NotificationsYou must be signed in to change notification settings
Fork6
Star31

Commit5787c67

committed

Skip extraneous locking in XLogCheckBuffer().

Heikki reported comment was wrong, so fixedcode to match the comment: we only need totake additional locking precautions when wehave a shared lock on the buffer.

1 parent47c4333 commit5787c67Copy full SHA for 5787c67

File tree

1 file changed

+16

-11

lines changed

src/backend/access/transam
- xlog.c

1 file changed

+16

-11

lines changed

`‎src/backend/access/transam/xlog.c`

Lines changed: 16 additions & 11 deletions

Original file line number	Diff line number	Diff line change
`@@ -646,7 +646,7 @@ static void CreateEndOfRecoveryRecord(void);`
`646`	`646`	`staticvoidCheckPointGuts(XLogRecPtrcheckPointRedo,intflags);`
`647`	`647`	`staticvoidKeepLogSeg(XLogRecPtrrecptr,XLogSegNo*logSegNo);`
`648`	`648`
`649`		`-staticboolXLogCheckBuffer(XLogRecData*rdata,booldoPageWrites,`
	`649`	`+staticboolXLogCheckBuffer(XLogRecData*rdata,boolholdsExclusiveLock,`
`650`	`650`	`XLogRecPtrlsn,BkpBlockbkpb);`
`651`	`651`	`staticBufferRestoreBackupBlockContents(XLogRecPtrlsn,BkpBlockbkpb,`
`652`	`652`	`char*blk,boolget_cleanup_lock,boolkeep_buffer);`
`@@ -822,7 +822,7 @@ begin:;`
`822`	`822`	`{`
`823`	`823`	`/* OK, put it in this slot */`
`824`	`824`	`dtbuf[i]=rdt->buffer;`
`825`		`-if (XLogCheckBuffer(rdt,doPageWrites,`
	`825`	`+if (doPageWrites&&XLogCheckBuffer(rdt,true,`
`826`	`826`	`&(dtbuf_lsn[i]),&(dtbuf_xlg[i])))`
`827`	`827`	`{`
`828`	`828`	`dtbuf_bkp[i]= true;`
`@@ -1243,23 +1243,25 @@ begin:;`
`1243`	`1243`	`* save the buffer's LSN at *lsn.`
`1244`	`1244`	`*/`
`1245`	`1245`	`staticbool`
`1246`		`-XLogCheckBuffer(XLogRecData*rdata,booldoPageWrites,`
	`1246`	`+XLogCheckBuffer(XLogRecData*rdata,boolholdsExclusiveLock,`
`1247`	`1247`	`XLogRecPtrlsn,BkpBlockbkpb)`
`1248`	`1248`	`{`
`1249`	`1249`	`Pagepage;`
`1250`	`1250`
`1251`	`1251`	`page=BufferGetPage(rdata->buffer);`
`1252`	`1252`
`1253`	`1253`	`/*`
`1254`		`- XXXWe assume page LSN is first data on every* page that can be passed`
`1255`		`- * to XLogInsert, whether itotherwisehas the standard page layout or`
`1256`		`- *not. Wedon't need the buffer header lock for PageGetLSNbecause we`
`1257`		`- *have exclusive lock on the page and/or the relation.`
	`1254`	`+ * We assume page LSN is first data on every page that can be passed`
	`1255`	`+ * to XLogInsert, whether it has the standard page layout or not. We`
	`1256`	`+ * don't needto takethe buffer header lock for PageGetLSNif we hold`
	`1257`	`+ *an exclusive lock on the page and/or the relation.`
`1258`	`1258`	`*/`
`1259`		`-*lsn=BufferGetLSNAtomic(rdata->buffer);`
	`1259`	`+if (holdsExclusiveLock)`
	`1260`	`+*lsn=PageGetLSN(page);`
	`1261`	`+else`
	`1262`	`+*lsn=BufferGetLSNAtomic(rdata->buffer);`
`1260`	`1263`
`1261`		`-if (doPageWrites&&`
`1262`		`-*lsn <=RedoRecPtr)`
	`1264`	`+if (*lsn <=RedoRecPtr)`
`1263`	`1265`	`{`
`1264`	`1266`	`/*`
`1265`	`1267`	`* The page needs to be backed up, so set up *bkpb`
`@@ -7683,7 +7685,10 @@ XLogSaveBufferForHint(Buffer buffer)`
`7683`	`7685`	`rdata[0].buffer=buffer;`
`7684`	`7686`	`rdata[0].buffer_std= true;`
`7685`	`7687`
`7686`		`-if (XLogCheckBuffer(rdata, true,&lsn,&bkpb))`
	`7688`	`+/*`
	`7689`	`+ * Check buffer while not holding an exclusive lock.`
	`7690`	`+ */`
	`7691`	`+if (XLogCheckBuffer(rdata, false,&lsn,&bkpb))`
`7687`	`7692`	`{`
`7688`	`7693`	`charcopied_buffer[BLCKSZ];`
`7689`	`7694`	`charorigdata= (char)BufferGetBlock(buffer);`

0 commit comments

Comments

(0)

Movatterモバイル変換

Navigation Menu

Search code, repositories, users, issues, pull requests...

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Commit5787c67

File tree

1 file changed

1 file changed

`‎src/backend/access/transam/xlog.c`

0 commit comments