Shave a few cycles so that performance is better than 3.7.4 in speed tests.

FossilOrigin-Name: e14649301138b6840e24a4bbd2cf5205c0f72409

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Modify\sthe\stest_quote.c\sdemonstration\sshim\sso\sthat\sit\sworks\swhen\nSQLITE_THREADSAFE=0\sis\sdefined.
+C Shave\sa\sfew\scycles\sso\sthat\sperformance\sis\sbetter\sthan\s3.7.4\sin\sspeed\stests.
-D 2011-01-24T20:18:05.760
+D 2011-01-25T04:34:51.468
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in de6498556d536ae60bb8bb10e8c1ba011448658c
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -122,7 +122,7 @@ F src/auth.c 523da7fb4979469955d822ff9298352d6b31de34
 F src/backup.c 8c39a1ebba1e9dc385519cc4d434c7b0cab6638c
 F src/bitvec.c af50f1c8c0ff54d6bdb7a80e2fceca5a93670bef
 F src/btmutex.c 96a12f50f7a17475155971a241d85ec5171573ff
-F src/btree.c a27c3b41082889fc258278ba501ff2594dda2a41
+F src/btree.c 9004c98fc576306eee4fc0562ffeb362ef53912c
 F src/btree.h 10f9296bf4edf034f5adce921b7b4383a56a1c90
 F src/btreeInt.h 20f73dc93b1eeb83afd7259fbc6bd7dcf2df7fe4
 F src/build.c 00a327120d81ace6267e714ae8010c997d55de5d
@@ -170,7 +170,7 @@ F src/pager.h 0ea59db2a33bc6c2c02cae34de33367e1effdf76
 F src/parse.y 12b7ebd61ea54f0e1b1083ff69cc2c8ce9353d58
 F src/pcache.c 09d38c44ab275db581f7a2f6ff8b9bc7f8c0faaa
 F src/pcache.h c683390d50f856d4cd8e24342ae62027d1bb6050
-F src/pcache1.c 2610bcebf127df5ff82730c0c130cb35d4d6debe
+F src/pcache1.c 54401ef4ea296b5bc2950bfbf5e68d6e931ab676
 F src/pragma.c 8a6cd3c787f882fa44f6490d2411fc26839ce8f3
 F src/prepare.c c8b877b80721d70b68053fd9ae30ec6d63eeeadc
 F src/printf.c df2ff3bb5409e8958136933342c46464fbd017e7
@@ -900,14 +900,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 8d1065411aadf189880606c48ab63dd2a56b9793
+P b70bcccaf5597c8a59cccb64fb997523f7b8fe4f
-R 0d85535bc15a93b18012673a71c32db9
+R db20a3af8ef33b3a30d380bbda0431c6
 U drh
-Z 70d633de5e7a3d8ed3285ad89550ec3c
+Z 4ead49fabdd8a6e774c2367e68e73ca5
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1.4.6 (GNU/Linux)
 
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+iD8DBQFNPlLvoxKgR168RlERApslAJ9T2ytfJxLqucALSfvcNNpr6129cACfegvL
-RmLBh/72A/WvCFzCC21cc98=
+qPLVUx7DCZ7ypVE082HOjX8=
-=oeId
+=7+yb
 -----END PGP SIGNATURE-----

manifest.uuid

@@ -1 +1 @@
-b70bcccaf5597c8a59cccb64fb997523f7b8fe4f
+e14649301138b6840e24a4bbd2cf5205c0f72409

src/btree.c

@@ -918,14 +918,9 @@ static void btreeParseCellPtr(
     /* This is the (easy) common case where the entire payload fits
     ** on the local page.  No overflow is required.
     */
-    int nSize;          /* Total size of cell content in bytes */
+    if( (pInfo->nSize = (u16)(n+nPayload))<4 ) pInfo->nSize = 4;
-    nSize = nPayload + n;
     pInfo->nLocal = (u16)nPayload;
     pInfo->iOverflow = 0;
-    if( (nSize & ~3)==0 ){
-      nSize = 4;        /* Minimum cell size is 4 */
-    }
-    pInfo->nSize = (u16)nSize;
   }else{
     /* If the payload will not fit completely on the local page, we have
     ** to decide how much to store locally and how much to spill onto

src/pcache1.c

@@ -50,6 +50,7 @@ struct PGroup {
   sqlite3_mutex *mutex;          /* MUTEX_STATIC_LRU or NULL */
   int nMaxPage;                  /* Sum of nMax for purgeable caches */
   int nMinPage;                  /* Sum of nMin for purgeable caches */
+  int mxPinned;                  /* nMaxpage + 10 - nMinPage */
   int nCurrentPage;              /* Number of purgeable pages allocated */
   PgHdr1 *pLruHead, *pLruTail;   /* LRU list of unpinned pages */
 };
@@ -73,6 +74,7 @@ struct PCache1 {
   int bPurgeable;                     /* True if cache is purgeable */
   unsigned int nMin;                  /* Minimum number of pages reserved */
   unsigned int nMax;                  /* Configured "cache_size" value */
+  unsigned int mxPinned;              /* nMax*9/10 */
 
   /* Hash table of all pages. The following variables may only be accessed
   ** when the accessor is holding the PGroup mutex.
@@ -516,6 +518,7 @@ static int pcache1Init(void *NotUsed){
     pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
     pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM);
   }
+  pcache1.grp.mxPinned = 10;
   pcache1.isInit = 1;
   return SQLITE_OK;
 }
@@ -565,6 +568,7 @@ static sqlite3_pcache *pcache1Create(int szPage, int bPurgeable){
     memset(pCache, 0, sz);
     if( separateCache ){
       pGroup = (PGroup*)&pCache[1];
+      pGroup->mxPinned = 10;
     }else{
       pGroup = &pcache1_g.grp;
     }
@@ -575,6 +579,7 @@ static sqlite3_pcache *pcache1Create(int szPage, int bPurgeable){
       pCache->nMin = 10;
       pcache1EnterMutex(pGroup);
       pGroup->nMinPage += pCache->nMin;
+      pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
       pcache1LeaveMutex(pGroup);
     }
   }
@@ -592,7 +597,9 @@ static void pcache1Cachesize(sqlite3_pcache *p, int nMax){
     PGroup *pGroup = pCache->pGroup;
     pcache1EnterMutex(pGroup);
     pGroup->nMaxPage += (nMax - pCache->nMax);
+    pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
     pCache->nMax = nMax;
+    pCache->mxPinned = nMax*9/10;
     pcache1EnforceMaxPage(pGroup);
     pcache1LeaveMutex(pGroup);
   }
@@ -667,12 +674,14 @@ static int pcache1Pagecount(sqlite3_pcache *p){
 static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
   unsigned int nPinned;
   PCache1 *pCache = (PCache1 *)p;
-  PGroup *pGroup = pCache->pGroup;
+  PGroup *pGroup;
   PgHdr1 *pPage = 0;
 
   assert( pCache->bPurgeable || createFlag!=1 );
-  pcache1EnterMutex(pGroup);
+  assert( pCache->bPurgeable || pCache->nMin==0 );
-  if( createFlag==1 ) sqlite3BeginBenignMalloc();
+  assert( pCache->bPurgeable==0 || pCache->nMin==10 );
+  assert( pCache->nMin==0 || pCache->bPurgeable );
+  pcache1EnterMutex(pGroup = pCache->pGroup);
 
   /* Step 1: Search the hash table for an existing entry. */
   if( pCache->nHash>0 ){
@@ -686,11 +695,25 @@ static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
     goto fetch_out;
   }
 
+  /* The pGroup local variable will normally be initialized by the
+  ** pcache1EnterMutex() macro above.  But if SQLITE_MUTEX_OMIT is defined,
+  ** then pcache1EnterMutex() is a no-op, so we have to initialize the
+  ** local variable here.  Delaying the initialization of pGroup is an
+  ** optimization:  The common case is to exit the module before reaching
+  ** this point.
+  */
+#ifdef SQLITE_MUTEX_OMIT
+  pGroup = pCache->pGroup;
+#endif
+
+
   /* Step 3: Abort if createFlag is 1 but the cache is nearly full */
   nPinned = pCache->nPage - pCache->nRecyclable;
+  assert( pGroup->mxPinned == pGroup->nMaxPage + 10 - pGroup->nMinPage );
+  assert( pCache->mxPinned == pCache->nMax*9/10 );
   if( createFlag==1 && (
-        nPinned>=(pGroup->nMaxPage+pCache->nMin-pGroup->nMinPage)
+        nPinned>=pGroup->mxPinned
-     || nPinned>=(pCache->nMax * 9 / 10)
+     || nPinned>=pCache->mxPinned
      || pcache1UnderMemoryPressure(pCache)
   )){
     goto fetch_out;
@@ -706,15 +729,16 @@ static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
       || pGroup->nCurrentPage>=pGroup->nMaxPage
       || pcache1UnderMemoryPressure(pCache)
   )){
+    PCache1 *pOtherCache;
     pPage = pGroup->pLruTail;
     pcache1RemoveFromHash(pPage);
     pcache1PinPage(pPage);
-    if( pPage->pCache->szPage!=pCache->szPage ){
+    if( (pOtherCache = pPage->pCache)->szPage!=pCache->szPage ){
       pcache1FreePage(pPage);
       pPage = 0;
     }else{
       pGroup->nCurrentPage -= 
-               (pPage->pCache->bPurgeable - pCache->bPurgeable);
+               (pOtherCache->bPurgeable - pCache->bPurgeable);
     }
   }
 
@@ -722,9 +746,11 @@ static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
   ** attempt to allocate a new one. 
   */
   if( !pPage ){
+    if( createFlag==1 ) sqlite3BeginBenignMalloc();
     pcache1LeaveMutex(pGroup);
     pPage = pcache1AllocPage(pCache);
     pcache1EnterMutex(pGroup);
+    if( createFlag==1 ) sqlite3EndBenignMalloc();
   }
 
   if( pPage ){
@@ -743,7 +769,6 @@ fetch_out:
   if( pPage && iKey>pCache->iMaxKey ){
     pCache->iMaxKey = iKey;
   }
-  if( createFlag==1 ) sqlite3EndBenignMalloc();
   pcache1LeaveMutex(pGroup);
   return (pPage ? PGHDR1_TO_PAGE(pPage) : 0);
 }
@@ -853,6 +878,7 @@ static void pcache1Destroy(sqlite3_pcache *p){
   pcache1TruncateUnsafe(pCache, 0);
   pGroup->nMaxPage -= pCache->nMax;
   pGroup->nMinPage -= pCache->nMin;
+  pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
   pcache1EnforceMaxPage(pGroup);
   pcache1LeaveMutex(pGroup);
   sqlite3_free(pCache->apHash);