mirror of
https://github.com/postgres/postgres.git
synced 2026-02-23 18:04:41 -05:00
fba105b109
"Blind writes" are a mechanism to push buffers down to disk when evicting them; since they may belong to different databases than the one a backend is connected to, the backend does not necessarily have a relation to link them to, and thus no way to blow them away. We were keeping those files open indefinitely, which would cause a problem if the underlying table was deleted, because the operating system would not be able to reclaim the disk space used by those files. To fix, have bufmgr mark such files as transient to smgr; the lower layer is allowed to close the file descriptor when the current transaction ends. We must be careful to have any other access of the file to remove the transient markings, to prevent unnecessary expensive system calls when evicting buffers belonging to our own database (which files we're likely to require again soon.) This commit fixes a bug in the previous one, which neglected to cleanly handle the LRU ring that fd.c uses to manage open files, and caused an unacceptable failure just before beta2 and was thus reverted.
141 lines
5.5 KiB
C
141 lines
5.5 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* smgr.h
|
|
* storage manager switch public interface declarations.
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2011, 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 "access/xlog.h"
|
|
#include "fmgr.h"
|
|
#include "storage/backendid.h"
|
|
#include "storage/block.h"
|
|
#include "storage/relfilenode.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 smgrclose(). Note that neither of these
|
|
* operations imply I/O, they just create or destroy a hashtable entry.
|
|
* (But smgrclose() may release associated resources, such as OS-level file
|
|
* descriptors.)
|
|
*
|
|
* An SMgrRelation may have an "owner", which is just a pointer to it from
|
|
* somewhere else; smgr.c will clear this pointer if the SMgrRelation is
|
|
* closed. We use this to avoid dangling pointers from relcache to smgr
|
|
* without having to make the smgr explicitly aware of relcache. There
|
|
* can't be more than one "owner" pointer per SMgrRelation, but that's
|
|
* all we need.
|
|
*/
|
|
typedef struct SMgrRelationData
|
|
{
|
|
/* rnode is the hashtable lookup key, so it must be first! */
|
|
RelFileNodeBackend smgr_rnode; /* relation physical identifier */
|
|
|
|
/* pointer to owning pointer, or NULL if none */
|
|
struct SMgrRelationData **smgr_owner;
|
|
|
|
/*
|
|
* These next three fields are not actually used or manipulated by smgr,
|
|
* except that they are reset to InvalidBlockNumber upon a cache flush
|
|
* event (in particular, upon truncation of the relation). Higher levels
|
|
* store cached state here so that it will be reset when truncation
|
|
* happens. In all three cases, InvalidBlockNumber means "unknown".
|
|
*/
|
|
BlockNumber smgr_targblock; /* current insertion target block */
|
|
BlockNumber smgr_fsm_nblocks; /* last known size of fsm fork */
|
|
BlockNumber smgr_vm_nblocks; /* last known size of vm fork */
|
|
|
|
/* 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 */
|
|
bool smgr_transient; /* T if files are to be closed at EOXact */
|
|
|
|
/* for md.c; NULL for forks that are not open */
|
|
struct _MdfdVec *md_fd[MAX_FORKNUM + 1];
|
|
} SMgrRelationData;
|
|
|
|
typedef SMgrRelationData *SMgrRelation;
|
|
|
|
#define SmgrIsTemp(smgr) \
|
|
((smgr)->smgr_rnode.backend != InvalidBackendId)
|
|
|
|
extern void smgrinit(void);
|
|
extern SMgrRelation smgropen(RelFileNode rnode, BackendId backend);
|
|
extern void smgrsettransient(SMgrRelation reln);
|
|
extern bool smgrexists(SMgrRelation reln, ForkNumber forknum);
|
|
extern void smgrsetowner(SMgrRelation *owner, SMgrRelation reln);
|
|
extern void smgrclose(SMgrRelation reln);
|
|
extern void smgrcloseall(void);
|
|
extern void smgrclosenode(RelFileNodeBackend rnode);
|
|
extern void smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo);
|
|
extern void smgrdounlink(SMgrRelation reln, ForkNumber forknum,
|
|
bool isRedo);
|
|
extern void smgrextend(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber blocknum, char *buffer, bool skipFsync);
|
|
extern void smgrprefetch(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber blocknum);
|
|
extern void smgrread(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber blocknum, char *buffer);
|
|
extern void smgrwrite(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber blocknum, char *buffer, bool skipFsync);
|
|
extern BlockNumber smgrnblocks(SMgrRelation reln, ForkNumber forknum);
|
|
extern void smgrtruncate(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber nblocks);
|
|
extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum);
|
|
extern void smgrpreckpt(void);
|
|
extern void smgrsync(void);
|
|
extern void smgrpostckpt(void);
|
|
|
|
|
|
/* internals: move me elsewhere -- ay 7/94 */
|
|
|
|
/* in md.c */
|
|
extern void mdinit(void);
|
|
extern void mdclose(SMgrRelation reln, ForkNumber forknum);
|
|
extern void mdcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo);
|
|
extern bool mdexists(SMgrRelation reln, ForkNumber forknum);
|
|
extern void mdunlink(RelFileNodeBackend rnode, ForkNumber forknum, bool isRedo);
|
|
extern void mdextend(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber blocknum, char *buffer, bool skipFsync);
|
|
extern void mdprefetch(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber blocknum);
|
|
extern void mdread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
|
|
char *buffer);
|
|
extern void mdwrite(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber blocknum, char *buffer, bool skipFsync);
|
|
extern BlockNumber mdnblocks(SMgrRelation reln, ForkNumber forknum);
|
|
extern void mdtruncate(SMgrRelation reln, ForkNumber forknum,
|
|
BlockNumber nblocks);
|
|
extern void mdimmedsync(SMgrRelation reln, ForkNumber forknum);
|
|
extern void mdpreckpt(void);
|
|
extern void mdsync(void);
|
|
extern void mdpostckpt(void);
|
|
|
|
extern void SetForwardFsyncRequests(void);
|
|
extern void RememberFsyncRequest(RelFileNodeBackend rnode, ForkNumber forknum,
|
|
BlockNumber segno);
|
|
extern void ForgetRelationFsyncRequests(RelFileNodeBackend rnode,
|
|
ForkNumber forknum);
|
|
extern void ForgetDatabaseFsyncRequests(Oid dbid);
|
|
|
|
/* smgrtype.c */
|
|
extern Datum smgrout(PG_FUNCTION_ARGS);
|
|
extern Datum smgrin(PG_FUNCTION_ARGS);
|
|
extern Datum smgreq(PG_FUNCTION_ARGS);
|
|
extern Datum smgrne(PG_FUNCTION_ARGS);
|
|
|
|
#endif /* SMGR_H */
|