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Add the new sqlite3PagerUnrefPageOne() pager method to deal with the special

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case of unreferencing page1.

FossilOrigin-Name: b2e2100cf766da1cb499aec0ca0a9969d7af5d93312ab8cf895fbf4a6ffb9b2f
This commit is contained in:
drh 2017-09-01 14:50:19 +00:00
parent dfcdc663f2
commit 3908fe90b1
5 changed files with 52 additions and 23 deletions
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16
manifest
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@ -1,5 +1,5 @@
C Remove\san\sobsolete\soptimization\sin\spcache\sthat\sdue\sto\smore\srecent\schanges\nwas\srecently\smaking\sthe\scode\sa\slittle\sslower.
D 2017-09-01T12:57:33.041
C Add\sthe\snew\ssqlite3PagerUnrefPageOne()\spager\smethod\sto\sdeal\swith\sthe\sspecial\ncase\sof\sunreferencing\spage1.
D 2017-09-01T14:50:19.167
F Makefile.in c644bbe8ebe4aae82ad6783eae6b6beea4c727b99ff97568b847ced5e2ac7afb
F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
F Makefile.msc 25b154da7f0b3d4924f27378c1f8d006285b80811f1ccf3ed953dbebf6282136
@ -399,7 +399,7 @@ F src/auth.c 6277d63837357549fe14e723490d6dc1a38768d71c795c5eb5c0f8a99f918f73
F src/backup.c faf17e60b43233c214aae6a8179d24503a61e83b
F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
F src/btmutex.c 0e9ce2d56159b89b9bc8e197e023ee11e39ff8ca
F src/btree.c 1033b88fe50aba7d364b5a19666a9a274caa8d4c25ab7f3914221997b46af44a
F src/btree.c f1ac9509f4595d034fe432982c39d51ac2bfc9bd83136d16255aede35c526b45
F src/btree.h 32ef5d3f25dc70ef1ee9cecf84a023c21378f06a57cd701d2e866e141b150f09
F src/btreeInt.h 55b702efce17e5d1941865464227d3802cfc9c7c832fac81d4c94dced47a71fc
F src/build.c e71e96a67daf3d1dd23188423e66cd6af38017e2ec73fead5d2b57da2d3c7e16
@ -443,8 +443,8 @@ F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
F src/os_unix.c 489aa972ccc34f7b4770b891694b32101c59ddd4be4ef0ddd9a4da58c145c1a6
F src/os_win.c 964165b66cde03abc72fe948198b01be608436894732eadb94c8720d2467f223
F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
F src/pager.c bf51378c57c8e05d7f4d7bb9861f403a2e40cde82e25513401216d1ed30bc3e5
F src/pager.h f2a99646c5533ffe11afa43e9e0bea74054e4efa
F src/pager.c 3936b32a0a45f1b80462b38ba1ed0556e62843554a089ab9c4be1a35c97f23bc
F src/pager.h 581698f2177e8bd4008fe4760898ce20b6133d1df22139b9101b5155f900df7a
F src/parse.y 52ef3cecd0934e9da4a45b585883a03243ad615d338ad94f44501a05891dcdfa
F src/pcache.c 4bada070456980c3c1f16d58ec2e64e389ad77b935e3d77e0c96e7bbd397289c
F src/pcache.h 072f94d29281cffd99e46c1539849f248c4b56ae7684c1f36626797fee375170
@ -1651,7 +1651,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P 919863b14859d958d6c078097faae02070c7bd082e2814cf3f84bd84921e4419
R 0eee553fc228f3f42e4580f46005e756
P c4e7e175eecfd79015f4fae99618dfce6baf97c21bf3c909ea535d4e12dcaaad
R 6f9a52521f107a3c330b7cfcb23523cf
U drh
Z 71c472332c9be0857de95ba6da186b34
Z f39368718f6b0d67941da00fc11a34d5

2
manifest.uuid
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@ -1 +1 @@
c4e7e175eecfd79015f4fae99618dfce6baf97c21bf3c909ea535d4e12dcaaad
b2e2100cf766da1cb499aec0ca0a9969d7af5d93312ab8cf895fbf4a6ffb9b2f

25
src/btree.c
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@ -439,7 +439,8 @@ static void downgradeAllSharedCacheTableLocks(Btree *p){
#endif /* SQLITE_OMIT_SHARED_CACHE */
static void releasePage(MemPage *pPage);
static void releasePage(MemPage *pPage); /* Forward reference */
static void releasePageOne(MemPage *pPage); /* Forward reference */
static void releasePageNotNull(MemPage *pPage); /* Forward reference */
/*
@ -2109,6 +2110,8 @@ getAndInitPage_error:
/*
** Release a MemPage. This should be called once for each prior
** call to btreeGetPage.
**
** Page1 is a special case and must be released using releasePageOne().
*/
static void releasePageNotNull(MemPage *pPage){
assert( pPage->aData );
@ -2122,6 +2125,16 @@ static void releasePageNotNull(MemPage *pPage){
static void releasePage(MemPage *pPage){
if( pPage ) releasePageNotNull(pPage);
}
static void releasePageOne(MemPage *pPage){
assert( pPage!=0 );
assert( pPage->aData );
assert( pPage->pBt );
assert( pPage->pDbPage!=0 );
assert( sqlite3PagerGetExtra(pPage->pDbPage) == (void*)pPage );
assert( sqlite3PagerGetData(pPage->pDbPage)==pPage->aData );
assert( sqlite3_mutex_held(pPage->pBt->mutex) );
sqlite3PagerUnrefPageOne(pPage->pDbPage);
}
/*
** Get an unused page.
@ -3000,7 +3013,7 @@ static int lockBtree(BtShared *pBt){
}else{
setDefaultSyncFlag(pBt, SQLITE_DEFAULT_WAL_SYNCHRONOUS+1);
if( isOpen==0 ){
releasePage(pPage1);
releasePageOne(pPage1);
return SQLITE_OK;
}
}
@ -3047,7 +3060,7 @@ static int lockBtree(BtShared *pBt){
** zero and return SQLITE_OK. The caller will call this function
** again with the correct page-size.
*/
releasePage(pPage1);
releasePageOne(pPage1);
pBt->usableSize = usableSize;
pBt->pageSize = pageSize;
freeTempSpace(pBt);
@ -3101,7 +3114,7 @@ static int lockBtree(BtShared *pBt){
return SQLITE_OK;
page1_init_failed:
releasePage(pPage1);
releasePageOne(pPage1);
pBt->pPage1 = 0;
return rc;
}
@ -3146,7 +3159,7 @@ static void unlockBtreeIfUnused(BtShared *pBt){
assert( pPage1->aData );
assert( sqlite3PagerRefcount(pBt->pPager)==1 );
pBt->pPage1 = 0;
releasePageNotNull(pPage1);
releasePageOne(pPage1);
}
}
@ -4068,7 +4081,7 @@ int sqlite3BtreeRollback(Btree *p, int tripCode, int writeOnly){
if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage);
testcase( pBt->nPage!=nPage );
pBt->nPage = nPage;
releasePage(pPage1);
releasePageOne(pPage1);
}
assert( countValidCursors(pBt, 1)==0 );
pBt->inTransaction = TRANS_READ;

31
src/pager.c
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@ -5350,7 +5350,8 @@ int sqlite3PagerSharedLock(Pager *pPager){
** nothing to rollback, so this routine is a no-op.
*/
static void pagerUnlockIfUnused(Pager *pPager){
if( pPager->nMmapOut==0 && (sqlite3PcacheRefCount(pPager->pPCache)==0) ){
if( sqlite3PcacheRefCount(pPager->pPCache)==0 ){
assert( pPager->nMmapOut==0 ); /* because page1 is never memory mapped */
pagerUnlockAndRollback(pPager);
}
}
@ -5636,25 +5637,39 @@ DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
/*
** Release a page reference.
**
** If the number of references to the page drop to zero, then the
** page is added to the LRU list. When all references to all pages
** are released, a rollback occurs and the lock on the database is
** removed.
** The sqlite3PagerUnref() and sqlite3PagerUnrefNotNull() may only be
** used if we know that the page being released is not the last page.
** The btree layer always holds page1 open until the end, so these first
** to routines can be used to release any page other than BtShared.pPage1.
**
** Use sqlite3PagerUnrefPageOne() to release page1. This latter routine
** checks the total number of outstanding pages and if the number of
** pages reaches zero it drops the database lock.
*/
void sqlite3PagerUnrefNotNull(DbPage *pPg){
Pager *pPager;
TESTONLY( Pager *pPager = pPg->pPager; )
assert( pPg!=0 );
pPager = pPg->pPager;
if( pPg->flags & PGHDR_MMAP ){
assert( pPg->pgno!=1 ); /* Page1 is never memory mapped */
pagerReleaseMapPage(pPg);
}else{
sqlite3PcacheRelease(pPg);
}
pagerUnlockIfUnused(pPager);
/* Do not use this routine to release the last reference to page1 */
assert( sqlite3PcacheRefCount(pPager->pPCache)>0 );
}
void sqlite3PagerUnref(DbPage *pPg){
if( pPg ) sqlite3PagerUnrefNotNull(pPg);
}
void sqlite3PagerUnrefPageOne(DbPage *pPg){
Pager *pPager;
assert( pPg!=0 );
assert( pPg->pgno==1 );
assert( (pPg->flags & PGHDR_MMAP)==0 ); /* Page1 is never memory mapped */
pPager = pPg->pPager;
sqlite3PcacheRelease(pPg);
pagerUnlockIfUnused(pPager);
}
/*
** This function is called at the start of every write transaction.

1
src/pager.h
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@ -151,6 +151,7 @@ DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno);
void sqlite3PagerRef(DbPage*);
void sqlite3PagerUnref(DbPage*);
void sqlite3PagerUnrefNotNull(DbPage*);
void sqlite3PagerUnrefPageOne(DbPage*);
/* Operations on page references. */
int sqlite3PagerWrite(DbPage*);