src/include/access/distributedlog.h

/*-------------------------------------------------------------------------
 *
 * distributedlog.h
 *     A GP parallel log to the Postgres clog that records the full distributed
 * xid information for each local transaction id.
 *
 * It is used to determine if the committed xid for a transaction we want to
 * determine the visibility of is for a distributed transaction or a
 * local transaction.
 *
 * By default, entries in the SLRU (Simple LRU) module used to implement this
 * log will be set to zero.  A non-zero entry indicates a committed distributed
 * transaction.
 *
 * We must persist this log and the DTM does reuse the DistributedTransactionId
 * between restarts, so we will be storing the upper half of the whole
 * distributed transaction identifier -- the timestamp -- also so we can
 * be sure which distributed transaction we are looking at.
 *
 * Portions Copyright (c) 2007-2008, Greenplum inc
 * Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
 *
 *
 * IDENTIFICATION
 *	    src/include/access/distributedlog.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef DISTRIBUTEDLOG_H
#define DISTRIBUTEDLOG_H

#include "access/xlog.h"
#include "storage/sync.h"

/*
 * The full binary representation of the distributed transaction id.
 * The DTM start time and the distributed xid.
 */
typedef struct DistributedLogEntry
{
	DistributedTransactionId distribXid;

} DistributedLogEntry;

struct SlruCtlData;
typedef struct SlruCtlData *SlruCtl;

extern void DistributedLog_SetCommittedTree(TransactionId xid, int nxids, TransactionId *xids,
								DistributedTransactionId distribXid,
								bool isRedo);
extern bool DistributedLog_CommittedCheck(
							  TransactionId localXid,
							  DistributedTransactionId *distribXid);
extern bool DistributedLog_ScanForPrevCommitted(
									TransactionId *indexXid,
									DistributedTransactionId *distribXid);
extern TransactionId DistributedLog_AdvanceOldestXmin(TransactionId oldestInProgressLocalXid,
								 DistributedTransactionId oldestDistribXid);
extern TransactionId DistributedLog_GetOldestXmin(TransactionId oldestLocalXmin);

extern Size DistributedLog_ShmemBuffers(void);
extern Size DistributedLog_ShmemSize(void);
extern void DistributedLog_ShmemInit(void);
extern void DistributedLog_BootStrap(void);
extern void DistributedLog_Startup(
					   TransactionId oldestActiveXid,
					   TransactionId nextXid);
extern void DistributedLog_CheckPoint(void);
extern void DistributedLog_Extend(TransactionId newestXid);
extern bool DistributedLog_GetLowWaterXid(
							  TransactionId *lowWaterXid);
extern void DistributedLog_InitOldestXmin(void);

/* XLOG stuff */
#define DISTRIBUTEDLOG_ZEROPAGE		0x00
#define DISTRIBUTEDLOG_TRUNCATE		0x10

extern void DistributedLog_redo(XLogReaderState *record);
extern void DistributedLog_desc(StringInfo buf, XLogReaderState *record);
extern const char *DistributedLog_identify(uint8 info);
extern void DistributedLog_GetDistributedXid(
				TransactionId 						localXid,
				DistributedTransactionId 			*distribXid);

extern int DistributedLog_syncfiletag(const FileTag *ftag, char *path);
extern SlruCtl DistributedLog_Ctl(void);
#endif							/* DISTRIBUTEDLOG_H */