Simplifications and performance improvement in pager_write().

FossilOrigin-Name: ab7aeeead395a05b91a921ef9ebe9252fffad667

manifest

@@ -1,5 +1,5 @@
-C Add\sthe\snew\sPGHDR_CLEAN\sbit\sto\sPgHdr.flags\sin\spcache.c.\s\sThis\sbit\sis\salways\nthe\sopposite\sof\sPGHDR_DIRTY.\s\sUse\sthe\sextra\sbit\sto\savoid\sa\scomparison\nfor\sa\ssmall\sperformance\sboost.
-D 2015-06-29T04:21:15.041
+C Simplifications\sand\sperformance\simprovement\sin\spager_write().
+D 2015-06-29T14:11:50.755
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 285a0a234ed7610d431d91671c136098c2bd86a9
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -267,7 +267,7 @@ F src/analyze.c f89727c36f997bd2bf6c5e546c2f51dc94e6f2a4
 F src/attach.c e944d0052b577703b9b83aac1638452ff42a8395
 F src/auth.c b56c78ebe40a2110fd361379f7e8162d23f92240
 F src/backup.c ff743689c4d6c5cb55ad42ed9d174b2b3e71f1e3
-F src/bitvec.c 828b218d3fc39f8ce9c9c5f4de4106fe08c92303
+F src/bitvec.c d1f21d7d91690747881f03940584f4cc548c9d3d
 F src/btmutex.c 45a968cc85afed9b5e6cf55bf1f42f8d18107f79
 F src/btree.c ce342e156716fb64b9cf5c040260d0b47989f37b
 F src/btree.h 969adc948e89e449220ff0ff724c94bb2a52e9f1
@@ -314,7 +314,7 @@ F src/os_setup.h c9d4553b5aaa6f73391448b265b89bed0b890faa
 F src/os_unix.c 23eb5f56fac54d8fe0cb204291f3b3b2d94f23fc
 F src/os_win.c 27cc135e2d0b8b1e2e4944db1e2669a6a18fa0f8
 F src/os_win.h eb7a47aa17b26b77eb97e4823f20a00b8bda12ca
-F src/pager.c db79b64a5498e2b3a72f0f6bc74faebe48da3e95
+F src/pager.c 7e745749c375e3c35ef92051e2c1f7425cfcb3de
 F src/pager.h c3476e7c89cdf1c6914e50a11f3714e30b4e0a77
 F src/parse.y 6d60dda8f8d418b6dc034f1fbccd816c459983a8
 F src/pcache.c 994f15b465337a079feb04aac34c199dbc610247
@@ -332,7 +332,7 @@ F src/shell.c 8af3cced094aebb5f57a8ad739b9dafc7867eed7
 F src/sqlite.h.in 76d2f5637eb795b6300d9dd3c3ec3632ffafd721
 F src/sqlite3.rc 992c9f5fb8285ae285d6be28240a7e8d3a7f2bad
 F src/sqlite3ext.h be1a718b7d2ce40ceba725ae92c8eb5f18003066
-F src/sqliteInt.h d5df694bc33870e77fb08f389d12309597fe3059
+F src/sqliteInt.h 89768198547bdd70a160e47643a0e493f711e8d0
 F src/sqliteLimit.h 216557999cb45f2e3578ed53ebefe228d779cb46
 F src/status.c f266ad8a2892d659b74f0f50cb6a88b6e7c12179
 F src/table.c 51b46b2a62d1b3a959633d593b89bab5e2c9155e
@@ -1364,7 +1364,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 9b3a7281bd45994edf813a687e4b7a0761697929
-R 07d5c4c2284ae7b5a16a8d841b25dd0d
+P 8619fc346d9a5a66a3c4566b4cc032b6b6bf73fd
+R 0aa742facd6911aa1b0a57fdcda4cf1c
 U drh
-Z fa5a6a0b1c08c7af0b43f02924ea472a
+Z 44e348c1758353ed5733624fd5385fad

manifest.uuid

@@ -1 +1 @@
-8619fc346d9a5a66a3c4566b4cc032b6b6bf73fd
+ab7aeeead395a05b91a921ef9ebe9252fffad667

src/bitvec.c

@@ -126,8 +126,8 @@ Bitvec *sqlite3BitvecCreate(u32 iSize){
 ** If p is NULL (if the bitmap has not been created) or if
 ** i is out of range, then return false.
 */
-int sqlite3BitvecTest(Bitvec *p, u32 i){
-  if( p==0 ) return 0;
+int sqlite3BitvecTestNotNull(Bitvec *p, u32 i){
+  assert( p!=0 );
   i--;
   if( i>=p->iSize ) return 0;
   while( p->iDivisor ){
@@ -149,6 +149,9 @@ int sqlite3BitvecTest(Bitvec *p, u32 i){
     return 0;
   }
 }
+int sqlite3BitvecTest(Bitvec *p, u32 i){
+  return p!=0 && sqlite3BitvecTestNotNull(p,i);
+}
 
 /*
 ** Set the i-th bit.  Return 0 on success and an error code if

src/pager.c

@@ -808,7 +808,7 @@ static const unsigned char aJournalMagic[] = {
 **
 **   if( pPager->jfd->pMethods ){ ...
 */
-#define isOpen(pFd) ((pFd)->pMethods)
+#define isOpen(pFd) ((pFd)->pMethods!=0)
 
 /*
 ** Return true if this pager uses a write-ahead log instead of the usual
@@ -1031,19 +1031,21 @@ static int subjRequiresPage(PgHdr *pPg){
   int i;
   for(i=0; i<pPager->nSavepoint; i++){
     p = &pPager->aSavepoint[i];
-    if( p->nOrig>=pgno && 0==sqlite3BitvecTest(p->pInSavepoint, pgno) ){
+    if( p->nOrig>=pgno && 0==sqlite3BitvecTestNotNull(p->pInSavepoint, pgno) ){
       return 1;
     }
   }
   return 0;
 }
 
+#ifdef SQLITE_DEBUG
 /*
 ** Return true if the page is already in the journal file.
 */
 static int pageInJournal(Pager *pPager, PgHdr *pPg){
   return sqlite3BitvecTest(pPager->pInJournal, pPg->pgno);
 }
+#endif
 
 /*
 ** Read a 32-bit integer from the given file descriptor.  Store the integer
@@ -5648,6 +5650,59 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
   return rc;
 }
 
+/*
+** Write page pPg onto the end of the rollback journal.
+*/
+static SQLITE_NOINLINE int pagerAddPageToRollbackJournal(PgHdr *pPg){
+  Pager *pPager = pPg->pPager;
+  int rc;
+  u32 cksum;
+  char *pData2;
+  i64 iOff = pPager->journalOff;
+
+  /* We should never write to the journal file the page that
+  ** contains the database locks.  The following assert verifies
+  ** that we do not. */
+  assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
+
+  assert( pPager->journalHdr<=pPager->journalOff );
+  CODEC2(pPager, pPg->pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
+  cksum = pager_cksum(pPager, (u8*)pData2);
+
+  /* Even if an IO or diskfull error occurs while journalling the
+  ** page in the block above, set the need-sync flag for the page.
+  ** Otherwise, when the transaction is rolled back, the logic in
+  ** playback_one_page() will think that the page needs to be restored
+  ** in the database file. And if an IO error occurs while doing so,
+  ** then corruption may follow.
+  */
+  pPg->flags |= PGHDR_NEED_SYNC;
+
+  rc = write32bits(pPager->jfd, iOff, pPg->pgno);
+  if( rc!=SQLITE_OK ) return rc;
+  rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, iOff+4);
+  if( rc!=SQLITE_OK ) return rc;
+  rc = write32bits(pPager->jfd, iOff+pPager->pageSize+4, cksum);
+  if( rc!=SQLITE_OK ) return rc;
+
+  IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno, 
+           pPager->journalOff, pPager->pageSize));
+  PAGER_INCR(sqlite3_pager_writej_count);
+  PAGERTRACE(("JOURNAL %d page %d needSync=%d hash(%08x)\n",
+       PAGERID(pPager), pPg->pgno, 
+       ((pPg->flags&PGHDR_NEED_SYNC)?1:0), pager_pagehash(pPg)));
+
+  pPager->journalOff += 8 + pPager->pageSize;
+  pPager->nRec++;
+  assert( pPager->pInJournal!=0 );
+  rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
+  testcase( rc==SQLITE_NOMEM );
+  assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+  rc |= addToSavepointBitvecs(pPager, pPg->pgno);
+  assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
+  return rc;
+}
+
 /*
 ** Mark a single data page as writeable. The page is written into the 
 ** main journal or sub-journal as required. If the page is written into
@@ -5658,7 +5713,6 @@ int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
 static int pager_write(PgHdr *pPg){
   Pager *pPager = pPg->pPager;
   int rc = SQLITE_OK;
-  int inJournal;
 
   /* This routine is not called unless a write-transaction has already 
   ** been started. The journal file may or may not be open at this point.
@@ -5671,7 +5725,6 @@ static int pager_write(PgHdr *pPg){
   assert( assert_pager_state(pPager) );
   assert( pPager->errCode==0 );
   assert( pPager->readOnly==0 );
-
   CHECK_PAGE(pPg);
 
   /* The journal file needs to be opened. Higher level routines have already
@@ -5690,91 +5743,41 @@ static int pager_write(PgHdr *pPg){
   assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
   assert( assert_pager_state(pPager) );
 
-  /* Mark the page as dirty.  If the page has already been written
-  ** to the journal then we can return right away.
-  */
+  /* Mark the page that is about to be modified as dirty. */
   sqlite3PcacheMakeDirty(pPg);
-  inJournal = pageInJournal(pPager, pPg);
-  if( inJournal && (pPager->nSavepoint==0 || !subjRequiresPage(pPg)) ){
-    assert( !pagerUseWal(pPager) );
-  }else{
 
-    /* The transaction journal now exists and we have a RESERVED or an
-    ** EXCLUSIVE lock on the main database file.  Write the current page to
-    ** the transaction journal if it is not there already.
-    */
-    if( !inJournal && !pagerUseWal(pPager) ){
-      assert( pagerUseWal(pPager)==0 );
-      if( pPg->pgno<=pPager->dbOrigSize && isOpen(pPager->jfd) ){
-        u32 cksum;
-        char *pData2;
-        i64 iOff = pPager->journalOff;
-
-        /* We should never write to the journal file the page that
-        ** contains the database locks.  The following assert verifies
-        ** that we do not. */
-        assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
-
-        assert( pPager->journalHdr<=pPager->journalOff );
-        CODEC2(pPager, pPg->pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
-        cksum = pager_cksum(pPager, (u8*)pData2);
-
-        /* Even if an IO or diskfull error occurs while journalling the
-        ** page in the block above, set the need-sync flag for the page.
-        ** Otherwise, when the transaction is rolled back, the logic in
-        ** playback_one_page() will think that the page needs to be restored
-        ** in the database file. And if an IO error occurs while doing so,
-        ** then corruption may follow.
-        */
-        pPg->flags |= PGHDR_NEED_SYNC;
-
-        rc = write32bits(pPager->jfd, iOff, pPg->pgno);
-        if( rc!=SQLITE_OK ) return rc;
-        rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, iOff+4);
-        if( rc!=SQLITE_OK ) return rc;
-        rc = write32bits(pPager->jfd, iOff+pPager->pageSize+4, cksum);
-        if( rc!=SQLITE_OK ) return rc;
-
-        IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno, 
-                 pPager->journalOff, pPager->pageSize));
-        PAGER_INCR(sqlite3_pager_writej_count);
-        PAGERTRACE(("JOURNAL %d page %d needSync=%d hash(%08x)\n",
-             PAGERID(pPager), pPg->pgno, 
-             ((pPg->flags&PGHDR_NEED_SYNC)?1:0), pager_pagehash(pPg)));
-
-        pPager->journalOff += 8 + pPager->pageSize;
-        pPager->nRec++;
-        assert( pPager->pInJournal!=0 );
-        rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
-        testcase( rc==SQLITE_NOMEM );
-        assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
-        rc |= addToSavepointBitvecs(pPager, pPg->pgno);
-        if( rc!=SQLITE_OK ){
-          assert( rc==SQLITE_NOMEM );
-          return rc;
-        }
-      }else{
-        if( pPager->eState!=PAGER_WRITER_DBMOD ){
-          pPg->flags |= PGHDR_NEED_SYNC;
-        }
-        PAGERTRACE(("APPEND %d page %d needSync=%d\n",
-                PAGERID(pPager), pPg->pgno,
-               ((pPg->flags&PGHDR_NEED_SYNC)?1:0)));
+  /* If a rollback journal is in use, them make sure the page that is about
+  ** to change is in the rollback journal, or if the page is a new page off
+  ** then end of the file, make sure it is marked as PGHDR_NEED_SYNC.
+  */
+  assert( (pPager->pInJournal!=0) == isOpen(pPager->jfd) );
+  if( pPager->pInJournal!=0                                      /* Journal open */
+   && sqlite3BitvecTestNotNull(pPager->pInJournal, pPg->pgno)==0 /* pPg not in jrnl */
+  ){
+    assert( pagerUseWal(pPager)==0 );
+    if( pPg->pgno<=pPager->dbOrigSize ){
+      rc = pagerAddPageToRollbackJournal(pPg);
+      if( rc!=SQLITE_OK ){
+        return rc;
       }
-    }
-  
-    /* If the statement journal is open and the page is not in it,
-    ** then write the current page to the statement journal.  Note that
-    ** the statement journal format differs from the standard journal format
-    ** in that it omits the checksums and the header.
-    */
-    if( pPager->nSavepoint>0 && subjRequiresPage(pPg) ){
-      rc = subjournalPage(pPg);
+    }else{
+      if( pPager->eState!=PAGER_WRITER_DBMOD ){
+        pPg->flags |= PGHDR_NEED_SYNC;
+      }
+      PAGERTRACE(("APPEND %d page %d needSync=%d\n",
+              PAGERID(pPager), pPg->pgno,
+             ((pPg->flags&PGHDR_NEED_SYNC)?1:0)));
     }
   }
   
-  /* Update the database size and return.
+  /* If the statement journal is open and the page is not in it,
+  ** then write the page into the statement journal.
   */
+  if( pPager->nSavepoint>0 && subjRequiresPage(pPg) ){
+    rc = subjournalPage(pPg);
+  }
+
+  /* Update the database size and return. */
   if( pPager->dbSize<pPg->pgno ){
     pPager->dbSize = pPg->pgno;
   }

src/sqliteInt.h

@@ -3238,6 +3238,7 @@ int sqlite3CodeOnce(Parse *);
 
 Bitvec *sqlite3BitvecCreate(u32);
 int sqlite3BitvecTest(Bitvec*, u32);
+int sqlite3BitvecTestNotNull(Bitvec*, u32);
 int sqlite3BitvecSet(Bitvec*, u32);
 void sqlite3BitvecClear(Bitvec*, u32, void*);
 void sqlite3BitvecDestroy(Bitvec*);