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Refactor the fsync queue for wider use.

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Previously, md.c and checkpointer.c were tightly integrated so that
fsync calls could be handed off and processed in the background.
Introduce a system of callbacks and file tags, so that other modules
can hand off fsync work in the same way.

For now only md.c uses the new interface, but other users are being
proposed.  Since there may be use cases that are not strictly SMGR
implementations, use a new function table for sync handlers rather
than extending the traditional SMGR one.

Instead of using a bitmapset of segment numbers for each RelFileNode
in the checkpointer's hash table, make the segment number part of the
key.  This requires sending explicit "forget" requests for every
segment individually when relations are dropped, but suits the file
layout schemes of proposed future users better (ie sparse or high
segment numbers).

Author: Shawn Debnath and Thomas Munro
Reviewed-by: Thomas Munro, Andres Freund
Discussion: https://postgr.es/m/CAEepm=2gTANm=e3ARnJT=n0h8hf88wqmaZxk0JYkxw+b21fNrw@mail.gmail.com
This commit is contained in:
Thomas Munro
2019-04-04 21:56:03 +13:00
parent 33215d113d
commit 3eb77eba5a
18 changed files with 904 additions and 890 deletions
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51
src/include/storage/md.h Normal file
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/*-------------------------------------------------------------------------
*
* md.h
* magnetic disk storage manager public interface declarations.
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/storage/md.h
*
*-------------------------------------------------------------------------
*/
#ifndef MD_H
#define MD_H
#include "storage/block.h"
#include "storage/relfilenode.h"
#include "storage/smgr.h"
#include "storage/sync.h"
/* md storage manager functionality */
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 void mdwriteback(SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, BlockNumber nblocks);
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 ForgetDatabaseSyncRequests(Oid dbid);
extern void DropRelationFiles(RelFileNode *delrels, int ndelrels, bool isRedo);
/* md sync callbacks */
extern int mdsyncfiletag(const FileTag *ftag, char *path);
extern int mdunlinkfiletag(const FileTag *ftag, char *path);
extern bool mdfiletagmatches(const FileTag *ftag, const FileTag *candidate);
#endif /* MD_H */