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45e191e3aa
So far md.c used a linked list of segments. That proved to be a problem when processing large relations, because every smgr.c/md.c level access to a page incurred walking through a linked list of all preceding segments. Thus making accessing pages O(#segments). Replace the linked list of segments hanging off SMgrRelationData with an array of opened segments. That allows O(1) access to individual segments, if they've previously been opened. Discussion: <20140331101001.GE13135@alap3.anarazel.de> Reviewed-By: Peter Geoghegan, Tom Lane (in an older version)
810 lines
23 KiB
C
810 lines
23 KiB
C
/*-------------------------------------------------------------------------
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*
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* smgr.c
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* public interface routines to storage manager switch.
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*
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* All file system operations in POSTGRES dispatch through these
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* routines.
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*
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* Portions Copyright (c) 1996-2016, 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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*
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* IDENTIFICATION
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* src/backend/storage/smgr/smgr.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "commands/tablespace.h"
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#include "storage/bufmgr.h"
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#include "storage/ipc.h"
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#include "storage/smgr.h"
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#include "utils/hsearch.h"
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#include "utils/inval.h"
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/*
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* This struct of function pointers defines the API between smgr.c and
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* any individual storage manager module. Note that smgr subfunctions are
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* generally expected to report problems via elog(ERROR). An exception is
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* that smgr_unlink should use elog(WARNING), rather than erroring out,
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* because we normally unlink relations during post-commit/abort cleanup,
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* and so it's too late to raise an error. Also, various conditions that
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* would normally be errors should be allowed during bootstrap and/or WAL
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* recovery --- see comments in md.c for details.
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*/
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typedef struct f_smgr
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{
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void (*smgr_init) (void); /* may be NULL */
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void (*smgr_shutdown) (void); /* may be NULL */
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void (*smgr_close) (SMgrRelation reln, ForkNumber forknum);
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void (*smgr_create) (SMgrRelation reln, ForkNumber forknum,
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bool isRedo);
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bool (*smgr_exists) (SMgrRelation reln, ForkNumber forknum);
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void (*smgr_unlink) (RelFileNodeBackend rnode, ForkNumber forknum,
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bool isRedo);
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void (*smgr_extend) (SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum, char *buffer, bool skipFsync);
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void (*smgr_prefetch) (SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum);
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void (*smgr_read) (SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum, char *buffer);
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void (*smgr_write) (SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum, char *buffer, bool skipFsync);
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void (*smgr_writeback) (SMgrRelation reln, ForkNumber forknum,
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BlockNumber blocknum, BlockNumber nblocks);
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BlockNumber (*smgr_nblocks) (SMgrRelation reln, ForkNumber forknum);
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void (*smgr_truncate) (SMgrRelation reln, ForkNumber forknum,
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BlockNumber nblocks);
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void (*smgr_immedsync) (SMgrRelation reln, ForkNumber forknum);
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void (*smgr_pre_ckpt) (void); /* may be NULL */
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void (*smgr_sync) (void); /* may be NULL */
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void (*smgr_post_ckpt) (void); /* may be NULL */
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} f_smgr;
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static const f_smgr smgrsw[] = {
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/* magnetic disk */
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{mdinit, NULL, mdclose, mdcreate, mdexists, mdunlink, mdextend,
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mdprefetch, mdread, mdwrite, mdwriteback, mdnblocks, mdtruncate,
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mdimmedsync, mdpreckpt, mdsync, mdpostckpt
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}
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};
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static const int NSmgr = lengthof(smgrsw);
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/*
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* Each backend has a hashtable that stores all extant SMgrRelation objects.
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* In addition, "unowned" SMgrRelation objects are chained together in a list.
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*/
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static HTAB *SMgrRelationHash = NULL;
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static SMgrRelation first_unowned_reln = NULL;
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/* local function prototypes */
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static void smgrshutdown(int code, Datum arg);
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static void add_to_unowned_list(SMgrRelation reln);
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static void remove_from_unowned_list(SMgrRelation reln);
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/*
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* smgrinit(), smgrshutdown() -- Initialize or shut down storage
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* managers.
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*
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* Note: smgrinit is called during backend startup (normal or standalone
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* case), *not* during postmaster start. Therefore, any resources created
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* here or destroyed in smgrshutdown are backend-local.
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*/
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void
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smgrinit(void)
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{
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int i;
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for (i = 0; i < NSmgr; i++)
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{
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if (smgrsw[i].smgr_init)
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(*(smgrsw[i].smgr_init)) ();
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}
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/* register the shutdown proc */
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on_proc_exit(smgrshutdown, 0);
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}
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/*
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* on_proc_exit hook for smgr cleanup during backend shutdown
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*/
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static void
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smgrshutdown(int code, Datum arg)
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{
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int i;
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for (i = 0; i < NSmgr; i++)
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{
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if (smgrsw[i].smgr_shutdown)
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(*(smgrsw[i].smgr_shutdown)) ();
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}
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}
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/*
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* smgropen() -- Return an SMgrRelation object, creating it if need be.
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*
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* This does not attempt to actually open the underlying file.
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*/
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SMgrRelation
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smgropen(RelFileNode rnode, BackendId backend)
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{
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RelFileNodeBackend brnode;
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SMgrRelation reln;
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bool found;
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if (SMgrRelationHash == NULL)
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{
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/* First time through: initialize the hash table */
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HASHCTL ctl;
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MemSet(&ctl, 0, sizeof(ctl));
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ctl.keysize = sizeof(RelFileNodeBackend);
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ctl.entrysize = sizeof(SMgrRelationData);
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SMgrRelationHash = hash_create("smgr relation table", 400,
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&ctl, HASH_ELEM | HASH_BLOBS);
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first_unowned_reln = NULL;
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}
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/* Look up or create an entry */
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brnode.node = rnode;
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brnode.backend = backend;
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reln = (SMgrRelation) hash_search(SMgrRelationHash,
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(void *) &brnode,
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HASH_ENTER, &found);
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/* Initialize it if not present before */
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if (!found)
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{
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int forknum;
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/* hash_search already filled in the lookup key */
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reln->smgr_owner = NULL;
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reln->smgr_targblock = InvalidBlockNumber;
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reln->smgr_fsm_nblocks = InvalidBlockNumber;
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reln->smgr_vm_nblocks = InvalidBlockNumber;
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reln->smgr_which = 0; /* we only have md.c at present */
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/* mark it not open */
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for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
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reln->md_num_open_segs[forknum] = 0;
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/* it has no owner yet */
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add_to_unowned_list(reln);
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}
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return reln;
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}
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/*
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* smgrsetowner() -- Establish a long-lived reference to an SMgrRelation object
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*
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* There can be only one owner at a time; this is sufficient since currently
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* the only such owners exist in the relcache.
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*/
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void
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smgrsetowner(SMgrRelation *owner, SMgrRelation reln)
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{
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/* We don't support "disowning" an SMgrRelation here, use smgrclearowner */
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Assert(owner != NULL);
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/*
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* First, unhook any old owner. (Normally there shouldn't be any, but it
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* seems possible that this can happen during swap_relation_files()
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* depending on the order of processing. It's ok to close the old
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* relcache entry early in that case.)
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*
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* If there isn't an old owner, then the reln should be in the unowned
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* list, and we need to remove it.
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*/
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if (reln->smgr_owner)
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*(reln->smgr_owner) = NULL;
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else
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remove_from_unowned_list(reln);
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/* Now establish the ownership relationship. */
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reln->smgr_owner = owner;
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*owner = reln;
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}
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/*
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* smgrclearowner() -- Remove long-lived reference to an SMgrRelation object
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* if one exists
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*/
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void
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smgrclearowner(SMgrRelation *owner, SMgrRelation reln)
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{
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/* Do nothing if the SMgrRelation object is not owned by the owner */
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if (reln->smgr_owner != owner)
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return;
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/* unset the owner's reference */
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*owner = NULL;
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/* unset our reference to the owner */
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reln->smgr_owner = NULL;
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add_to_unowned_list(reln);
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}
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/*
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* add_to_unowned_list -- link an SMgrRelation onto the unowned list
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*
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* Check remove_from_unowned_list()'s comments for performance
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* considerations.
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*/
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static void
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add_to_unowned_list(SMgrRelation reln)
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{
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/* place it at head of the list (to make smgrsetowner cheap) */
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reln->next_unowned_reln = first_unowned_reln;
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first_unowned_reln = reln;
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}
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/*
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* remove_from_unowned_list -- unlink an SMgrRelation from the unowned list
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*
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* If the reln is not present in the list, nothing happens. Typically this
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* would be caller error, but there seems no reason to throw an error.
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*
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* In the worst case this could be rather slow; but in all the cases that seem
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* likely to be performance-critical, the reln being sought will actually be
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* first in the list. Furthermore, the number of unowned relns touched in any
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* one transaction shouldn't be all that high typically. So it doesn't seem
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* worth expending the additional space and management logic needed for a
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* doubly-linked list.
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*/
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static void
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remove_from_unowned_list(SMgrRelation reln)
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{
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SMgrRelation *link;
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SMgrRelation cur;
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for (link = &first_unowned_reln, cur = *link;
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cur != NULL;
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link = &cur->next_unowned_reln, cur = *link)
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{
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if (cur == reln)
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{
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*link = cur->next_unowned_reln;
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cur->next_unowned_reln = NULL;
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break;
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}
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}
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}
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/*
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* smgrexists() -- Does the underlying file for a fork exist?
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*/
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bool
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smgrexists(SMgrRelation reln, ForkNumber forknum)
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{
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return (*(smgrsw[reln->smgr_which].smgr_exists)) (reln, forknum);
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}
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/*
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* smgrclose() -- Close and delete an SMgrRelation object.
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*/
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void
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smgrclose(SMgrRelation reln)
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{
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SMgrRelation *owner;
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ForkNumber forknum;
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for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
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(*(smgrsw[reln->smgr_which].smgr_close)) (reln, forknum);
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owner = reln->smgr_owner;
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if (!owner)
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remove_from_unowned_list(reln);
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if (hash_search(SMgrRelationHash,
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(void *) &(reln->smgr_rnode),
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HASH_REMOVE, NULL) == NULL)
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elog(ERROR, "SMgrRelation hashtable corrupted");
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/*
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* Unhook the owner pointer, if any. We do this last since in the remote
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* possibility of failure above, the SMgrRelation object will still exist.
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*/
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if (owner)
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*owner = NULL;
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}
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/*
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* smgrcloseall() -- Close all existing SMgrRelation objects.
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*/
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void
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smgrcloseall(void)
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{
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HASH_SEQ_STATUS status;
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SMgrRelation reln;
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/* Nothing to do if hashtable not set up */
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if (SMgrRelationHash == NULL)
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return;
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hash_seq_init(&status, SMgrRelationHash);
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while ((reln = (SMgrRelation) hash_seq_search(&status)) != NULL)
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smgrclose(reln);
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}
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/*
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* smgrclosenode() -- Close SMgrRelation object for given RelFileNode,
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* if one exists.
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*
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* This has the same effects as smgrclose(smgropen(rnode)), but it avoids
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* uselessly creating a hashtable entry only to drop it again when no
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* such entry exists already.
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*/
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void
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smgrclosenode(RelFileNodeBackend rnode)
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{
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SMgrRelation reln;
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/* Nothing to do if hashtable not set up */
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if (SMgrRelationHash == NULL)
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return;
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reln = (SMgrRelation) hash_search(SMgrRelationHash,
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(void *) &rnode,
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HASH_FIND, NULL);
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if (reln != NULL)
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smgrclose(reln);
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}
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/*
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* smgrcreate() -- Create a new relation.
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*
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* Given an already-created (but presumably unused) SMgrRelation,
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* cause the underlying disk file or other storage for the fork
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* to be created.
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*
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* If isRedo is true, it is okay for the underlying file to exist
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* already because we are in a WAL replay sequence.
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*/
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void
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smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo)
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{
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/*
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* Exit quickly in WAL replay mode if we've already opened the file. If
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* it's open, it surely must exist.
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*/
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if (isRedo && reln->md_num_open_segs[forknum] > 0)
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return;
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/*
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* We may be using the target table space for the first time in this
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* database, so create a per-database subdirectory if needed.
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*
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* XXX this is a fairly ugly violation of module layering, but this seems
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* to be the best place to put the check. Maybe TablespaceCreateDbspace
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* should be here and not in commands/tablespace.c? But that would imply
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* importing a lot of stuff that smgr.c oughtn't know, either.
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*/
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TablespaceCreateDbspace(reln->smgr_rnode.node.spcNode,
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reln->smgr_rnode.node.dbNode,
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isRedo);
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(*(smgrsw[reln->smgr_which].smgr_create)) (reln, forknum, isRedo);
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}
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/*
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* smgrdounlink() -- Immediately unlink all forks of a relation.
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*
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* All forks of the relation are removed from the store. This should
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* not be used during transactional operations, since it can't be undone.
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*
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* If isRedo is true, it is okay for the underlying file(s) to be gone
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* already.
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*
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* This is equivalent to calling smgrdounlinkfork for each fork, but
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* it's significantly quicker so should be preferred when possible.
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*/
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void
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smgrdounlink(SMgrRelation reln, bool isRedo)
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{
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RelFileNodeBackend rnode = reln->smgr_rnode;
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int which = reln->smgr_which;
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ForkNumber forknum;
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/* Close the forks at smgr level */
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for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
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(*(smgrsw[which].smgr_close)) (reln, forknum);
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/*
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* Get rid of any remaining buffers for the relation. bufmgr will just
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* drop them without bothering to write the contents.
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*/
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DropRelFileNodesAllBuffers(&rnode, 1);
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/*
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* It'd be nice to tell the stats collector to forget it immediately, too.
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* But we can't because we don't know the OID (and in cases involving
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* relfilenode swaps, it's not always clear which table OID to forget,
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* anyway).
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*/
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/*
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* Send a shared-inval message to force other backends to close any
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* dangling smgr references they may have for this rel. We should do this
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* before starting the actual unlinking, in case we fail partway through
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* that step. Note that the sinval message will eventually come back to
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* this backend, too, and thereby provide a backstop that we closed our
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* own smgr rel.
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*/
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CacheInvalidateSmgr(rnode);
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/*
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* Delete the physical file(s).
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*
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* Note: smgr_unlink must treat deletion failure as a WARNING, not an
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* ERROR, because we've already decided to commit or abort the current
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* xact.
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*/
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(*(smgrsw[which].smgr_unlink)) (rnode, InvalidForkNumber, isRedo);
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}
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/*
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* smgrdounlinkall() -- Immediately unlink all forks of all given relations
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*
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* All forks of all given relations are removed from the store. This
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* should not be used during transactional operations, since it can't be
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* undone.
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*
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* If isRedo is true, it is okay for the underlying file(s) to be gone
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* already.
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*
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* This is equivalent to calling smgrdounlink for each relation, but it's
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* significantly quicker so should be preferred when possible.
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*/
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void
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smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo)
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{
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int i = 0;
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RelFileNodeBackend *rnodes;
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ForkNumber forknum;
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if (nrels == 0)
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return;
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/*
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* create an array which contains all relations to be dropped, and close
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* each relation's forks at the smgr level while at it
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*/
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rnodes = palloc(sizeof(RelFileNodeBackend) * nrels);
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for (i = 0; i < nrels; i++)
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{
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RelFileNodeBackend rnode = rels[i]->smgr_rnode;
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int which = rels[i]->smgr_which;
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rnodes[i] = rnode;
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/* Close the forks at smgr level */
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for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
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(*(smgrsw[which].smgr_close)) (rels[i], forknum);
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}
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/*
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* Get rid of any remaining buffers for the relations. bufmgr will just
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* drop them without bothering to write the contents.
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*/
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DropRelFileNodesAllBuffers(rnodes, nrels);
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/*
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* It'd be nice to tell the stats collector to forget them immediately,
|
|
* too. But we can't because we don't know the OIDs.
|
|
*/
|
|
|
|
/*
|
|
* Send a shared-inval message to force other backends to close any
|
|
* dangling smgr references they may have for these rels. We should do
|
|
* this before starting the actual unlinking, in case we fail partway
|
|
* through that step. Note that the sinval messages will eventually come
|
|
* back to this backend, too, and thereby provide a backstop that we
|
|
* closed our own smgr rel.
|
|
*/
|
|
for (i = 0; i < nrels; i++)
|
|
CacheInvalidateSmgr(rnodes[i]);
|
|
|
|
/*
|
|
* Delete the physical file(s).
|
|
*
|
|
* Note: smgr_unlink must treat deletion failure as a WARNING, not an
|
|
* ERROR, because we've already decided to commit or abort the current
|
|
* xact.
|
|
*/
|
|
|
|
for (i = 0; i < nrels; i++)
|
|
{
|
|
int which = rels[i]->smgr_which;
|
|
|
|
for (forknum = 0; forknum <= MAX_FORKNUM; forknum++)
|
|
(*(smgrsw[which].smgr_unlink)) (rnodes[i], forknum, isRedo);
|
|
}
|
|
|
|
pfree(rnodes);
|
|
}
|
|
|
|
/*
|
|
* smgrdounlinkfork() -- Immediately unlink one fork of a relation.
|
|
*
|
|
* The specified fork of the relation is removed from the store. This
|
|
* should not be used during transactional operations, since it can't be
|
|
* undone.
|
|
*
|
|
* If isRedo is true, it is okay for the underlying file to be gone
|
|
* already.
|
|
*/
|
|
void
|
|
smgrdounlinkfork(SMgrRelation reln, ForkNumber forknum, bool isRedo)
|
|
{
|
|
RelFileNodeBackend rnode = reln->smgr_rnode;
|
|
int which = reln->smgr_which;
|
|
|
|
/* Close the fork at smgr level */
|
|
(*(smgrsw[which].smgr_close)) (reln, forknum);
|
|
|
|
/*
|
|
* Get rid of any remaining buffers for the fork. bufmgr will just drop
|
|
* them without bothering to write the contents.
|
|
*/
|
|
DropRelFileNodeBuffers(rnode, forknum, 0);
|
|
|
|
/*
|
|
* It'd be nice to tell the stats collector to forget it immediately, too.
|
|
* But we can't because we don't know the OID (and in cases involving
|
|
* relfilenode swaps, it's not always clear which table OID to forget,
|
|
* anyway).
|
|
*/
|
|
|
|
/*
|
|
* Send a shared-inval message to force other backends to close any
|
|
* dangling smgr references they may have for this rel. We should do this
|
|
* before starting the actual unlinking, in case we fail partway through
|
|
* that step. Note that the sinval message will eventually come back to
|
|
* this backend, too, and thereby provide a backstop that we closed our
|
|
* own smgr rel.
|
|
*/
|
|
CacheInvalidateSmgr(rnode);
|
|
|
|
/*
|
|
* Delete the physical file(s).
|
|
*
|
|
* Note: smgr_unlink must treat deletion failure as a WARNING, not an
|
|
* ERROR, because we've already decided to commit or abort the current
|
|
* xact.
|
|
*/
|
|
(*(smgrsw[which].smgr_unlink)) (rnode, forknum, isRedo);
|
|
}
|
|
|
|
/*
|
|
* smgrextend() -- Add a new block to a file.
|
|
*
|
|
* The semantics are nearly the same as smgrwrite(): write at the
|
|
* specified position. However, this is to be used for the case of
|
|
* extending a relation (i.e., blocknum is at or beyond the current
|
|
* EOF). Note that we assume writing a block beyond current EOF
|
|
* causes intervening file space to become filled with zeroes.
|
|
*/
|
|
void
|
|
smgrextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
|
|
char *buffer, bool skipFsync)
|
|
{
|
|
(*(smgrsw[reln->smgr_which].smgr_extend)) (reln, forknum, blocknum,
|
|
buffer, skipFsync);
|
|
}
|
|
|
|
/*
|
|
* smgrprefetch() -- Initiate asynchronous read of the specified block of a relation.
|
|
*/
|
|
void
|
|
smgrprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum)
|
|
{
|
|
(*(smgrsw[reln->smgr_which].smgr_prefetch)) (reln, forknum, blocknum);
|
|
}
|
|
|
|
/*
|
|
* smgrread() -- read a particular block from a relation into the supplied
|
|
* buffer.
|
|
*
|
|
* This routine is called from the buffer manager in order to
|
|
* instantiate pages in the shared buffer cache. All storage managers
|
|
* return pages in the format that POSTGRES expects.
|
|
*/
|
|
void
|
|
smgrread(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
|
|
char *buffer)
|
|
{
|
|
(*(smgrsw[reln->smgr_which].smgr_read)) (reln, forknum, blocknum, buffer);
|
|
}
|
|
|
|
/*
|
|
* smgrwrite() -- Write the supplied buffer out.
|
|
*
|
|
* This is to be used only for updating already-existing blocks of a
|
|
* relation (ie, those before the current EOF). To extend a relation,
|
|
* use smgrextend().
|
|
*
|
|
* This is not a synchronous write -- the block is not necessarily
|
|
* on disk at return, only dumped out to the kernel. However,
|
|
* provisions will be made to fsync the write before the next checkpoint.
|
|
*
|
|
* skipFsync indicates that the caller will make other provisions to
|
|
* fsync the relation, so we needn't bother. Temporary relations also
|
|
* do not require fsync.
|
|
*/
|
|
void
|
|
smgrwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
|
|
char *buffer, bool skipFsync)
|
|
{
|
|
(*(smgrsw[reln->smgr_which].smgr_write)) (reln, forknum, blocknum,
|
|
buffer, skipFsync);
|
|
}
|
|
|
|
|
|
/*
|
|
* smgrwriteback() -- Trigger kernel writeback for the supplied range of
|
|
* blocks.
|
|
*/
|
|
void
|
|
smgrwriteback(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
|
|
BlockNumber nblocks)
|
|
{
|
|
(*(smgrsw[reln->smgr_which].smgr_writeback)) (reln, forknum, blocknum,
|
|
nblocks);
|
|
}
|
|
|
|
/*
|
|
* smgrnblocks() -- Calculate the number of blocks in the
|
|
* supplied relation.
|
|
*/
|
|
BlockNumber
|
|
smgrnblocks(SMgrRelation reln, ForkNumber forknum)
|
|
{
|
|
return (*(smgrsw[reln->smgr_which].smgr_nblocks)) (reln, forknum);
|
|
}
|
|
|
|
/*
|
|
* smgrtruncate() -- Truncate supplied relation to the specified number
|
|
* of blocks
|
|
*
|
|
* The truncation is done immediately, so this can't be rolled back.
|
|
*/
|
|
void
|
|
smgrtruncate(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
|
|
{
|
|
/*
|
|
* Get rid of any buffers for the about-to-be-deleted blocks. bufmgr will
|
|
* just drop them without bothering to write the contents.
|
|
*/
|
|
DropRelFileNodeBuffers(reln->smgr_rnode, forknum, nblocks);
|
|
|
|
/*
|
|
* Send a shared-inval message to force other backends to close any smgr
|
|
* references they may have for this rel. This is useful because they
|
|
* might have open file pointers to segments that got removed, and/or
|
|
* smgr_targblock variables pointing past the new rel end. (The inval
|
|
* message will come back to our backend, too, causing a
|
|
* probably-unnecessary local smgr flush. But we don't expect that this
|
|
* is a performance-critical path.) As in the unlink code, we want to be
|
|
* sure the message is sent before we start changing things on-disk.
|
|
*/
|
|
CacheInvalidateSmgr(reln->smgr_rnode);
|
|
|
|
/*
|
|
* Do the truncation.
|
|
*/
|
|
(*(smgrsw[reln->smgr_which].smgr_truncate)) (reln, forknum, nblocks);
|
|
}
|
|
|
|
/*
|
|
* smgrimmedsync() -- Force the specified relation to stable storage.
|
|
*
|
|
* Synchronously force all previous writes to the specified relation
|
|
* down to disk.
|
|
*
|
|
* This is useful for building completely new relations (eg, new
|
|
* indexes). Instead of incrementally WAL-logging the index build
|
|
* steps, we can just write completed index pages to disk with smgrwrite
|
|
* or smgrextend, and then fsync the completed index file before
|
|
* committing the transaction. (This is sufficient for purposes of
|
|
* crash recovery, since it effectively duplicates forcing a checkpoint
|
|
* for the completed index. But it is *not* sufficient if one wishes
|
|
* to use the WAL log for PITR or replication purposes: in that case
|
|
* we have to make WAL entries as well.)
|
|
*
|
|
* The preceding writes should specify skipFsync = true to avoid
|
|
* duplicative fsyncs.
|
|
*
|
|
* Note that you need to do FlushRelationBuffers() first if there is
|
|
* any possibility that there are dirty buffers for the relation;
|
|
* otherwise the sync is not very meaningful.
|
|
*/
|
|
void
|
|
smgrimmedsync(SMgrRelation reln, ForkNumber forknum)
|
|
{
|
|
(*(smgrsw[reln->smgr_which].smgr_immedsync)) (reln, forknum);
|
|
}
|
|
|
|
|
|
/*
|
|
* smgrpreckpt() -- Prepare for checkpoint.
|
|
*/
|
|
void
|
|
smgrpreckpt(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NSmgr; i++)
|
|
{
|
|
if (smgrsw[i].smgr_pre_ckpt)
|
|
(*(smgrsw[i].smgr_pre_ckpt)) ();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* smgrsync() -- Sync files to disk during checkpoint.
|
|
*/
|
|
void
|
|
smgrsync(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NSmgr; i++)
|
|
{
|
|
if (smgrsw[i].smgr_sync)
|
|
(*(smgrsw[i].smgr_sync)) ();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* smgrpostckpt() -- Post-checkpoint cleanup.
|
|
*/
|
|
void
|
|
smgrpostckpt(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NSmgr; i++)
|
|
{
|
|
if (smgrsw[i].smgr_post_ckpt)
|
|
(*(smgrsw[i].smgr_post_ckpt)) ();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* AtEOXact_SMgr
|
|
*
|
|
* This routine is called during transaction commit or abort (it doesn't
|
|
* particularly care which). All transient SMgrRelation objects are closed.
|
|
*
|
|
* We do this as a compromise between wanting transient SMgrRelations to
|
|
* live awhile (to amortize the costs of blind writes of multiple blocks)
|
|
* and needing them to not live forever (since we're probably holding open
|
|
* a kernel file descriptor for the underlying file, and we need to ensure
|
|
* that gets closed reasonably soon if the file gets deleted).
|
|
*/
|
|
void
|
|
AtEOXact_SMgr(void)
|
|
{
|
|
/*
|
|
* Zap all unowned SMgrRelations. We rely on smgrclose() to remove each
|
|
* one from the list.
|
|
*/
|
|
while (first_unowned_reln != NULL)
|
|
{
|
|
Assert(first_unowned_reln->smgr_owner == NULL);
|
|
smgrclose(first_unowned_reln);
|
|
}
|
|
}
|