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apache / cloudberry / refs/heads/cbdb-postgres-merge / . / src / backend / storage / file / fd.c
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/*-------------------------------------------------------------------------
*
* fd.c
* Virtual file descriptor code.
*
* Portions Copyright (c) 2007-2009, Greenplum inc
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/storage/file/fd.c
*
* NOTES:
*
* This code manages a cache of 'virtual' file descriptors (VFDs).
* The server opens many file descriptors for a variety of reasons,
* including base tables, scratch files (e.g., sort and hash spool
* files), and random calls to C library routines like system(3); it
* is quite easy to exceed system limits on the number of open files a
* single process can have. (This is around 1024 on many modern
* operating systems, but may be lower on others.)
*
* VFDs are managed as an LRU pool, with actual OS file descriptors
* being opened and closed as needed. Obviously, if a routine is
* opened using these interfaces, all subsequent operations must also
* be through these interfaces (the File type is not a real file
* descriptor).
*
* For this scheme to work, most (if not all) routines throughout the
* server should use these interfaces instead of calling the C library
* routines (e.g., open(2) and fopen(3)) themselves. Otherwise, we
* may find ourselves short of real file descriptors anyway.
*
* INTERFACE ROUTINES
*
* PathNameOpenFile and OpenTemporaryFile are used to open virtual files.
* A File opened with OpenTemporaryFile is automatically deleted when the
* File is closed, either explicitly or implicitly at end of transaction or
* process exit. PathNameOpenFile is intended for files that are held open
* for a long time, like relation files. It is the caller's responsibility
* to close them, there is no automatic mechanism in fd.c for that.
*
* PathName(Create|Open|Delete)Temporary(File|Dir) are used to manage
* temporary files that have names so that they can be shared between
* backends. Such files are automatically closed and count against the
* temporary file limit of the backend that creates them, but unlike anonymous
* files they are not automatically deleted. See sharedfileset.c for a shared
* ownership mechanism that provides automatic cleanup for shared files when
* the last of a group of backends detaches.
*
* AllocateFile, AllocateDir, OpenPipeStream and OpenTransientFile are
* wrappers around fopen(3), opendir(3), popen(3) and open(2), respectively.
* They behave like the corresponding native functions, except that the handle
* is registered with the current subtransaction, and will be automatically
* closed at abort. These are intended mainly for short operations like
* reading a configuration file; there is a limit on the number of files that
* can be opened using these functions at any one time.
*
* Finally, BasicOpenFile is just a thin wrapper around open() that can
* release file descriptors in use by the virtual file descriptors if
* necessary. There is no automatic cleanup of file descriptors returned by
* BasicOpenFile, it is solely the caller's responsibility to close the file
* descriptor by calling close(2).
*
* If a non-virtual file descriptor needs to be held open for any length of
* time, report it to fd.c by calling AcquireExternalFD or ReserveExternalFD
* (and eventually ReleaseExternalFD), so that we can take it into account
* while deciding how many VFDs can be open. This applies to FDs obtained
* with BasicOpenFile as well as those obtained without use of any fd.c API.
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <dirent.h>
#include <sys/file.h>
#include <sys/param.h>
#include <sys/resource.h> /* for getrlimit */
#include <sys/stat.h>
#include <sys/types.h>
#ifndef WIN32
#include <sys/mman.h>
#endif
#include <limits.h>
#include <unistd.h>
#include <fcntl.h>
#include "access/xact.h"
#include "access/xlog.h"
#include "catalog/pg_tablespace.h"
#include "cdb/cdbvars.h"
#include "common/file_perm.h"
#include "common/file_utils.h"
#include "common/pg_prng.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "portability/mem.h"
#include "postmaster/startup.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "utils/guc.h"
#include "utils/guc_hooks.h"
#include "utils/resowner_private.h"
#include "utils/workfile_mgr.h"
#include "utils/faultinjector.h"
#include "utils/varlena.h"
/* Define PG_FLUSH_DATA_WORKS if we have an implementation for pg_flush_data */
#if defined(HAVE_SYNC_FILE_RANGE)
#define PG_FLUSH_DATA_WORKS 1
#elif !defined(WIN32) && defined(MS_ASYNC)
#define PG_FLUSH_DATA_WORKS 1
#elif defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED)
#define PG_FLUSH_DATA_WORKS 1
#endif
/*
* We must leave some file descriptors free for system(), the dynamic loader,
* and other code that tries to open files without consulting fd.c. This
* is the number left free. (While we try fairly hard to prevent EMFILE
* errors, there's never any guarantee that we won't get ENFILE due to
* other processes chewing up FDs. So it's a bad idea to try to open files
* without consulting fd.c. Nonetheless we cannot control all code.)
*
* Because this is just a fixed setting, we are effectively assuming that
* no such code will leave FDs open over the long term; otherwise the slop
* is likely to be insufficient. Note in particular that we expect that
* loading a shared library does not result in any permanent increase in
* the number of open files. (This appears to be true on most if not
* all platforms as of Feb 2004.)
*/
#define NUM_RESERVED_FDS 10
/*
* If we have fewer than this many usable FDs after allowing for the reserved
* ones, choke. (This value is chosen to work with "ulimit -n 64", but not
* much less than that. Note that this value ensures numExternalFDs can be
* at least 16; as of this writing, the contrib/postgres_fdw regression tests
* will not pass unless that can grow to at least 14.)
*/
#define FD_MINFREE 48
/*
* A number of platforms allow individual processes to open many more files
* than they can really support when *many* processes do the same thing.
* This GUC parameter lets the DBA limit max_safe_fds to something less than
* what the postmaster's initial probe suggests will work.
*/
int max_files_per_process = 1000;
/*
* Maximum number of file descriptors to open for operations that fd.c knows
* about (VFDs, AllocateFile etc, or "external" FDs). This is initialized
* to a conservative value, and remains that way indefinitely in bootstrap or
* standalone-backend cases. In normal postmaster operation, the postmaster
* calls set_max_safe_fds() late in initialization to update the value, and
* that value is then inherited by forked subprocesses.
*
* Note: the value of max_files_per_process is taken into account while
* setting this variable, and so need not be tested separately.
*/
int max_safe_fds = FD_MINFREE; /* default if not changed */
/* Whether it is safe to continue running after fsync() fails. */
bool data_sync_retry = false;
/* How SyncDataDirectory() should do its job. */
int recovery_init_sync_method = RECOVERY_INIT_SYNC_METHOD_FSYNC;
/* Which kinds of files should be opened with PG_O_DIRECT. */
int io_direct_flags;
/* Debugging.... */
#ifdef FDDEBUG
#define DO_DB(A) \
do { \
int _do_db_save_errno = errno; \
A; \
errno = _do_db_save_errno; \
} while (0)
#else
#define DO_DB(A) \
((void) 0)
#endif
#define VFD_CLOSED (-1)
#define FileIsValid(file) \
((file) > 0 && (file) < (int) SizeVfdCache && VfdCache[file].fileName != NULL)
#define FileIsNotOpen(file) (VfdCache[file].fd == VFD_CLOSED)
/* these are the assigned bits in fdstate below: */
#define FD_DELETE_AT_CLOSE (1 << 0) /* T = delete when closed */
#define FD_CLOSE_AT_EOXACT (1 << 1) /* T = close at eoXact */
#define FD_TEMP_FILE_LIMIT (1 << 2) /* T = respect temp_file_limit */
/* GPDB private flag */
#define FD_WORKFILE (1 << 3) /* tracked by workfile manager */
typedef struct vfd
{
int fd; /* current FD, or VFD_CLOSED if none */
unsigned short fdstate; /* bitflags for VFD's state */
ResourceOwner resowner; /* owner, for automatic cleanup */
File nextFree; /* link to next free VFD, if in freelist */
File lruMoreRecently; /* doubly linked recency-of-use list */
File lruLessRecently;
off_t fileSize; /* current size of file (0 if not temporary) */
char *fileName; /* name of file, or NULL for unused VFD */
/* NB: fileName is malloc'd, and must be free'd when closing the VFD */
int fileFlags; /* open(2) flags for (re)opening the file */
mode_t fileMode; /* mode to pass to open(2) */
} Vfd;
/*
* Virtual File Descriptor array pointer and size. This grows as
* needed. 'File' values are indexes into this array.
* Note that VfdCache[0] is not a usable VFD, just a list header.
*/
static Vfd *VfdCache;
static Size SizeVfdCache = 0;
/*
* Number of file descriptors known to be in use by VFD entries.
*/
static int nfile = 0;
/*
* Flag to tell whether it's worth scanning VfdCache looking for temp files
* to close
*/
static bool have_xact_temporary_files = false;
/*
* Tracks the total size of all temporary files. Note: when temp_file_limit
* is being enforced, this cannot overflow since the limit cannot be more
* than INT_MAX kilobytes. When not enforcing, it could theoretically
* overflow, but we don't care.
*/
static uint64 temporary_files_size = 0;
/* Temporary file access initialized and not yet shut down? */
#ifdef USE_ASSERT_CHECKING
static bool temporary_files_allowed = false;
#endif
/*
* List of OS handles opened with AllocateFile, AllocateDir and
* OpenTransientFile.
*
* Since we don't want to encourage heavy use of those functions,
* it seems OK to put a pretty small maximum limit on the number of
* simultaneously allocated descs.
*/
typedef enum
{
AllocateDescFile,
AllocateDescPipe,
AllocateDescDir,
AllocateDescRawFD
} AllocateDescKind;
typedef struct
{
AllocateDescKind kind;
SubTransactionId create_subid;
union
{
FILE *file;
DIR *dir;
int fd;
} desc;
} AllocateDesc;
static int numAllocatedDescs = 0;
static int maxAllocatedDescs = 0;
static AllocateDesc *allocatedDescs = NULL;
/*
* Number of open "external" FDs reported to Reserve/ReleaseExternalFD.
*/
static int numExternalFDs = 0;
/*
* Number of temporary files opened during the current session;
* this is used in generation of tempfile names.
*/
static long tempFileCounter = 0;
/*
* Array of OIDs of temp tablespaces. (Some entries may be InvalidOid,
* indicating that the current database's default tablespace should be used.)
* When numTempTableSpaces is -1, this has not been set in the current
* transaction.
*/
static Oid *tempTableSpaces = NULL;
static int numTempTableSpaces = -1;
static int nextTempTableSpace = 0;
/*--------------------
*
* Private Routines
*
* Delete - delete a file from the Lru ring
* LruDelete - remove a file from the Lru ring and close its FD
* Insert - put a file at the front of the Lru ring
* LruInsert - put a file at the front of the Lru ring and open it
* ReleaseLruFile - Release an fd by closing the last entry in the Lru ring
* ReleaseLruFiles - Release fd(s) until we're under the max_safe_fds limit
* AllocateVfd - grab a free (or new) file record (from VfdCache)
* FreeVfd - free a file record
*
* The Least Recently Used ring is a doubly linked list that begins and
* ends on element zero. Element zero is special -- it doesn't represent
* a file and its "fd" field always == VFD_CLOSED. Element zero is just an
* anchor that shows us the beginning/end of the ring.
* Only VFD elements that are currently really open (have an FD assigned) are
* in the Lru ring. Elements that are "virtually" open can be recognized
* by having a non-null fileName field.
*
* example:
*
* /--less----\ /---------\
* v \ v \
* #0 --more---> LeastRecentlyUsed --more-\ \
* ^\ | |
* \\less--> MostRecentlyUsedFile <---/ |
* \more---/ \--less--/
*
*--------------------
*/
static void Delete(File file);
static void LruDelete(File file);
static void Insert(File file);
static int LruInsert(File file);
static bool ReleaseLruFile(void);
static void ReleaseLruFiles(void);
static File AllocateVfd(void);
static void FreeVfd(File file);
static int FileAccess(File file);
static File OpenTemporaryFileInTablespace(Oid tblspcOid, bool rejectError,
const char *filename, bool makenameunique, bool create);
static bool reserveAllocatedDesc(void);
static int FreeDesc(AllocateDesc *desc);
static void BeforeShmemExit_Files(int code, Datum arg);
static void CleanupTempFiles(bool isCommit, bool isProcExit);
static void RemovePgTempRelationFiles(const char *tsdirname);
static void RemovePgTempRelationFilesInDbspace(const char *dbspacedirname);
static void walkdir(const char *path,
void (*action) (const char *fname, bool isdir, int elevel),
bool process_symlinks,
int elevel);
#ifdef PG_FLUSH_DATA_WORKS
static void pre_sync_fname(const char *fname, bool isdir, int elevel);
#endif
static void datadir_fsync_fname(const char *fname, bool isdir, int elevel);
static void unlink_if_exists_fname(const char *fname, bool isdir, int elevel);
static int fsync_parent_path(const char *fname, int elevel);
/*
* pg_fsync --- do fsync with or without writethrough
*/
int
pg_fsync(int fd)
{
#if !defined(WIN32) && defined(USE_ASSERT_CHECKING)
struct stat st;
/*
* Some operating system implementations of fsync() have requirements
* about the file access modes that were used when their file descriptor
* argument was opened, and these requirements differ depending on whether
* the file descriptor is for a directory.
*
* For any file descriptor that may eventually be handed to fsync(), we
* should have opened it with access modes that are compatible with
* fsync() on all supported systems, otherwise the code may not be
* portable, even if it runs ok on the current system.
*
* We assert here that a descriptor for a file was opened with write
* permissions (either O_RDWR or O_WRONLY) and for a directory without
* write permissions (O_RDONLY).
*
* Ignore any fstat errors and let the follow-up fsync() do its work.
* Doing this sanity check here counts for the case where fsync() is
* disabled.
*/
if (fstat(fd, &st) == 0)
{
int desc_flags = fcntl(fd, F_GETFL);
/*
* O_RDONLY is historically 0, so just make sure that for directories
* no write flags are used.
*/
if (S_ISDIR(st.st_mode))
Assert((desc_flags & (O_RDWR | O_WRONLY)) == 0);
else
Assert((desc_flags & (O_RDWR | O_WRONLY)) != 0);
}
errno = 0;
#endif
/* #if is to skip the sync_method test if there's no need for it */
#if defined(HAVE_FSYNC_WRITETHROUGH) && !defined(FSYNC_WRITETHROUGH_IS_FSYNC)
if (sync_method == SYNC_METHOD_FSYNC_WRITETHROUGH)
return pg_fsync_writethrough(fd);
else
#endif
return pg_fsync_no_writethrough(fd);
}
/*
* pg_fsync_no_writethrough --- same as fsync except does nothing if
* enableFsync is off
*/
int
pg_fsync_no_writethrough(int fd)
{
int rc;
if (!enableFsync)
return 0;
retry:
rc = fsync(fd);
if (rc == -1 && errno == EINTR)
goto retry;
return rc;
}
/*
* pg_fsync_writethrough
*/
int
pg_fsync_writethrough(int fd)
{
if (enableFsync)
{
#ifdef WIN32
return _commit(fd);
#elif defined(F_FULLFSYNC)
return (fcntl(fd, F_FULLFSYNC, 0) == -1) ? -1 : 0;
#else
errno = ENOSYS;
return -1;
#endif
}
else
return 0;
}
/*
* pg_fdatasync --- same as fdatasync except does nothing if enableFsync is off
*/
int
pg_fdatasync(int fd)
{
int rc;
if (!enableFsync)
return 0;
retry:
rc = fdatasync(fd);
if (rc == -1 && errno == EINTR)
goto retry;
return rc;
}
/*
* pg_flush_data --- advise OS that the described dirty data should be flushed
*
* offset of 0 with nbytes 0 means that the entire file should be flushed
*/
void
pg_flush_data(int fd, off_t offset, off_t nbytes)
{
/*
* Right now file flushing is primarily used to avoid making later
* fsync()/fdatasync() calls have less impact. Thus don't trigger flushes
* if fsyncs are disabled - that's a decision we might want to make
* configurable at some point.
*/
if (!enableFsync)
return;
/*
* We compile all alternatives that are supported on the current platform,
* to find portability problems more easily.
*/
#if defined(HAVE_SYNC_FILE_RANGE)
{
int rc;
static bool not_implemented_by_kernel = false;
if (not_implemented_by_kernel)
return;
retry:
/*
* sync_file_range(SYNC_FILE_RANGE_WRITE), currently linux specific,
* tells the OS that writeback for the specified blocks should be
* started, but that we don't want to wait for completion. Note that
* this call might block if too much dirty data exists in the range.
* This is the preferable method on OSs supporting it, as it works
* reliably when available (contrast to msync()) and doesn't flush out
* clean data (like FADV_DONTNEED).
*/
rc = sync_file_range(fd, offset, nbytes,
SYNC_FILE_RANGE_WRITE);
if (rc != 0)
{
int elevel;
if (rc == EINTR)
goto retry;
/*
* For systems that don't have an implementation of
* sync_file_range() such as Windows WSL, generate only one
* warning and then suppress all further attempts by this process.
*/
if (errno == ENOSYS)
{
elevel = WARNING;
not_implemented_by_kernel = true;
}
else
elevel = data_sync_elevel(WARNING);
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not flush dirty data: %m")));
}
return;
}
#endif
#if !defined(WIN32) && defined(MS_ASYNC)
{
void *p;
static int pagesize = 0;
/*
* On several OSs msync(MS_ASYNC) on a mmap'ed file triggers
* writeback. On linux it only does so if MS_SYNC is specified, but
* then it does the writeback synchronously. Luckily all common linux
* systems have sync_file_range(). This is preferable over
* FADV_DONTNEED because it doesn't flush out clean data.
*
* We map the file (mmap()), tell the kernel to sync back the contents
* (msync()), and then remove the mapping again (munmap()).
*/
/* mmap() needs actual length if we want to map whole file */
if (offset == 0 && nbytes == 0)
{
nbytes = lseek(fd, 0, SEEK_END);
if (nbytes < 0)
{
ereport(WARNING,
(errcode_for_file_access(),
errmsg("could not determine dirty data size: %m")));
return;
}
}
/*
* Some platforms reject partial-page mmap() attempts. To deal with
* that, just truncate the request to a page boundary. If any extra
* bytes don't get flushed, well, it's only a hint anyway.
*/
/* fetch pagesize only once */
if (pagesize == 0)
pagesize = sysconf(_SC_PAGESIZE);
/* align length to pagesize, dropping any fractional page */
if (pagesize > 0)
nbytes = (nbytes / pagesize) * pagesize;
/* fractional-page request is a no-op */
if (nbytes <= 0)
return;
/*
* mmap could well fail, particularly on 32-bit platforms where there
* may simply not be enough address space. If so, silently fall
* through to the next implementation.
*/
if (nbytes <= (off_t) SSIZE_MAX)
p = mmap(NULL, nbytes, PROT_READ, MAP_SHARED, fd, offset);
else
p = MAP_FAILED;
if (p != MAP_FAILED)
{
int rc;
rc = msync(p, (size_t) nbytes, MS_ASYNC);
if (rc != 0)
{
ereport(data_sync_elevel(WARNING),
(errcode_for_file_access(),
errmsg("could not flush dirty data: %m")));
/* NB: need to fall through to munmap()! */
}
rc = munmap(p, (size_t) nbytes);
if (rc != 0)
{
/* FATAL error because mapping would remain */
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not munmap() while flushing data: %m")));
}
return;
}
}
#endif
#if defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED)
{
int rc;
/*
* Signal the kernel that the passed in range should not be cached
* anymore. This has the, desired, side effect of writing out dirty
* data, and the, undesired, side effect of likely discarding useful
* clean cached blocks. For the latter reason this is the least
* preferable method.
*/
rc = posix_fadvise(fd, offset, nbytes, POSIX_FADV_DONTNEED);
if (rc != 0)
{
/* don't error out, this is just a performance optimization */
ereport(WARNING,
(errcode_for_file_access(),
errmsg("could not flush dirty data: %m")));
}
return;
}
#endif
}
/*
* Retrying close in case it gets interrupted. If that happens, it will cause
* unlink to fail later.
*/
int
gp_retry_close(int fd)
{
int err = 0;
do
{
err = close(fd);
} while (err == -1 && errno == EINTR);
return err;
}
/*
* Truncate an open file to a given length.
*/
static int
pg_ftruncate(int fd, off_t length)
{
int ret;
retry:
ret = ftruncate(fd, length);
if (ret == -1 && errno == EINTR)
goto retry;
return ret;
}
/*
* Truncate a file to a given length by name.
*/
int
pg_truncate(const char *path, off_t length)
{
int ret;
#ifdef WIN32
int save_errno;
int fd;
fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
if (fd >= 0)
{
ret = pg_ftruncate(fd, length);
save_errno = errno;
CloseTransientFile(fd);
errno = save_errno;
}
else
ret = -1;
#else
retry:
ret = truncate(path, length);
if (ret == -1 && errno == EINTR)
goto retry;
#endif
return ret;
}
/*
* fsync_fname -- fsync a file or directory, handling errors properly
*
* Try to fsync a file or directory. When doing the latter, ignore errors that
* indicate the OS just doesn't allow/require fsyncing directories.
*/
void
fsync_fname(const char *fname, bool isdir)
{
fsync_fname_ext(fname, isdir, false, data_sync_elevel(ERROR));
}
/*
* durable_rename -- rename(2) wrapper, issuing fsyncs required for durability
*
* This routine ensures that, after returning, the effect of renaming file
* persists in case of a crash. A crash while this routine is running will
* leave you with either the pre-existing or the moved file in place of the
* new file; no mixed state or truncated files are possible.
*
* It does so by using fsync on the old filename and the possibly existing
* target filename before the rename, and the target file and directory after.
*
* Note that rename() cannot be used across arbitrary directories, as they
* might not be on the same filesystem. Therefore this routine does not
* support renaming across directories.
*
* Log errors with the caller specified severity.
*
* Returns 0 if the operation succeeded, -1 otherwise. Note that errno is not
* valid upon return.
*/
int
durable_rename(const char *oldfile, const char *newfile, int elevel)
{
int fd;
/*
* First fsync the old and target path (if it exists), to ensure that they
* are properly persistent on disk. Syncing the target file is not
* strictly necessary, but it makes it easier to reason about crashes;
* because it's then guaranteed that either source or target file exists
* after a crash.
*/
if (fsync_fname_ext(oldfile, false, false, elevel) != 0)
return -1;
fd = OpenTransientFile(newfile, PG_BINARY | O_RDWR);
if (fd < 0)
{
if (errno != ENOENT)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", newfile)));
return -1;
}
}
else
{
if (pg_fsync(fd) != 0)
{
int save_errno;
/* close file upon error, might not be in transaction context */
save_errno = errno;
CloseTransientFile(fd);
errno = save_errno;
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m", newfile)));
return -1;
}
if (CloseTransientFile(fd) != 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", newfile)));
return -1;
}
}
/* Time to do the real deal... */
if (rename(oldfile, newfile) < 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\": %m",
oldfile, newfile)));
return -1;
}
/*
* To guarantee renaming the file is persistent, fsync the file with its
* new name, and its containing directory.
*/
if (fsync_fname_ext(newfile, false, false, elevel) != 0)
return -1;
if (fsync_parent_path(newfile, elevel) != 0)
return -1;
return 0;
}
/*
* durable_unlink -- remove a file in a durable manner
*
* This routine ensures that, after returning, the effect of removing file
* persists in case of a crash. A crash while this routine is running will
* leave the system in no mixed state.
*
* It does so by using fsync on the parent directory of the file after the
* actual removal is done.
*
* Log errors with the severity specified by caller.
*
* Returns 0 if the operation succeeded, -1 otherwise. Note that errno is not
* valid upon return.
*/
int
durable_unlink(const char *fname, int elevel)
{
if (unlink(fname) < 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m",
fname)));
return -1;
}
/*
* To guarantee that the removal of the file is persistent, fsync its
* parent directory.
*/
if (fsync_parent_path(fname, elevel) != 0)
return -1;
return 0;
}
/*
* durable_rename_excl -- rename a file in a durable manner.
*
* Similar to durable_rename(), except that this routine tries (but does not
* guarantee) not to overwrite the target file.
*
* Note that a crash in an unfortunate moment can leave you with two links to
* the target file.
*
* Log errors with the caller specified severity.
*
* On Windows, using a hard link followed by unlink() causes concurrency
* issues, while a simple rename() does not cause that, so be careful when
* changing the logic of this routine.
*
* Returns 0 if the operation succeeded, -1 otherwise. Note that errno is not
* valid upon return.
*/
int
durable_rename_excl(const char *oldfile, const char *newfile, int elevel)
{
/*
* Ensure that, if we crash directly after the rename/link, a file with
* valid contents is moved into place.
*/
if (fsync_fname_ext(oldfile, false, false, elevel) != 0)
return -1;
#ifdef HAVE_WORKING_LINK
if (link(oldfile, newfile) < 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not link file \"%s\" to \"%s\": %m",
oldfile, newfile),
(AmCheckpointerProcess() ?
errhint("This is known to fail occasionally during archive recovery, where it is harmless.") :
0)));
return -1;
}
unlink(oldfile);
#else
if (rename(oldfile, newfile) < 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\": %m",
oldfile, newfile),
(AmCheckpointerProcess() ?
errhint("This is known to fail occasionally during archive recovery, where it is harmless.") :
0)));
return -1;
}
#endif
/*
* Make change persistent in case of an OS crash, both the new entry and
* its parent directory need to be flushed.
*/
if (fsync_fname_ext(newfile, false, false, elevel) != 0)
return -1;
/* Same for parent directory */
if (fsync_parent_path(newfile, elevel) != 0)
return -1;
return 0;
}
/*
=======
>>>>>>> REL_16_9
* InitFileAccess --- initialize this module during backend startup
*
* This is called during either normal or standalone backend start.
* It is *not* called in the postmaster.
*
* Note that this does not initialize temporary file access, that is
* separately initialized via InitTemporaryFileAccess().
*/
void
InitFileAccess(void)
{
Assert(SizeVfdCache == 0); /* call me only once */
/* initialize cache header entry */
VfdCache = (Vfd *) malloc(sizeof(Vfd));
if (VfdCache == NULL)
ereport(FATAL,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
MemSet((char *) &(VfdCache[0]), 0, sizeof(Vfd));
VfdCache->fd = VFD_CLOSED;
SizeVfdCache = 1;
}
/*
* InitTemporaryFileAccess --- initialize temporary file access during startup
*
* This is called during either normal or standalone backend start.
* It is *not* called in the postmaster.
*
* This is separate from InitFileAccess() because temporary file cleanup can
* cause pgstat reporting. As pgstat is shut down during before_shmem_exit(),
* our reporting has to happen before that. Low level file access should be
* available for longer, hence the separate initialization / shutdown of
* temporary file handling.
*/
void
InitTemporaryFileAccess(void)
{
Assert(SizeVfdCache != 0); /* InitFileAccess() needs to have run */
Assert(!temporary_files_allowed); /* call me only once */
/*
* Register before-shmem-exit hook to ensure temp files are dropped while
* we can still report stats.
*/
before_shmem_exit(BeforeShmemExit_Files, 0);
#ifdef USE_ASSERT_CHECKING
temporary_files_allowed = true;
#endif
}
/*
* count_usable_fds --- count how many FDs the system will let us open,
* and estimate how many are already open.
*
* We stop counting if usable_fds reaches max_to_probe. Note: a small
* value of max_to_probe might result in an underestimate of already_open;
* we must fill in any "gaps" in the set of used FDs before the calculation
* of already_open will give the right answer. In practice, max_to_probe
* of a couple of dozen should be enough to ensure good results.
*
* We assume stderr (FD 2) is available for dup'ing. While the calling
* script could theoretically close that, it would be a really bad idea,
* since then one risks loss of error messages from, e.g., libc.
*/
static void
count_usable_fds(int max_to_probe, int *usable_fds, int *already_open)
{
int *fd;
int size;
int used = 0;
int highestfd = 0;
int j;
#ifdef HAVE_GETRLIMIT
struct rlimit rlim;
int getrlimit_status;
#endif
size = 1024;
fd = (int *) palloc(size * sizeof(int));
#ifdef HAVE_GETRLIMIT
getrlimit_status = getrlimit(RLIMIT_NOFILE, &rlim);
if (getrlimit_status != 0)
ereport(WARNING, (errmsg("getrlimit failed: %m")));
#endif /* HAVE_GETRLIMIT */
/* dup until failure or probe limit reached */
for (;;)
{
int thisfd;
#ifdef HAVE_GETRLIMIT
/*
* don't go beyond RLIMIT_NOFILE; causes irritating kernel logs on
* some platforms
*/
if (getrlimit_status == 0 && highestfd >= rlim.rlim_cur - 1)
break;
#endif
thisfd = dup(2);
if (thisfd < 0)
{
/* Expect EMFILE or ENFILE, else it's fishy */
if (errno != EMFILE && errno != ENFILE)
elog(WARNING, "duplicating stderr file descriptor failed after %d successes: %m", used);
break;
}
if (used >= size)
{
size *= 2;
fd = (int *) repalloc(fd, size * sizeof(int));
}
fd[used++] = thisfd;
if (highestfd < thisfd)
highestfd = thisfd;
if (used >= max_to_probe)
break;
}
/* release the files we opened */
for (j = 0; j < used; j++)
close(fd[j]);
pfree(fd);
/*
* Return results. usable_fds is just the number of successful dups. We
* assume that the system limit is highestfd+1 (remember 0 is a legal FD
* number) and so already_open is highestfd+1 - usable_fds.
*/
*usable_fds = used;
*already_open = highestfd + 1 - used;
}
/*
* set_max_safe_fds
* Determine number of file descriptors that fd.c is allowed to use
*/
void
set_max_safe_fds(void)
{
int usable_fds;
int already_open;
/*----------
* We want to set max_safe_fds to
* MIN(usable_fds, max_files_per_process - already_open)
* less the slop factor for files that are opened without consulting
* fd.c. This ensures that we won't exceed either max_files_per_process
* or the experimentally-determined EMFILE limit.
*----------
*/
count_usable_fds(max_files_per_process,
&usable_fds, &already_open);
max_safe_fds = Min(usable_fds, max_files_per_process - already_open);
/*
* Take off the FDs reserved for system() etc.
*/
max_safe_fds -= NUM_RESERVED_FDS;
/*
* Make sure we still have enough to get by.
*/
if (max_safe_fds < FD_MINFREE)
ereport(FATAL,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("insufficient file descriptors available to start server process"),
errdetail("System allows %d, server needs at least %d.",
max_safe_fds + NUM_RESERVED_FDS,
FD_MINFREE + NUM_RESERVED_FDS)));
elog(DEBUG2, "max_safe_fds = %d, usable_fds = %d, already_open = %d",
max_safe_fds, usable_fds, already_open);
}
/*
* Open a file with BasicOpenFilePerm() and pass default file mode for the
* fileMode parameter.
*/
int
BasicOpenFile(const char *fileName, int fileFlags)
{
return BasicOpenFilePerm(fileName, fileFlags, pg_file_create_mode);
}
/*
* BasicOpenFilePerm --- same as open(2) except can free other FDs if needed
*
* This is exported for use by places that really want a plain kernel FD,
* but need to be proof against running out of FDs. Once an FD has been
* successfully returned, it is the caller's responsibility to ensure that
* it will not be leaked on ereport()! Most users should *not* call this
* routine directly, but instead use the VFD abstraction level, which
* provides protection against descriptor leaks as well as management of
* files that need to be open for more than a short period of time.
*
* Ideally this should be the *only* direct call of open() in the backend.
* In practice, the postmaster calls open() directly, and there are some
* direct open() calls done early in backend startup. Those are OK since
* this module wouldn't have any open files to close at that point anyway.
*/
int
BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
{
int fd;
tryAgain:
#ifdef PG_O_DIRECT_USE_F_NOCACHE
/*
* The value we defined to stand in for O_DIRECT when simulating it with
* F_NOCACHE had better not collide with any of the standard flags.
*/
StaticAssertStmt((PG_O_DIRECT &
(O_APPEND |
O_CLOEXEC |
O_CREAT |
O_DSYNC |
O_EXCL |
O_RDWR |
O_RDONLY |
O_SYNC |
O_TRUNC |
O_WRONLY)) == 0,
"PG_O_DIRECT value collides with standard flag");
fd = open(fileName, fileFlags & ~PG_O_DIRECT, fileMode);
#else
fd = open(fileName, fileFlags, fileMode);
#endif
if (fd >= 0)
{
#ifdef PG_O_DIRECT_USE_F_NOCACHE
if (fileFlags & PG_O_DIRECT)
{
if (fcntl(fd, F_NOCACHE, 1) < 0)
{
int save_errno = errno;
close(fd);
errno = save_errno;
return -1;
}
}
#endif
return fd; /* success! */
}
if (errno == EMFILE || errno == ENFILE)
{
int save_errno = errno;
ereport(LOG,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("out of file descriptors: %m; release and retry")));
errno = 0;
if (ReleaseLruFile())
goto tryAgain;
errno = save_errno;
}
return -1; /* failure */
}
/*
* AcquireExternalFD - attempt to reserve an external file descriptor
*
* This should be used by callers that need to hold a file descriptor open
* over more than a short interval, but cannot use any of the other facilities
* provided by this module.
*
* The difference between this and the underlying ReserveExternalFD function
* is that this will report failure (by setting errno and returning false)
* if "too many" external FDs are already reserved. This should be used in
* any code where the total number of FDs to be reserved is not predictable
* and small.
*/
bool
AcquireExternalFD(void)
{
/*
* We don't want more than max_safe_fds / 3 FDs to be consumed for
* "external" FDs.
*/
if (numExternalFDs < max_safe_fds / 3)
{
ReserveExternalFD();
return true;
}
errno = EMFILE;
return false;
}
/*
* ReserveExternalFD - report external consumption of a file descriptor
*
* This should be used by callers that need to hold a file descriptor open
* over more than a short interval, but cannot use any of the other facilities
* provided by this module. This just tracks the use of the FD and closes
* VFDs if needed to ensure we keep NUM_RESERVED_FDS FDs available.
*
* Call this directly only in code where failure to reserve the FD would be
* fatal; for example, the WAL-writing code does so, since the alternative is
* session failure. Also, it's very unwise to do so in code that could
* consume more than one FD per process.
*
* Note: as long as everybody plays nice so that NUM_RESERVED_FDS FDs remain
* available, it doesn't matter too much whether this is called before or
* after actually opening the FD; but doing so beforehand reduces the risk of
* an EMFILE failure if not everybody played nice. In any case, it's solely
* caller's responsibility to keep the external-FD count in sync with reality.
*/
void
ReserveExternalFD(void)
{
/*
* Release VFDs if needed to stay safe. Because we do this before
* incrementing numExternalFDs, the final state will be as desired, i.e.,
* nfile + numAllocatedDescs + numExternalFDs <= max_safe_fds.
*/
ReleaseLruFiles();
numExternalFDs++;
}
/*
* ReleaseExternalFD - report release of an external file descriptor
*
* This is guaranteed not to change errno, so it can be used in failure paths.
*/
void
ReleaseExternalFD(void)
{
Assert(numExternalFDs > 0);
numExternalFDs--;
}
#if defined(FDDEBUG)
static void
_dump_lru(void)
{
int mru = VfdCache[0].lruLessRecently;
Vfd *vfdP = &VfdCache[mru];
char buf[2048];
snprintf(buf, sizeof(buf), "LRU: MOST %d ", mru);
while (mru != 0)
{
mru = vfdP->lruLessRecently;
vfdP = &VfdCache[mru];
snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "%d ", mru);
}
snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "LEAST");
elog(LOG, "%s", buf);
}
#endif /* FDDEBUG */
static void
Delete(File file)
{
Vfd *vfdP;
Assert(file != 0);
DO_DB(elog(LOG, "Delete %d (%s)",
file, VfdCache[file].fileName));
DO_DB(_dump_lru());
vfdP = &VfdCache[file];
VfdCache[vfdP->lruLessRecently].lruMoreRecently = vfdP->lruMoreRecently;
VfdCache[vfdP->lruMoreRecently].lruLessRecently = vfdP->lruLessRecently;
DO_DB(_dump_lru());
}
static void
LruDelete(File file)
{
Vfd *vfdP;
Assert(file != 0);
DO_DB(elog(LOG, "LruDelete %d (%s)",
file, VfdCache[file].fileName));
vfdP = &VfdCache[file];
/*
* Close the file. We aren't expecting this to fail; if it does, better
* to leak the FD than to mess up our internal state.
*/
if (close(vfdP->fd) != 0)
elog(vfdP->fdstate & FD_TEMP_FILE_LIMIT ? LOG : data_sync_elevel(LOG),
"could not close file \"%s\": %m", vfdP->fileName);
vfdP->fd = VFD_CLOSED;
--nfile;
/* delete the vfd record from the LRU ring */
Delete(file);
}
static void
Insert(File file)
{
Vfd *vfdP;
Assert(file != 0);
DO_DB(elog(LOG, "Insert %d (%s)",
file, VfdCache[file].fileName));
DO_DB(_dump_lru());
vfdP = &VfdCache[file];
vfdP->lruMoreRecently = 0;
vfdP->lruLessRecently = VfdCache[0].lruLessRecently;
VfdCache[0].lruLessRecently = file;
VfdCache[vfdP->lruLessRecently].lruMoreRecently = file;
DO_DB(_dump_lru());
}
/* returns 0 on success, -1 on re-open failure (with errno set) */
static int
LruInsert(File file)
{
Vfd *vfdP;
Assert(file != 0);
DO_DB(elog(LOG, "LruInsert %d (%s)",
file, VfdCache[file].fileName));
vfdP = &VfdCache[file];
if (FileIsNotOpen(file))
{
/* Close excess kernel FDs. */
ReleaseLruFiles();
/*
* The open could still fail for lack of file descriptors, eg due to
* overall system file table being full. So, be prepared to release
* another FD if necessary...
*/
vfdP->fd = BasicOpenFilePerm(vfdP->fileName, vfdP->fileFlags,
vfdP->fileMode);
if (vfdP->fd < 0)
{
DO_DB(elog(LOG, "re-open failed: %m"));
return -1;
}
else
{
++nfile;
}
}
/*
* put it at the head of the Lru ring
*/
Insert(file);
return 0;
}
/*
* Release one kernel FD by closing the least-recently-used VFD.
*/
static bool
ReleaseLruFile(void)
{
DO_DB(elog(LOG, "ReleaseLruFile. Opened %d", nfile));
if (nfile > 0)
{
/*
* There are opened files and so there should be at least one used vfd
* in the ring.
*/
Assert(VfdCache[0].lruMoreRecently != 0);
LruDelete(VfdCache[0].lruMoreRecently);
return true; /* freed a file */
}
return false; /* no files available to free */
}
/*
* Release kernel FDs as needed to get under the max_safe_fds limit.
* After calling this, it's OK to try to open another file.
*/
static void
ReleaseLruFiles(void)
{
while (nfile + numAllocatedDescs + numExternalFDs >= max_safe_fds)
{
if (!ReleaseLruFile())
break;
}
}
static File
AllocateVfd(void)
{
Index i;
File file;
DO_DB(elog(LOG, "AllocateVfd. Size %zu", SizeVfdCache));
Assert(SizeVfdCache > 0); /* InitFileAccess not called? */
if (VfdCache[0].nextFree == 0)
{
/*
* The free list is empty so it is time to increase the size of the
* array. We choose to double it each time this happens. However,
* there's not much point in starting *real* small.
*/
Size newCacheSize = SizeVfdCache * 2;
Vfd *newVfdCache;
if (newCacheSize < 32)
newCacheSize = 32;
/*
* Be careful not to clobber VfdCache ptr if realloc fails.
*/
newVfdCache = (Vfd *) realloc(VfdCache, sizeof(Vfd) * newCacheSize);
if (newVfdCache == NULL)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
VfdCache = newVfdCache;
/*
* Initialize the new entries and link them into the free list.
*/
for (i = SizeVfdCache; i < newCacheSize; i++)
{
MemSet((char *) &(VfdCache[i]), 0, sizeof(Vfd));
VfdCache[i].nextFree = i + 1;
VfdCache[i].fd = VFD_CLOSED;
}
VfdCache[newCacheSize - 1].nextFree = 0;
VfdCache[0].nextFree = SizeVfdCache;
/*
* Record the new size
*/
SizeVfdCache = newCacheSize;
}
file = VfdCache[0].nextFree;
VfdCache[0].nextFree = VfdCache[file].nextFree;
return file;
}
static void
FreeVfd(File file)
{
Vfd *vfdP = &VfdCache[file];
DO_DB(elog(LOG, "FreeVfd: %d (%s)",
file, vfdP->fileName ? vfdP->fileName : ""));
if (vfdP->fileName != NULL)
{
free(vfdP->fileName);
vfdP->fileName = NULL;
}
vfdP->fdstate = 0x0;
vfdP->nextFree = VfdCache[0].nextFree;
VfdCache[0].nextFree = file;
}
/* returns 0 on success, -1 on re-open failure (with errno set) */
static int
FileAccess(File file)
{
int returnValue;
DO_DB(elog(LOG, "FileAccess %d (%s)",
file, VfdCache[file].fileName));
/*
* Is the file open? If not, open it and put it at the head of the LRU
* ring (possibly closing the least recently used file to get an FD).
*/
if (FileIsNotOpen(file))
{
returnValue = LruInsert(file);
if (returnValue != 0)
return returnValue;
}
else if (VfdCache[0].lruLessRecently != file)
{
/*
* We now know that the file is open and that it is not the last one
* accessed, so we need to move it to the head of the Lru ring.
*/
Delete(file);
Insert(file);
}
return 0;
}
/*
* Called whenever a temporary file is deleted to report its size.
*/
static void
ReportTemporaryFileUsage(const char *path, off_t size)
{
pgstat_report_tempfile(size);
if (log_temp_files >= 0)
{
if ((size / 1024) >= log_temp_files)
ereport(LOG,
(errmsg("temporary file: path \"%s\", size %lu",
path, (unsigned long) size)));
}
}
/*
* Called to register a temporary file for automatic close.
* ResourceOwnerEnlargeFiles(CurrentResourceOwner) must have been called
* before the file was opened.
*/
static void
RegisterTemporaryFile(File file)
{
ResourceOwnerRememberFile(CurrentResourceOwner, file);
VfdCache[file].resowner = CurrentResourceOwner;
/* Backup mechanism for closing at end of xact. */
VfdCache[file].fdstate |= FD_CLOSE_AT_EOXACT;
have_xact_temporary_files = true;
}
/*
* Called when we get a shared invalidation message on some relation.
*/
#ifdef NOT_USED
void
FileInvalidate(File file)
{
Assert(FileIsValid(file));
if (!FileIsNotOpen(file))
LruDelete(file);
}
#endif
/*
* Open a file with PathNameOpenFilePerm() and pass default file mode for the
* fileMode parameter.
*/
File
PathNameOpenFile(const char *fileName, int fileFlags)
{
return PathNameOpenFilePerm(fileName, fileFlags, pg_file_create_mode);
}
/*
* open a file in an arbitrary directory
*
* NB: if the passed pathname is relative (which it usually is),
* it will be interpreted relative to the process' working directory
* (which should always be $PGDATA when this code is running).
*/
File
PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
{
char *fnamecopy;
File file;
Vfd *vfdP;
DO_DB(elog(LOG, "PathNameOpenFilePerm: %s %x %o",
fileName, fileFlags, fileMode));
/*
* We need a malloc'd copy of the file name; fail cleanly if no room.
*/
fnamecopy = strdup(fileName);
if (fnamecopy == NULL)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
file = AllocateVfd();
vfdP = &VfdCache[file];
/* Close excess kernel FDs. */
ReleaseLruFiles();
/*
* Descriptors managed by VFDs are implicitly marked O_CLOEXEC. The
* client shouldn't be expected to know which kernel descriptors are
* currently open, so it wouldn't make sense for them to be inherited by
* executed subprograms.
*/
fileFlags |= O_CLOEXEC;
vfdP->fd = BasicOpenFilePerm(fileName, fileFlags, fileMode);
if (vfdP->fd < 0)
{
int save_errno = errno;
FreeVfd(file);
free(fnamecopy);
errno = save_errno;
return -1;
}
++nfile;
DO_DB(elog(LOG, "PathNameOpenFile: success %d",
vfdP->fd));
vfdP->fileName = fnamecopy;
/* Saved flags are adjusted to be OK for re-opening file */
vfdP->fileFlags = fileFlags & ~(O_CREAT | O_TRUNC | O_EXCL);
vfdP->fileMode = fileMode;
vfdP->fileSize = 0;
vfdP->fdstate = 0x0;
vfdP->resowner = NULL;
Insert(file);
return file;
}
/*
* Create directory 'directory'. If necessary, create 'basedir', which must
* be the directory above it. This is designed for creating the top-level
* temporary directory on demand before creating a directory underneath it.
* Do nothing if the directory already exists.
*
* Directories created within the top-level temporary directory should begin
* with PG_TEMP_FILE_PREFIX, so that they can be identified as temporary and
* deleted at startup by RemovePgTempFiles(). Further subdirectories below
* that do not need any particular prefix.
*/
void
PathNameCreateTemporaryDir(const char *basedir, const char *directory)
{
if (MakePGDirectory(directory) < 0)
{
if (errno == EEXIST)
return;
/*
* Failed. Try to create basedir first in case it's missing. Tolerate
* EEXIST to close a race against another process following the same
* algorithm.
*/
if (MakePGDirectory(basedir) < 0 && errno != EEXIST)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("cannot create temporary directory \"%s\": %m",
basedir)));
/* Try again. */
if (MakePGDirectory(directory) < 0 && errno != EEXIST)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("cannot create temporary subdirectory \"%s\": %m",
directory)));
}
}
/*
* Delete a directory and everything in it, if it exists.
*/
void
PathNameDeleteTemporaryDir(const char *dirname)
{
struct stat statbuf;
/* Silently ignore missing directory. */
if (stat(dirname, &statbuf) != 0 && errno == ENOENT)
return;
/*
* Currently, walkdir doesn't offer a way for our passed in function to
* maintain state. Perhaps it should, so that we could tell the caller
* whether this operation succeeded or failed. Since this operation is
* used in a cleanup path, we wouldn't actually behave differently: we'll
* just log failures.
*/
walkdir(dirname, unlink_if_exists_fname, false, LOG);
}
/*
* Open a temporary file that will disappear when we close it.
*
* This routine takes care of generating an appropriate tempfile name.
* There's no need to pass in fileFlags or fileMode either, since only
* one setting makes any sense for a temp file.
*
* Unless interXact is true, the file is remembered by CurrentResourceOwner
* to ensure it's closed and deleted when it's no longer needed, typically at
* the end-of-transaction. In most cases, you don't want temporary files to
* outlive the transaction that created them, so this should be false -- but
* if you need "somewhat" temporary storage, this might be useful. In either
* case, the file is removed when the File is explicitly closed.
*
* GPDB: As a convenience for monitoring and debugging, the given 'filePrefix'
* string is embedded in the file name. It can be NULL.
*/
File
OpenTemporaryFile(bool interXact, const char *filePrefix)
{
File file = 0;
Assert(temporary_files_allowed); /* check temp file access is up */
/*
* Make sure the current resource owner has space for this File before we
* open it, if we'll be registering it below.
*/
if (!interXact)
ResourceOwnerEnlargeFiles(CurrentResourceOwner);
/*
* If some temp tablespace(s) have been given to us, try to use the next
* one. If a given tablespace can't be found, we silently fall back to
* the database's default tablespace.
*
* BUT: if the temp file is slated to outlive the current transaction,
* force it into the database's default tablespace, so that it will not
* pose a threat to possible tablespace drop attempts.
*/
if (numTempTableSpaces > 0 && !interXact)
{
Oid tblspcOid = GetNextTempTableSpace();
if (OidIsValid(tblspcOid))
file = OpenTemporaryFileInTablespace(tblspcOid,
false, /* rejectError */
filePrefix,
true, /* makenameunique */
true); /* create */
}
/*
* If not, or if tablespace is bad, create in database's default
* tablespace. MyDatabaseTableSpace should normally be set before we get
* here, but just in case it isn't, fall back to pg_default tablespace.
*/
if (file <= 0)
file = OpenTemporaryFileInTablespace(MyDatabaseTableSpace ?
MyDatabaseTableSpace :
DEFAULTTABLESPACE_OID,
true,
filePrefix,
true, /* makenameunique */
true); /* create */
/* Mark it for deletion at close and temporary file size limit */
VfdCache[file].fdstate |= FD_DELETE_AT_CLOSE | FD_TEMP_FILE_LIMIT;
/* Register it with the current resource owner */
if (!interXact)
RegisterTemporaryFile(file);
return file;
}
/*
* Return the path of the temp directory in a given tablespace.
*/
void
TempTablespacePath(char *path, Oid tablespace)
{
/*
* Identify the tempfile directory for this tablespace.
*
* If someone tries to specify pg_global, use pg_default instead.
*/
if (tablespace == InvalidOid ||
tablespace == DEFAULTTABLESPACE_OID ||
tablespace == GLOBALTABLESPACE_OID)
snprintf(path, MAXPGPATH, "base/%s", PG_TEMP_FILES_DIR);
else
{
/* All other tablespaces are accessed via symlinks */
snprintf(path, MAXPGPATH, "pg_tblspc/%u/%s/%s",
tablespace, GP_TABLESPACE_VERSION_DIRECTORY, PG_TEMP_FILES_DIR);
}
}
/*
* Open a temporary file in a specific tablespace.
* Subroutine for OpenTemporaryFile, which see for details.
*/
static File
OpenTemporaryFileInTablespace(Oid tblspcOid, bool rejectError,
const char *filename, bool makenameunique, bool create)
{
char tempdirpath[MAXPGPATH];
char tempfilepath[MAXPGPATH];
File file;
int flags;
TempTablespacePath(tempdirpath, tblspcOid);
/*
* Generate a tempfile name that should be unique within the current
* database instance.
*/
if (filename == NULL)
{
Assert (makenameunique);
filename = "";
}
if (makenameunique)
{
Assert(create);
snprintf(tempfilepath, sizeof(tempfilepath), "%s/%s%s%d.%ld",
tempdirpath, PG_TEMP_FILE_PREFIX, filename, MyProcPid, tempFileCounter++);
}
else
snprintf(tempfilepath, sizeof(tempfilepath), "%s/%s_%s",
tempdirpath, PG_TEMP_FILE_PREFIX, filename);
/*
* Open the file. Note: we don't use O_EXCL, in case there is an orphaned
* temp file that can be reused.
*/
flags = O_RDWR | PG_BINARY;
if (create)
flags |= O_CREAT | O_TRUNC;
file = PathNameOpenFile(tempfilepath,
flags);
if (file <= 0)
{
/*
* We might need to create the tablespace's tempfile directory, if no
* one has yet done so.
*
* Don't check for an error from MakePGDirectory; it could fail if
* someone else just did the same thing. If it doesn't work then
* we'll bomb out on the second create attempt, instead.
*/
(void) MakePGDirectory(tempdirpath);
file = PathNameOpenFile(tempfilepath,
flags);
if (file <= 0 && rejectError)
{
if (create)
elog(ERROR, "could not create temporary file \"%s\": %m",
tempfilepath);
else
elog(ERROR, "could not open existing temporary file \"%s\": %m",
tempfilepath);
}
}
return file;
}
/*
* Create a new file. The directory containing it must already exist. Files
* created this way are subject to temp_file_limit and are automatically
* closed at end of transaction, but are not automatically deleted on close
* because they are intended to be shared between cooperating backends.
*
* If the file is inside the top-level temporary directory, its name should
* begin with PG_TEMP_FILE_PREFIX so that it can be identified as temporary
* and deleted at startup by RemovePgTempFiles(). Alternatively, it can be
* inside a directory created with PathNameCreateTemporaryDir(), in which case
* the prefix isn't needed.
*/
File
PathNameCreateTemporaryFile(const char *path, bool error_on_failure)
{
File file;
Assert(temporary_files_allowed); /* check temp file access is up */
ResourceOwnerEnlargeFiles(CurrentResourceOwner);
/*
* Open the file. Note: we don't use O_EXCL, in case there is an orphaned
* temp file that can be reused.
*/
file = PathNameOpenFile(path, O_RDWR | O_CREAT | O_TRUNC | PG_BINARY);
if (file <= 0)
{
if (error_on_failure)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not create temporary file \"%s\": %m",
path)));
else
return file;
}
/* Mark it for temp_file_limit accounting. */
VfdCache[file].fdstate |= FD_TEMP_FILE_LIMIT;
/* Register it for automatic close. */
RegisterTemporaryFile(file);
return file;
}
/*
* Open a file that was created with PathNameCreateTemporaryFile, possibly in
* another backend. Files opened this way don't count against the
* temp_file_limit of the caller, are automatically closed at the end of the
* transaction but are not deleted on close.
*/
File
PathNameOpenTemporaryFile(const char *path, int mode)
{
File file;
Assert(temporary_files_allowed); /* check temp file access is up */
ResourceOwnerEnlargeFiles(CurrentResourceOwner);
file = PathNameOpenFile(path, mode | PG_BINARY);
/* If no such file, then we don't raise an error. */
if (file <= 0 && errno != ENOENT)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open temporary file \"%s\": %m",
path)));
if (file > 0)
{
/* Register it for automatic close. */
RegisterTemporaryFile(file);
}
return file;
}
/*
* Delete a file by pathname. Return true if the file existed, false if
* didn't.
*/
bool
PathNameDeleteTemporaryFile(const char *path, bool error_on_failure)
{
struct stat filestats;
int stat_errno;
/* Get the final size for pgstat reporting. */
if (stat(path, &filestats) != 0)
stat_errno = errno;
else
stat_errno = 0;
/*
* Unlike FileClose's automatic file deletion code, we tolerate
* non-existence to support BufFileDeleteFileSet which doesn't know how
* many segments it has to delete until it runs out.
*/
if (stat_errno == ENOENT)
return false;
if (unlink(path) < 0)
{
if (errno != ENOENT)
ereport(error_on_failure ? ERROR : LOG,
(errcode_for_file_access(),
errmsg("could not unlink temporary file \"%s\": %m",
path)));
return false;
}
if (stat_errno == 0)
ReportTemporaryFileUsage(path, filestats.st_size);
else
{
errno = stat_errno;
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m", path)));
}
return true;
}
/*
* close a file when done with it
*/
void
FileClose(File file)
{
Vfd *vfdP;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileClose: %d (%s)",
file, VfdCache[file].fileName));
vfdP = &VfdCache[file];
if (!FileIsNotOpen(file))
{
/* close the file */
if (gp_retry_close(vfdP->fd))
{
/*
* We may need to panic on failure to close non-temporary files;
* see LruDelete.
*/
elog(vfdP->fdstate & FD_TEMP_FILE_LIMIT ? LOG : data_sync_elevel(LOG),
"could not close file \"%s\": %m", vfdP->fileName);
}
--nfile;
vfdP->fd = VFD_CLOSED;
/* remove the file from the lru ring */
Delete(file);
}
if (vfdP->fdstate & FD_TEMP_FILE_LIMIT)
{
/* Subtract its size from current usage (do first in case of error) */
temporary_files_size -= vfdP->fileSize;
vfdP->fileSize = 0;
}
/*
* Delete the file if it was temporary, and make a log entry if wanted
*/
if (vfdP->fdstate & FD_DELETE_AT_CLOSE)
{
struct stat filestats;
int stat_errno;
/*
* If we get an error, as could happen within the ereport/elog calls,
* we'll come right back here during transaction abort. Reset the
* flag to ensure that we can't get into an infinite loop. This code
* is arranged to ensure that the worst-case consequence is failing to
* emit log message(s), not failing to attempt the unlink.
*/
vfdP->fdstate &= ~FD_DELETE_AT_CLOSE;
/* first try the stat() */
if (stat(vfdP->fileName, &filestats))
stat_errno = errno;
else
stat_errno = 0;
/* in any case do the unlink */
if (unlink(vfdP->fileName))
ereport(DEBUG1,
(errcode_for_file_access(),
errmsg("could not delete file \"%s\": %m", vfdP->fileName)));
/* and last report the stat results */
if (stat_errno == 0)
ReportTemporaryFileUsage(vfdP->fileName, filestats.st_size);
else
{
errno = stat_errno;
ereport(DEBUG1,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m", vfdP->fileName)));
}
}
/* Unregister it from the resource owner */
if (vfdP->resowner)
ResourceOwnerForgetFile(vfdP->resowner, file);
/* Unregister it from the workfile set */
if (vfdP->fdstate & FD_WORKFILE)
WorkFileDeleted(file, true);
/*
* Return the Vfd slot to the free list
*/
FreeVfd(file);
}
/*
* FilePrefetch - initiate asynchronous read of a given range of the file.
*
* Currently the only implementation of this function is using posix_fadvise
* which is the simplest standardized interface that accomplishes this.
* We could add an implementation using libaio in the future; but note that
* this API is inappropriate for libaio, which wants to have a buffer provided
* to read into.
*/
int
FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info)
{
#if defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_WILLNEED)
int returnCode;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FilePrefetch: %d (%s) " INT64_FORMAT " " INT64_FORMAT,
file, VfdCache[file].fileName,
(int64) offset, (int64) amount));
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
retry:
pgstat_report_wait_start(wait_event_info);
returnCode = posix_fadvise(VfdCache[file].fd, offset, amount,
POSIX_FADV_WILLNEED);
pgstat_report_wait_end();
if (returnCode == EINTR)
goto retry;
return returnCode;
#else
Assert(FileIsValid(file));
return 0;
#endif
}
void
FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info)
{
int returnCode;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileWriteback: %d (%s) " INT64_FORMAT " " INT64_FORMAT,
file, VfdCache[file].fileName,
(int64) offset, (int64) nbytes));
if (nbytes <= 0)
return;
if (VfdCache[file].fileFlags & PG_O_DIRECT)
return;
returnCode = FileAccess(file);
if (returnCode < 0)
return;
pgstat_report_wait_start(wait_event_info);
pg_flush_data(VfdCache[file].fd, offset, nbytes);
pgstat_report_wait_end();
}
int
FileRead(File file, void *buffer, size_t amount, off_t offset,
uint32 wait_event_info)
{
int returnCode;
Vfd *vfdP;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileRead: %d (%s) " INT64_FORMAT " %zu %p",
file, VfdCache[file].fileName,
(int64) offset,
amount, buffer));
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
vfdP = &VfdCache[file];
retry:
pgstat_report_wait_start(wait_event_info);
returnCode = pg_pread(vfdP->fd, buffer, amount, offset);
pgstat_report_wait_end();
if (returnCode < 0)
{
/*
* Windows may run out of kernel buffers and return "Insufficient
* system resources" error. Wait a bit and retry to solve it.
*
* It is rumored that EINTR is also possible on some Unix filesystems,
* in which case immediate retry is indicated.
*/
#ifdef WIN32
DWORD error = GetLastError();
switch (error)
{
case ERROR_NO_SYSTEM_RESOURCES:
pg_usleep(1000L);
errno = EINTR;
break;
default:
_dosmaperr(error);
break;
}
#endif
/* OK to retry if interrupted */
if (errno == EINTR)
goto retry;
}
return returnCode;
}
int
FileWrite(File file, const void *buffer, size_t amount, off_t offset,
uint32 wait_event_info)
{
int returnCode;
Vfd *vfdP;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileWrite: %d (%s) " INT64_FORMAT " %zu %p",
file, VfdCache[file].fileName,
(int64) offset,
amount, buffer));
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
vfdP = &VfdCache[file];
/*
* If enforcing temp_file_limit and it's a temp file, check to see if the
* write would overrun temp_file_limit, and throw error if so. Note: it's
* really a modularity violation to throw error here; we should set errno
* and return -1. However, there's no way to report a suitable error
* message if we do that. All current callers would just throw error
* immediately anyway, so this is safe at present.
*/
if (temp_file_limit >= 0 && (vfdP->fdstate & FD_TEMP_FILE_LIMIT))
{
off_t past_write = offset + amount;
if (past_write > vfdP->fileSize)
{
uint64 newTotal = temporary_files_size;
newTotal += past_write - vfdP->fileSize;
if (newTotal > (uint64) temp_file_limit * (uint64) 1024)
ereport(ERROR,
(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
errmsg("temporary file size exceeds temp_file_limit (%dkB)",
temp_file_limit)));
}
}
/*
* Also update the stats in workfile manager. This might also
* throw an error, if we're over the limits.
*
* Because we update the stats in workfile manager first, if the write
* fails, the workfile manager's status will be out of sync with reality.
* That's OK, the inaccuracy doesn't accumulate, and it doesn't need to be
* totallyaccurate.
*/
if ((VfdCache[file].fdstate & FD_WORKFILE) != 0)
{
off_t newPos = offset + amount;
if (newPos > VfdCache[file].fileSize)
UpdateWorkFileSize(file, newPos);
}
retry:
errno = 0;
pgstat_report_wait_start(wait_event_info);
returnCode = pg_pwrite(VfdCache[file].fd, buffer, amount, offset);
pgstat_report_wait_end();
/* if write didn't set errno, assume problem is no disk space */
if (returnCode != amount && errno == 0)
errno = ENOSPC;
if (returnCode >= 0)
{
/*
* Maintain fileSize and temporary_files_size if it's a temp file.
*/
if (vfdP->fdstate & FD_TEMP_FILE_LIMIT)
{
off_t past_write = offset + amount;
if (past_write > vfdP->fileSize)
{
temporary_files_size += past_write - vfdP->fileSize;
vfdP->fileSize = past_write;
}
}
}
else
{
/*
* See comments in FileRead()
*/
#ifdef WIN32
DWORD error = GetLastError();
switch (error)
{
case ERROR_NO_SYSTEM_RESOURCES:
pg_usleep(1000L);
errno = EINTR;
break;
default:
_dosmaperr(error);
break;
}
#endif
/* OK to retry if interrupted */
if (errno == EINTR)
goto retry;
}
return returnCode;
}
int
FileSync(File file, uint32 wait_event_info)
{
int returnCode;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileSync: %d (%s)",
file, VfdCache[file].fileName));
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
pgstat_report_wait_start(wait_event_info);
returnCode = pg_fsync(VfdCache[file].fd);
pgstat_report_wait_end();
return returnCode;
}
/*
* Get the size of a physical file by using fstat()
*
* Returns size in bytes if successful, < 0 otherwise
*/
int64
FileDiskSize(File file)
{
int returnCode = 0;
struct stat buf;
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
returnCode = fstat(VfdCache[file].fd, &buf);
if (returnCode < 0)
return returnCode;
return (int64) buf.st_size;
}
/*
* Zero a region of the file.
*
* Returns 0 on success, -1 otherwise. In the latter case errno is set to the
* appropriate error.
*/
int
FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info)
{
int returnCode;
ssize_t written;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileZero: %d (%s) " INT64_FORMAT " " INT64_FORMAT,
file, VfdCache[file].fileName,
(int64) offset, (int64) amount));
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
pgstat_report_wait_start(wait_event_info);
written = pg_pwrite_zeros(VfdCache[file].fd, amount, offset);
pgstat_report_wait_end();
if (written < 0)
return -1;
else if (written != amount)
{
/* if errno is unset, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
return -1;
}
return 0;
}
/*
* Try to reserve file space with posix_fallocate(). If posix_fallocate() is
* not implemented on the operating system or fails with EINVAL / EOPNOTSUPP,
* use FileZero() instead.
*
* Note that at least glibc() implements posix_fallocate() in userspace if not
* implemented by the filesystem. That's not the case for all environments
* though.
*
* Returns 0 on success, -1 otherwise. In the latter case errno is set to the
* appropriate error.
*/
int
FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info)
{
#ifdef HAVE_POSIX_FALLOCATE
int returnCode;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileFallocate: %d (%s) " INT64_FORMAT " " INT64_FORMAT,
file, VfdCache[file].fileName,
(int64) offset, (int64) amount));
returnCode = FileAccess(file);
if (returnCode < 0)
return -1;
retry:
pgstat_report_wait_start(wait_event_info);
returnCode = posix_fallocate(VfdCache[file].fd, offset, amount);
pgstat_report_wait_end();
if (returnCode == 0)
return 0;
else if (returnCode == EINTR)
goto retry;
/* for compatibility with %m printing etc */
errno = returnCode;
/*
* Return in cases of a "real" failure, if fallocate is not supported,
* fall through to the FileZero() backed implementation.
*/
if (returnCode != EINVAL && returnCode != EOPNOTSUPP)
return -1;
#endif
return FileZero(file, offset, amount, wait_event_info);
}
off_t
FileSize(File file)
{
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileSize %d (%s)",
file, VfdCache[file].fileName));
if (FileIsNotOpen(file))
{
if (FileAccess(file) < 0)
return (off_t) -1;
}
return lseek(VfdCache[file].fd, 0, SEEK_END);
}
int
FileTruncate(File file, int64 offset, uint32 wait_event_info)
{
int returnCode;
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileTruncate %d (%s)",
file, VfdCache[file].fileName));
returnCode = FileAccess(file);
if (returnCode < 0)
return returnCode;
/*
* Call ftruncate with a int64 value.
*
* WARNING:DO NOT typecast this down to a 32-bit long or
* append-only vacuum full adjustment of the eof will erroneously remove
* table data.
*/
pgstat_report_wait_start(wait_event_info);
returnCode = pg_ftruncate(VfdCache[file].fd, offset);
pgstat_report_wait_end();
if (returnCode == 0 && VfdCache[file].fileSize > offset)
{
/* adjust our state for truncation of a temp file */
Assert(VfdCache[file].fdstate & FD_TEMP_FILE_LIMIT);
temporary_files_size -= VfdCache[file].fileSize - offset;
VfdCache[file].fileSize = offset;
}
return returnCode;
}
/*
* Return the pathname associated with an open file.
*
* The returned string points to an internal buffer, which is valid until
* the file is closed.
*/
char *
FilePathName(File file)
{
Assert(FileIsValid(file));
return VfdCache[file].fileName;
}
/*
* Return the raw file descriptor of an opened file.
*
* The returned file descriptor will be valid until the file is closed, but
* there are a lot of things that can make that happen. So the caller should
* be careful not to do much of anything else before it finishes using the
* returned file descriptor.
*/
int
FileGetRawDesc(File file)
{
Assert(FileIsValid(file));
return VfdCache[file].fd;
}
/*
* FileGetRawFlags - returns the file flags on open(2)
*/
int
FileGetRawFlags(File file)
{
Assert(FileIsValid(file));
return VfdCache[file].fileFlags;
}
/*
* FileGetRawMode - returns the mode bitmask passed to open(2)
*/
mode_t
FileGetRawMode(File file)
{
Assert(FileIsValid(file));
return VfdCache[file].fileMode;
}
/*
* Make room for another allocatedDescs[] array entry if needed and possible.
* Returns true if an array element is available.
*/
static bool
reserveAllocatedDesc(void)
{
AllocateDesc *newDescs;
int newMax;
/* Quick out if array already has a free slot. */
if (numAllocatedDescs < maxAllocatedDescs)
return true;
/*
* If the array hasn't yet been created in the current process, initialize
* it with FD_MINFREE / 3 elements. In many scenarios this is as many as
* we will ever need, anyway. We don't want to look at max_safe_fds
* immediately because set_max_safe_fds() may not have run yet.
*/
if (allocatedDescs == NULL)
{
newMax = FD_MINFREE / 3;
newDescs = (AllocateDesc *) malloc(newMax * sizeof(AllocateDesc));
/* Out of memory already? Treat as fatal error. */
if (newDescs == NULL)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
allocatedDescs = newDescs;
maxAllocatedDescs = newMax;
return true;
}
/*
* Consider enlarging the array beyond the initial allocation used above.
* By the time this happens, max_safe_fds should be known accurately.
*
* We mustn't let allocated descriptors hog all the available FDs, and in
* practice we'd better leave a reasonable number of FDs for VFD use. So
* set the maximum to max_safe_fds / 3. (This should certainly be at
* least as large as the initial size, FD_MINFREE / 3, so we aren't
* tightening the restriction here.) Recall that "external" FDs are
* allowed to consume another third of max_safe_fds.
*/
newMax = max_safe_fds / 3;
if (newMax > maxAllocatedDescs)
{
newDescs = (AllocateDesc *) realloc(allocatedDescs,
newMax * sizeof(AllocateDesc));
/* Treat out-of-memory as a non-fatal error. */
if (newDescs == NULL)
return false;
allocatedDescs = newDescs;
maxAllocatedDescs = newMax;
return true;
}
/* Can't enlarge allocatedDescs[] any more. */
return false;
}
/*
* Routines that want to use stdio (ie, FILE*) should use AllocateFile
* rather than plain fopen(). This lets fd.c deal with freeing FDs if
* necessary to open the file. When done, call FreeFile rather than fclose.
*
* Note that files that will be open for any significant length of time
* should NOT be handled this way, since they cannot share kernel file
* descriptors with other files; there is grave risk of running out of FDs
* if anyone locks down too many FDs. Most callers of this routine are
* simply reading a config file that they will read and close immediately.
*
* fd.c will automatically close all files opened with AllocateFile at
* transaction commit or abort; this prevents FD leakage if a routine
* that calls AllocateFile is terminated prematurely by ereport(ERROR).
*
* Ideally this should be the *only* direct call of fopen() in the backend.
*/
FILE *
AllocateFile(const char *name, const char *mode)
{
FILE *file;
DO_DB(elog(LOG, "AllocateFile: Allocated %d (%s)",
numAllocatedDescs, name));
/* Can we allocate another non-virtual FD? */
if (!reserveAllocatedDesc())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("exceeded maxAllocatedDescs (%d) while trying to open file \"%s\"",
maxAllocatedDescs, name)));
/* Close excess kernel FDs. */
ReleaseLruFiles();
TryAgain:
if ((file = fopen(name, mode)) != NULL)
{
AllocateDesc *desc = &allocatedDescs[numAllocatedDescs];
desc->kind = AllocateDescFile;
desc->desc.file = file;
desc->create_subid = GetCurrentSubTransactionId();
numAllocatedDescs++;
return desc->desc.file;
}
if (errno == EMFILE || errno == ENFILE)
{
int save_errno = errno;
ereport(LOG,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("out of file descriptors: %m; release and retry")));
errno = 0;
if (ReleaseLruFile())
goto TryAgain;
errno = save_errno;
}
/*
* TEMPORARY hack to log the Windows error code on fopen failures, in
* hopes of diagnosing some hard-to-reproduce problems.
*/
#ifdef WIN32
{
int save_errno = errno;
elog(LOG, "Windows fopen(\"%s\",\"%s\") failed: code %lu, errno %d",
name, mode, GetLastError(), save_errno);
errno = save_errno;
}
#endif
return NULL;
}
/*
* Open a file with OpenTransientFilePerm() and pass default file mode for
* the fileMode parameter.
*/
int
OpenTransientFile(const char *fileName, int fileFlags)
{
return OpenTransientFilePerm(fileName, fileFlags, pg_file_create_mode);
}
/*
* Like AllocateFile, but returns an unbuffered fd like open(2)
*/
int
OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
{
int fd;
DO_DB(elog(LOG, "OpenTransientFile: Allocated %d (%s)",
numAllocatedDescs, fileName));
/* Can we allocate another non-virtual FD? */
if (!reserveAllocatedDesc())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("exceeded maxAllocatedDescs (%d) while trying to open file \"%s\"",
maxAllocatedDescs, fileName)));
/* Close excess kernel FDs. */
ReleaseLruFiles();
fd = BasicOpenFilePerm(fileName, fileFlags, fileMode);
if (fd >= 0)
{
AllocateDesc *desc = &allocatedDescs[numAllocatedDescs];
desc->kind = AllocateDescRawFD;
desc->desc.fd = fd;
desc->create_subid = GetCurrentSubTransactionId();
numAllocatedDescs++;
return fd;
}
return -1; /* failure */
}
/*
* Routines that want to initiate a pipe stream should use OpenPipeStream
* rather than plain popen(). This lets fd.c deal with freeing FDs if
* necessary. When done, call ClosePipeStream rather than pclose.
*
* This function also ensures that the popen'd program is run with default
* SIGPIPE processing, rather than the SIG_IGN setting the backend normally
* uses. This ensures desirable response to, eg, closing a read pipe early.
*/
FILE *
OpenPipeStream(const char *command, const char *mode)
{
FILE *file;
int save_errno;
DO_DB(elog(LOG, "OpenPipeStream: Allocated %d (%s)",
numAllocatedDescs, command));
/* Can we allocate another non-virtual FD? */
if (!reserveAllocatedDesc())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("exceeded maxAllocatedDescs (%d) while trying to execute command \"%s\"",
maxAllocatedDescs, command)));
/* Close excess kernel FDs. */
ReleaseLruFiles();
TryAgain:
fflush(NULL);
pqsignal(SIGPIPE, SIG_DFL);
errno = 0;
file = popen(command, mode);
save_errno = errno;
pqsignal(SIGPIPE, SIG_IGN);
errno = save_errno;
if (file != NULL)
{
AllocateDesc *desc = &allocatedDescs[numAllocatedDescs];
desc->kind = AllocateDescPipe;
desc->desc.file = file;
desc->create_subid = GetCurrentSubTransactionId();
numAllocatedDescs++;
return desc->desc.file;
}
if (errno == EMFILE || errno == ENFILE)
{
ereport(LOG,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("out of file descriptors: %m; release and retry")));
if (ReleaseLruFile())
goto TryAgain;
errno = save_errno;
}
return NULL;
}
/*
* Free an AllocateDesc of any type.
*
* The argument *must* point into the allocatedDescs[] array.
*/
static int
FreeDesc(AllocateDesc *desc)
{
int result;
/* Close the underlying object */
switch (desc->kind)
{
case AllocateDescFile:
result = fclose(desc->desc.file);
break;
case AllocateDescPipe:
result = pclose(desc->desc.file);
break;
case AllocateDescDir:
result = closedir(desc->desc.dir);
break;
case AllocateDescRawFD:
result = close(desc->desc.fd);
break;
default:
elog(ERROR, "AllocateDesc kind not recognized");
result = 0; /* keep compiler quiet */
break;
}
/* Compact storage in the allocatedDescs array */
numAllocatedDescs--;
*desc = allocatedDescs[numAllocatedDescs];
return result;
}
/*
* Close a file returned by AllocateFile.
*
* Note we do not check fclose's return value --- it is up to the caller
* to handle close errors.
*/
int
FreeFile(FILE *file)
{
int i;
DO_DB(elog(LOG, "FreeFile: Allocated %d", numAllocatedDescs));
/* Remove file from list of allocated files, if it's present */
for (i = numAllocatedDescs; --i >= 0;)
{
AllocateDesc *desc = &allocatedDescs[i];
if (desc->kind == AllocateDescFile && desc->desc.file == file)
return FreeDesc(desc);
}
/* Only get here if someone passes us a file not in allocatedDescs */
elog(WARNING, "file passed to FreeFile was not obtained from AllocateFile");
Assert(false);
return fclose(file);
}
/*
* Close a file returned by OpenTransientFile.
*
* Note we do not check close's return value --- it is up to the caller
* to handle close errors.
*/
int
CloseTransientFile(int fd)
{
int i;
DO_DB(elog(LOG, "CloseTransientFile: Allocated %d", numAllocatedDescs));
/* Remove fd from list of allocated files, if it's present */
for (i = numAllocatedDescs; --i >= 0;)
{
AllocateDesc *desc = &allocatedDescs[i];
if (desc->kind == AllocateDescRawFD && desc->desc.fd == fd)
return FreeDesc(desc);
}
/* Only get here if someone passes us a file not in allocatedDescs */
elog(WARNING, "fd passed to CloseTransientFile was not obtained from OpenTransientFile");
return close(fd);
}
/*
* Routines that want to use <dirent.h> (ie, DIR*) should use AllocateDir
* rather than plain opendir(). This lets fd.c deal with freeing FDs if
* necessary to open the directory, and with closing it after an elog.
* When done, call FreeDir rather than closedir.
*
* Returns NULL, with errno set, on failure. Note that failure detection
* is commonly left to the following call of ReadDir or ReadDirExtended;
* see the comments for ReadDir.
*
* Ideally this should be the *only* direct call of opendir() in the backend.
*/
DIR *
AllocateDir(const char *dirname)
{
DIR *dir;
DO_DB(elog(LOG, "AllocateDir: Allocated %d (%s)",
numAllocatedDescs, dirname));
/* Can we allocate another non-virtual FD? */
if (!reserveAllocatedDesc())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("exceeded maxAllocatedDescs (%d) while trying to open directory \"%s\"",
maxAllocatedDescs, dirname)));
/* Close excess kernel FDs. */
ReleaseLruFiles();
TryAgain:
if ((dir = opendir(dirname)) != NULL)
{
AllocateDesc *desc = &allocatedDescs[numAllocatedDescs];
desc->kind = AllocateDescDir;
desc->desc.dir = dir;
desc->create_subid = GetCurrentSubTransactionId();
numAllocatedDescs++;
return desc->desc.dir;
}
if (errno == EMFILE || errno == ENFILE)
{
int save_errno = errno;
ereport(LOG,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("out of file descriptors: %m; release and retry")));
errno = 0;
if (ReleaseLruFile())
goto TryAgain;
errno = save_errno;
}
return NULL;
}
/*
* Read a directory opened with AllocateDir, ereport'ing any error.
*
* This is easier to use than raw readdir() since it takes care of some
* otherwise rather tedious and error-prone manipulation of errno. Also,
* if you are happy with a generic error message for AllocateDir failure,
* you can just do
*
* dir = AllocateDir(path);
* while ((dirent = ReadDir(dir, path)) != NULL)
* process dirent;
* FreeDir(dir);
*
* since a NULL dir parameter is taken as indicating AllocateDir failed.
* (Make sure errno isn't changed between AllocateDir and ReadDir if you
* use this shortcut.)
*
* The pathname passed to AllocateDir must be passed to this routine too,
* but it is only used for error reporting.
*/
struct dirent *
ReadDir(DIR *dir, const char *dirname)
{
return ReadDirExtended(dir, dirname, ERROR);
}
/*
* Alternate version of ReadDir that allows caller to specify the elevel
* for any error report (whether it's reporting an initial failure of
* AllocateDir or a subsequent directory read failure).
*
* If elevel < ERROR, returns NULL after any error. With the normal coding
* pattern, this will result in falling out of the loop immediately as
* though the directory contained no (more) entries.
*/
struct dirent *
ReadDirExtended(DIR *dir, const char *dirname, int elevel)
{
struct dirent *dent;
/* Give a generic message for AllocateDir failure, if caller didn't */
if (dir == NULL)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not open directory \"%s\": %m",
dirname)));
return NULL;
}
errno = 0;
if ((dent = readdir(dir)) != NULL)
return dent;
if (errno)
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not read directory \"%s\": %m",
dirname)));
return NULL;
}
/*
* Close a directory opened with AllocateDir.
*
* Returns closedir's return value (with errno set if it's not 0).
* Note we do not check the return value --- it is up to the caller
* to handle close errors if wanted.
*
* Does nothing if dir == NULL; we assume that directory open failure was
* already reported if desired.
*/
int
FreeDir(DIR *dir)
{
int i;
/* Nothing to do if AllocateDir failed */
if (dir == NULL)
return 0;
DO_DB(elog(LOG, "FreeDir: Allocated %d", numAllocatedDescs));
/* Remove dir from list of allocated dirs, if it's present */
for (i = numAllocatedDescs; --i >= 0;)
{
AllocateDesc *desc = &allocatedDescs[i];
if (desc->kind == AllocateDescDir && desc->desc.dir == dir)
return FreeDesc(desc);
}
/* Only get here if someone passes us a dir not in allocatedDescs */
elog(WARNING, "dir passed to FreeDir was not obtained from AllocateDir");
Assert(false);
return closedir(dir);
}
/*
* Close a pipe stream returned by OpenPipeStream.
*/
int
ClosePipeStream(FILE *file)
{
int i;
DO_DB(elog(LOG, "ClosePipeStream: Allocated %d", numAllocatedDescs));
/* Remove file from list of allocated files, if it's present */
for (i = numAllocatedDescs; --i >= 0;)
{
AllocateDesc *desc = &allocatedDescs[i];
if (desc->kind == AllocateDescPipe && desc->desc.file == file)
return FreeDesc(desc);
}
/* Only get here if someone passes us a file not in allocatedDescs */
elog(WARNING, "file passed to ClosePipeStream was not obtained from OpenPipeStream");
return pclose(file);
}
/*
* closeAllVfds
*
* Force all VFDs into the physically-closed state, so that the fewest
* possible number of kernel file descriptors are in use. There is no
* change in the logical state of the VFDs.
*/
void
closeAllVfds(void)
{
Index i;
if (SizeVfdCache > 0)
{
Assert(FileIsNotOpen(0)); /* Make sure ring not corrupted */
for (i = 1; i < SizeVfdCache; i++)
{
if (!FileIsNotOpen(i))
LruDelete(i);
}
}
}
/*
* SetTempTablespaces
*
* Define a list (actually an array) of OIDs of tablespaces to use for
* temporary files. This list will be used until end of transaction,
* unless this function is called again before then. It is caller's
* responsibility that the passed-in array has adequate lifespan (typically
* it'd be allocated in TopTransactionContext).
*
* Some entries of the array may be InvalidOid, indicating that the current
* database's default tablespace should be used.
*/
void
SetTempTablespaces(Oid *tableSpaces, int numSpaces)
{
Assert(numSpaces >= 0);
tempTableSpaces = tableSpaces;
numTempTableSpaces = numSpaces;
/*
* Select a random starting point in the list. This is to minimize
* conflicts between backends that are most likely sharing the same list
* of temp tablespaces. Note that if we create multiple temp files in the
* same transaction, we'll advance circularly through the list --- this
* ensures that large temporary sort files are nicely spread across all
* available tablespaces.
*/
if (numSpaces > 1)
nextTempTableSpace = pg_prng_uint64_range(&pg_global_prng_state,
0, numSpaces - 1);
else
nextTempTableSpace = 0;
}
/*
* TempTablespacesAreSet
*
* Returns true if SetTempTablespaces has been called in current transaction.
* (This is just so that tablespaces.c doesn't need its own per-transaction
* state.)
*/
bool
TempTablespacesAreSet(void)
{
return (numTempTableSpaces >= 0);
}
/*
* GetTempTablespaces
*
* Populate an array with the OIDs of the tablespaces that should be used for
* temporary files. (Some entries may be InvalidOid, indicating that the
* current database's default tablespace should be used.) At most numSpaces
* entries will be filled.
* Returns the number of OIDs that were copied into the output array.
*/
int
GetTempTablespaces(Oid *tableSpaces, int numSpaces)
{
int i;
/*
* GPDB: This function is called only by SharedFileSetInit(), in which
* we call PrepareTempTablespaces() just before this function. In upstream
* Postgres, we would only go through this code path inside a transaction.
* However, in GPDB, SharedFileSetInit() may also get called in the process
* of ExecSquelchShareInputScan(), which could happen during abort
* transaction. If we are not in a transaction, PrepareTempTablespaces()
* would have to return early without setting the temp tablespaces. The
* shared fileset in this case will be writen in the default table space
* rather than the temp tablespaces.
*/
Assert(TempTablespacesAreSet() || IsAbortInProgress());
for (i = 0; i < numTempTableSpaces && i < numSpaces; ++i)
tableSpaces[i] = tempTableSpaces[i];
return i;
}
/*
* GetNextTempTableSpace
*
* Select the next temp tablespace to use. A result of InvalidOid means
* to use the current database's default tablespace.
*/
Oid
GetNextTempTableSpace(void)
{
if (numTempTableSpaces > 0)
{
/* Advance nextTempTableSpace counter with wraparound */
if (++nextTempTableSpace >= numTempTableSpaces)
nextTempTableSpace = 0;
return tempTableSpaces[nextTempTableSpace];
}
return InvalidOid;
}
/*
* AtEOSubXact_Files
*
* Take care of subtransaction commit/abort. At abort, we close temp files
* that the subtransaction may have opened. At commit, we reassign the
* files that were opened to the parent subtransaction.
*/
void
AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
SubTransactionId parentSubid)
{
Index i;
for (i = 0; i < numAllocatedDescs; i++)
{
if (allocatedDescs[i].create_subid == mySubid)
{
if (isCommit)
allocatedDescs[i].create_subid = parentSubid;
else
{
/* have to recheck the item after FreeDesc (ugly) */
FreeDesc(&allocatedDescs[i--]);
}
}
}
}
/*
* AtEOXact_Files
*
* This routine is called during transaction commit or abort. All still-open
* per-transaction temporary file VFDs are closed, which also causes the
* underlying files to be deleted (although they should've been closed already
* by the ResourceOwner cleanup). Furthermore, all "allocated" stdio files are
* closed. We also forget any transaction-local temp tablespace list.
*
* The isCommit flag is used only to decide whether to emit warnings about
* unclosed files.
*/
void
AtEOXact_Files(bool isCommit)
{
CleanupTempFiles(isCommit, false);
tempTableSpaces = NULL;
numTempTableSpaces = -1;
}
/*
* BeforeShmemExit_Files
*
* before_shmem_exit hook to clean up temp files during backend shutdown.
* Here, we want to clean up *all* temp files including interXact ones.
*/
static void
BeforeShmemExit_Files(int code, Datum arg)
{
CleanupTempFiles(false, true);
/* prevent further temp files from being created */
#ifdef USE_ASSERT_CHECKING
temporary_files_allowed = false;
#endif
}
/*
* Close temporary files and delete their underlying files.
*
* isCommit: if true, this is normal transaction commit, and we don't
* expect any remaining files; warn if there are some.
*
* isProcExit: if true, this is being called as the backend process is
* exiting. If that's the case, we should remove all temporary files; if
* that's not the case, we are being called for transaction commit/abort
* and should only remove transaction-local temp files. In either case,
* also clean up "allocated" stdio files, dirs and fds.
*/
static void
CleanupTempFiles(bool isCommit, bool isProcExit)
{
Index i;
/*
* Careful here: at proc_exit we need extra cleanup, not just
* xact_temporary files.
*/
if (isProcExit || have_xact_temporary_files)
{
Assert(FileIsNotOpen(0)); /* Make sure ring not corrupted */
for (i = 1; i < SizeVfdCache; i++)
{
unsigned short fdstate = VfdCache[i].fdstate;
if (((fdstate & FD_DELETE_AT_CLOSE) || (fdstate & FD_CLOSE_AT_EOXACT)) &&
VfdCache[i].fileName != NULL)
{
/*
* If we're in the process of exiting a backend process, close
* all temporary files. Otherwise, only close temporary files
* local to the current transaction. They should be closed by
* the ResourceOwner mechanism already, so this is just a
* debugging cross-check.
*/
if (isProcExit)
FileClose(i);
else if (fdstate & FD_CLOSE_AT_EOXACT)
{
elog(WARNING,
"temporary file %s not closed at end-of-transaction",
VfdCache[i].fileName);
FileClose(i);
}
}
}
have_xact_temporary_files = false;
}
/* Complain if any allocated files remain open at commit. */
if (isCommit && numAllocatedDescs > 0)
elog(WARNING, "%d temporary files and directories not closed at end-of-transaction",
numAllocatedDescs);
/* Clean up "allocated" stdio files, dirs and fds. */
while (numAllocatedDescs > 0)
FreeDesc(&allocatedDescs[0]);
}
/*
* Remove temporary and temporary relation files left over from a prior
* postmaster session
*
* This should be called during postmaster startup. It will forcibly
* remove any leftover files created by OpenTemporaryFile and any leftover
* temporary relation files created by mdcreate.
*
* During post-backend-crash restart cycle, this routine is called when
* remove_temp_files_after_crash GUC is enabled. Multiple crashes while
* queries are using temp files could result in useless storage usage that can
* only be reclaimed by a service restart. The argument against enabling it is
* that someone might want to examine the temporary files for debugging
* purposes. This does however mean that OpenTemporaryFile had better allow for
* collision with an existing temp file name.
*
* NOTE: this function and its subroutines generally report syscall failures
* with ereport(LOG) and keep going. Removing temp files is not so critical
* that we should fail to start the database when we can't do it.
*/
void
RemovePgTempFiles(void)
{
char temp_path[MAXPGPATH + 11 + MAX_DBID_STRING_LENGTH + 1 + sizeof(GP_TABLESPACE_VERSION_DIRECTORY) + sizeof(PG_TEMP_FILES_DIR)];
DIR *spc_dir;
struct dirent *spc_de;
/*
* First process temp files in pg_default ($PGDATA/base)
*/
snprintf(temp_path, sizeof(temp_path), "base/%s", PG_TEMP_FILES_DIR);
RemovePgTempFilesInDir(temp_path, true, false);
RemovePgTempRelationFiles("base");
/*
* Cycle through temp directories for all non-default tablespaces.
*/
spc_dir = AllocateDir("pg_tblspc");
while ((spc_de = ReadDirExtended(spc_dir, "pg_tblspc", LOG)) != NULL)
{
if (strcmp(spc_de->d_name, ".") == 0 ||
strcmp(spc_de->d_name, "..") == 0)
continue;
snprintf(temp_path, sizeof(temp_path), "pg_tblspc/%s/%s/%s",
spc_de->d_name, GP_TABLESPACE_VERSION_DIRECTORY, PG_TEMP_FILES_DIR);
RemovePgTempFilesInDir(temp_path, true, false);
snprintf(temp_path, sizeof(temp_path), "pg_tblspc/%s/%s",
spc_de->d_name, GP_TABLESPACE_VERSION_DIRECTORY);
RemovePgTempRelationFiles(temp_path);
}
FreeDir(spc_dir);
/*
* In EXEC_BACKEND case there is a pgsql_tmp directory at the top level of
* DataDir as well. However, that is *not* cleaned here because doing so
* would create a race condition. It's done separately, earlier in
* postmaster startup.
*/
}
/*
* Process one pgsql_tmp directory for RemovePgTempFiles.
*
* If missing_ok is true, it's all right for the named directory to not exist.
* Any other problem results in a LOG message. (missing_ok should be true at
* the top level, since pgsql_tmp directories are not created until needed.)
*
* At the top level, this should be called with unlink_all = false, so that
* only files matching the temporary name prefix will be unlinked. When
* recursing it will be called with unlink_all = true to unlink everything
* under a top-level temporary directory.
*
* (These two flags could be replaced by one, but it seems clearer to keep
* them separate.)
*/
void
RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok, bool unlink_all)
{
DIR *temp_dir;
struct dirent *temp_de;
char rm_path[MAXPGPATH * 2];
temp_dir = AllocateDir(tmpdirname);
if (temp_dir == NULL && errno == ENOENT && missing_ok)
return;
while ((temp_de = ReadDirExtended(temp_dir, tmpdirname, LOG)) != NULL)
{
if (strcmp(temp_de->d_name, ".") == 0 ||
strcmp(temp_de->d_name, "..") == 0)
continue;
snprintf(rm_path, sizeof(rm_path), "%s/%s",
tmpdirname, temp_de->d_name);
if (unlink_all ||
strncmp(temp_de->d_name,
PG_TEMP_FILE_PREFIX,
strlen(PG_TEMP_FILE_PREFIX)) == 0)
{
PGFileType type = get_dirent_type(rm_path, temp_de, false, LOG);
if (type == PGFILETYPE_ERROR)
continue;
else if (type == PGFILETYPE_DIR)
{
/* recursively remove contents, then directory itself */
RemovePgTempFilesInDir(rm_path, false, true);
if (rmdir(rm_path) < 0)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not remove directory \"%s\": %m",
rm_path)));
}
else
{
if (unlink(rm_path) < 0)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m",
rm_path)));
}
}
else
ereport(LOG,
(errmsg("unexpected file found in temporary-files directory: \"%s\"",
rm_path)));
}
FreeDir(temp_dir);
}
/* Process one tablespace directory, look for per-DB subdirectories */
static void
RemovePgTempRelationFiles(const char *tsdirname)
{
DIR *ts_dir;
struct dirent *de;
char dbspace_path[MAXPGPATH * 2];
ts_dir = AllocateDir(tsdirname);
while ((de = ReadDirExtended(ts_dir, tsdirname, LOG)) != NULL)
{
/*
* We're only interested in the per-database directories, which have
* numeric names. Note that this code will also (properly) ignore "."
* and "..".
*/
if (strspn(de->d_name, "0123456789") != strlen(de->d_name))
continue;
snprintf(dbspace_path, sizeof(dbspace_path), "%s/%s",
tsdirname, de->d_name);
RemovePgTempRelationFilesInDbspace(dbspace_path);
}
FreeDir(ts_dir);
}
/* Process one per-dbspace directory for RemovePgTempRelationFiles */
static void
RemovePgTempRelationFilesInDbspace(const char *dbspacedirname)
{
DIR *dbspace_dir;
struct dirent *de;
char rm_path[MAXPGPATH * 2];
dbspace_dir = AllocateDir(dbspacedirname);
while ((de = ReadDirExtended(dbspace_dir, dbspacedirname, LOG)) != NULL)
{
if (!looks_like_temp_rel_name(de->d_name))
continue;
snprintf(rm_path, sizeof(rm_path), "%s/%s",
dbspacedirname, de->d_name);
if (unlink(rm_path) < 0)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m",
rm_path)));
}
FreeDir(dbspace_dir);
}
/*
* In PostgreSQL, the pattern is:
*
* t<digits>_<digits>, or t<digits>_<digits>_<forkname>
*
* In GPDB, however, we leave out the first <digits>. In PostgreSQL it's
* used for the backend ID, but we don't use that in GPDB because even
* temporary relation are kept in shared buffers, and need to be accessible
* from multiple backends. So the pattern in GPDB is:
*
* t_<digits>, or t_<digits>_<forkname>
*/
bool
looks_like_temp_rel_name(const char *name)
{
int pos;
int savepos;
/* Must start with "t". */
if (name[0] != 't')
return false;
/* Followed by underscode. */
if (name[1] != '_')
return false;
pos = 1;
/* Followed by another nonempty string of digits. */
for (savepos = ++pos; isdigit((unsigned char) name[pos]); ++pos)
;
if (savepos == pos)
return false;
/* We might have _forkname or .segment or both. */
if (name[pos] == '_')
{
int forkchar = forkname_chars(&name[pos + 1], NULL);
if (forkchar <= 0)
return false;
pos += forkchar + 1;
}
if (name[pos] == '.')
{
int segchar;
for (segchar = 1; isdigit((unsigned char) name[pos + segchar]); ++segchar)
;
if (segchar <= 1)
return false;
pos += segchar;
}
/* Now we should be at the end. */
if (name[pos] != '\0')
return false;
return true;
}
/*
* Synchronize all xlog files and pg_wal itself in pg_wal
*
* This is called at the beginning of recovery.
*/
void
SyncAllXLogFiles(void)
{
/* We can skip this whole thing if fsync is disabled. */
if (!enableFsync)
return;
ereport(LOG, (errmsg("Synchronization of the wal directory starts.")));
walkdir("pg_wal", datadir_fsync_fname, false, LOG);
ereport(LOG, (errmsg("synchronization of the wal directory finishes.")));
}
#ifdef HAVE_SYNCFS
static void
do_syncfs(const char *path)
{
int fd;
ereport_startup_progress("syncing data directory (syncfs), elapsed time: %ld.%02d s, current path: %s",
path);
fd = OpenTransientFile(path, O_RDONLY);
if (fd < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", path)));
return;
}
if (syncfs(fd) < 0)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not synchronize file system for file \"%s\": %m", path)));
CloseTransientFile(fd);
}
#endif
/*
* Issue fsync recursively on PGDATA and all its contents, or issue syncfs for
* all potential filesystem, depending on recovery_init_sync_method setting.
*
* We fsync regular files and directories wherever they are, but we
* follow symlinks only for pg_wal and immediately under pg_tblspc.
* Other symlinks are presumed to point at files we're not responsible
* for fsyncing, and might not have privileges to write at all.
*
* Errors are logged but not considered fatal; that's because this is used
* only during database startup, to deal with the possibility that there are
* issued-but-unsynced writes pending against the data directory. We want to
* ensure that such writes reach disk before anything that's done in the new
* run. However, aborting on error would result in failure to start for
* harmless cases such as read-only files in the data directory, and that's
* not good either.
*
* Note that if we previously crashed due to a PANIC on fsync(), we'll be
* rewriting all changes again during recovery.
*
* Note we assume we're chdir'd into PGDATA to begin with.
*/
void
SyncDataDirectory(void)
{
bool xlog_is_symlink;
/* We can skip this whole thing if fsync is disabled. */
if (!enableFsync)
return;
/*
* If pg_wal is a symlink, we'll need to recurse into it separately,
* because the first walkdir below will ignore it.
*/
xlog_is_symlink = false;
{
struct stat st;
if (lstat("pg_wal", &st) < 0)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m",
"pg_wal")));
else if (S_ISLNK(st.st_mode))
xlog_is_symlink = true;
}
#ifdef HAVE_SYNCFS
if (recovery_init_sync_method == RECOVERY_INIT_SYNC_METHOD_SYNCFS)
{
DIR *dir;
struct dirent *de;
/*
* On Linux, we don't have to open every single file one by one. We
* can use syncfs() to sync whole filesystems. We only expect
* filesystem boundaries to exist where we tolerate symlinks, namely
* pg_wal and the tablespaces, so we call syncfs() for each of those
* directories.
*/
/* Prepare to report progress syncing the data directory via syncfs. */
begin_startup_progress_phase();
/* Sync the top level pgdata directory. */
do_syncfs(".");
/* If any tablespaces are configured, sync each of those. */
dir = AllocateDir("pg_tblspc");
while ((de = ReadDirExtended(dir, "pg_tblspc", LOG)))
{
char path[MAXPGPATH];
if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
continue;
snprintf(path, MAXPGPATH, "pg_tblspc/%s", de->d_name);
do_syncfs(path);
}
FreeDir(dir);
/* If pg_wal is a symlink, process that too. */
if (xlog_is_symlink)
do_syncfs("pg_wal");
return;
}
#endif /* !HAVE_SYNCFS */
#ifdef PG_FLUSH_DATA_WORKS
/* Prepare to report progress of the pre-fsync phase. */
begin_startup_progress_phase();
/*
* If possible, hint to the kernel that we're soon going to fsync the data
* directory and its contents. Errors in this step are even less
* interesting than normal, so log them only at DEBUG1.
*/
walkdir(".", pre_sync_fname, false, DEBUG1);
if (xlog_is_symlink)
walkdir("pg_wal", pre_sync_fname, false, DEBUG1);
walkdir("pg_tblspc", pre_sync_fname, true, DEBUG1);
#endif
/* Prepare to report progress syncing the data directory via fsync. */
begin_startup_progress_phase();
/*
* Now we do the fsync()s in the same order.
*
* The main call ignores symlinks, so in addition to specially processing
* pg_wal if it's a symlink, pg_tblspc has to be visited separately with
* process_symlinks = true. Note that if there are any plain directories
* in pg_tblspc, they'll get fsync'd twice. That's not an expected case
* so we don't worry about optimizing it.
*/
walkdir(".", datadir_fsync_fname, false, LOG);
if (xlog_is_symlink)
walkdir("pg_wal", datadir_fsync_fname, false, LOG);
walkdir("pg_tblspc", datadir_fsync_fname, true, LOG);
}
/*
* walkdir: recursively walk a directory, applying the action to each
* regular file and directory (including the named directory itself).
*
* If process_symlinks is true, the action and recursion are also applied
* to regular files and directories that are pointed to by symlinks in the
* given directory; otherwise symlinks are ignored. Symlinks are always
* ignored in subdirectories, ie we intentionally don't pass down the
* process_symlinks flag to recursive calls.
*
* Errors are reported at level elevel, which might be ERROR or less.
*
* See also walkdir in file_utils.c, which is a frontend version of this
* logic.
*/
static void
walkdir(const char *path,
void (*action) (const char *fname, bool isdir, int elevel),
bool process_symlinks,
int elevel)
{
DIR *dir;
struct dirent *de;
dir = AllocateDir(path);
while ((de = ReadDirExtended(dir, path, elevel)) != NULL)
{
char subpath[MAXPGPATH * 2];
CHECK_FOR_INTERRUPTS();
if (strcmp(de->d_name, ".") == 0 ||
strcmp(de->d_name, "..") == 0)
continue;
snprintf(subpath, sizeof(subpath), "%s/%s", path, de->d_name);
switch (get_dirent_type(subpath, de, process_symlinks, elevel))
{
case PGFILETYPE_REG:
(*action) (subpath, false, elevel);
break;
case PGFILETYPE_DIR:
walkdir(subpath, action, false, elevel);
break;
default:
/*
* Errors are already reported directly by get_dirent_type(),
* and any remaining symlinks and unknown file types are
* ignored.
*/
break;
}
}
FreeDir(dir); /* we ignore any error here */
/*
* It's important to fsync the destination directory itself as individual
* file fsyncs don't guarantee that the directory entry for the file is
* synced. However, skip this if AllocateDir failed; the action function
* might not be robust against that.
*/
if (dir)
(*action) (path, true, elevel);
}
/*
* Hint to the OS that it should get ready to fsync() this file.
*
* Ignores errors trying to open unreadable files, and logs other errors at a
* caller-specified level.
*/
#ifdef PG_FLUSH_DATA_WORKS
static void
pre_sync_fname(const char *fname, bool isdir, int elevel)
{
int fd;
/* Don't try to flush directories, it'll likely just fail */
if (isdir)
return;
ereport_startup_progress("syncing data directory (pre-fsync), elapsed time: %ld.%02d s, current path: %s",
fname);
fd = OpenTransientFile(fname, O_RDONLY | PG_BINARY);
if (fd < 0)
{
if (errno == EACCES)
return;
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", fname)));
return;
}
/*
* pg_flush_data() ignores errors, which is ok because this is only a
* hint.
*/
pg_flush_data(fd, 0, 0);
if (CloseTransientFile(fd) != 0)
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", fname)));
}
#endif /* PG_FLUSH_DATA_WORKS */
static void
datadir_fsync_fname(const char *fname, bool isdir, int elevel)
{
ereport_startup_progress("syncing data directory (fsync), elapsed time: %ld.%02d s, current path: %s",
fname);
/*
* We want to silently ignoring errors about unreadable files. Pass that
* desire on to fsync_fname_ext().
*/
fsync_fname_ext(fname, isdir, true, elevel);
}
static void
unlink_if_exists_fname(const char *fname, bool isdir, int elevel)
{
if (isdir)
{
if (rmdir(fname) != 0 && errno != ENOENT)
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not remove directory \"%s\": %m", fname)));
}
else
{
/* Use PathNameDeleteTemporaryFile to report filesize */
PathNameDeleteTemporaryFile(fname, false);
}
}
/*
* fsync_fname_ext -- Try to fsync a file or directory
*
* If ignore_perm is true, ignore errors upon trying to open unreadable
* files. Logs other errors at a caller-specified level.
*
* Returns 0 if the operation succeeded, -1 otherwise.
*/
int
fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel)
{
int fd;
int flags;
int returncode;
/*
* Some OSs require directories to be opened read-only whereas other
* systems don't allow us to fsync files opened read-only; so we need both
* cases here. Using O_RDWR will cause us to fail to fsync files that are
* not writable by our userid, but we assume that's OK.
*/
flags = PG_BINARY;
if (!isdir)
flags |= O_RDWR;
else
flags |= O_RDONLY;
fd = OpenTransientFile(fname, flags);
/*
* Some OSs don't allow us to open directories at all (Windows returns
* EACCES), just ignore the error in that case. If desired also silently
* ignoring errors about unreadable files. Log others.
*/
if (fd < 0 && isdir && (errno == EISDIR || errno == EACCES))
return 0;
else if (fd < 0 && ignore_perm && errno == EACCES)
return 0;
else if (fd < 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", fname)));
return -1;
}
returncode = pg_fsync(fd);
/*
* Some OSes don't allow us to fsync directories at all, so we can ignore
* those errors. Anything else needs to be logged.
*/
if (returncode != 0 && !(isdir && (errno == EBADF || errno == EINVAL)))
{
int save_errno;
/* close file upon error, might not be in transaction context */
save_errno = errno;
(void) CloseTransientFile(fd);
errno = save_errno;
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not fsync file \"%s\": %m", fname)));
return -1;
}
if (CloseTransientFile(fd) != 0)
{
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", fname)));
return -1;
}
return 0;
}
/*
* fsync_parent_path -- fsync the parent path of a file or directory
*
* This is aimed at making file operations persistent on disk in case of
* an OS crash or power failure.
*/
static int
fsync_parent_path(const char *fname, int elevel)
{
char parentpath[MAXPGPATH];
strlcpy(parentpath, fname, MAXPGPATH);
get_parent_directory(parentpath);
/*
* get_parent_directory() returns an empty string if the input argument is
* just a file name (see comments in path.c), so handle that as being the
* current directory.
*/
if (strlen(parentpath) == 0)
strlcpy(parentpath, ".", MAXPGPATH);
if (fsync_fname_ext(parentpath, true, false, elevel) != 0)
return -1;
return 0;
}
const char *
FileGetFilename(File file)
{
Assert(FileIsValid(file));
DO_DB(elog(LOG, "FileSeek: %d (%s) " INT64_FORMAT " " INT64_FORMAT " %d",
file, VfdCache[file].fileName,
(int64) VfdCache[file].seekPos,
(int64) offset, whence));
return VfdCache[file].fileName;
}
/*
* Mark the file as a "work file" that should be tracked by the workfile manager.
*/
void
FileSetIsWorkfile(File file)
{
VfdCache[file].fdstate |= FD_WORKFILE;
}
/*
* Create a PostgreSQL data sub-directory
*
* The data directory itself, and most of its sub-directories, are created at
* initdb time, but we do have some occasions when we create directories in
* the backend (CREATE TABLESPACE, for example). In those cases, we want to
* make sure that those directories are created consistently. Today, that means
* making sure that the created directory has the correct permissions, which is
* what pg_dir_create_mode tracks for us.
*
* Note that we also set the umask() based on what we understand the correct
* permissions to be (see file_perm.c).
*
* For permissions other than the default, mkdir() can be used directly, but
* be sure to consider carefully such cases -- a sub-directory with incorrect
* permissions in a PostgreSQL data directory could cause backups and other
* processes to fail.
*/
int
MakePGDirectory(const char *directoryName)
{
return mkdir(directoryName, pg_dir_create_mode);
}
/*
* Return the passed-in error level, or PANIC if data_sync_retry is off.
*
* Failure to fsync any data file is cause for immediate panic, unless
* data_sync_retry is enabled. Data may have been written to the operating
* system and removed from our buffer pool already, and if we are running on
* an operating system that forgets dirty data on write-back failure, there
* may be only one copy of the data remaining: in the WAL. A later attempt to
* fsync again might falsely report success. Therefore we must not allow any
* further checkpoints to be attempted. data_sync_retry can in theory be
* enabled on systems known not to drop dirty buffered data on write-back
* failure (with the likely outcome that checkpoints will continue to fail
* until the underlying problem is fixed).
*
* Any code that reports a failure from fsync() or related functions should
* filter the error level with this function.
*/
int
data_sync_elevel(int elevel)
{
return data_sync_retry ? elevel : PANIC;
}
bool
check_debug_io_direct(char **newval, void **extra, GucSource source)
{
bool result = true;
int flags;
#if PG_O_DIRECT == 0
if (strcmp(*newval, "") != 0)
{
GUC_check_errdetail("debug_io_direct is not supported on this platform.");
result = false;
}
flags = 0;
#else
List *elemlist;
ListCell *l;
char *rawstring;
/* Need a modifiable copy of string */
rawstring = pstrdup(*newval);
if (!SplitGUCList(rawstring, ',', &elemlist))
{
GUC_check_errdetail("invalid list syntax in parameter \"%s\"",
"debug_io_direct");
pfree(rawstring);
list_free(elemlist);
return false;
}
flags = 0;
foreach(l, elemlist)
{
char *item = (char *) lfirst(l);
if (pg_strcasecmp(item, "data") == 0)
flags |= IO_DIRECT_DATA;
else if (pg_strcasecmp(item, "wal") == 0)
flags |= IO_DIRECT_WAL;
else if (pg_strcasecmp(item, "wal_init") == 0)
flags |= IO_DIRECT_WAL_INIT;
else
{
GUC_check_errdetail("invalid option \"%s\"", item);
result = false;
break;
}
}
/*
* It's possible to configure block sizes smaller than our assumed I/O
* alignment size, which could result in invalid I/O requests.
*/
#if XLOG_BLCKSZ < PG_IO_ALIGN_SIZE
if (result && (flags & (IO_DIRECT_WAL | IO_DIRECT_WAL_INIT)))
{
GUC_check_errdetail("debug_io_direct is not supported for WAL because XLOG_BLCKSZ is too small");
result = false;
}
#endif
#if BLCKSZ < PG_IO_ALIGN_SIZE
if (result && (flags & IO_DIRECT_DATA))
{
GUC_check_errdetail("debug_io_direct is not supported for data because BLCKSZ is too small");
result = false;
}
#endif
pfree(rawstring);
list_free(elemlist);
#endif
if (!result)
return result;
/* Save the flags in *extra, for use by assign_debug_io_direct */
*extra = guc_malloc(ERROR, sizeof(int));
*((int *) *extra) = flags;
return result;
}
extern void
assign_debug_io_direct(const char *newval, void *extra)
{
int *flags = (int *) extra;
io_direct_flags = *flags;
}
void FileSetTempfile(File file, bool isTemp)
{
if (isTemp)
VfdCache[file].fdstate |= FD_DELETE_AT_CLOSE;
else
VfdCache[file].fdstate &= ~FD_DELETE_AT_CLOSE;
}