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/*-------------------------------------------------------------------------
*
* smgr.h
* storage manager switch public interface declarations.
*
*
* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/storage/smgr.h
*
*-------------------------------------------------------------------------
*/
#ifndef SMGR_H
#define SMGR_H
#include "lib/ilist.h"
#include "storage/block.h"
#include "storage/relfilelocator.h"
/*
* smgr.c maintains a table of SMgrRelation objects, which are essentially
* cached file handles. An SMgrRelation is created (if not already present)
* by smgropen(), and destroyed by smgrdestroy(). Note that neither of these
* operations imply I/O, they just create or destroy a hashtable entry. (But
* smgrdestroy() may release associated resources, such as OS-level file
* descriptors.)
*
* An SMgrRelation may be "pinned", to prevent it from being destroyed while
* it's in use. We use this to prevent pointers in relcache to smgr from being
* invalidated. SMgrRelations that are not pinned are deleted at end of
* transaction.
*/
typedef struct SMgrRelationData
{
/* rlocator is the hashtable lookup key, so it must be first! */
RelFileLocatorBackend smgr_rlocator; /* relation physical identifier */
/*
* The following fields are reset to InvalidBlockNumber upon a cache flush
* event, and hold the last known size for each fork. This information is
* currently only reliable during recovery, since there is no cache
* invalidation for fork extension.
*/
BlockNumber smgr_targblock; /* current insertion target block */
BlockNumber smgr_cached_nblocks[MAX_FORKNUM + 1]; /* last known size */
/* additional public fields may someday exist here */
/*
* Fields below here are intended to be private to smgr.c and its
* submodules. Do not touch them from elsewhere.
*/
int smgr_which; /* storage manager selector */
/*
* for md.c; per-fork arrays of the number of open segments
* (md_num_open_segs) and the segments themselves (md_seg_fds).
*/
int md_num_open_segs[MAX_FORKNUM + 1];
struct _MdfdVec *md_seg_fds[MAX_FORKNUM + 1];
/*
* Pinning support. If unpinned (ie. pincount == 0), 'node' is a list
* link in list of all unpinned SMgrRelations.
*/
int pincount;
dlist_node node;
} SMgrRelationData;
typedef SMgrRelationData *SMgrRelation;
#define SmgrIsTemp(smgr) \
RelFileLocatorBackendIsTemp((smgr)->smgr_rlocator)
extern void smgrinit(void);
extern SMgrRelation smgropen(RelFileLocator rlocator, ProcNumber backend);
extern bool smgrexists(SMgrRelation reln, ForkNumber forknum);
extern void smgrpin(SMgrRelation reln);
extern void smgrunpin(SMgrRelation reln);
extern void smgrclose(SMgrRelation reln);
extern void smgrdestroyall(void);
extern void smgrrelease(SMgrRelation reln);
extern void smgrreleaseall(void);
extern void smgrreleaserellocator(RelFileLocatorBackend rlocator);
extern void smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo);
extern void smgrdosyncall(SMgrRelation *rels, int nrels);
extern void smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo);
extern void smgrextend(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, const void *buffer, bool skipFsync);
extern void smgrzeroextend(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, int nblocks, bool skipFsync);
extern bool smgrprefetch(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, int nblocks);
extern uint32 smgrmaxcombine(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum);
extern void smgrreadv(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum,
void **buffers, BlockNumber nblocks);
extern void smgrwritev(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum,
const void **buffers, BlockNumber nblocks,
bool skipFsync);
extern void smgrwriteback(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, BlockNumber nblocks);
extern BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum);
extern BlockNumber smgrnblocks_cached(SMgrRelation reln, ForkNumber forknum);
extern void smgrtruncate(SMgrRelation reln, ForkNumber *forknum, int nforks,
BlockNumber *old_nblocks,
BlockNumber *nblocks);
extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum);
extern void smgrregistersync(SMgrRelation reln, ForkNumber forknum);
extern void AtEOXact_SMgr(void);
extern bool ProcessBarrierSmgrRelease(void);
static inline void
smgrread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
void *buffer)
{
smgrreadv(reln, forknum, blocknum, &buffer, 1);
}
static inline void
smgrwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
const void *buffer, bool skipFsync)
{
smgrwritev(reln, forknum, blocknum, &buffer, 1, skipFsync);
}
#endif /* SMGR_H */
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