_as_top);
static void ReorderBufferTransferSnapToParent(ReorderBufferTXN *txn,
ReorderBufferTXN *subtxn);
static void AssertTXNLsnOrder(ReorderBuffer *rb);
/* ---------------------------------------
* support functions for lsn-order iterating over the ->changes of a
* transaction and its subtransactions
*
* used for iteration over the k-way heap merge of a transaction and its
* subtransactions
* ---------------------------------------
*/
static void ReorderBufferIterTXNInit(ReorderBuffer *rb, ReorderBufferTXN *txn,
ReorderBufferIterTXNState *volatile *iter_state);
static ReorderBufferChange *ReorderBufferIterTXNNext(ReorderBuffer *rb, ReorderBufferIterTXNState *state);
static void ReorderBufferIterTXNFinish(ReorderBuffer *rb,
ReorderBufferIterTXNState *state);
static void ReorderBufferExecuteInvalidations(uint32 nmsgs, SharedInvalidationMessage *msgs);
/*
* ---------------------------------------
* Disk serialization support functions
* ---------------------------------------
*/
static void ReorderBufferCheckMemoryLimit(ReorderBuffer *rb);
static void ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn);
static void ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
int fd, ReorderBufferChange *change);
static Size ReorderBufferRestoreChanges(ReorderBuffer *rb, ReorderBufferTXN *txn,
TXNEntryFile *file, XLogSegNo *segno);
static void ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
char *change);
static void ReorderBufferRestoreCleanup(ReorderBuffer *rb, ReorderBufferTXN *txn);
static void ReorderBufferTruncateTXN(ReorderBuffer *rb, ReorderBufferTXN *txn,
bool txn_prepared);
static void ReorderBufferCleanupSerializedTXNs(const char *slotname);
static void ReorderBufferSerializedPath(char *path, ReplicationSlot *slot,
TransactionId xid, XLogSegNo segno);
static void ReorderBufferFreeSnap(ReorderBuffer *rb, Snapshot snap);
static Snapshot ReorderBufferCopySnap(ReorderBuffer *rb, Snapshot orig_snap,
ReorderBufferTXN *txn, CommandId cid);
/*
* ---------------------------------------
* Streaming support functions
* ---------------------------------------
*/
static inline bool ReorderBufferCanStream(ReorderBuffer *rb);
static inline bool ReorderBufferCanStartStreaming(ReorderBuffer *rb);
static void ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn);
static void ReorderBufferStreamCommit(ReorderBuffer *rb, ReorderBufferTXN *txn);
/* ---------------------------------------
* toast reassembly support
* ---------------------------------------
*/
static void ReorderBufferToastInitHash(ReorderBuffer *rb, ReorderBufferTXN *txn);
static void ReorderBufferToastReset(ReorderBuffer *rb, ReorderBufferTXN *txn);
static void ReorderBufferToastReplace(ReorderBuffer *rb, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change);
static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change);
/*
* ---------------------------------------
* memory accounting
* ---------------------------------------
*/
static Size ReorderBufferChangeSize(ReorderBufferChange *change);
static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
ReorderBufferChange *change,
bool addition, Size sz);
/*
* Allocate a new ReorderBuffer and clean out any old serialized state from
* prior ReorderBuffer instances for the same slot.
*/
ReorderBuffer *
ReorderBufferAllocate(void)
{
ReorderBuffer *buffer;
HASHCTL hash_ctl;
MemoryContext new_ctx;
Assert(MyReplicationSlot != NULL);
/* allocate memory in own context, to have better accountability */
new_ctx = AllocSetContextCreate(CurrentMemoryContext,
"ReorderBuffer",
ALLOCSET_DEFAULT_SIZES);
buffer =
(ReorderBuffer *) MemoryContextAlloc(new_ctx, sizeof(ReorderBuffer));
memset(&hash_ctl, 0, sizeof(hash_ctl));
buffer->context = new_ctx;
buffer->change_context = SlabContextCreate(new_ctx,
"Change",
SLAB_DEFAULT_BLOCK_SIZE,
sizeof(ReorderBufferChange));
buffer->txn_context = SlabContextCreate(new_ctx,
"TXN",
SLAB_DEFAULT_BLOCK_SIZE,
sizeof(ReorderBufferTXN));
buffer->tup_context = GenerationContextCreate(new_ctx,
"Tuples",
SLAB_LARGE_BLOCK_SIZE);
hash_ctl.keysize = sizeof(TransactionId);
hash_ctl.entrysize = sizeof(ReorderBufferTXNByIdEnt);
hash_ctl.hcxt = buffer->context;
buffer->by_txn = hash_create("ReorderBufferByXid", 1000, &hash_ctl,
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
buffer->by_txn_last_xid = InvalidTransactionId;
buffer->by_txn_last_txn = NULL;
buffer->outbuf = NULL;
buffer->outbufsize = 0;
buffer->size = 0;
buffer->spillTxns = 0;
buffer->spillCount = 0;
buffer->spillBytes = 0;
buffer->streamTxns = 0;
buffer->streamCount = 0;
buffer->streamBytes = 0;
buffer->totalTxns = 0;
buffer->totalBytes = 0;
buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
dlist_init(&buffer->toplevel_by_lsn);
dlist_init(&buffer->txns_by_base_snapshot_lsn);
/*
* Ensure there's no stale data from prior uses of this slot, in case some
* prior exit avoided calling ReorderBufferFree. Failure to do this can
* produce duplicated txns, and it's very cheap if there's nothing there.
*/
ReorderBufferCleanupSerializedTXNs(NameStr(MyReplicationSlot->data.name));
return buffer;
}
/*
* Free a ReorderBuffer
*/
void
ReorderBufferFree(ReorderBuffer *rb)
{
MemoryContext context = rb->context;
/*
* We free separately allocated data by entirely scrapping reorderbuffer's
* memory context.
*/
MemoryContextDelete(context);
/* Free disk space used by unconsumed reorder buffers */
ReorderBufferCleanupSerializedTXNs(NameStr(MyReplicationSlot->data.name));
}
/*
* Get an unused, possibly preallocated, ReorderBufferTXN.
*/
static ReorderBufferTXN *
ReorderBufferGetTXN(ReorderBuffer *rb)
{
ReorderBufferTXN *txn;
txn = (ReorderBufferTXN *)
MemoryContextAlloc(rb->txn_context, sizeof(ReorderBufferTXN));
memset(txn, 0, sizeof(ReorderBufferTXN));
dlist_init(&txn->changes);
dlist_init(&txn->tuplecids);
dlist_init(&txn->subtxns);
/* InvalidCommandId is not zero, so set it explicitly */
txn->command_id = InvalidCommandId;
txn->output_plugin_private = NULL;
return txn;
}
/*
* Free a ReorderBufferTXN.
*/
static void
ReorderBufferReturnTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
/* clean the lookup cache if we were cached (quite likely) */
if (rb->by_txn_last_xid == txn->xid)
{
rb->by_txn_last_xid = InvalidTransactionId;
rb->by_txn_last_txn = NULL;
}
/* free data that's contained */
if (txn->gid != NULL)
{
pfree(txn->gid);
txn->gid = NULL;
}
if (txn->tuplecid_hash != NULL)
{
hash_destroy(txn->tuplecid_hash);
txn->tuplecid_hash = NULL;
}
if (txn->invalidations)
{
pfree(txn->invalidations);
txn->invalidations = NULL;
}
/* Reset the toast hash */
ReorderBufferToastReset(rb, txn);
pfree(txn);
}
/*
* Get a fresh ReorderBufferChange.
*/
ReorderBufferChange *
ReorderBufferGetChange(ReorderBuffer *rb)
{
ReorderBufferChange *change;
change = (ReorderBufferChange *)
MemoryContextAlloc(rb->change_context, sizeof(ReorderBufferChange));
memset(change, 0, sizeof(ReorderBufferChange));
return change;
}
/*
* Free a ReorderBufferChange and update memory accounting, if requested.
*/
void
ReorderBufferReturnChange(ReorderBuffer *rb, ReorderBufferChange *change,
bool upd_mem)
{
/* update memory accounting info */
if (upd_mem)
ReorderBufferChangeMemoryUpdate(rb, change, false,
ReorderBufferChangeSize(change));
/* free contained data */
switch (change->action)
{
case REORDER_BUFFER_CHANGE_INSERT:
case REORDER_BUFFER_CHANGE_UPDATE:
case REORDER_BUFFER_CHANGE_DELETE:
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
if (change->data.tp.newtuple)
{
ReorderBufferReturnTupleBuf(rb, change->data.tp.newtuple);
change->data.tp.newtuple = NULL;
}
if (change->data.tp.oldtuple)
{
ReorderBufferReturnTupleBuf(rb, change->data.tp.oldtuple);
change->data.tp.oldtuple = NULL;
}
break;
case REORDER_BUFFER_CHANGE_MESSAGE:
if (change->data.msg.prefix != NULL)
pfree(change->data.msg.prefix);
change->data.msg.prefix = NULL;
if (change->data.msg.message != NULL)
pfree(change->data.msg.message);
change->data.msg.message = NULL;
break;
case REORDER_BUFFER_CHANGE_INVALIDATION:
if (change->data.inval.invalidations)
pfree(change->data.inval.invalidations);
change->data.inval.invalidations = NULL;
break;
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
if (change->data.snapshot)
{
ReorderBufferFreeSnap(rb, change->data.snapshot);
change->data.snapshot = NULL;
}
break;
/* no data in addition to the struct itself */
case REORDER_BUFFER_CHANGE_TRUNCATE:
if (change->data.truncate.relids != NULL)
{
ReorderBufferReturnRelids(rb, change->data.truncate.relids);
change->data.truncate.relids = NULL;
}
break;
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
break;
}
pfree(change);
}
/*
* Get a fresh ReorderBufferTupleBuf fitting at least a tuple of size
* tuple_len (excluding header overhead).
*/
ReorderBufferTupleBuf *
ReorderBufferGetTupleBuf(ReorderBuffer *rb, Size tuple_len)
{
ReorderBufferTupleBuf *tuple;
Size alloc_len;
alloc_len = tuple_len + SizeofHeapTupleHeader;
tuple = (ReorderBufferTupleBuf *)
MemoryContextAlloc(rb->tup_context,
sizeof(ReorderBufferTupleBuf) +
MAXIMUM_ALIGNOF + alloc_len);
tuple->alloc_tuple_size = alloc_len;
tuple->tuple.t_data = ReorderBufferTupleBufData(tuple);
return tuple;
}
/*
* Free a ReorderBufferTupleBuf.
*/
void
ReorderBufferReturnTupleBuf(ReorderBuffer *rb, ReorderBufferTupleBuf *tuple)
{
pfree(tuple);
}
/*
* Get an array for relids of truncated relations.
*
* We use the global memory context (for the whole reorder buffer), because
* none of the existing ones seems like a good match (some are SLAB, so we
* can't use those, and tup_context is meant for tuple data, not relids). We
* could add yet another context, but it seems like an overkill - TRUNCATE is
* not particularly common operation, so it does not seem worth it.
*/
Oid *
ReorderBufferGetRelids(ReorderBuffer *rb, int nrelids)
{
Oid *relids;
Size alloc_len;
alloc_len = sizeof(Oid) * nrelids;
relids = (Oid *) MemoryContextAlloc(rb->context, alloc_len);
return relids;
}
/*
* Free an array of relids.
*/
void
ReorderBufferReturnRelids(ReorderBuffer *rb, Oid *relids)
{
pfree(relids);
}
/*
* Return the ReorderBufferTXN from the given buffer, specified by Xid.
* If create is true, and a transaction doesn't already exist, create it
* (with the given LSN, and as top transaction if that's specified);
* when this happens, is_new is set to true.
*/
static ReorderBufferTXN *
ReorderBufferTXNByXid(ReorderBuffer *rb, TransactionId xid, bool create,
bool *is_new, XLogRecPtr lsn, bool create_as_top)
{
ReorderBufferTXN *txn;
ReorderBufferTXNByIdEnt *ent;
bool found;
Assert(TransactionIdIsValid(xid));
/*
* Check the one-entry lookup cache first
*/
if (TransactionIdIsValid(rb->by_txn_last_xid) &&
rb->by_txn_last_xid == xid)
{
txn = rb->by_txn_last_txn;
if (txn != NULL)
{
/* found it, and it's valid */
if (is_new)
*is_new = false;
return txn;
}
/*
* cached as non-existent, and asked not to create? Then nothing else
* to do.
*/
if (!create)
return NULL;
/* otherwise fall through to create it */
}
/*
* If the cache wasn't hit or it yielded a "does-not-exist" and we want
* to create an entry.
*/
/* search the lookup table */
ent = (ReorderBufferTXNByIdEnt *)
hash_search(rb->by_txn,
(void *) &xid,
create ? HASH_ENTER : HASH_FIND,
&found);
if (found)
txn = ent->txn;
else if (create)
{
/* initialize the new entry, if creation was requested */
Assert(ent != NULL);
Assert(lsn != InvalidXLogRecPtr);
ent->txn = ReorderBufferGetTXN(rb);
ent->txn->xid = xid;
txn = ent->txn;
txn->first_lsn = lsn;
txn->restart_decoding_lsn = rb->current_restart_decoding_lsn;
if (create_as_top)
{
dlist_push_tail(&rb->toplevel_by_lsn, &txn->node);
AssertTXNLsnOrder(rb);
}
}
else
txn = NULL; /* not found and not asked to create */
/* update cache */
rb->by_txn_last_xid = xid;
rb->by_txn_last_txn = txn;
if (is_new)
*is_new = !found;
Assert(!create || txn != NULL);
return txn;
}
/*
* Record the partial change for the streaming of in-progress transactions. We
* can stream only complete changes so if we have a partial change like toast
* table insert or speculative insert then we mark such a 'txn' so that it
* can't be streamed. We also ensure that if the changes in such a 'txn' are
* above logical_decoding_work_mem threshold then we stream them as soon as we
* have a complete change.
*/
static void
ReorderBufferProcessPartialChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
ReorderBufferChange *change,
bool toast_insert)
{
ReorderBufferTXN *toptxn;
/*
* The partial changes need to be processed only while streaming
* in-progress transactions.
*/
if (!ReorderBufferCanStream(rb))
return;
/* Get the top transaction. */
if (txn->toptxn != NULL)
toptxn = txn->toptxn;
else
toptxn = txn;
/*
* Indicate a partial change for toast inserts. The change will be
* considered as complete once we get the insert or update on the main
* table and we are sure that the pending toast chunks are not required
* anymore.
*
* If we allow streaming when there are pending toast chunks then such
* chunks won't be released till the insert (multi_insert) is complete and
* we expect the txn to have streamed all changes after streaming. This
* restriction is mainly to ensure the correctness of streamed
* transactions and it doesn't seem worth uplifting such a restriction
* just to allow this case because anyway we will stream the transaction
* once such an insert is complete.
*/
if (toast_insert)
toptxn->txn_flags |= RBTXN_HAS_PARTIAL_CHANGE;
else if (rbtxn_has_partial_change(toptxn) &&
IsInsertOrUpdate(change->action) &&
change->data.tp.clear_toast_afterwards)
toptxn->txn_flags &= ~RBTXN_HAS_PARTIAL_CHANGE;
/*
* Indicate a partial change for speculative inserts. The change will be
* considered as complete once we get the speculative confirm or abort
* token.
*/
if (IsSpecInsert(change->action))
toptxn->txn_flags |= RBTXN_HAS_PARTIAL_CHANGE;
else if (rbtxn_has_partial_change(toptxn) &&
IsSpecConfirmOrAbort(change->action))
toptxn->txn_flags &= ~RBTXN_HAS_PARTIAL_CHANGE;
/*
* Stream the transaction if it is serialized before and the changes are
* now complete in the top-level transaction.
*
* The reason for doing the streaming of such a transaction as soon as we
* get the complete change for it is that previously it would have reached
* the memory threshold and wouldn't get streamed because of incomplete
* changes. Delaying such transactions would increase apply lag for them.
*/
if (ReorderBufferCanStartStreaming(rb) &&
!(rbtxn_has_partial_change(toptxn)) &&
rbtxn_is_serialized(txn))
ReorderBufferStreamTXN(rb, toptxn);
}
/*
* Queue a change into a transaction so it can be replayed upon commit or will be
* streamed when we reach logical_decoding_work_mem threshold.
*/
void
ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn,
ReorderBufferChange *change, bool toast_insert)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
/*
* While streaming the previous changes we have detected that the
* transaction is aborted. So there is no point in collecting further
* changes for it.
*/
if (txn->concurrent_abort)
{
/*
* We don't need to update memory accounting for this change as we
* have not added it to the queue yet.
*/
ReorderBufferReturnChange(rb, change, false);
return;
}
change->lsn = lsn;
change->txn = txn;
Assert(InvalidXLogRecPtr != lsn);
dlist_push_tail(&txn->changes, &change->node);
txn->nentries++;
txn->nentries_mem++;
/* update memory accounting information */
ReorderBufferChangeMemoryUpdate(rb, change, true,
ReorderBufferChangeSize(change));
/* process partial change */
ReorderBufferProcessPartialChange(rb, txn, change, toast_insert);
/* check the memory limits and evict something if needed */
ReorderBufferCheckMemoryLimit(rb);
}
/*
* A transactional message is queued to be processed upon commit and a
* non-transactional message gets processed immediately.
*/
void
ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
Snapshot snapshot, XLogRecPtr lsn,
bool transactional, const char *prefix,
Size message_size, const char *message)
{
if (transactional)
{
MemoryContext oldcontext;
ReorderBufferChange *change;
Assert(xid != InvalidTransactionId);
oldcontext = MemoryContextSwitchTo(rb->context);
change = ReorderBufferGetChange(rb);
change->action = REORDER_BUFFER_CHANGE_MESSAGE;
change->data.msg.prefix = pstrdup(prefix);
change->data.msg.message_size = message_size;
change->data.msg.message = palloc(message_size);
memcpy(change->data.msg.message, message, message_size);
ReorderBufferQueueChange(rb, xid, lsn, change, false);
MemoryContextSwitchTo(oldcontext);
}
else
{
ReorderBufferTXN *txn = NULL;
volatile Snapshot snapshot_now = snapshot;
if (xid != InvalidTransactionId)
txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
/* setup snapshot to allow catalog access */
SetupHistoricSnapshot(snapshot_now, NULL);
PG_TRY();
{
rb->message(rb, txn, lsn, false, prefix, message_size, message);
TeardownHistoricSnapshot(false);
}
PG_CATCH();
{
TeardownHistoricSnapshot(true);
PG_RE_THROW();
}
PG_END_TRY();
}
}
/*
* AssertTXNLsnOrder
* Verify LSN ordering of transaction lists in the reorderbuffer
*
* Other LSN-related invariants are checked too.
*
* No-op if assertions are not in use.
*/
static void
AssertTXNLsnOrder(ReorderBuffer *rb)
{
#ifdef USE_ASSERT_CHECKING
dlist_iter iter;
XLogRecPtr prev_first_lsn = InvalidXLogRecPtr;
XLogRecPtr prev_base_snap_lsn = InvalidXLogRecPtr;
dlist_foreach(iter, &rb->toplevel_by_lsn)
{
ReorderBufferTXN *cur_txn = dlist_container(ReorderBufferTXN, node,
iter.cur);
/* start LSN must be set */
Assert(cur_txn->first_lsn != InvalidXLogRecPtr);
/* If there is an end LSN, it must be higher than start LSN */
if (cur_txn->end_lsn != InvalidXLogRecPtr)
Assert(cur_txn->first_lsn <= cur_txn->end_lsn);
/* Current initial LSN must be strictly higher than previous */
if (prev_first_lsn != InvalidXLogRecPtr)
Assert(prev_first_lsn < cur_txn->first_lsn);
/* known-as-subtxn txns must not be listed */
Assert(!rbtxn_is_known_subxact(cur_txn));
prev_first_lsn = cur_txn->first_lsn;
}
dlist_foreach(iter, &rb->txns_by_base_snapshot_lsn)
{
ReorderBufferTXN *cur_txn = dlist_container(ReorderBufferTXN,
base_snapshot_node,
iter.cur);
/* base snapshot (and its LSN) must be set */
Assert(cur_txn->base_snapshot != NULL);
Assert(cur_txn->base_snapshot_lsn != InvalidXLogRecPtr);
/* current LSN must be strictly higher than previous */
if (prev_base_snap_lsn != InvalidXLogRecPtr)
Assert(prev_base_snap_lsn < cur_txn->base_snapshot_lsn);
/* known-as-subtxn txns must not be listed */
Assert(!rbtxn_is_known_subxact(cur_txn));
prev_base_snap_lsn = cur_txn->base_snapshot_lsn;
}
#endif
}
/*
* AssertChangeLsnOrder
*
* Check ordering of changes in the (sub)transaction.
*/
static void
AssertChangeLsnOrder(ReorderBufferTXN *txn)
{
#ifdef USE_ASSERT_CHECKING
dlist_iter iter;
XLogRecPtr prev_lsn = txn->first_lsn;
dlist_foreach(iter, &txn->changes)
{
ReorderBufferChange *cur_change;
cur_change = dlist_container(ReorderBufferChange, node, iter.cur);
Assert(txn->first_lsn != InvalidXLogRecPtr);
Assert(cur_change->lsn != InvalidXLogRecPtr);
Assert(txn->first_lsn <= cur_change->lsn);
if (txn->end_lsn != InvalidXLogRecPtr)
Assert(cur_change->lsn <= txn->end_lsn);
Assert(prev_lsn <= cur_change->lsn);
prev_lsn = cur_change->lsn;
}
#endif
}
/*
* ReorderBufferGetOldestTXN
* Return oldest transaction in reorderbuffer
*/
ReorderBufferTXN *
ReorderBufferGetOldestTXN(ReorderBuffer *rb)
{
ReorderBufferTXN *txn;
AssertTXNLsnOrder(rb);
if (dlist_is_empty(&rb->toplevel_by_lsn))
return NULL;
txn = dlist_head_element(ReorderBufferTXN, node, &rb->toplevel_by_lsn);
Assert(!rbtxn_is_known_subxact(txn));
Assert(txn->first_lsn != InvalidXLogRecPtr);
return txn;
}
/*
* ReorderBufferGetOldestXmin
* Return oldest Xmin in reorderbuffer
*
* Returns oldest possibly running Xid from the point of view of snapshots
* used in the transactions kept by reorderbuffer, or InvalidTransactionId if
* there are none.
*
* Since snapshots are assigned monotonically, this equals the Xmin of the
* base snapshot with minimal base_snapshot_lsn.
*/
TransactionId
ReorderBufferGetOldestXmin(ReorderBuffer *rb)
{
ReorderBufferTXN *txn;
AssertTXNLsnOrder(rb);
if (dlist_is_empty(&rb->txns_by_base_snapshot_lsn))
return InvalidTransactionId;
txn = dlist_head_element(ReorderBufferTXN, base_snapshot_node,
&rb->txns_by_base_snapshot_lsn);
return txn->base_snapshot->xmin;
}
void
ReorderBufferSetRestartPoint(ReorderBuffer *rb, XLogRecPtr ptr)
{
rb->current_restart_decoding_lsn = ptr;
}
/*
* ReorderBufferAssignChild
*
* Make note that we know that subxid is a subtransaction of xid, seen as of
* the given lsn.
*/
void
ReorderBufferAssignChild(ReorderBuffer *rb, TransactionId xid,
TransactionId subxid, XLogRecPtr lsn)
{
ReorderBufferTXN *txn;
ReorderBufferTXN *subtxn;
bool new_top;
bool new_sub;
txn = ReorderBufferTXNByXid(rb, xid, true, &new_top, lsn, true);
subtxn = ReorderBufferTXNByXid(rb, subxid, true, &new_sub, lsn, false);
if (!new_sub)
{
if (rbtxn_is_known_subxact(subtxn))
{
/* already associated, nothing to do */
return;
}
else
{
/*
* We already saw this transaction, but initially added it to the
* list of top-level txns. Now that we know it's not top-level,
* remove it from there.
*/
dlist_delete(&subtxn->node);
}
}
subtxn->txn_flags |= RBTXN_IS_SUBXACT;
subtxn->toplevel_xid = xid;
Assert(subtxn->nsubtxns == 0);
/* set the reference to top-level transaction */
subtxn->toptxn = txn;
/* add to subtransaction list */
dlist_push_tail(&txn->subtxns, &subtxn->node);
txn->nsubtxns++;
/* Possibly transfer the subtxn's snapshot to its top-level txn. */
ReorderBufferTransferSnapToParent(txn, subtxn);
/* Verify LSN-ordering invariant */
AssertTXNLsnOrder(rb);
}
/*
* ReorderBufferTransferSnapToParent
* Transfer base snapshot from subtxn to top-level txn, if needed
*
* This is done if the top-level txn doesn't have a base snapshot, or if the
* subtxn's base snapshot has an earlier LSN than the top-level txn's base
* snapshot's LSN. This can happen if there are no changes in the toplevel
* txn but there are some in the subtxn, or the first change in subtxn has
* earlier LSN than first change in the top-level txn and we learned about
* their kinship only now.
*
* The subtransaction's snapshot is cleared regardless of the transfer
* happening, since it's not needed anymore in either case.
*
* We do this as soon as we become aware of their kinship, to avoid queueing
* extra snapshots to txns known-as-subtxns -- only top-level txns will
* receive further snapshots.
*/
static void
ReorderBufferTransferSnapToParent(ReorderBufferTXN *txn,
ReorderBufferTXN *subtxn)
{
Assert(subtxn->toplevel_xid == txn->xid);
if (subtxn->base_snapshot != NULL)
{
if (txn->base_snapshot == NULL ||
subtxn->base_snapshot_lsn < txn->base_snapshot_lsn)
{
/*
* If the toplevel transaction already has a base snapshot but
* it's newer than the subxact's, purge it.
*/
if (txn->base_snapshot != NULL)
{
SnapBuildSnapDecRefcount(txn->base_snapshot);
dlist_delete(&txn->base_snapshot_node);
}
/*
* The snapshot is now the top transaction's; transfer it, and
* adjust the list position of the top transaction in the list by
* moving it to where the subtransaction is.
*/
txn->base_snapshot = subtxn->base_snapshot;
txn->base_snapshot_lsn = subtxn->base_snapshot_lsn;
dlist_insert_before(&subtxn->base_snapshot_node,
&txn->base_snapshot_node);
/*
* The subtransaction doesn't have a snapshot anymore (so it
* mustn't be in the list.)
*/
subtxn->base_snapshot = NULL;
subtxn->base_snapshot_lsn = InvalidXLogRecPtr;
dlist_delete(&subtxn->base_snapshot_node);
}
else
{
/* Base snap of toplevel is fine, so subxact's is not needed */
SnapBuildSnapDecRefcount(subtxn->base_snapshot);
dlist_delete(&subtxn->base_snapshot_node);
subtxn->base_snapshot = NULL;
subtxn->base_snapshot_lsn = InvalidXLogRecPtr;
}
}
}
/*
* Associate a subtransaction with its toplevel transaction at commit
* time. There may be no further changes added after this.
*/
void
ReorderBufferCommitChild(ReorderBuffer *rb, TransactionId xid,
TransactionId subxid, XLogRecPtr commit_lsn,
XLogRecPtr end_lsn)
{
ReorderBufferTXN *subtxn;
subtxn = ReorderBufferTXNByXid(rb, subxid, false, NULL,
InvalidXLogRecPtr, false);
/*
* No need to do anything if that subtxn didn't contain any changes
*/
if (!subtxn)
return;
subtxn->final_lsn = commit_lsn;
subtxn->end_lsn = end_lsn;
/*
* Assign this subxact as a child of the toplevel xact (no-op if already
* done.)
*/
ReorderBufferAssignChild(rb, xid, subxid, InvalidXLogRecPtr);
}
/*
* Support for efficiently iterating over a transaction's and its
* subtransactions' changes.
*
* We do by doing a k-way merge between transactions/subtransactions. For that
* we model the current heads of the different transactions as a binary heap
* so we easily know which (sub-)transaction has the change with the smallest
* lsn next.
*
* We assume the changes in individual transactions are already sorted by LSN.
*/
/*
* Binary heap comparison function.
*/
static int
ReorderBufferIterCompare(Datum a, Datum b, void *arg)
{
ReorderBufferIterTXNState *state = (ReorderBufferIterTXNState *) arg;
XLogRecPtr pos_a = state->entries[DatumGetInt32(a)].lsn;
XLogRecPtr pos_b = state->entries[DatumGetInt32(b)].lsn;
if (pos_a < pos_b)
return 1;
else if (pos_a == pos_b)
return 0;
return -1;
}
/*
* Allocate & initialize an iterator which iterates in lsn order over a
* transaction and all its subtransactions.
*
* Note: The iterator state is returned through iter_state parameter rather
* than the function's return value. This is because the state gets cleaned up
* in a PG_CATCH block in the caller, so we want to make sure the caller gets
* back the state even if this function throws an exception.
*/
static void
ReorderBufferIterTXNInit(ReorderBuffer *rb, ReorderBufferTXN *txn,
ReorderBufferIterTXNState *volatile *iter_state)
{
Size nr_txns = 0;
ReorderBufferIterTXNState *state;
dlist_iter cur_txn_i;
int32 off;
*iter_state = NULL;
/* Check ordering of changes in the toplevel transaction. */
AssertChangeLsnOrder(txn);
/*
* Calculate the size of our heap: one element for every transaction that
* contains changes. (Besides the transactions already in the reorder
* buffer, we count the one we were directly passed.)
*/
if (txn->nentries > 0)
nr_txns++;
dlist_foreach(cur_txn_i, &txn->subtxns)
{
ReorderBufferTXN *cur_txn;
cur_txn = dlist_container(ReorderBufferTXN, node, cur_txn_i.cur);
/* Check ordering of changes in this subtransaction. */
AssertChangeLsnOrder(cur_txn);
if (cur_txn->nentries > 0)
nr_txns++;
}
/* allocate iteration state */
state = (ReorderBufferIterTXNState *)
MemoryContextAllocZero(rb->context,
sizeof(ReorderBufferIterTXNState) +
sizeof(ReorderBufferIterTXNEntry) * nr_txns);
state->nr_txns = nr_txns;
dlist_init(&state->old_change);
for (off = 0; off < state->nr_txns; off++)
{
state->entries[off].file.vfd = -1;
state->entries[off].segno = 0;
}
/* allocate heap */
state->heap = binaryheap_allocate(state->nr_txns,
ReorderBufferIterCompare,
state);
/* Now that the state fields are initialized, it is safe to return it. */
*iter_state = state;
/*
* Now insert items into the binary heap, in an unordered fashion. (We
* will run a heap assembly step at the end; this is more efficient.)
*/
off = 0;
/* add toplevel transaction if it contains changes */
if (txn->nentries > 0)
{
ReorderBufferChange *cur_change;
if (rbtxn_is_serialized(txn))
{
/* serialize remaining changes */
ReorderBufferSerializeTXN(rb, txn);
ReorderBufferRestoreChanges(rb, txn, &state->entries[off].file,
&state->entries[off].segno);
}
cur_change = dlist_head_element(ReorderBufferChange, node,
&txn->changes);
state->entries[off].lsn = cur_change->lsn;
state->entries[off].change = cur_change;
state->entries[off].txn = txn;
binaryheap_add_unordered(state->heap, Int32GetDatum(off++));
}
/* add subtransactions if they contain changes */
dlist_foreach(cur_txn_i, &txn->subtxns)
{
ReorderBufferTXN *cur_txn;
cur_txn = dlist_container(ReorderBufferTXN, node, cur_txn_i.cur);
if (cur_txn->nentries > 0)
{
ReorderBufferChange *cur_change;
if (rbtxn_is_serialized(cur_txn))
{
/* serialize remaining changes */
ReorderBufferSerializeTXN(rb, cur_txn);
ReorderBufferRestoreChanges(rb, cur_txn,
&state->entries[off].file,
&state->entries[off].segno);
}
cur_change = dlist_head_element(ReorderBufferChange, node,
&cur_txn->changes);
state->entries[off].lsn = cur_change->lsn;
state->entries[off].change = cur_change;
state->entries[off].txn = cur_txn;
binaryheap_add_unordered(state->heap, Int32GetDatum(off++));
}
}
/* assemble a valid binary heap */
binaryheap_build(state->heap);
}
/*
* Return the next change when iterating over a transaction and its
* subtransactions.
*
* Returns NULL when no further changes exist.
*/
static ReorderBufferChange *
ReorderBufferIterTXNNext(ReorderBuffer *rb, ReorderBufferIterTXNState *state)
{
ReorderBufferChange *change;
ReorderBufferIterTXNEntry *entry;
int32 off;
/* nothing there anymore */
if (state->heap->bh_size == 0)
return NULL;
off = DatumGetInt32(binaryheap_first(state->heap));
entry = &state->entries[off];
/* free memory we might have "leaked" in the previous *Next call */
if (!dlist_is_empty(&state->old_change))
{
change = dlist_container(ReorderBufferChange, node,
dlist_pop_head_node(&state->old_change));
ReorderBufferReturnChange(rb, change, true);
Assert(dlist_is_empty(&state->old_change));
}
change = entry->change;
/*
* update heap with information about which transaction has the next
* relevant change in LSN order
*/
/* there are in-memory changes */
if (dlist_has_next(&entry->txn->changes, &entry->change->node))
{
dlist_node *next = dlist_next_node(&entry->txn->changes, &change->node);
ReorderBufferChange *next_change =
dlist_container(ReorderBufferChange, node, next);
/* txn stays the same */
state->entries[off].lsn = next_change->lsn;
state->entries[off].change = next_change;
binaryheap_replace_first(state->heap, Int32GetDatum(off));
return change;
}
/* try to load changes from disk */
if (entry->txn->nentries != entry->txn->nentries_mem)
{
/*
* Ugly: restoring changes will reuse *Change records, thus delete the
* current one from the per-tx list and only free in the next call.
*/
dlist_delete(&change->node);
dlist_push_tail(&state->old_change, &change->node);
/*
* Update the total bytes processed by the txn for which we are
* releasing the current set of changes and restoring the new set of
* changes.
*/
rb->totalBytes += entry->txn->size;
if (ReorderBufferRestoreChanges(rb, entry->txn, &entry->file,
&state->entries[off].segno))
{
/* successfully restored changes from disk */
ReorderBufferChange *next_change =
dlist_head_element(ReorderBufferChange, node,
&entry->txn->changes);
elog(DEBUG2, "restored %u/%u changes from disk",
(uint32) entry->txn->nentries_mem,
(uint32) entry->txn->nentries);
Assert(entry->txn->nentries_mem);
/* txn stays the same */
state->entries[off].lsn = next_change->lsn;
state->entries[off].change = next_change;
binaryheap_replace_first(state->heap, Int32GetDatum(off));
return change;
}
}
/* ok, no changes there anymore, remove */
binaryheap_remove_first(state->heap);
return change;
}
/*
* Deallocate the iterator
*/
static void
ReorderBufferIterTXNFinish(ReorderBuffer *rb,
ReorderBufferIterTXNState *state)
{
int32 off;
for (off = 0; off < state->nr_txns; off++)
{
if (state->entries[off].file.vfd != -1)
FileClose(state->entries[off].file.vfd);
}
/* free memory we might have "leaked" in the last *Next call */
if (!dlist_is_empty(&state->old_change))
{
ReorderBufferChange *change;
change = dlist_container(ReorderBufferChange, node,
dlist_pop_head_node(&state->old_change));
ReorderBufferReturnChange(rb, change, true);
Assert(dlist_is_empty(&state->old_change));
}
binaryheap_free(state->heap);
pfree(state);
}
/*
* Cleanup the contents of a transaction, usually after the transaction
* committed or aborted.
*/
static void
ReorderBufferCleanupTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
bool found;
dlist_mutable_iter iter;
/* cleanup subtransactions & their changes */
dlist_foreach_modify(iter, &txn->subtxns)
{
ReorderBufferTXN *subtxn;
subtxn = dlist_container(ReorderBufferTXN, node, iter.cur);
/*
* Subtransactions are always associated to the toplevel TXN, even if
* they originally were happening inside another subtxn, so we won't
* ever recurse more than one level deep here.
*/
Assert(rbtxn_is_known_subxact(subtxn));
Assert(subtxn->nsubtxns == 0);
ReorderBufferCleanupTXN(rb, subtxn);
}
/* cleanup changes in the txn */
dlist_foreach_modify(iter, &txn->changes)
{
ReorderBufferChange *change;
change = dlist_container(ReorderBufferChange, node, iter.cur);
/* Check we're not mixing changes from different transactions. */
Assert(change->txn == txn);
ReorderBufferReturnChange(rb, change, true);
}
/*
* Cleanup the tuplecids we stored for decoding catalog snapshot access.
* They are always stored in the toplevel transaction.
*/
dlist_foreach_modify(iter, &txn->tuplecids)
{
ReorderBufferChange *change;
change = dlist_container(ReorderBufferChange, node, iter.cur);
/* Check we're not mixing changes from different transactions. */
Assert(change->txn == txn);
Assert(change->action == REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID);
ReorderBufferReturnChange(rb, change, true);
}
/*
* Cleanup the base snapshot, if set.
*/
if (txn->base_snapshot != NULL)
{
SnapBuildSnapDecRefcount(txn->base_snapshot);
dlist_delete(&txn->base_snapshot_node);
}
/*
* Cleanup the snapshot for the last streamed run.
*/
if (txn->snapshot_now != NULL)
{
Assert(rbtxn_is_streamed(txn));
ReorderBufferFreeSnap(rb, txn->snapshot_now);
}
/*
* Remove TXN from its containing list.
*
* Note: if txn is known as subxact, we are deleting the TXN from its
* parent's list of known subxacts; this leaves the parent's nsubxacts
* count too high, but we don't care. Otherwise, we are deleting the TXN
* from the LSN-ordered list of toplevel TXNs.
*/
dlist_delete(&txn->node);
/* now remove reference from buffer */
hash_search(rb->by_txn,
(void *) &txn->xid,
HASH_REMOVE,
&found);
Assert(found);
/* remove entries spilled to disk */
if (rbtxn_is_serialized(txn))
ReorderBufferRestoreCleanup(rb, txn);
/* deallocate */
ReorderBufferReturnTXN(rb, txn);
}
/*
* Discard changes from a transaction (and subtransactions), either after
* streaming or decoding them at PREPARE. Keep the remaining info -
* transactions, tuplecids, invalidations and snapshots.
*
* We additionaly remove tuplecids after decoding the transaction at prepare
* time as we only need to perform invalidation at rollback or commit prepared.
*
* 'txn_prepared' indicates that we have decoded the transaction at prepare
* time.
*/
static void
ReorderBufferTruncateTXN(ReorderBuffer *rb, ReorderBufferTXN *txn, bool txn_prepared)
{
dlist_mutable_iter iter;
/* cleanup subtransactions & their changes */
dlist_foreach_modify(iter, &txn->subtxns)
{
ReorderBufferTXN *subtxn;
subtxn = dlist_container(ReorderBufferTXN, node, iter.cur);
/*
* Subtransactions are always associated to the toplevel TXN, even if
* they originally were happening inside another subtxn, so we won't
* ever recurse more than one level deep here.
*/
Assert(rbtxn_is_known_subxact(subtxn));
Assert(subtxn->nsubtxns == 0);
ReorderBufferTruncateTXN(rb, subtxn, txn_prepared);
}
/* cleanup changes in the txn */
dlist_foreach_modify(iter, &txn->changes)
{
ReorderBufferChange *change;
change = dlist_container(ReorderBufferChange, node, iter.cur);
/* Check we're not mixing changes from different transactions. */
Assert(change->txn == txn);
/* remove the change from it's containing list */
dlist_delete(&change->node);
ReorderBufferReturnChange(rb, change, true);
}
/*
* Mark the transaction as streamed.
*
* The toplevel transaction, identified by (toptxn==NULL), is marked as
* streamed always, even if it does not contain any changes (that is, when
* all the changes are in subtransactions).
*
* For subtransactions, we only mark them as streamed when there are
* changes in them.
*
* We do it this way because of aborts - we don't want to send aborts for
* XIDs the downstream is not aware of. And of course, it always knows
* about the toplevel xact (we send the XID in all messages), but we never
* stream XIDs of empty subxacts.
*/
if ((!txn_prepared) && ((!txn->toptxn) || (txn->nentries_mem != 0)))
txn->txn_flags |= RBTXN_IS_STREAMED;
if (txn_prepared)
{
/*
* If this is a prepared txn, cleanup the tuplecids we stored for
* decoding catalog snapshot access. They are always stored in the
* toplevel transaction.
*/
dlist_foreach_modify(iter, &txn->tuplecids)
{
ReorderBufferChange *change;
change = dlist_container(ReorderBufferChange, node, iter.cur);
/* Check we're not mixing changes from different transactions. */
Assert(change->txn == txn);
Assert(change->action == REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID);
/* Remove the change from its containing list. */
dlist_delete(&change->node);
ReorderBufferReturnChange(rb, change, true);
}
}
/*
* Destroy the (relfilenode, ctid) hashtable, so that we don't leak any
* memory. We could also keep the hash table and update it with new ctid
* values, but this seems simpler and good enough for now.
*/
if (txn->tuplecid_hash != NULL)
{
hash_destroy(txn->tuplecid_hash);
txn->tuplecid_hash = NULL;
}
/* If this txn is serialized then clean the disk space. */
if (rbtxn_is_serialized(txn))
{
ReorderBufferRestoreCleanup(rb, txn);
txn->txn_flags &= ~RBTXN_IS_SERIALIZED;
/*
* We set this flag to indicate if the transaction is ever serialized.
* We need this to accurately update the stats as otherwise the same
* transaction can be counted as serialized multiple times.
*/
txn->txn_flags |= RBTXN_IS_SERIALIZED_CLEAR;
}
/* also reset the number of entries in the transaction */
txn->nentries_mem = 0;
txn->nentries = 0;
}
/*
* Build a hash with a (relfilenode, ctid) -> (cmin, cmax) mapping for use by
* HeapTupleSatisfiesHistoricMVCC.
*/
static void
ReorderBufferBuildTupleCidHash(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
dlist_iter iter;
HASHCTL hash_ctl;
if (!rbtxn_has_catalog_changes(txn) || dlist_is_empty(&txn->tuplecids))
return;
hash_ctl.keysize = sizeof(ReorderBufferTupleCidKey);
hash_ctl.entrysize = sizeof(ReorderBufferTupleCidEnt);
hash_ctl.hcxt = rb->context;
/*
* create the hash with the exact number of to-be-stored tuplecids from
* the start
*/
txn->tuplecid_hash =
hash_create("ReorderBufferTupleCid", txn->ntuplecids, &hash_ctl,
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
dlist_foreach(iter, &txn->tuplecids)
{
ReorderBufferTupleCidKey key;
ReorderBufferTupleCidEnt *ent;
bool found;
ReorderBufferChange *change;
change = dlist_container(ReorderBufferChange, node, iter.cur);
Assert(change->action == REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID);
/* be careful about padding */
memset(&key, 0, sizeof(ReorderBufferTupleCidKey));
key.relnode = change->data.tuplecid.node;
ItemPointerCopy(&change->data.tuplecid.tid,
&key.tid);
ent = (ReorderBufferTupleCidEnt *)
hash_search(txn->tuplecid_hash,
(void *) &key,
HASH_ENTER,
&found);
if (!found)
{
ent->cmin = change->data.tuplecid.cmin;
ent->cmax = change->data.tuplecid.cmax;
ent->combocid = change->data.tuplecid.combocid;
}
else
{
/*
* Maybe we already saw this tuple before in this transaction, but
* if so it must have the same cmin.
*/
Assert(ent->cmin == change->data.tuplecid.cmin);
/*
* cmax may be initially invalid, but once set it can only grow,
* and never become invalid again.
*/
Assert((ent->cmax == InvalidCommandId) ||
((change->data.tuplecid.cmax != InvalidCommandId) &&
(change->data.tuplecid.cmax > ent->cmax)));
ent->cmax = change->data.tuplecid.cmax;
}
}
}
/*
* Copy a provided snapshot so we can modify it privately. This is needed so
* that catalog modifying transactions can look into intermediate catalog
* states.
*/
static Snapshot
ReorderBufferCopySnap(ReorderBuffer *rb, Snapshot orig_snap,
ReorderBufferTXN *txn, CommandId cid)
{
Snapshot snap;
dlist_iter iter;
int i = 0;
Size size;
size = sizeof(SnapshotData) +
sizeof(TransactionId) * orig_snap->xcnt +
sizeof(TransactionId) * (txn->nsubtxns + 1);
snap = MemoryContextAllocZero(rb->context, size);
memcpy(snap, orig_snap, sizeof(SnapshotData));
snap->copied = true;
snap->active_count = 1; /* mark as active so nobody frees it */
snap->regd_count = 0;
snap->xip = (TransactionId *) (snap + 1);
memcpy(snap->xip, orig_snap->xip, sizeof(TransactionId) * snap->xcnt);
/*
* snap->subxip contains all txids that belong to our transaction which we
* need to check via cmin/cmax. That's why we store the toplevel
* transaction in there as well.
*/
snap->subxip = snap->xip + snap->xcnt;
snap->subxip[i++] = txn->xid;
/*
* subxcnt isn't decreased when subtransactions abort, so count manually.
* Since it's an upper boundary it is safe to use it for the allocation
* above.
*/
snap->subxcnt = 1;
dlist_foreach(iter, &txn->subtxns)
{
ReorderBufferTXN *sub_txn;
sub_txn = dlist_container(ReorderBufferTXN, node, iter.cur);
snap->subxip[i++] = sub_txn->xid;
snap->subxcnt++;
}
/* sort so we can bsearch() later */
qsort(snap->subxip, snap->subxcnt, sizeof(TransactionId), xidComparator);
/* store the specified current CommandId */
snap->curcid = cid;
return snap;
}
/*
* Free a previously ReorderBufferCopySnap'ed snapshot
*/
static void
ReorderBufferFreeSnap(ReorderBuffer *rb, Snapshot snap)
{
if (snap->copied)
pfree(snap);
else
SnapBuildSnapDecRefcount(snap);
}
/*
* If the transaction was (partially) streamed, we need to prepare or commit
* it in a 'streamed' way. That is, we first stream the remaining part of the
* transaction, and then invoke stream_prepare or stream_commit message as per
* the case.
*/
static void
ReorderBufferStreamCommit(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
/* we should only call this for previously streamed transactions */
Assert(rbtxn_is_streamed(txn));
ReorderBufferStreamTXN(rb, txn);
if (rbtxn_prepared(txn))
{
/*
* Note, we send stream prepare even if a concurrent abort is
* detected. See DecodePrepare for more information.
*/
rb->stream_prepare(rb, txn, txn->final_lsn);
/*
* This is a PREPARED transaction, part of a two-phase commit. The
* full cleanup will happen as part of the COMMIT PREPAREDs, so now
* just truncate txn by removing changes and tuple_cids.
*/
ReorderBufferTruncateTXN(rb, txn, true);
/* Reset the CheckXidAlive */
CheckXidAlive = InvalidTransactionId;
}
else
{
rb->stream_commit(rb, txn, txn->final_lsn);
ReorderBufferCleanupTXN(rb, txn);
}
}
/*
* Set xid to detect concurrent aborts.
*
* While streaming an in-progress transaction or decoding a prepared
* transaction there is a possibility that the (sub)transaction might get
* aborted concurrently. In such case if the (sub)transaction has catalog
* update then we might decode the tuple using wrong catalog version. For
* example, suppose there is one catalog tuple with (xmin: 500, xmax: 0). Now,
* the transaction 501 updates the catalog tuple and after that we will have
* two tuples (xmin: 500, xmax: 501) and (xmin: 501, xmax: 0). Now, if 501 is
* aborted and some other transaction say 502 updates the same catalog tuple
* then the first tuple will be changed to (xmin: 500, xmax: 502). So, the
* problem is that when we try to decode the tuple inserted/updated in 501
* after the catalog update, we will see the catalog tuple with (xmin: 500,
* xmax: 502) as visible because it will consider that the tuple is deleted by
* xid 502 which is not visible to our snapshot. And when we will try to
* decode with that catalog tuple, it can lead to a wrong result or a crash.
* So, it is necessary to detect concurrent aborts to allow streaming of
* in-progress transactions or decoding of prepared transactions.
*
* For detecting the concurrent abort we set CheckXidAlive to the current
* (sub)transaction's xid for which this change belongs to. And, during
* catalog scan we can check the status of the xid and if it is aborted we will
* report a specific error so that we can stop streaming current transaction
* and discard the already streamed changes on such an error. We might have
* already streamed some of the changes for the aborted (sub)transaction, but
* that is fine because when we decode the abort we will stream abort message
* to truncate the changes in the subscriber. Similarly, for prepared
* transactions, we stop decoding if concurrent abort is detected and then
* rollback the changes when rollback prepared is encountered. See
* DecodePrepare.
*/
static inline void
SetupCheckXidLive(TransactionId xid)
{
/*
* If the input transaction id is already set as a CheckXidAlive then
* nothing to do.
*/
if (TransactionIdEquals(CheckXidAlive, xid))
return;
/*
* setup CheckXidAlive if it's not committed yet. We don't check if the
* xid is aborted. That will happen during catalog access.
*/
if (!TransactionIdDidCommit(xid))
CheckXidAlive = xid;
else
CheckXidAlive = InvalidTransactionId;
}
/*
* Helper function for ReorderBufferProcessTXN for applying change.
*/
static inline void
ReorderBufferApplyChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change,
bool streaming)
{
if (streaming)
rb->stream_change(rb, txn, relation, change);
else
rb->apply_change(rb, txn, relation, change);
}
/*
* Helper function for ReorderBufferProcessTXN for applying the truncate.
*/
static inline void
ReorderBufferApplyTruncate(ReorderBuffer *rb, ReorderBufferTXN *txn,
int nrelations, Relation *relations,
ReorderBufferChange *change, bool streaming)
{
if (streaming)
rb->stream_truncate(rb, txn, nrelations, relations, change);
else
rb->apply_truncate(rb, txn, nrelations, relations, change);
}
/*
* Helper function for ReorderBufferProcessTXN for applying the message.
*/
static inline void
ReorderBufferApplyMessage(ReorderBuffer *rb, ReorderBufferTXN *txn,
ReorderBufferChange *change, bool streaming)
{
if (streaming)
rb->stream_message(rb, txn, change->lsn, true,
change->data.msg.prefix,
change->data.msg.message_size,
change->data.msg.message);
else
rb->message(rb, txn, change->lsn, true,
change->data.msg.prefix,
change->data.msg.message_size,
change->data.msg.message);
}
/*
* Function to store the command id and snapshot at the end of the current
* stream so that we can reuse the same while sending the next stream.
*/
static inline void
ReorderBufferSaveTXNSnapshot(ReorderBuffer *rb, ReorderBufferTXN *txn,
Snapshot snapshot_now, CommandId command_id)
{
txn->command_id = command_id;
/* Avoid copying if it's already copied. */
if (snapshot_now->copied)
txn->snapshot_now = snapshot_now;
else
txn->snapshot_now = ReorderBufferCopySnap(rb, snapshot_now,
txn, command_id);
}
/*
* Helper function for ReorderBufferProcessTXN to handle the concurrent
* abort of the streaming transaction. This resets the TXN such that it
* can be used to stream the remaining data of transaction being processed.
* This can happen when the subtransaction is aborted and we still want to
* continue processing the main or other subtransactions data.
*/
static void
ReorderBufferResetTXN(ReorderBuffer *rb, ReorderBufferTXN *txn,
Snapshot snapshot_now,
CommandId command_id,
XLogRecPtr last_lsn,
ReorderBufferChange *specinsert)
{
/* Discard the changes that we just streamed */
ReorderBufferTruncateTXN(rb, txn, rbtxn_prepared(txn));
/* Free all resources allocated for toast reconstruction */
ReorderBufferToastReset(rb, txn);
/* Return the spec insert change if it is not NULL */
if (specinsert != NULL)
{
ReorderBufferReturnChange(rb, specinsert, true);
specinsert = NULL;
}
/*
* For the streaming case, stop the stream and remember the command ID and
* snapshot for the streaming run.
*/
if (rbtxn_is_streamed(txn))
{
rb->stream_stop(rb, txn, last_lsn);
ReorderBufferSaveTXNSnapshot(rb, txn, snapshot_now, command_id);
}
}
/*
* Helper function for ReorderBufferReplay and ReorderBufferStreamTXN.
*
* Send data of a transaction (and its subtransactions) to the
* output plugin. We iterate over the top and subtransactions (using a k-way
* merge) and replay the changes in lsn order.
*
* If streaming is true then data will be sent using stream API.
*
* Note: "volatile" markers on some parameters are to avoid trouble with
* PG_TRY inside the function.
*/
static void
ReorderBufferProcessTXN(ReorderBuffer *rb, ReorderBufferTXN *txn,
XLogRecPtr commit_lsn,
volatile Snapshot snapshot_now,
volatile CommandId command_id,
bool streaming)
{
bool using_subtxn;
MemoryContext ccxt = CurrentMemoryContext;
ReorderBufferIterTXNState *volatile iterstate = NULL;
volatile XLogRecPtr prev_lsn = InvalidXLogRecPtr;
ReorderBufferChange *volatile specinsert = NULL;
volatile bool stream_started = false;
ReorderBufferTXN *volatile curtxn = NULL;
/* build data to be able to lookup the CommandIds of catalog tuples */
ReorderBufferBuildTupleCidHash(rb, txn);
/* setup the initial snapshot */
SetupHistoricSnapshot(snapshot_now, txn->tuplecid_hash);
/*
* Decoding needs access to syscaches et al., which in turn use
* heavyweight locks and such. Thus we need to have enough state around to
* keep track of those. The easiest way is to simply use a transaction
* internally. That also allows us to easily enforce that nothing writes
* to the database by checking for xid assignments.
*
* When we're called via the SQL SRF there's already a transaction
* started, so start an explicit subtransaction there.
*/
using_subtxn = IsTransactionOrTransactionBlock();
PG_TRY();
{
ReorderBufferChange *change;
if (using_subtxn)
BeginInternalSubTransaction(streaming ? "stream" : "replay");
else
StartTransactionCommand();
/*
* We only need to send begin/begin-prepare for non-streamed
* transactions.
*/
if (!streaming)
{
if (rbtxn_prepared(txn))
rb->begin_prepare(rb, txn);
else
rb->begin(rb, txn);
}
ReorderBufferIterTXNInit(rb, txn, &iterstate);
while ((change = ReorderBufferIterTXNNext(rb, iterstate)) != NULL)
{
Relation relation = NULL;
Oid reloid;
/*
* We can't call start stream callback before processing first
* change.
*/
if (prev_lsn == InvalidXLogRecPtr)
{
if (streaming)
{
txn->origin_id = change->origin_id;
rb->stream_start(rb, txn, change->lsn);
stream_started = true;
}
}
/*
* Enforce correct ordering of changes, merged from multiple
* subtransactions. The changes may have the same LSN due to
* MULTI_INSERT xlog records.
*/
Assert(prev_lsn == InvalidXLogRecPtr || prev_lsn <= change->lsn);
prev_lsn = change->lsn;
/*
* Set the current xid to detect concurrent aborts. This is
* required for the cases when we decode the changes before the
* COMMIT record is processed.
*/
if (streaming || rbtxn_prepared(change->txn))
{
curtxn = change->txn;
SetupCheckXidLive(curtxn->xid);
}
switch (change->action)
{
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
/*
* Confirmation for speculative insertion arrived. Simply
* use as a normal record. It'll be cleaned up at the end
* of INSERT processing.
*/
if (specinsert == NULL)
elog(ERROR, "invalid ordering of speculative insertion changes");
Assert(specinsert->data.tp.oldtuple == NULL);
change = specinsert;
change->action = REORDER_BUFFER_CHANGE_INSERT;
/* intentionally fall through */
case REORDER_BUFFER_CHANGE_INSERT:
case REORDER_BUFFER_CHANGE_UPDATE:
case REORDER_BUFFER_CHANGE_DELETE:
Assert(snapshot_now);
reloid = RelidByRelfilenode(change->data.tp.relnode.spcNode,
change->data.tp.relnode.relNode);
/*
* Mapped catalog tuple without data, emitted while
* catalog table was in the process of being rewritten. We
* can fail to look up the relfilenode, because the
* relmapper has no "historic" view, in contrast to the
* normal catalog during decoding. Thus repeated rewrites
* can cause a lookup failure. That's OK because we do not
* decode catalog changes anyway. Normally such tuples
* would be skipped over below, but we can't identify
* whether the table should be logically logged without
* mapping the relfilenode to the oid.
*/
if (reloid == InvalidOid &&
change->data.tp.newtuple == NULL &&
change->data.tp.oldtuple == NULL)
goto change_done;
else if (reloid == InvalidOid)
elog(ERROR, "could not map filenode \"%s\" to relation OID",
relpathperm(change->data.tp.relnode,
MAIN_FORKNUM));
relation = RelationIdGetRelation(reloid);
if (!RelationIsValid(relation))
elog(ERROR, "could not open relation with OID %u (for filenode \"%s\")",
reloid,
relpathperm(change->data.tp.relnode,
MAIN_FORKNUM));
if (!RelationIsLogicallyLogged(relation))
goto change_done;
/*
* Ignore temporary heaps created during DDL unless the
* plugin has asked for them.
*/
if (relation->rd_rel->relrewrite && !rb->output_rewrites)
goto change_done;
/*
* For now ignore sequence changes entirely. Most of the
* time they don't log changes using records we
* understand, so it doesn't make sense to handle the few
* cases we do.
*/
if (relation->rd_rel->relkind == RELKIND_SEQUENCE)
goto change_done;
/* user-triggered change */
if (!IsToastRelation(relation))
{
ReorderBufferToastReplace(rb, txn, relation, change);
ReorderBufferApplyChange(rb, txn, relation, change,
streaming);
/*
* Only clear reassembled toast chunks if we're sure
* they're not required anymore. The creator of the
* tuple tells us.
*/
if (change->data.tp.clear_toast_afterwards)
ReorderBufferToastReset(rb, txn);
}
/* we're not interested in toast deletions */
else if (change->action == REORDER_BUFFER_CHANGE_INSERT)
{
/*
* Need to reassemble the full toasted Datum in
* memory, to ensure the chunks don't get reused till
* we're done remove it from the list of this
* transaction's changes. Otherwise it will get
* freed/reused while restoring spooled data from
* disk.
*/
Assert(change->data.tp.newtuple != NULL);
dlist_delete(&change->node);
ReorderBufferToastAppendChunk(rb, txn, relation,
change);
}
change_done:
/*
* If speculative insertion was confirmed, the record
* isn't needed anymore.
*/
if (specinsert != NULL)
{
ReorderBufferReturnChange(rb, specinsert, true);
specinsert = NULL;
}
if (RelationIsValid(relation))
{
RelationClose(relation);
relation = NULL;
}
break;
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
/*
* Speculative insertions are dealt with by delaying the
* processing of the insert until the confirmation record
* arrives. For that we simply unlink the record from the
* chain, so it does not get freed/reused while restoring
* spooled data from disk.
*
* This is safe in the face of concurrent catalog changes
* because the relevant relation can't be changed between
* speculative insertion and confirmation due to
* CheckTableNotInUse() and locking.
*/
/* clear out a pending (and thus failed) speculation */
if (specinsert != NULL)
{
ReorderBufferReturnChange(rb, specinsert, true);
specinsert = NULL;
}
/* and memorize the pending insertion */
dlist_delete(&change->node);
specinsert = change;
break;
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
/*
* Abort for speculative insertion arrived. So cleanup the
* specinsert tuple and toast hash.
*
* Note that we get the spec abort change for each toast
* entry but we need to perform the cleanup only the first
* time we get it for the main table.
*/
if (specinsert != NULL)
{
/*
* We must clean the toast hash before processing a
* completely new tuple to avoid confusion about the
* previous tuple's toast chunks.
*/
Assert(change->data.tp.clear_toast_afterwards);
ReorderBufferToastReset(rb, txn);
/* We don't need this record anymore. */
ReorderBufferReturnChange(rb, specinsert, true);
specinsert = NULL;
}
break;
case REORDER_BUFFER_CHANGE_TRUNCATE:
{
int i;
int nrelids = change->data.truncate.nrelids;
int nrelations = 0;
Relation *relations;
relations = palloc0(nrelids * sizeof(Relation));
for (i = 0; i < nrelids; i++)
{
Oid relid = change->data.truncate.relids[i];
Relation relation;
relation = RelationIdGetRelation(relid);
if (!RelationIsValid(relation))
elog(ERROR, "could not open relation with OID %u", relid);
if (!RelationIsLogicallyLogged(relation))
continue;
relations[nrelations++] = relation;
}
/* Apply the truncate. */
ReorderBufferApplyTruncate(rb, txn, nrelations,
relations, change,
streaming);
for (i = 0; i < nrelations; i++)
RelationClose(relations[i]);
break;
}
case REORDER_BUFFER_CHANGE_MESSAGE:
ReorderBufferApplyMessage(rb, txn, change, streaming);
break;
case REORDER_BUFFER_CHANGE_INVALIDATION:
/* Execute the invalidation messages locally */
ReorderBufferExecuteInvalidations(
change->data.inval.ninvalidations,
change->data.inval.invalidations);
break;
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
/* get rid of the old */
TeardownHistoricSnapshot(false);
if (snapshot_now->copied)
{
ReorderBufferFreeSnap(rb, snapshot_now);
snapshot_now =
ReorderBufferCopySnap(rb, change->data.snapshot,
txn, command_id);
}
/*
* Restored from disk, need to be careful not to double
* free. We could introduce refcounting for that, but for
* now this seems infrequent enough not to care.
*/
else if (change->data.snapshot->copied)
{
snapshot_now =
ReorderBufferCopySnap(rb, change->data.snapshot,
txn, command_id);
}
else
{
snapshot_now = change->data.snapshot;
}
/* and continue with the new one */
SetupHistoricSnapshot(snapshot_now, txn->tuplecid_hash);
break;
case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
Assert(change->data.command_id != InvalidCommandId);
if (command_id < change->data.command_id)
{
command_id = change->data.command_id;
if (!snapshot_now->copied)
{
/* we don't use the global one anymore */
snapshot_now = ReorderBufferCopySnap(rb, snapshot_now,
txn, command_id);
}
snapshot_now->curcid = command_id;
TeardownHistoricSnapshot(false);
SetupHistoricSnapshot(snapshot_now, txn->tuplecid_hash);
}
break;
case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
elog(ERROR, "tuplecid value in changequeue");
break;
}
}
/* speculative insertion record must be freed by now */
Assert(!specinsert);
/* clean up the iterator */
ReorderBufferIterTXNFinish(rb, iterstate);
iterstate = NULL;
/*
* Update total transaction count and total bytes processed by the
* transaction and its subtransactions. Ensure to not count the
* streamed transaction multiple times.
*
* Note that the statistics computation has to be done after
* ReorderBufferIterTXNFinish as it releases the serialized change
* which we have already accounted in ReorderBufferIterTXNNext.
*/
if (!rbtxn_is_streamed(txn))
rb->totalTxns++;
rb->totalBytes += txn->total_size;
/*
* Done with current changes, send the last message for this set of
* changes depending upon streaming mode.
*/
if (streaming)
{
if (stream_started)
{
rb->stream_stop(rb, txn, prev_lsn);
stream_started = false;
}
}
else
{
/*
* Call either PREPARE (for two-phase transactions) or COMMIT (for
* regular ones).
*/
if (rbtxn_prepared(txn))
rb->prepare(rb, txn, commit_lsn);
else
rb->commit(rb, txn, commit_lsn);
}
/* this is just a sanity check against bad output plugin behaviour */
if (GetCurrentTransactionIdIfAny() != InvalidTransactionId)
elog(ERROR, "output plugin used XID %u",
GetCurrentTransactionId());
/*
* Remember the command ID and snapshot for the next set of changes in
* streaming mode.
*/
if (streaming)
ReorderBufferSaveTXNSnapshot(rb, txn, snapshot_now, command_id);
else if (snapshot_now->copied)
ReorderBufferFreeSnap(rb, snapshot_now);
/* cleanup */
TeardownHistoricSnapshot(false);
/*
* Aborting the current (sub-)transaction as a whole has the right
* semantics. We want all locks acquired in here to be released, not
* reassigned to the parent and we do not want any database access
* have persistent effects.
*/
AbortCurrentTransaction();
/* make sure there's no cache pollution */
ReorderBufferExecuteInvalidations(txn->ninvalidations, txn->invalidations);
if (using_subtxn)
RollbackAndReleaseCurrentSubTransaction();
/*
* We are here due to one of the four reasons: 1. Decoding an
* in-progress txn. 2. Decoding a prepared txn. 3. Decoding of a
* prepared txn that was (partially) streamed. 4. Decoding a committed
* txn.
*
* For 1, we allow truncation of txn data by removing the changes
* already streamed but still keeping other things like invalidations,
* snapshot, and tuplecids. For 2 and 3, we indicate
* ReorderBufferTruncateTXN to do more elaborate truncation of txn
* data as the entire transaction has been decoded except for commit.
* For 4, as the entire txn has been decoded, we can fully clean up
* the TXN reorder buffer.
*/
if (streaming || rbtxn_prepared(txn))
{
ReorderBufferTruncateTXN(rb, txn, rbtxn_prepared(txn));
/* Reset the CheckXidAlive */
CheckXidAlive = InvalidTransactionId;
}
else
ReorderBufferCleanupTXN(rb, txn);
}
PG_CATCH();
{
MemoryContext ecxt = MemoryContextSwitchTo(ccxt);
ErrorData *errdata = CopyErrorData();
/* TODO: Encapsulate cleanup from the PG_TRY and PG_CATCH blocks */
if (iterstate)
ReorderBufferIterTXNFinish(rb, iterstate);
TeardownHistoricSnapshot(true);
/*
* Force cache invalidation to happen outside of a valid transaction
* to prevent catalog access as we just caught an error.
*/
AbortCurrentTransaction();
/* make sure there's no cache pollution */
ReorderBufferExecuteInvalidations(txn->ninvalidations,
txn->invalidations);
if (using_subtxn)
RollbackAndReleaseCurrentSubTransaction();
/*
* The error code ERRCODE_TRANSACTION_ROLLBACK indicates a concurrent
* abort of the (sub)transaction we are streaming or preparing. We
* need to do the cleanup and return gracefully on this error, see
* SetupCheckXidLive.
*
* This error code can be thrown by one of the callbacks we call
* during decoding so we need to ensure that we return gracefully only
* when we are sending the data in streaming mode and the streaming is
* not finished yet or when we are sending the data out on a PREPARE
* during a two-phase commit.
*/
if (errdata->sqlerrcode == ERRCODE_TRANSACTION_ROLLBACK &&
(stream_started || rbtxn_prepared(txn)))
{
/* curtxn must be set for streaming or prepared transactions */
Assert(curtxn);
/* Cleanup the temporary error state. */
FlushErrorState();
FreeErrorData(errdata);
errdata = NULL;
curtxn->concurrent_abort = true;
/* Reset the TXN so that it is allowed to stream remaining data. */
ReorderBufferResetTXN(rb, txn, snapshot_now,
command_id, prev_lsn,
specinsert);
}
else
{
ReorderBufferCleanupTXN(rb, txn);
MemoryContextSwitchTo(ecxt);
PG_RE_THROW();
}
}
PG_END_TRY();
}
/*
* Perform the replay of a transaction and its non-aborted subtransactions.
*
* Subtransactions previously have to be processed by
* ReorderBufferCommitChild(), even if previously assigned to the toplevel
* transaction with ReorderBufferAssignChild.
*
* This interface is called once a prepare or toplevel commit is read for both
* streamed as well as non-streamed transactions.
*/
static void
ReorderBufferReplay(ReorderBufferTXN *txn,
ReorderBuffer *rb, TransactionId xid,
XLogRecPtr commit_lsn, XLogRecPtr end_lsn,
TimestampTz commit_time,
RepOriginId origin_id, XLogRecPtr origin_lsn)
{
Snapshot snapshot_now;
CommandId command_id = FirstCommandId;
txn->final_lsn = commit_lsn;
txn->end_lsn = end_lsn;
txn->commit_time = commit_time;
txn->origin_id = origin_id;
txn->origin_lsn = origin_lsn;
/*
* If the transaction was (partially) streamed, we need to commit it in a
* 'streamed' way. That is, we first stream the remaining part of the
* transaction, and then invoke stream_commit message.
*
* Called after everything (origin ID, LSN, ...) is stored in the
* transaction to avoid passing that information directly.
*/
if (rbtxn_is_streamed(txn))
{
ReorderBufferStreamCommit(rb, txn);
return;
}
/*
* If this transaction has no snapshot, it didn't make any changes to the
* database, so there's nothing to decode. Note that
* ReorderBufferCommitChild will have transferred any snapshots from
* subtransactions if there were any.
*/
if (txn->base_snapshot == NULL)
{
Assert(txn->ninvalidations == 0);
/*
* Removing this txn before a commit might result in the computation
* of an incorrect restart_lsn. See SnapBuildProcessRunningXacts.
*/
if (!rbtxn_prepared(txn))
ReorderBufferCleanupTXN(rb, txn);
return;
}
snapshot_now = txn->base_snapshot;
/* Process and send the changes to output plugin. */
ReorderBufferProcessTXN(rb, txn, commit_lsn, snapshot_now,
command_id, false);
}
/*
* Commit a transaction.
*
* See comments for ReorderBufferReplay().
*/
void
ReorderBufferCommit(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr commit_lsn, XLogRecPtr end_lsn,
TimestampTz commit_time,
RepOriginId origin_id, XLogRecPtr origin_lsn)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
false);
/* unknown transaction, nothing to replay */
if (txn == NULL)
return;
ReorderBufferReplay(txn, rb, xid, commit_lsn, end_lsn, commit_time,
origin_id, origin_lsn);
}
/*
* Record the prepare information for a transaction.
*/
bool
ReorderBufferRememberPrepareInfo(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr prepare_lsn, XLogRecPtr end_lsn,
TimestampTz prepare_time,
RepOriginId origin_id, XLogRecPtr origin_lsn)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr, false);
/* unknown transaction, nothing to do */
if (txn == NULL)
return false;
/*
* Remember the prepare information to be later used by commit prepared in
* case we skip doing prepare.
*/
txn->final_lsn = prepare_lsn;
txn->end_lsn = end_lsn;
txn->commit_time = prepare_time;
txn->origin_id = origin_id;
txn->origin_lsn = origin_lsn;
return true;
}
/* Remember that we have skipped prepare */
void
ReorderBufferSkipPrepare(ReorderBuffer *rb, TransactionId xid)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr, false);
/* unknown transaction, nothing to do */
if (txn == NULL)
return;
txn->txn_flags |= RBTXN_SKIPPED_PREPARE;
}
/*
* Prepare a two-phase transaction.
*
* See comments for ReorderBufferReplay().
*/
void
ReorderBufferPrepare(ReorderBuffer *rb, TransactionId xid,
char *gid)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
false);
/* unknown transaction, nothing to replay */
if (txn == NULL)
return;
txn->txn_flags |= RBTXN_PREPARE;
txn->gid = pstrdup(gid);
/* The prepare info must have been updated in txn by now. */
Assert(txn->final_lsn != InvalidXLogRecPtr);
ReorderBufferReplay(txn, rb, xid, txn->final_lsn, txn->end_lsn,
txn->commit_time, txn->origin_id, txn->origin_lsn);
/*
* We send the prepare for the concurrently aborted xacts so that later
* when rollback prepared is decoded and sent, the downstream should be
* able to rollback such a xact. See comments atop DecodePrepare.
*
* Note, for the concurrent_abort + streaming case a stream_prepare was
* already sent within the ReorderBufferReplay call above.
*/
if (txn->concurrent_abort && !rbtxn_is_streamed(txn))
rb->prepare(rb, txn, txn->final_lsn);
}
/*
* This is used to handle COMMIT/ROLLBACK PREPARED.
*/
void
ReorderBufferFinishPrepared(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr commit_lsn, XLogRecPtr end_lsn,
XLogRecPtr initial_consistent_point,
TimestampTz commit_time, RepOriginId origin_id,
XLogRecPtr origin_lsn, char *gid, bool is_commit)
{
ReorderBufferTXN *txn;
XLogRecPtr prepare_end_lsn;
TimestampTz prepare_time;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, commit_lsn, false);
/* unknown transaction, nothing to do */
if (txn == NULL)
return;
/*
* By this time the txn has the prepare record information, remember it to
* be later used for rollback.
*/
prepare_end_lsn = txn->end_lsn;
prepare_time = txn->commit_time;
/* add the gid in the txn */
txn->gid = pstrdup(gid);
/*
* It is possible that this transaction is not decoded at prepare time
* either because by that time we didn't have a consistent snapshot or it
* was decoded earlier but we have restarted. We only need to send the
* prepare if it was not decoded earlier. We don't need to decode the xact
* for aborts if it is not done already.
*/
if ((txn->final_lsn < initial_consistent_point) && is_commit)
{
txn->txn_flags |= RBTXN_PREPARE;
/*
* The prepare info must have been updated in txn even if we skip
* prepare.
*/
Assert(txn->final_lsn != InvalidXLogRecPtr);
/*
* By this time the txn has the prepare record information and it is
* important to use that so that downstream gets the accurate
* information. If instead, we have passed commit information here
* then downstream can behave as it has already replayed commit
* prepared after the restart.
*/
ReorderBufferReplay(txn, rb, xid, txn->final_lsn, txn->end_lsn,
txn->commit_time, txn->origin_id, txn->origin_lsn);
}
txn->final_lsn = commit_lsn;
txn->end_lsn = end_lsn;
txn->commit_time = commit_time;
txn->origin_id = origin_id;
txn->origin_lsn = origin_lsn;
if (is_commit)
rb->commit_prepared(rb, txn, commit_lsn);
else
rb->rollback_prepared(rb, txn, prepare_end_lsn, prepare_time);
/* cleanup: make sure there's no cache pollution */
ReorderBufferExecuteInvalidations(txn->ninvalidations,
txn->invalidations);
ReorderBufferCleanupTXN(rb, txn);
}
/*
* Abort a transaction that possibly has previous changes. Needs to be first
* called for subtransactions and then for the toplevel xid.
*
* NB: Transactions handled here have to have actively aborted (i.e. have
* produced an abort record). Implicitly aborted transactions are handled via
* ReorderBufferAbortOld(); transactions we're just not interested in, but
* which have committed are handled in ReorderBufferForget().
*
* This function purges this transaction and its contents from memory and
* disk.
*/
void
ReorderBufferAbort(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
false);
/* unknown, nothing to remove */
if (txn == NULL)
return;
/* For streamed transactions notify the remote node about the abort. */
if (rbtxn_is_streamed(txn))
{
rb->stream_abort(rb, txn, lsn);
/*
* We might have decoded changes for this transaction that could load
* the cache as per the current transaction's view (consider DDL's
* happened in this transaction). We don't want the decoding of future
* transactions to use those cache entries so execute invalidations.
*/
if (txn->ninvalidations > 0)
ReorderBufferImmediateInvalidation(rb, txn->ninvalidations,
txn->invalidations);
}
/* cosmetic... */
txn->final_lsn = lsn;
/* remove potential on-disk data, and deallocate */
ReorderBufferCleanupTXN(rb, txn);
}
/*
* Abort all transactions that aren't actually running anymore because the
* server restarted.
*
* NB: These really have to be transactions that have aborted due to a server
* crash/immediate restart, as we don't deal with invalidations here.
*/
void
ReorderBufferAbortOld(ReorderBuffer *rb, TransactionId oldestRunningXid)
{
dlist_mutable_iter it;
/*
* Iterate through all (potential) toplevel TXNs and abort all that are
* older than what possibly can be running. Once we've found the first
* that is alive we stop, there might be some that acquired an xid earlier
* but started writing later, but it's unlikely and they will be cleaned
* up in a later call to this function.
*/
dlist_foreach_modify(it, &rb->toplevel_by_lsn)
{
ReorderBufferTXN *txn;
txn = dlist_container(ReorderBufferTXN, node, it.cur);
if (TransactionIdPrecedes(txn->xid, oldestRunningXid))
{
elog(DEBUG2, "aborting old transaction %u", txn->xid);
/* remove potential on-disk data, and deallocate this tx */
ReorderBufferCleanupTXN(rb, txn);
}
else
return;
}
}
/*
* Forget the contents of a transaction if we aren't interested in its
* contents. Needs to be first called for subtransactions and then for the
* toplevel xid.
*
* This is significantly different to ReorderBufferAbort() because
* transactions that have committed need to be treated differently from aborted
* ones since they may have modified the catalog.
*
* Note that this is only allowed to be called in the moment a transaction
* commit has just been read, not earlier; otherwise later records referring
* to this xid might re-create the transaction incompletely.
*/
void
ReorderBufferForget(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
false);
/* unknown, nothing to forget */
if (txn == NULL)
return;
/* For streamed transactions notify the remote node about the abort. */
if (rbtxn_is_streamed(txn))
rb->stream_abort(rb, txn, lsn);
/* cosmetic... */
txn->final_lsn = lsn;
/*
* Process cache invalidation messages if there are any. Even if we're not
* interested in the transaction's contents, it could have manipulated the
* catalog and we need to update the caches according to that.
*/
if (txn->base_snapshot != NULL && txn->ninvalidations > 0)
ReorderBufferImmediateInvalidation(rb, txn->ninvalidations,
txn->invalidations);
else
Assert(txn->ninvalidations == 0);
/* remove potential on-disk data, and deallocate */
ReorderBufferCleanupTXN(rb, txn);
}
/*
* Invalidate cache for those transactions that need to be skipped just in case
* catalogs were manipulated as part of the transaction.
*
* Note that this is a special-purpose function for prepared transactions where
* we don't want to clean up the TXN even when we decide to skip it. See
* DecodePrepare.
*/
void
ReorderBufferInvalidate(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
false);
/* unknown, nothing to do */
if (txn == NULL)
return;
/*
* Process cache invalidation messages if there are any. Even if we're not
* interested in the transaction's contents, it could have manipulated the
* catalog and we need to update the caches according to that.
*/
if (txn->base_snapshot != NULL && txn->ninvalidations > 0)
ReorderBufferImmediateInvalidation(rb, txn->ninvalidations,
txn->invalidations);
else
Assert(txn->ninvalidations == 0);
}
/*
* Execute invalidations happening outside the context of a decoded
* transaction. That currently happens either for xid-less commits
* (cf. RecordTransactionCommit()) or for invalidations in uninteresting
* transactions (via ReorderBufferForget()).
*/
void
ReorderBufferImmediateInvalidation(ReorderBuffer *rb, uint32 ninvalidations,
SharedInvalidationMessage *invalidations)
{
bool use_subtxn = IsTransactionOrTransactionBlock();
int i;
if (use_subtxn)
BeginInternalSubTransaction("replay");
/*
* Force invalidations to happen outside of a valid transaction - that way
* entries will just be marked as invalid without accessing the catalog.
* That's advantageous because we don't need to setup the full state
* necessary for catalog access.
*/
if (use_subtxn)
AbortCurrentTransaction();
for (i = 0; i < ninvalidations; i++)
LocalExecuteInvalidationMessage(&invalidations[i]);
if (use_subtxn)
RollbackAndReleaseCurrentSubTransaction();
}
/*
* Tell reorderbuffer about an xid seen in the WAL stream. Has to be called at
* least once for every xid in XLogRecord->xl_xid (other places in records
* may, but do not have to be passed through here).
*
* Reorderbuffer keeps some datastructures about transactions in LSN order,
* for efficiency. To do that it has to know about when transactions are seen
* first in the WAL. As many types of records are not actually interesting for
* logical decoding, they do not necessarily pass though here.
*/
void
ReorderBufferProcessXid(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
{
/* many records won't have an xid assigned, centralize check here */
if (xid != InvalidTransactionId)
ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
}
/*
* Add a new snapshot to this transaction that may only used after lsn 'lsn'
* because the previous snapshot doesn't describe the catalog correctly for
* following rows.
*/
void
ReorderBufferAddSnapshot(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr lsn, Snapshot snap)
{
ReorderBufferChange *change = ReorderBufferGetChange(rb);
change->data.snapshot = snap;
change->action = REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT;
ReorderBufferQueueChange(rb, xid, lsn, change, false);
}
/*
* Set up the transaction's base snapshot.
*
* If we know that xid is a subtransaction, set the base snapshot on the
* top-level transaction instead.
*/
void
ReorderBufferSetBaseSnapshot(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr lsn, Snapshot snap)
{
ReorderBufferTXN *txn;
bool is_new;
AssertArg(snap != NULL);
/*
* Fetch the transaction to operate on. If we know it's a subtransaction,
* operate on its top-level transaction instead.
*/
txn = ReorderBufferTXNByXid(rb, xid, true, &is_new, lsn, true);
if (rbtxn_is_known_subxact(txn))
txn = ReorderBufferTXNByXid(rb, txn->toplevel_xid, false,
NULL, InvalidXLogRecPtr, false);
Assert(txn->base_snapshot == NULL);
txn->base_snapshot = snap;
txn->base_snapshot_lsn = lsn;
dlist_push_tail(&rb->txns_by_base_snapshot_lsn, &txn->base_snapshot_node);
AssertTXNLsnOrder(rb);
}
/*
* Access the catalog with this CommandId at this point in the changestream.
*
* May only be called for command ids > 1
*/
void
ReorderBufferAddNewCommandId(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr lsn, CommandId cid)
{
ReorderBufferChange *change = ReorderBufferGetChange(rb);
change->data.command_id = cid;
change->action = REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID;
ReorderBufferQueueChange(rb, xid, lsn, change, false);
}
/*
* Update memory counters to account for the new or removed change.
*
* We update two counters - in the reorder buffer, and in the transaction
* containing the change. The reorder buffer counter allows us to quickly
* decide if we reached the memory limit, the transaction counter allows
* us to quickly pick the largest transaction for eviction.
*
* When streaming is enabled, we need to update the toplevel transaction
* counters instead - we don't really care about subtransactions as we
* can't stream them individually anyway, and we only pick toplevel
* transactions for eviction. So only toplevel transactions matter.
*/
static void
ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
ReorderBufferChange *change,
bool addition, Size sz)
{
ReorderBufferTXN *txn;
ReorderBufferTXN *toptxn;
Assert(change->txn);
/*
* Ignore tuple CID changes, because those are not evicted when reaching
* memory limit. So we just don't count them, because it might easily
* trigger a pointless attempt to spill.
*/
if (change->action == REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID)
return;
txn = change->txn;
/*
* Update the total size in top level as well. This is later used to
* compute the decoding stats.
*/
if (txn->toptxn != NULL)
toptxn = txn->toptxn;
else
toptxn = txn;
if (addition)
{
txn->size += sz;
rb->size += sz;
/* Update the total size in the top transaction. */
toptxn->total_size += sz;
}
else
{
Assert((rb->size >= sz) && (txn->size >= sz));
txn->size -= sz;
rb->size -= sz;
/* Update the total size in the top transaction. */
toptxn->total_size -= sz;
}
Assert(txn->size <= rb->size);
}
/*
* Add new (relfilenode, tid) -> (cmin, cmax) mappings.
*
* We do not include this change type in memory accounting, because we
* keep CIDs in a separate list and do not evict them when reaching
* the memory limit.
*/
void
ReorderBufferAddNewTupleCids(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr lsn, RelFileNode node,
ItemPointerData tid, CommandId cmin,
CommandId cmax, CommandId combocid)
{
ReorderBufferChange *change = ReorderBufferGetChange(rb);
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
change->data.tuplecid.node = node;
change->data.tuplecid.tid = tid;
change->data.tuplecid.cmin = cmin;
change->data.tuplecid.cmax = cmax;
change->data.tuplecid.combocid = combocid;
change->lsn = lsn;
change->txn = txn;
change->action = REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID;
dlist_push_tail(&txn->tuplecids, &change->node);
txn->ntuplecids++;
}
/*
* Setup the invalidation of the toplevel transaction.
*
* This needs to be called for each XLOG_XACT_INVALIDATIONS message and
* accumulates all the invalidation messages in the toplevel transaction as
* well as in the form of change in reorder buffer. We require to record it in
* form of the change so that we can execute only the required invalidations
* instead of executing all the invalidations on each CommandId increment. We
* also need to accumulate these in the toplevel transaction because in some
* cases we skip processing the transaction (see ReorderBufferForget), we need
* to execute all the invalidations together.
*/
void
ReorderBufferAddInvalidations(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr lsn, Size nmsgs,
SharedInvalidationMessage *msgs)
{
ReorderBufferTXN *txn;
MemoryContext oldcontext;
ReorderBufferChange *change;
txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
oldcontext = MemoryContextSwitchTo(rb->context);
/*
* Collect all the invalidations under the top transaction so that we can
* execute them all together. See comment atop this function
*/
if (txn->toptxn)
txn = txn->toptxn;
Assert(nmsgs > 0);
/* Accumulate invalidations. */
if (txn->ninvalidations == 0)
{
txn->ninvalidations = nmsgs;
txn->invalidations = (SharedInvalidationMessage *)
palloc(sizeof(SharedInvalidationMessage) * nmsgs);
memcpy(txn->invalidations, msgs,
sizeof(SharedInvalidationMessage) * nmsgs);
}
else
{
txn->invalidations = (SharedInvalidationMessage *)
repalloc(txn->invalidations, sizeof(SharedInvalidationMessage) *
(txn->ninvalidations + nmsgs));
memcpy(txn->invalidations + txn->ninvalidations, msgs,
nmsgs * sizeof(SharedInvalidationMessage));
txn->ninvalidations += nmsgs;
}
change = ReorderBufferGetChange(rb);
change->action = REORDER_BUFFER_CHANGE_INVALIDATION;
change->data.inval.ninvalidations = nmsgs;
change->data.inval.invalidations = (SharedInvalidationMessage *)
palloc(sizeof(SharedInvalidationMessage) * nmsgs);
memcpy(change->data.inval.invalidations, msgs,
sizeof(SharedInvalidationMessage) * nmsgs);
ReorderBufferQueueChange(rb, xid, lsn, change, false);
MemoryContextSwitchTo(oldcontext);
}
/*
* Apply all invalidations we know. Possibly we only need parts at this point
* in the changestream but we don't know which those are.
*/
static void
ReorderBufferExecuteInvalidations(uint32 nmsgs, SharedInvalidationMessage *msgs)
{
int i;
for (i = 0; i < nmsgs; i++)
LocalExecuteInvalidationMessage(&msgs[i]);
}
/*
* Mark a transaction as containing catalog changes
*/
void
ReorderBufferXidSetCatalogChanges(ReorderBuffer *rb, TransactionId xid,
XLogRecPtr lsn)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, true, NULL, lsn, true);
txn->txn_flags |= RBTXN_HAS_CATALOG_CHANGES;
/*
* Mark top-level transaction as having catalog changes too if one of its
* children has so that the ReorderBufferBuildTupleCidHash can
* conveniently check just top-level transaction and decide whether to
* build the hash table or not.
*/
if (txn->toptxn != NULL)
txn->toptxn->txn_flags |= RBTXN_HAS_CATALOG_CHANGES;
}
/*
* Query whether a transaction is already *known* to contain catalog
* changes. This can be wrong until directly before the commit!
*/
bool
ReorderBufferXidHasCatalogChanges(ReorderBuffer *rb, TransactionId xid)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false, NULL, InvalidXLogRecPtr,
false);
if (txn == NULL)
return false;
return rbtxn_has_catalog_changes(txn);
}
/*
* ReorderBufferXidHasBaseSnapshot
* Have we already set the base snapshot for the given txn/subtxn?
*/
bool
ReorderBufferXidHasBaseSnapshot(ReorderBuffer *rb, TransactionId xid)
{
ReorderBufferTXN *txn;
txn = ReorderBufferTXNByXid(rb, xid, false,
NULL, InvalidXLogRecPtr, false);
/* transaction isn't known yet, ergo no snapshot */
if (txn == NULL)
return false;
/* a known subtxn? operate on top-level txn instead */
if (rbtxn_is_known_subxact(txn))
txn = ReorderBufferTXNByXid(rb, txn->toplevel_xid, false,
NULL, InvalidXLogRecPtr, false);
return txn->base_snapshot != NULL;
}
/*
* ---------------------------------------
* Disk serialization support
* ---------------------------------------
*/
/*
* Ensure the IO buffer is >= sz.
*/
static void
ReorderBufferSerializeReserve(ReorderBuffer *rb, Size sz)
{
if (!rb->outbufsize)
{
rb->outbuf = MemoryContextAlloc(rb->context, sz);
rb->outbufsize = sz;
}
else if (rb->outbufsize < sz)
{
rb->outbuf = repalloc(rb->outbuf, sz);
rb->outbufsize = sz;
}
}
/*
* Find the largest transaction (toplevel or subxact) to evict (spill to disk).
*
* XXX With many subtransactions this might be quite slow, because we'll have
* to walk through all of them. There are some options how we could improve
* that: (a) maintain some secondary structure with transactions sorted by
* amount of changes, (b) not looking for the entirely largest transaction,
* but e.g. for transaction using at least some fraction of the memory limit,
* and (c) evicting multiple transactions at once, e.g. to free a given portion
* of the memory limit (e.g. 50%).
*/
static ReorderBufferTXN *
ReorderBufferLargestTXN(ReorderBuffer *rb)
{
HASH_SEQ_STATUS hash_seq;
ReorderBufferTXNByIdEnt *ent;
ReorderBufferTXN *largest = NULL;
hash_seq_init(&hash_seq, rb->by_txn);
while ((ent = hash_seq_search(&hash_seq)) != NULL)
{
ReorderBufferTXN *txn = ent->txn;
/* if the current transaction is larger, remember it */
if ((!largest) || (txn->size > largest->size))
largest = txn;
}
Assert(largest);
Assert(largest->size > 0);
Assert(largest->size <= rb->size);
return largest;
}
/*
* Find the largest toplevel transaction to evict (by streaming).
*
* This can be seen as an optimized version of ReorderBufferLargestTXN, which
* should give us the same transaction (because we don't update memory account
* for subtransaction with streaming, so it's always 0). But we can simply
* iterate over the limited number of toplevel transactions that have a base
* snapshot. There is no use of selecting a transaction that doesn't have base
* snapshot because we don't decode such transactions.
*
* Note that, we skip transactions that contains incomplete changes. There
* is a scope of optimization here such that we can select the largest
* transaction which has incomplete changes. But that will make the code and
* design quite complex and that might not be worth the benefit. If we plan to
* stream the transactions that contains incomplete changes then we need to
* find a way to partially stream/truncate the transaction changes in-memory
* and build a mechanism to partially truncate the spilled files.
* Additionally, whenever we partially stream the transaction we need to
* maintain the last streamed lsn and next time we need to restore from that
* segment and the offset in WAL. As we stream the changes from the top
* transaction and restore them subtransaction wise, we need to even remember
* the subxact from where we streamed the last change.
*/
static ReorderBufferTXN *
ReorderBufferLargestTopTXN(ReorderBuffer *rb)
{
dlist_iter iter;
Size largest_size = 0;
ReorderBufferTXN *largest = NULL;
/* Find the largest top-level transaction having a base snapshot. */
dlist_foreach(iter, &rb->txns_by_base_snapshot_lsn)
{
ReorderBufferTXN *txn;
txn = dlist_container(ReorderBufferTXN, base_snapshot_node, iter.cur);
/* must not be a subtxn */
Assert(!rbtxn_is_known_subxact(txn));
/* base_snapshot must be set */
Assert(txn->base_snapshot != NULL);
if ((largest == NULL || txn->total_size > largest_size) &&
(txn->total_size > 0) && !(rbtxn_has_partial_change(txn)))
{
largest = txn;
largest_size = txn->total_size;
}
}
return largest;
}
/*
* Check whether the logical_decoding_work_mem limit was reached, and if yes
* pick the largest (sub)transaction at-a-time to evict and spill its changes to
* disk until we reach under the memory limit.
*
* XXX At this point we select the transactions until we reach under the memory
* limit, but we might also adapt a more elaborate eviction strategy - for example
* evicting enough transactions to free certain fraction (e.g. 50%) of the memory
* limit.
*/
static void
ReorderBufferCheckMemoryLimit(ReorderBuffer *rb)
{
ReorderBufferTXN *txn;
/* bail out if we haven't exceeded the memory limit */
if (rb->size < logical_decoding_work_mem * 1024L)
return;
/*
* Loop until we reach under the memory limit. One might think that just
* by evicting the largest (sub)transaction we will come under the memory
* limit based on assumption that the selected transaction is at least as
* large as the most recent change (which caused us to go over the memory
* limit). However, that is not true because a user can reduce the
* logical_decoding_work_mem to a smaller value before the most recent
* change.
*/
while (rb->size >= logical_decoding_work_mem * 1024L)
{
/*
* Pick the largest transaction (or subtransaction) and evict it from
* memory by streaming, if possible. Otherwise, spill to disk.
*/
if (ReorderBufferCanStartStreaming(rb) &&
(txn = ReorderBufferLargestTopTXN(rb)) != NULL)
{
/* we know there has to be one, because the size is not zero */
Assert(txn && !txn->toptxn);
Assert(txn->total_size > 0);
Assert(rb->size >= txn->total_size);
ReorderBufferStreamTXN(rb, txn);
}
else
{
/*
* Pick the largest transaction (or subtransaction) and evict it
* from memory by serializing it to disk.
*/
txn = ReorderBufferLargestTXN(rb);
/* we know there has to be one, because the size is not zero */
Assert(txn);
Assert(txn->size > 0);
Assert(rb->size >= txn->size);
ReorderBufferSerializeTXN(rb, txn);
}
/*
* After eviction, the transaction should have no entries in memory,
* and should use 0 bytes for changes.
*/
Assert(txn->size == 0);
Assert(txn->nentries_mem == 0);
}
/* We must be under the memory limit now. */
Assert(rb->size < logical_decoding_work_mem * 1024L);
}
/*
* Spill data of a large transaction (and its subtransactions) to disk.
*/
static void
ReorderBufferSerializeTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
dlist_iter subtxn_i;
dlist_mutable_iter change_i;
int fd = -1;
XLogSegNo curOpenSegNo = 0;
Size spilled = 0;
Size size = txn->size;
elog(DEBUG2, "spill %u changes in XID %u to disk",
(uint32) txn->nentries_mem, txn->xid);
/* do the same to all child TXs */
dlist_foreach(subtxn_i, &txn->subtxns)
{
ReorderBufferTXN *subtxn;
subtxn = dlist_container(ReorderBufferTXN, node, subtxn_i.cur);
ReorderBufferSerializeTXN(rb, subtxn);
}
/* serialize changestream */
dlist_foreach_modify(change_i, &txn->changes)
{
ReorderBufferChange *change;
change = dlist_container(ReorderBufferChange, node, change_i.cur);
/*
* store in segment in which it belongs by start lsn, don't split over
* multiple segments tho
*/
if (fd == -1 ||
!XLByteInSeg(change->lsn, curOpenSegNo, wal_segment_size))
{
char path[MAXPGPATH];
if (fd != -1)
CloseTransientFile(fd);
XLByteToSeg(change->lsn, curOpenSegNo, wal_segment_size);
/*
* No need to care about TLIs here, only used during a single run,
* so each LSN only maps to a specific WAL record.
*/
ReorderBufferSerializedPath(path, MyReplicationSlot, txn->xid,
curOpenSegNo);
/* open segment, create it if necessary */
fd = OpenTransientFile(path,
O_CREAT | O_WRONLY | O_APPEND | PG_BINARY);
if (fd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", path)));
}
ReorderBufferSerializeChange(rb, txn, fd, change);
dlist_delete(&change->node);
ReorderBufferReturnChange(rb, change, true);
spilled++;
}
/* update the statistics iff we have spilled anything */
if (spilled)
{
rb->spillCount += 1;
rb->spillBytes += size;
/* don't consider already serialized transactions */
rb->spillTxns += (rbtxn_is_serialized(txn) || rbtxn_is_serialized_clear(txn)) ? 0 : 1;
/* update the decoding stats */
UpdateDecodingStats((LogicalDecodingContext *) rb->private_data);
}
Assert(spilled == txn->nentries_mem);
Assert(dlist_is_empty(&txn->changes));
txn->nentries_mem = 0;
txn->txn_flags |= RBTXN_IS_SERIALIZED;
if (fd != -1)
CloseTransientFile(fd);
}
/*
* Serialize individual change to disk.
*/
static void
ReorderBufferSerializeChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
int fd, ReorderBufferChange *change)
{
ReorderBufferDiskChange *ondisk;
Size sz = sizeof(ReorderBufferDiskChange);
ReorderBufferSerializeReserve(rb, sz);
ondisk = (ReorderBufferDiskChange *) rb->outbuf;
memcpy(&ondisk->change, change, sizeof(ReorderBufferChange));
switch (change->action)
{
/* fall through these, they're all similar enough */
case REORDER_BUFFER_CHANGE_INSERT:
case REORDER_BUFFER_CHANGE_UPDATE:
case REORDER_BUFFER_CHANGE_DELETE:
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
{
char *data;
ReorderBufferTupleBuf *oldtup,
*newtup;
Size oldlen = 0;
Size newlen = 0;
oldtup = change->data.tp.oldtuple;
newtup = change->data.tp.newtuple;
if (oldtup)
{
sz += sizeof(HeapTupleData);
oldlen = oldtup->tuple.t_len;
sz += oldlen;
}
if (newtup)
{
sz += sizeof(HeapTupleData);
newlen = newtup->tuple.t_len;
sz += newlen;
}
/* make sure we have enough space */
ReorderBufferSerializeReserve(rb, sz);
data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
/* might have been reallocated above */
ondisk = (ReorderBufferDiskChange *) rb->outbuf;
if (oldlen)
{
memcpy(data, &oldtup->tuple, sizeof(HeapTupleData));
data += sizeof(HeapTupleData);
memcpy(data, oldtup->tuple.t_data, oldlen);
data += oldlen;
}
if (newlen)
{
memcpy(data, &newtup->tuple, sizeof(HeapTupleData));
data += sizeof(HeapTupleData);
memcpy(data, newtup->tuple.t_data, newlen);
data += newlen;
}
break;
}
case REORDER_BUFFER_CHANGE_MESSAGE:
{
char *data;
Size prefix_size = strlen(change->data.msg.prefix) + 1;
sz += prefix_size + change->data.msg.message_size +
sizeof(Size) + sizeof(Size);
ReorderBufferSerializeReserve(rb, sz);
data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
/* might have been reallocated above */
ondisk = (ReorderBufferDiskChange *) rb->outbuf;
/* write the prefix including the size */
memcpy(data, &prefix_size, sizeof(Size));
data += sizeof(Size);
memcpy(data, change->data.msg.prefix,
prefix_size);
data += prefix_size;
/* write the message including the size */
memcpy(data, &change->data.msg.message_size, sizeof(Size));
data += sizeof(Size);
memcpy(data, change->data.msg.message,
change->data.msg.message_size);
data += change->data.msg.message_size;
break;
}
case REORDER_BUFFER_CHANGE_INVALIDATION:
{
char *data;
Size inval_size = sizeof(SharedInvalidationMessage) *
change->data.inval.ninvalidations;
sz += inval_size;
ReorderBufferSerializeReserve(rb, sz);
data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
/* might have been reallocated above */
ondisk = (ReorderBufferDiskChange *) rb->outbuf;
memcpy(data, change->data.inval.invalidations, inval_size);
data += inval_size;
break;
}
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
{
Snapshot snap;
char *data;
snap = change->data.snapshot;
sz += sizeof(SnapshotData) +
sizeof(TransactionId) * snap->xcnt +
sizeof(TransactionId) * snap->subxcnt;
/* make sure we have enough space */
ReorderBufferSerializeReserve(rb, sz);
data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
/* might have been reallocated above */
ondisk = (ReorderBufferDiskChange *) rb->outbuf;
memcpy(data, snap, sizeof(SnapshotData));
data += sizeof(SnapshotData);
if (snap->xcnt)
{
memcpy(data, snap->xip,
sizeof(TransactionId) * snap->xcnt);
data += sizeof(TransactionId) * snap->xcnt;
}
if (snap->subxcnt)
{
memcpy(data, snap->subxip,
sizeof(TransactionId) * snap->subxcnt);
data += sizeof(TransactionId) * snap->subxcnt;
}
break;
}
case REORDER_BUFFER_CHANGE_TRUNCATE:
{
Size size;
char *data;
/* account for the OIDs of truncated relations */
size = sizeof(Oid) * change->data.truncate.nrelids;
sz += size;
/* make sure we have enough space */
ReorderBufferSerializeReserve(rb, sz);
data = ((char *) rb->outbuf) + sizeof(ReorderBufferDiskChange);
/* might have been reallocated above */
ondisk = (ReorderBufferDiskChange *) rb->outbuf;
memcpy(data, change->data.truncate.relids, size);
data += size;
break;
}
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
/* ReorderBufferChange contains everything important */
break;
}
ondisk->size = sz;
errno = 0;
pgstat_report_wait_start(WAIT_EVENT_REORDER_BUFFER_WRITE);
if (write(fd, rb->outbuf, ondisk->size) != ondisk->size)
{
int save_errno = errno;
CloseTransientFile(fd);
/* if write didn't set errno, assume problem is no disk space */
errno = save_errno ? save_errno : ENOSPC;
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not write to data file for XID %u: %m",
txn->xid)));
}
pgstat_report_wait_end();
/*
* Keep the transaction's final_lsn up to date with each change we send to
* disk, so that ReorderBufferRestoreCleanup works correctly. (We used to
* only do this on commit and abort records, but that doesn't work if a
* system crash leaves a transaction without its abort record).
*
* Make sure not to move it backwards.
*/
if (txn->final_lsn < change->lsn)
txn->final_lsn = change->lsn;
Assert(ondisk->change.action == change->action);
}
/* Returns true, if the output plugin supports streaming, false, otherwise. */
static inline bool
ReorderBufferCanStream(ReorderBuffer *rb)
{
LogicalDecodingContext *ctx = rb->private_data;
return ctx->streaming;
}
/* Returns true, if the streaming can be started now, false, otherwise. */
static inline bool
ReorderBufferCanStartStreaming(ReorderBuffer *rb)
{
LogicalDecodingContext *ctx = rb->private_data;
SnapBuild *builder = ctx->snapshot_builder;
/* We can't start streaming unless a consistent state is reached. */
if (SnapBuildCurrentState(builder) < SNAPBUILD_CONSISTENT)
return false;
/*
* We can't start streaming immediately even if the streaming is enabled
* because we previously decoded this transaction and now just are
* restarting.
*/
if (ReorderBufferCanStream(rb) &&
!SnapBuildXactNeedsSkip(builder, ctx->reader->EndRecPtr))
return true;
return false;
}
/*
* Send data of a large transaction (and its subtransactions) to the
* output plugin, but using the stream API.
*/
static void
ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
Snapshot snapshot_now;
CommandId command_id;
Size stream_bytes;
bool txn_is_streamed;
/* We can never reach here for a subtransaction. */
Assert(txn->toptxn == NULL);
/*
* We can't make any assumptions about base snapshot here, similar to what
* ReorderBufferCommit() does. That relies on base_snapshot getting
* transferred from subxact in ReorderBufferCommitChild(), but that was
* not yet called as the transaction is in-progress.
*
* So just walk the subxacts and use the same logic here. But we only need
* to do that once, when the transaction is streamed for the first time.
* After that we need to reuse the snapshot from the previous run.
*
* Unlike DecodeCommit which adds xids of all the subtransactions in
* snapshot's xip array via SnapBuildCommittedTxn, we can't do that here
* but we do add them to subxip array instead via ReorderBufferCopySnap.
* This allows the catalog changes made in subtransactions decoded till
* now to be visible.
*/
if (txn->snapshot_now == NULL)
{
dlist_iter subxact_i;
/* make sure this transaction is streamed for the first time */
Assert(!rbtxn_is_streamed(txn));
/* at the beginning we should have invalid command ID */
Assert(txn->command_id == InvalidCommandId);
dlist_foreach(subxact_i, &txn->subtxns)
{
ReorderBufferTXN *subtxn;
subtxn = dlist_container(ReorderBufferTXN, node, subxact_i.cur);
ReorderBufferTransferSnapToParent(txn, subtxn);
}
/*
* If this transaction has no snapshot, it didn't make any changes to
* the database till now, so there's nothing to decode.
*/
if (txn->base_snapshot == NULL)
{
Assert(txn->ninvalidations == 0);
return;
}
command_id = FirstCommandId;
snapshot_now = ReorderBufferCopySnap(rb, txn->base_snapshot,
txn, command_id);
}
else
{
/* the transaction must have been already streamed */
Assert(rbtxn_is_streamed(txn));
/*
* Nah, we already have snapshot from the previous streaming run. We
* assume new subxacts can't move the LSN backwards, and so can't beat
* the LSN condition in the previous branch (so no need to walk
* through subxacts again). In fact, we must not do that as we may be
* using snapshot half-way through the subxact.
*/
command_id = txn->command_id;
/*
* We can't use txn->snapshot_now directly because after the last
* streaming run, we might have got some new sub-transactions. So we
* need to add them to the snapshot.
*/
snapshot_now = ReorderBufferCopySnap(rb, txn->snapshot_now,
txn, command_id);
/* Free the previously copied snapshot. */
Assert(txn->snapshot_now->copied);
ReorderBufferFreeSnap(rb, txn->snapshot_now);
txn->snapshot_now = NULL;
}
/*
* Remember this information to be used later to update stats. We can't
* update the stats here as an error while processing the changes would
* lead to the accumulation of stats even though we haven't streamed all
* the changes.
*/
txn_is_streamed = rbtxn_is_streamed(txn);
stream_bytes = txn->total_size;
/* Process and send the changes to output plugin. */
ReorderBufferProcessTXN(rb, txn, InvalidXLogRecPtr, snapshot_now,
command_id, true);
rb->streamCount += 1;
rb->streamBytes += stream_bytes;
/* Don't consider already streamed transaction. */
rb->streamTxns += (txn_is_streamed) ? 0 : 1;
/* update the decoding stats */
UpdateDecodingStats((LogicalDecodingContext *) rb->private_data);
Assert(dlist_is_empty(&txn->changes));
Assert(txn->nentries == 0);
Assert(txn->nentries_mem == 0);
}
/*
* Size of a change in memory.
*/
static Size
ReorderBufferChangeSize(ReorderBufferChange *change)
{
Size sz = sizeof(ReorderBufferChange);
switch (change->action)
{
/* fall through these, they're all similar enough */
case REORDER_BUFFER_CHANGE_INSERT:
case REORDER_BUFFER_CHANGE_UPDATE:
case REORDER_BUFFER_CHANGE_DELETE:
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
{
ReorderBufferTupleBuf *oldtup,
*newtup;
Size oldlen = 0;
Size newlen = 0;
oldtup = change->data.tp.oldtuple;
newtup = change->data.tp.newtuple;
if (oldtup)
{
sz += sizeof(HeapTupleData);
oldlen = oldtup->tuple.t_len;
sz += oldlen;
}
if (newtup)
{
sz += sizeof(HeapTupleData);
newlen = newtup->tuple.t_len;
sz += newlen;
}
break;
}
case REORDER_BUFFER_CHANGE_MESSAGE:
{
Size prefix_size = strlen(change->data.msg.prefix) + 1;
sz += prefix_size + change->data.msg.message_size +
sizeof(Size) + sizeof(Size);
break;
}
case REORDER_BUFFER_CHANGE_INVALIDATION:
{
sz += sizeof(SharedInvalidationMessage) *
change->data.inval.ninvalidations;
break;
}
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
{
Snapshot snap;
snap = change->data.snapshot;
sz += sizeof(SnapshotData) +
sizeof(TransactionId) * snap->xcnt +
sizeof(TransactionId) * snap->subxcnt;
break;
}
case REORDER_BUFFER_CHANGE_TRUNCATE:
{
sz += sizeof(Oid) * change->data.truncate.nrelids;
break;
}
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
/* ReorderBufferChange contains everything important */
break;
}
return sz;
}
/*
* Restore a number of changes spilled to disk back into memory.
*/
static Size
ReorderBufferRestoreChanges(ReorderBuffer *rb, ReorderBufferTXN *txn,
TXNEntryFile *file, XLogSegNo *segno)
{
Size restored = 0;
XLogSegNo last_segno;
dlist_mutable_iter cleanup_iter;
File *fd = &file->vfd;
Assert(txn->first_lsn != InvalidXLogRecPtr);
Assert(txn->final_lsn != InvalidXLogRecPtr);
/* free current entries, so we have memory for more */
dlist_foreach_modify(cleanup_iter, &txn->changes)
{
ReorderBufferChange *cleanup =
dlist_container(ReorderBufferChange, node, cleanup_iter.cur);
dlist_delete(&cleanup->node);
ReorderBufferReturnChange(rb, cleanup, true);
}
txn->nentries_mem = 0;
Assert(dlist_is_empty(&txn->changes));
XLByteToSeg(txn->final_lsn, last_segno, wal_segment_size);
while (restored < max_changes_in_memory && *segno <= last_segno)
{
int readBytes;
ReorderBufferDiskChange *ondisk;
if (*fd == -1)
{
char path[MAXPGPATH];
/* first time in */
if (*segno == 0)
XLByteToSeg(txn->first_lsn, *segno, wal_segment_size);
Assert(*segno != 0 || dlist_is_empty(&txn->changes));
/*
* No need to care about TLIs here, only used during a single run,
* so each LSN only maps to a specific WAL record.
*/
ReorderBufferSerializedPath(path, MyReplicationSlot, txn->xid,
*segno);
*fd = PathNameOpenFile(path, O_RDONLY | PG_BINARY);
/* No harm in resetting the offset even in case of failure */
file->curOffset = 0;
if (*fd < 0 && errno == ENOENT)
{
*fd = -1;
(*segno)++;
continue;
}
else if (*fd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m",
path)));
}
/*
* Read the statically sized part of a change which has information
* about the total size. If we couldn't read a record, we're at the
* end of this file.
*/
ReorderBufferSerializeReserve(rb, sizeof(ReorderBufferDiskChange));
readBytes = FileRead(file->vfd, rb->outbuf,
sizeof(ReorderBufferDiskChange),
file->curOffset, WAIT_EVENT_REORDER_BUFFER_READ);
/* eof */
if (readBytes == 0)
{
FileClose(*fd);
*fd = -1;
(*segno)++;
continue;
}
else if (readBytes < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from reorderbuffer spill file: %m")));
else if (readBytes != sizeof(ReorderBufferDiskChange))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from reorderbuffer spill file: read %d instead of %u bytes",
readBytes,
(uint32) sizeof(ReorderBufferDiskChange))));
file->curOffset += readBytes;
ondisk = (ReorderBufferDiskChange *) rb->outbuf;
ReorderBufferSerializeReserve(rb,
sizeof(ReorderBufferDiskChange) + ondisk->size);
ondisk = (ReorderBufferDiskChange *) rb->outbuf;
readBytes = FileRead(file->vfd,
rb->outbuf + sizeof(ReorderBufferDiskChange),
ondisk->size - sizeof(ReorderBufferDiskChange),
file->curOffset,
WAIT_EVENT_REORDER_BUFFER_READ);
if (readBytes < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from reorderbuffer spill file: %m")));
else if (readBytes != ondisk->size - sizeof(ReorderBufferDiskChange))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from reorderbuffer spill file: read %d instead of %u bytes",
readBytes,
(uint32) (ondisk->size - sizeof(ReorderBufferDiskChange)))));
file->curOffset += readBytes;
/*
* ok, read a full change from disk, now restore it into proper
* in-memory format
*/
ReorderBufferRestoreChange(rb, txn, rb->outbuf);
restored++;
}
return restored;
}
/*
* Convert change from its on-disk format to in-memory format and queue it onto
* the TXN's ->changes list.
*
* Note: although "data" is declared char*, at entry it points to a
* maxalign'd buffer, making it safe in most of this function to assume
* that the pointed-to data is suitably aligned for direct access.
*/
static void
ReorderBufferRestoreChange(ReorderBuffer *rb, ReorderBufferTXN *txn,
char *data)
{
ReorderBufferDiskChange *ondisk;
ReorderBufferChange *change;
ondisk = (ReorderBufferDiskChange *) data;
change = ReorderBufferGetChange(rb);
/* copy static part */
memcpy(change, &ondisk->change, sizeof(ReorderBufferChange));
data += sizeof(ReorderBufferDiskChange);
/* restore individual stuff */
switch (change->action)
{
/* fall through these, they're all similar enough */
case REORDER_BUFFER_CHANGE_INSERT:
case REORDER_BUFFER_CHANGE_UPDATE:
case REORDER_BUFFER_CHANGE_DELETE:
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT:
if (change->data.tp.oldtuple)
{
uint32 tuplelen = ((HeapTuple) data)->t_len;
change->data.tp.oldtuple =
ReorderBufferGetTupleBuf(rb, tuplelen - SizeofHeapTupleHeader);
/* restore ->tuple */
memcpy(&change->data.tp.oldtuple->tuple, data,
sizeof(HeapTupleData));
data += sizeof(HeapTupleData);
/* reset t_data pointer into the new tuplebuf */
change->data.tp.oldtuple->tuple.t_data =
ReorderBufferTupleBufData(change->data.tp.oldtuple);
/* restore tuple data itself */
memcpy(change->data.tp.oldtuple->tuple.t_data, data, tuplelen);
data += tuplelen;
}
if (change->data.tp.newtuple)
{
/* here, data might not be suitably aligned! */
uint32 tuplelen;
memcpy(&tuplelen, data + offsetof(HeapTupleData, t_len),
sizeof(uint32));
change->data.tp.newtuple =
ReorderBufferGetTupleBuf(rb, tuplelen - SizeofHeapTupleHeader);
/* restore ->tuple */
memcpy(&change->data.tp.newtuple->tuple, data,
sizeof(HeapTupleData));
data += sizeof(HeapTupleData);
/* reset t_data pointer into the new tuplebuf */
change->data.tp.newtuple->tuple.t_data =
ReorderBufferTupleBufData(change->data.tp.newtuple);
/* restore tuple data itself */
memcpy(change->data.tp.newtuple->tuple.t_data, data, tuplelen);
data += tuplelen;
}
break;
case REORDER_BUFFER_CHANGE_MESSAGE:
{
Size prefix_size;
/* read prefix */
memcpy(&prefix_size, data, sizeof(Size));
data += sizeof(Size);
change->data.msg.prefix = MemoryContextAlloc(rb->context,
prefix_size);
memcpy(change->data.msg.prefix, data, prefix_size);
Assert(change->data.msg.prefix[prefix_size - 1] == '\0');
data += prefix_size;
/* read the message */
memcpy(&change->data.msg.message_size, data, sizeof(Size));
data += sizeof(Size);
change->data.msg.message = MemoryContextAlloc(rb->context,
change->data.msg.message_size);
memcpy(change->data.msg.message, data,
change->data.msg.message_size);
data += change->data.msg.message_size;
break;
}
case REORDER_BUFFER_CHANGE_INVALIDATION:
{
Size inval_size = sizeof(SharedInvalidationMessage) *
change->data.inval.ninvalidations;
change->data.inval.invalidations =
MemoryContextAlloc(rb->context, inval_size);
/* read the message */
memcpy(change->data.inval.invalidations, data, inval_size);
break;
}
case REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT:
{
Snapshot oldsnap;
Snapshot newsnap;
Size size;
oldsnap = (Snapshot) data;
size = sizeof(SnapshotData) +
sizeof(TransactionId) * oldsnap->xcnt +
sizeof(TransactionId) * (oldsnap->subxcnt + 0);
change->data.snapshot = MemoryContextAllocZero(rb->context, size);
newsnap = change->data.snapshot;
memcpy(newsnap, data, size);
newsnap->xip = (TransactionId *)
(((char *) newsnap) + sizeof(SnapshotData));
newsnap->subxip = newsnap->xip + newsnap->xcnt;
newsnap->copied = true;
break;
}
/* the base struct contains all the data, easy peasy */
case REORDER_BUFFER_CHANGE_TRUNCATE:
{
Oid *relids;
relids = ReorderBufferGetRelids(rb,
change->data.truncate.nrelids);
memcpy(relids, data, change->data.truncate.nrelids * sizeof(Oid));
change->data.truncate.relids = relids;
break;
}
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM:
case REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT:
case REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID:
case REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID:
break;
}
dlist_push_tail(&txn->changes, &change->node);
txn->nentries_mem++;
/*
* Update memory accounting for the restored change. We need to do this
* although we don't check the memory limit when restoring the changes in
* this branch (we only do that when initially queueing the changes after
* decoding), because we will release the changes later, and that will
* update the accounting too (subtracting the size from the counters). And
* we don't want to underflow there.
*/
ReorderBufferChangeMemoryUpdate(rb, change, true,
ReorderBufferChangeSize(change));
}
/*
* Remove all on-disk stored for the passed in transaction.
*/
static void
ReorderBufferRestoreCleanup(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
XLogSegNo first;
XLogSegNo cur;
XLogSegNo last;
Assert(txn->first_lsn != InvalidXLogRecPtr);
Assert(txn->final_lsn != InvalidXLogRecPtr);
XLByteToSeg(txn->first_lsn, first, wal_segment_size);
XLByteToSeg(txn->final_lsn, last, wal_segment_size);
/* iterate over all possible filenames, and delete them */
for (cur = first; cur <= last; cur++)
{
char path[MAXPGPATH];
ReorderBufferSerializedPath(path, MyReplicationSlot, txn->xid, cur);
if (unlink(path) != 0 && errno != ENOENT)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m", path)));
}
}
/*
* Remove any leftover serialized reorder buffers from a slot directory after a
* prior crash or decoding session exit.
*/
static void
ReorderBufferCleanupSerializedTXNs(const char *slotname)
{
DIR *spill_dir;
struct dirent *spill_de;
struct stat statbuf;
char path[MAXPGPATH * 2 + 12];
sprintf(path, "pg_replslot/%s", slotname);
/* we're only handling directories here, skip if it's not ours */
if (lstat(path, &statbuf) == 0 && !S_ISDIR(statbuf.st_mode))
return;
spill_dir = AllocateDir(path);
while ((spill_de = ReadDirExtended(spill_dir, path, INFO)) != NULL)
{
/* only look at names that can be ours */
if (strncmp(spill_de->d_name, "xid", 3) == 0)
{
snprintf(path, sizeof(path),
"pg_replslot/%s/%s", slotname,
spill_de->d_name);
if (unlink(path) != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\" during removal of pg_replslot/%s/xid*: %m",
path, slotname)));
}
}
FreeDir(spill_dir);
}
/*
* Given a replication slot, transaction ID and segment number, fill in the
* corresponding spill file into 'path', which is a caller-owned buffer of size
* at least MAXPGPATH.
*/
static void
ReorderBufferSerializedPath(char *path, ReplicationSlot *slot, TransactionId xid,
XLogSegNo segno)
{
XLogRecPtr recptr;
XLogSegNoOffsetToRecPtr(segno, 0, wal_segment_size, recptr);
snprintf(path, MAXPGPATH, "pg_replslot/%s/xid-%u-lsn-%X-%X.spill",
NameStr(MyReplicationSlot->data.name),
xid, LSN_FORMAT_ARGS(recptr));
}
/*
* Delete all data spilled to disk after we've restarted/crashed. It will be
* recreated when the respective slots are reused.
*/
void
StartupReorderBuffer(void)
{
DIR *logical_dir;
struct dirent *logical_de;
logical_dir = AllocateDir("pg_replslot");
while ((logical_de = ReadDir(logical_dir, "pg_replslot")) != NULL)
{
if (strcmp(logical_de->d_name, ".") == 0 ||
strcmp(logical_de->d_name, "..") == 0)
continue;
/* if it cannot be a slot, skip the directory */
if (!ReplicationSlotValidateName(logical_de->d_name, DEBUG2))
continue;
/*
* ok, has to be a surviving logical slot, iterate and delete
* everything starting with xid-*
*/
ReorderBufferCleanupSerializedTXNs(logical_de->d_name);
}
FreeDir(logical_dir);
}
/* ---------------------------------------
* toast reassembly support
* ---------------------------------------
*/
/*
* Initialize per tuple toast reconstruction support.
*/
static void
ReorderBufferToastInitHash(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
HASHCTL hash_ctl;
Assert(txn->toast_hash == NULL);
hash_ctl.keysize = sizeof(Oid);
hash_ctl.entrysize = sizeof(ReorderBufferToastEnt);
hash_ctl.hcxt = rb->context;
txn->toast_hash = hash_create("ReorderBufferToastHash", 5, &hash_ctl,
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
}
/*
* Per toast-chunk handling for toast reconstruction
*
* Appends a toast chunk so we can reconstruct it when the tuple "owning" the
* toasted Datum comes along.
*/
static void
ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change)
{
ReorderBufferToastEnt *ent;
ReorderBufferTupleBuf *newtup;
bool found;
int32 chunksize;
bool isnull;
Pointer chunk;
TupleDesc desc = RelationGetDescr(relation);
Oid chunk_id;
int32 chunk_seq;
if (txn->toast_hash == NULL)
ReorderBufferToastInitHash(rb, txn);
Assert(IsToastRelation(relation));
newtup = change->data.tp.newtuple;
chunk_id = DatumGetObjectId(fastgetattr(&newtup->tuple, 1, desc, &isnull));
Assert(!isnull);
chunk_seq = DatumGetInt32(fastgetattr(&newtup->tuple, 2, desc, &isnull));
Assert(!isnull);
ent = (ReorderBufferToastEnt *)
hash_search(txn->toast_hash,
(void *) &chunk_id,
HASH_ENTER,
&found);
if (!found)
{
Assert(ent->chunk_id == chunk_id);
ent->num_chunks = 0;
ent->last_chunk_seq = 0;
ent->size = 0;
ent->reconstructed = NULL;
dlist_init(&ent->chunks);
if (chunk_seq != 0)
elog(ERROR, "got sequence entry %d for toast chunk %u instead of seq 0",
chunk_seq, chunk_id);
}
else if (found && chunk_seq != ent->last_chunk_seq + 1)
elog(ERROR, "got sequence entry %d for toast chunk %u instead of seq %d",
chunk_seq, chunk_id, ent->last_chunk_seq + 1);
chunk = DatumGetPointer(fastgetattr(&newtup->tuple, 3, desc, &isnull));
Assert(!isnull);
/* calculate size so we can allocate the right size at once later */
if (!VARATT_IS_EXTENDED(chunk))
chunksize = VARSIZE(chunk) - VARHDRSZ;
else if (VARATT_IS_SHORT(chunk))
/* could happen due to heap_form_tuple doing its thing */
chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
else
elog(ERROR, "unexpected type of toast chunk");
ent->size += chunksize;
ent->last_chunk_seq = chunk_seq;
ent->num_chunks++;
dlist_push_tail(&ent->chunks, &change->node);
}
/*
* Rejigger change->newtuple to point to in-memory toast tuples instead to
* on-disk toast tuples that may not longer exist (think DROP TABLE or VACUUM).
*
* We cannot replace unchanged toast tuples though, so those will still point
* to on-disk toast data.
*
* While updating the existing change with detoasted tuple data, we need to
* update the memory accounting info, because the change size will differ.
* Otherwise the accounting may get out of sync, triggering serialization
* at unexpected times.
*
* We simply subtract size of the change before rejiggering the tuple, and
* then adding the new size. This makes it look like the change was removed
* and then added back, except it only tweaks the accounting info.
*
* In particular it can't trigger serialization, which would be pointless
* anyway as it happens during commit processing right before handing
* the change to the output plugin.
*/
static void
ReorderBufferToastReplace(ReorderBuffer *rb, ReorderBufferTXN *txn,
Relation relation, ReorderBufferChange *change)
{
TupleDesc desc;
int natt;
Datum *attrs;
bool *isnull;
bool *free;
HeapTuple tmphtup;
Relation toast_rel;
TupleDesc toast_desc;
MemoryContext oldcontext;
ReorderBufferTupleBuf *newtup;
Size old_size;
/* no toast tuples changed */
if (txn->toast_hash == NULL)
return;
/*
* We're going to modify the size of the change. So, to make sure the
* accounting is correct we record the current change size and then after
* re-computing the change we'll subtract the recorded size and then
* re-add the new change size at the end. We don't immediately subtract
* the old size because if there is any error before we add the new size,
* we will release the changes and that will update the accounting info
* (subtracting the size from the counters). And we don't want to
* underflow there.
*/
old_size = ReorderBufferChangeSize(change);
oldcontext = MemoryContextSwitchTo(rb->context);
/* we should only have toast tuples in an INSERT or UPDATE */
Assert(change->data.tp.newtuple);
desc = RelationGetDescr(relation);
toast_rel = RelationIdGetRelation(relation->rd_rel->reltoastrelid);
if (!RelationIsValid(toast_rel))
elog(ERROR, "could not open toast relation with OID %u (base relation \"%s\")",
relation->rd_rel->reltoastrelid, RelationGetRelationName(relation));
toast_desc = RelationGetDescr(toast_rel);
/* should we allocate from stack instead? */
attrs = palloc0(sizeof(Datum) * desc->natts);
isnull = palloc0(sizeof(bool) * desc->natts);
free = palloc0(sizeof(bool) * desc->natts);
newtup = change->data.tp.newtuple;
heap_deform_tuple(&newtup->tuple, desc, attrs, isnull);
for (natt = 0; natt < desc->natts; natt++)
{
Form_pg_attribute attr = TupleDescAttr(desc, natt);
ReorderBufferToastEnt *ent;
struct varlena *varlena;
/* va_rawsize is the size of the original datum -- including header */
struct varatt_external toast_pointer;
struct varatt_indirect redirect_pointer;
struct varlena *new_datum = NULL;
struct varlena *reconstructed;
dlist_iter it;
Size data_done = 0;
/* system columns aren't toasted */
if (attr->attnum < 0)
continue;
if (attr->attisdropped)
continue;
/* not a varlena datatype */
if (attr->attlen != -1)
continue;
/* no data */
if (isnull[natt])
continue;
/* ok, we know we have a toast datum */
varlena = (struct varlena *) DatumGetPointer(attrs[natt]);
/* no need to do anything if the tuple isn't external */
if (!VARATT_IS_EXTERNAL(varlena))
continue;
VARATT_EXTERNAL_GET_POINTER(toast_pointer, varlena);
/*
* Check whether the toast tuple changed, replace if so.
*/
ent = (ReorderBufferToastEnt *)
hash_search(txn->toast_hash,
(void *) &toast_pointer.va_valueid,
HASH_FIND,
NULL);
if (ent == NULL)
continue;
new_datum =
(struct varlena *) palloc0(INDIRECT_POINTER_SIZE);
free[natt] = true;
reconstructed = palloc0(toast_pointer.va_rawsize);
ent->reconstructed = reconstructed;
/* stitch toast tuple back together from its parts */
dlist_foreach(it, &ent->chunks)
{
bool isnull;
ReorderBufferChange *cchange;
ReorderBufferTupleBuf *ctup;
Pointer chunk;
cchange = dlist_container(ReorderBufferChange, node, it.cur);
ctup = cchange->data.tp.newtuple;
chunk = DatumGetPointer(fastgetattr(&ctup->tuple, 3, toast_desc, &isnull));
Assert(!isnull);
Assert(!VARATT_IS_EXTERNAL(chunk));
Assert(!VARATT_IS_SHORT(chunk));
memcpy(VARDATA(reconstructed) + data_done,
VARDATA(chunk),
VARSIZE(chunk) - VARHDRSZ);
data_done += VARSIZE(chunk) - VARHDRSZ;
}
Assert(data_done == VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer));
/* make sure its marked as compressed or not */
if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
SET_VARSIZE_COMPRESSED(reconstructed, data_done + VARHDRSZ);
else
SET_VARSIZE(reconstructed, data_done + VARHDRSZ);
memset(&redirect_pointer, 0, sizeof(redirect_pointer));
redirect_pointer.pointer = reconstructed;
SET_VARTAG_EXTERNAL(new_datum, VARTAG_INDIRECT);
memcpy(VARDATA_EXTERNAL(new_datum), &redirect_pointer,
sizeof(redirect_pointer));
attrs[natt] = PointerGetDatum(new_datum);
}
/*
* Build tuple in separate memory & copy tuple back into the tuplebuf
* passed to the output plugin. We can't directly heap_fill_tuple() into
* the tuplebuf because attrs[] will point back into the current content.
*/
tmphtup = heap_form_tuple(desc, attrs, isnull);
Assert(newtup->tuple.t_len <= MaxHeapTupleSize);
Assert(ReorderBufferTupleBufData(newtup) == newtup->tuple.t_data);
memcpy(newtup->tuple.t_data, tmphtup->t_data, tmphtup->t_len);
newtup->tuple.t_len = tmphtup->t_len;
/*
* free resources we won't further need, more persistent stuff will be
* free'd in ReorderBufferToastReset().
*/
RelationClose(toast_rel);
pfree(tmphtup);
for (natt = 0; natt < desc->natts; natt++)
{
if (free[natt])
pfree(DatumGetPointer(attrs[natt]));
}
pfree(attrs);
pfree(free);
pfree(isnull);
MemoryContextSwitchTo(oldcontext);
/* subtract the old change size */
ReorderBufferChangeMemoryUpdate(rb, change, false, old_size);
/* now add the change back, with the correct size */
ReorderBufferChangeMemoryUpdate(rb, change, true,
ReorderBufferChangeSize(change));
}
/*
* Free all resources allocated for toast reconstruction.
*/
static void
ReorderBufferToastReset(ReorderBuffer *rb, ReorderBufferTXN *txn)
{
HASH_SEQ_STATUS hstat;
ReorderBufferToastEnt *ent;
if (txn->toast_hash == NULL)
return;
/* sequentially walk over the hash and free everything */
hash_seq_init(&hstat, txn->toast_hash);
while ((ent = (ReorderBufferToastEnt *) hash_seq_search(&hstat)) != NULL)
{
dlist_mutable_iter it;
if (ent->reconstructed != NULL)
pfree(ent->reconstructed);
dlist_foreach_modify(it, &ent->chunks)
{
ReorderBufferChange *change =
dlist_container(ReorderBufferChange, node, it.cur);
dlist_delete(&change->node);
ReorderBufferReturnChange(rb, change, true);
}
}
hash_destroy(txn->toast_hash);
txn->toast_hash = NULL;
}
/* ---------------------------------------
* Visibility support for logical decoding
*
*
* Lookup actual cmin/cmax values when using decoding snapshot. We can't
* always rely on stored cmin/cmax values because of two scenarios:
*
* * A tuple got changed multiple times during a single transaction and thus
* has got a combo CID. Combo CIDs are only valid for the duration of a
* single transaction.
* * A tuple with a cmin but no cmax (and thus no combo CID) got
* deleted/updated in another transaction than the one which created it
* which we are looking at right now. As only one of cmin, cmax or combo CID
* is actually stored in the heap we don't have access to the value we
* need anymore.
*
* To resolve those problems we have a per-transaction hash of (cmin,
* cmax) tuples keyed by (relfilenode, ctid) which contains the actual
* (cmin, cmax) values. That also takes care of combo CIDs by simply
* not caring about them at all. As we have the real cmin/cmax values
* combo CIDs aren't interesting.
*
* As we only care about catalog tuples here the overhead of this
* hashtable should be acceptable.
*
* Heap rewrites complicate this a bit, check rewriteheap.c for
* details.
* -------------------------------------------------------------------------
*/
/* struct for sorting mapping files by LSN efficiently */
typedef struct RewriteMappingFile
{
XLogRecPtr lsn;
char fname[MAXPGPATH];
} RewriteMappingFile;
#ifdef NOT_USED
static void
DisplayMapping(HTAB *tuplecid_data)
{
HASH_SEQ_STATUS hstat;
ReorderBufferTupleCidEnt *ent;
hash_seq_init(&hstat, tuplecid_data);
while ((ent = (ReorderBufferTupleCidEnt *) hash_seq_search(&hstat)) != NULL)
{
elog(DEBUG3, "mapping: node: %u/%u/%u tid: %u/%u cmin: %u, cmax: %u",
ent->key.relnode.dbNode,
ent->key.relnode.spcNode,
ent->key.relnode.relNode,
ItemPointerGetBlockNumber(&ent->key.tid),
ItemPointerGetOffsetNumber(&ent->key.tid),
ent->cmin,
ent->cmax
);
}
}
#endif
/*
* Apply a single mapping file to tuplecid_data.
*
* The mapping file has to have been verified to be a) committed b) for our
* transaction c) applied in LSN order.
*/
static void
ApplyLogicalMappingFile(HTAB *tuplecid_data, Oid relid, const char *fname)
{
char path[MAXPGPATH];
int fd;
int readBytes;
LogicalRewriteMappingData map;
sprintf(path, "pg_logical/mappings/%s", fname);
fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
if (fd < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", path)));
while (true)
{
ReorderBufferTupleCidKey key;
ReorderBufferTupleCidEnt *ent;
ReorderBufferTupleCidEnt *new_ent;
bool found;
/* be careful about padding */
memset(&key, 0, sizeof(ReorderBufferTupleCidKey));
/* read all mappings till the end of the file */
pgstat_report_wait_start(WAIT_EVENT_REORDER_LOGICAL_MAPPING_READ);
readBytes = read(fd, &map, sizeof(LogicalRewriteMappingData));
pgstat_report_wait_end();
if (readBytes < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read file \"%s\": %m",
path)));
else if (readBytes == 0) /* EOF */
break;
else if (readBytes != sizeof(LogicalRewriteMappingData))
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from file \"%s\": read %d instead of %d bytes",
path, readBytes,
(int32) sizeof(LogicalRewriteMappingData))));
key.relnode = map.old_node;
ItemPointerCopy(&map.old_tid,
&key.tid);
ent = (ReorderBufferTupleCidEnt *)
hash_search(tuplecid_data,
(void *) &key,
HASH_FIND,
NULL);
/* no existing mapping, no need to update */
if (!ent)
continue;
key.relnode = map.new_node;
ItemPointerCopy(&map.new_tid,
&key.tid);
new_ent = (ReorderBufferTupleCidEnt *)
hash_search(tuplecid_data,
(void *) &key,
HASH_ENTER,
&found);
if (found)
{
/*
* Make sure the existing mapping makes sense. We sometime update
* old records that did not yet have a cmax (e.g. pg_class' own
* entry while rewriting it) during rewrites, so allow that.
*/
Assert(ent->cmin == InvalidCommandId || ent->cmin == new_ent->cmin);
Assert(ent->cmax == InvalidCommandId || ent->cmax == new_ent->cmax);
}
else
{
/* update mapping */
new_ent->cmin = ent->cmin;
new_ent->cmax = ent->cmax;
new_ent->combocid = ent->combocid;
}
}
if (CloseTransientFile(fd) != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", path)));
}
/*
* Check whether the TransactionId 'xid' is in the pre-sorted array 'xip'.
*/
static bool
TransactionIdInArray(TransactionId xid, TransactionId *xip, Size num)
{
return bsearch(&xid, xip, num,
sizeof(TransactionId), xidComparator) != NULL;
}
/*
* list_sort() comparator for sorting RewriteMappingFiles in LSN order.
*/
static int
file_sort_by_lsn(const ListCell *a_p, const ListCell *b_p)
{
RewriteMappingFile *a = (RewriteMappingFile *) lfirst(a_p);
RewriteMappingFile *b = (RewriteMappingFile *) lfirst(b_p);
if (a->lsn < b->lsn)
return -1;
else if (a->lsn > b->lsn)
return 1;
return 0;
}
/*
* Apply any existing logical remapping files if there are any targeted at our
* transaction for relid.
*/
static void
UpdateLogicalMappings(HTAB *tuplecid_data, Oid relid, Snapshot snapshot)
{
DIR *mapping_dir;
struct dirent *mapping_de;
List *files = NIL;
ListCell *file;
Oid dboid = IsSharedRelation(relid) ? InvalidOid : MyDatabaseId;
mapping_dir = AllocateDir("pg_logical/mappings");
while ((mapping_de = ReadDir(mapping_dir, "pg_logical/mappings")) != NULL)
{
Oid f_dboid;
Oid f_relid;
TransactionId f_mapped_xid;
TransactionId f_create_xid;
XLogRecPtr f_lsn;
uint32 f_hi,
f_lo;
RewriteMappingFile *f;
if (strcmp(mapping_de->d_name, ".") == 0 ||
strcmp(mapping_de->d_name, "..") == 0)
continue;
/* Ignore files that aren't ours */
if (strncmp(mapping_de->d_name, "map-", 4) != 0)
continue;
if (sscanf(mapping_de->d_name, LOGICAL_REWRITE_FORMAT,
&f_dboid, &f_relid, &f_hi, &f_lo,
&f_mapped_xid, &f_create_xid) != 6)
elog(ERROR, "could not parse filename \"%s\"", mapping_de->d_name);
f_lsn = ((uint64) f_hi) << 32 | f_lo;
/* mapping for another database */
if (f_dboid != dboid)
continue;
/* mapping for another relation */
if (f_relid != relid)
continue;
/* did the creating transaction abort? */
if (!TransactionIdDidCommit(f_create_xid))
continue;
/* not for our transaction */
if (!TransactionIdInArray(f_mapped_xid, snapshot->subxip, snapshot->subxcnt))
continue;
/* ok, relevant, queue for apply */
f = palloc(sizeof(RewriteMappingFile));
f->lsn = f_lsn;
strcpy(f->fname, mapping_de->d_name);
files = lappend(files, f);
}
FreeDir(mapping_dir);
/* sort files so we apply them in LSN order */
list_sort(files, file_sort_by_lsn);
foreach(file, files)
{
RewriteMappingFile *f = (RewriteMappingFile *) lfirst(file);
elog(DEBUG1, "applying mapping: \"%s\" in %u", f->fname,
snapshot->subxip[0]);
ApplyLogicalMappingFile(tuplecid_data, relid, f->fname);
pfree(f);
}
}
/*
* Lookup cmin/cmax of a tuple, during logical decoding where we can't rely on
* combo CIDs.
*/
bool
ResolveCminCmaxDuringDecoding(HTAB *tuplecid_data,
Snapshot snapshot,
HeapTuple htup, Buffer buffer,
CommandId *cmin, CommandId *cmax)
{
ReorderBufferTupleCidKey key;
ReorderBufferTupleCidEnt *ent;
ForkNumber forkno;
BlockNumber blockno;
bool updated_mapping = false;
/*
* Return unresolved if tuplecid_data is not valid. That's because when
* streaming in-progress transactions we may run into tuples with the CID
* before actually decoding them. Think e.g. about INSERT followed by
* TRUNCATE, where the TRUNCATE may not be decoded yet when applying the
* INSERT. So in such cases, we assume the CID is from the future
* command.
*/
if (tuplecid_data == NULL)
return false;
/* be careful about padding */
memset(&key, 0, sizeof(key));
Assert(!BufferIsLocal(buffer));
/*
* get relfilenode from the buffer, no convenient way to access it other
* than that.
*/
BufferGetTag(buffer, &key.relnode, &forkno, &blockno);
/* tuples can only be in the main fork */
Assert(forkno == MAIN_FORKNUM);
Assert(blockno == ItemPointerGetBlockNumber(&htup->t_self));
ItemPointerCopy(&htup->t_self,
&key.tid);
restart:
ent = (ReorderBufferTupleCidEnt *)
hash_search(tuplecid_data,
(void *) &key,
HASH_FIND,
NULL);
/*
* failed to find a mapping, check whether the table was rewritten and
* apply mapping if so, but only do that once - there can be no new
* mappings while we are in here since we have to hold a lock on the
* relation.
*/
if (ent == NULL && !updated_mapping)
{
UpdateLogicalMappings(tuplecid_data, htup->t_tableOid, snapshot);
/* now check but don't update for a mapping again */
updated_mapping = true;
goto restart;
}
else if (ent == NULL)
return false;
if (cmin)
*cmin = ent->cmin;
if (cmax)
*cmax = ent->cmax;
return true;
}