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Size and performance optimization the readDbPage() routine in the pager.

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FossilOrigin-Name: ca9e1875c3a893321d70a131fc4ffc76d169ad05e0b48b7006f53b6b467db4be
This commit is contained in:
drh 2017-08-18 21:14:50 +00:00
parent c68886bb9e
commit 56520ab848
3 changed files with 18 additions and 25 deletions
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12
manifest
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@ -1,5 +1,5 @@
C For\sthe\sunix\sVFS,\savoid\san\sunnecessary\sstat()\ssystem\scall\sprior\sto\sopening\nany\sfile\sin\sthe\scommon\scase\swhere\sthere\sare\sno\sunused\sfile\sdescriptors.
D 2017-08-18T16:09:52.797
C Size\sand\sperformance\soptimization\sthe\sreadDbPage()\sroutine\sin\sthe\spager.
D 2017-08-18T21:14:50.622
F Makefile.in d9873c9925917cca9990ee24be17eb9613a668012c85a343aef7e5536ae266e8
F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
F Makefile.msc 02b469e9dcd5b7ee63fc1fb05babc174260ee4cfa4e0ef2e48c3c6801567a016
@ -443,7 +443,7 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
F src/os_unix.c 0a7730f6cb797ba1fd12825e4ea751e1325041410c063c258e30089ca71f9a88
F src/os_win.c 964165b66cde03abc72fe948198b01be608436894732eadb94c8720d2467f223
F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
F src/pager.c 6f2ae58c0d4ddf510d324cb2ec38f471b5cff8f3e061afd32717ad790685cc7f
F src/pager.c fb9a8f40417d6dfbd6b8be91237f2f64d51cc867ab28687420acbc5cab786a3c
F src/pager.h f2a99646c5533ffe11afa43e9e0bea74054e4efa
F src/parse.y 52ef3cecd0934e9da4a45b585883a03243ad615d338ad94f44501a05891dcdfa
F src/pcache.c 62835bed959e2914edd26afadfecce29ece0e870
@ -1649,7 +1649,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P eb1202b5e43f1f029ad2bdf845509e7f31361e4dc189943e5e2bd4462e2ef3f3
R 75fd277ce5c40358998ed365a587d991
P 3075cfa07489eaf13cb9a2760e2391e79dd73181fe1730fae7bdcd6ad66d2a1f
R 73e91e0689b3737aa34e053426722c6a
U drh
Z 8da9bd8ec0af0fa3e80213d960cc13a7
Z 58f532a67b173dfa15cad7f44c1bc81c

2
manifest.uuid
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@ -1 +1 @@
3075cfa07489eaf13cb9a2760e2391e79dd73181fe1730fae7bdcd6ad66d2a1f
ca9e1875c3a893321d70a131fc4ffc76d169ad05e0b48b7006f53b6b467db4be

29
src/pager.c
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@ -2982,7 +2982,8 @@ end_playback:
/*
** Read the content for page pPg out of the database file and into
** Read the content for page pPg out of the database file (or out of
** the WAL if that is where the most recent copy if found) into
** pPg->pData. A shared lock or greater must be held on the database
** file before this function is called.
**
@ -2992,22 +2993,23 @@ end_playback:
** If an IO error occurs, then the IO error is returned to the caller.
** Otherwise, SQLITE_OK is returned.
*/
static int readDbPage(PgHdr *pPg, u32 iFrame){
static int readDbPage(PgHdr *pPg){
Pager *pPager = pPg->pPager; /* Pager object associated with page pPg */
Pgno pgno = pPg->pgno; /* Page number to read */
int rc = SQLITE_OK; /* Return code */
int pgsz = pPager->pageSize; /* Number of bytes to read */
u32 iFrame = 0; /* Frame of WAL containing pgno */
assert( pPager->eState>=PAGER_READER && !MEMDB );
assert( isOpen(pPager->fd) );
#ifndef SQLITE_OMIT_WAL
if( pagerUseWal(pPager) ){
rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
if( rc ) return rc;
}
if( iFrame ){
/* Try to pull the page from the write-ahead log. */
rc = sqlite3WalReadFrame(pPager->pWal, iFrame, pgsz, pPg->pData);
}else
#endif
{
}else{
i64 iOffset = (pgno-1)*(i64)pPager->pageSize;
rc = sqlite3OsRead(pPager->fd, pPg->pData, pgsz, iOffset);
if( rc==SQLITE_IOERR_SHORT_READ ){
@ -3092,11 +3094,7 @@ static int pagerUndoCallback(void *pCtx, Pgno iPg){
if( sqlite3PcachePageRefcount(pPg)==1 ){
sqlite3PcacheDrop(pPg);
}else{
u32 iFrame = 0;
rc = sqlite3WalFindFrame(pPager->pWal, pPg->pgno, &iFrame);
if( rc==SQLITE_OK ){
rc = readDbPage(pPg, iFrame);
}
rc = readDbPage(pPg);
if( rc==SQLITE_OK ){
pPager->xReiniter(pPg);
}
@ -5489,14 +5487,9 @@ static int getPageNormal(
memset(pPg->pData, 0, pPager->pageSize);
IOTRACE(("ZERO %p %d\n", pPager, pgno));
}else{
u32 iFrame = 0; /* Frame to read from WAL file */
if( pagerUseWal(pPager) ){
rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
if( rc!=SQLITE_OK ) goto pager_acquire_err;
}
assert( pPg->pPager==pPager );
pPager->aStat[PAGER_STAT_MISS]++;
rc = readDbPage(pPg, iFrame);
rc = readDbPage(pPg);
if( rc!=SQLITE_OK ){
goto pager_acquire_err;
}