110 lines
4.3 KiB
C
110 lines
4.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* smgr.h
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* storage manager switch public interface declarations.
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*
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*
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* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/storage/smgr.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef SMGR_H
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#define SMGR_H
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#include "lib/ilist.h"
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#include "storage/block.h"
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#include "storage/relfilenode.h"
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/*
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* smgr.c maintains a table of SMgrRelation objects, which are essentially
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* cached file handles. An SMgrRelation is created (if not already present)
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* by smgropen(), and destroyed by smgrclose(). Note that neither of these
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* operations imply I/O, they just create or destroy a hashtable entry.
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* (But smgrclose() may release associated resources, such as OS-level file
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* descriptors.)
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*
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* An SMgrRelation may have an "owner", which is just a pointer to it from
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* somewhere else; smgr.c will clear this pointer if the SMgrRelation is
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* closed. We use this to avoid dangling pointers from relcache to smgr
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* without having to make the smgr explicitly aware of relcache. There
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* can't be more than one "owner" pointer per SMgrRelation, but that's
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* all we need.
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*
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* SMgrRelations that do not have an "owner" are considered to be transient,
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* and are deleted at end of transaction.
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*/
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typedef struct SMgrRelationData
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{
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/* rnode is the hashtable lookup key, so it must be first! */
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RelFileNodeBackend smgr_rnode; /* relation physical identifier */
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/* pointer to owning pointer, or NULL if none */
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struct SMgrRelationData **smgr_owner;
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/*
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* These next three fields are not actually used or manipulated by smgr,
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* except that they are reset to InvalidBlockNumber upon a cache flush
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* event (in particular, upon truncation of the relation). Higher levels
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* store cached state here so that it will be reset when truncation
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* happens. In all three cases, InvalidBlockNumber means "unknown".
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*/
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BlockNumber smgr_targblock; /* current insertion target block */
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BlockNumber smgr_fsm_nblocks; /* last known size of fsm fork */
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BlockNumber smgr_vm_nblocks; /* last known size of vm fork */
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/* additional public fields may someday exist here */
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/*
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* Fields below here are intended to be private to smgr.c and its
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* submodules. Do not touch them from elsewhere.
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*/
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int smgr_which; /* storage manager selector */
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/*
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* for md.c; per-fork arrays of the number of open segments
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* (md_num_open_segs) and the segments themselves (md_seg_fds).
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*/
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int md_num_open_segs[MAX_FORKNUM + 1];
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struct _MdfdVec *md_seg_fds[MAX_FORKNUM + 1];
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/* if unowned, list link in list of all unowned SMgrRelations */
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dlist_node node;
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} SMgrRelationData;
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typedef SMgrRelationData *SMgrRelation;
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#define SmgrIsTemp(smgr) \
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RelFileNodeBackendIsTemp((smgr)->smgr_rnode)
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extern void smgrinit(void);
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extern SMgrRelation smgropen(RelFileNode rnode, BackendId backend);
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extern bool smgrexists(SMgrRelation reln, ForkNumber forknum);
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extern void smgrsetowner(SMgrRelation *owner, SMgrRelation reln);
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extern void smgrclearowner(SMgrRelation *owner, SMgrRelation reln);
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extern void smgrclose(SMgrRelation reln);
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extern void smgrcloseall(void);
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extern void smgrclosenode(RelFileNodeBackend rnode);
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extern void smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo);
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extern void smgrdounlink(SMgrRelation reln, bool isRedo);
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extern void smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo);
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extern void smgrextend(SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum, char *buffer, bool skipFsync);
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extern void smgrprefetch(SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum);
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extern void smgrread(SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum, char *buffer);
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extern void smgrwrite(SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum, char *buffer, bool skipFsync);
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extern void smgrwriteback(SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum, BlockNumber nblocks);
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extern BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum);
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extern void smgrtruncate(SMgrRelation reln, ForkNumber *forknum,
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int nforks, BlockNumber *nblocks);
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extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum);
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extern void AtEOXact_SMgr(void);
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#endif /* SMGR_H */
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