Small performance optimization in pcache1.

FossilOrigin-Name: ffd437da9541f8a2792e3e07c0a43f388f856fdc211fe42755eb51bfa5995d9f

diff --git a/manifest b/manifest
index a460f66c1ff3adca8d4563d2a8e6d07357278c3d..236c5cdbbad09efc624f3963db554ac5949f81c4 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Faster\smemory\sallocation\sfrom\slookaside\sby\snot\strying\sto\skeep\strack\sof\sthe\nnumber\sof\soutstanding\sallocations,\sand\srather\scomputing\sthat\svalue\sonly\nwhen\srequested.
-D 2017-08-29T20:21:12.167
+C Small\sperformance\soptimization\sin\spcache1.
+D 2017-08-30T04:44:59.152
 F Makefile.in c644bbe8ebe4aae82ad6783eae6b6beea4c727b99ff97568b847ced5e2ac7afb
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 25b154da7f0b3d4924f27378c1f8d006285b80811f1ccf3ed953dbebf6282136
@@ -448,7 +448,7 @@ F src/pager.h f2a99646c5533ffe11afa43e9e0bea74054e4efa
 F src/parse.y 52ef3cecd0934e9da4a45b585883a03243ad615d338ad94f44501a05891dcdfa
 F src/pcache.c 62835bed959e2914edd26afadfecce29ece0e870
 F src/pcache.h 521bb9610d38ef17a3cc9b5ddafd4546c2ea67fa3d0e464823d73c2a28d50e11
-F src/pcache1.c ad5bc71727c2e825dcbf342413e1b4b09ed8520cd83903671e8bd03bc30b4c98
+F src/pcache1.c 716975564c15eb6679e97f734cec1bfd6c16ac3d4010f05f1f8e509fc7d19880
 F src/pragma.c a4e5028dfc8af4c5c347cd0e91bd2f0c0f81fcd9b2c6e0acf8da7da51df7f1fe
 F src/pragma.h bb83728944b42f6d409c77f5838a8edbdb0fe83046c5496ffc9602b40340a324
 F src/prepare.c 9a141a1b02dca53beaa9771699d390aafcac01f5d1f1c0ae6e23ded8dcdb709a
@@ -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 64a8ae68381b7fbb29b659901ca7ce8d50510e4753758d5761f7e41539288cef
-R bf9afa7c8e223eb9e939beb0ed77930c
+P a06263f1efd2d45eac88b8d59e8fe8e458670fa3808c795feaa7f247fc36cbe9
+R bcdeb031d82a94a75572b4604ebe0254
 U drh
-Z 4dae0b64b90b0b3580ad9499179d8a8f
+Z 5debc6036b056965ebab42f5ae8d1e01

diff --git a/manifest.uuid b/manifest.uuid
index 9d0521f6c3f20c46a769f058d149fe4d014c9b42..f8c62cd0d57cd16ffb15b0193f61a926b10deae0 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-a06263f1efd2d45eac88b8d59e8fe8e458670fa3808c795feaa7f247fc36cbe9
\ No newline at end of file
+ffd437da9541f8a2792e3e07c0a43f388f856fdc211fe42755eb51bfa5995d9f
\ No newline at end of file

diff --git a/src/pcache1.c b/src/pcache1.c
index 7a19bd96745fd917c634fefc913f6759e8a566a1..fc3cbc5abe0a167dd80d3d802a09ad9ecae9d294 100644 (file)
--- a/src/pcache1.c
+++ b/src/pcache1.c
@@ -137,7 +137,7 @@ struct PGroup {
   unsigned int nMaxPage;         /* Sum of nMax for purgeable caches */
   unsigned int nMinPage;         /* Sum of nMin for purgeable caches */
   unsigned int mxPinned;         /* nMaxpage + 10 - nMinPage */
-  unsigned int nCurrentPage;     /* Number of purgeable pages allocated */
+  unsigned int nPurgeable;       /* Number of purgeable pages allocated */
   PgHdr1 lru;                    /* The beginning and end of the LRU list */
 };
 
@@ -151,11 +151,13 @@ struct PGroup {
 */
 struct PCache1 {
   /* Cache configuration parameters. Page size (szPage) and the purgeable
-  ** flag (bPurgeable) are set when the cache is created. nMax may be 
+  ** flag (bPurgeable) and the pnPurgeable pointer are all set when the
+  ** cache is created and are never changed thereafter. nMax may be 
   ** modified at any time by a call to the pcache1Cachesize() method.
   ** The PGroup mutex must be held when accessing nMax.
   */
   PGroup *pGroup;                     /* PGroup this cache belongs to */
+  unsigned int *pnPurgeable;          /* Pointer to pGroup->nPurgeable */
   int szPage;                         /* Size of database content section */
   int szExtra;                        /* sizeof(MemPage)+sizeof(PgHdr) */
   int szAlloc;                        /* Total size of one pcache line */
@@ -443,9 +445,7 @@ static PgHdr1 *pcache1AllocPage(PCache1 *pCache, int benignMalloc){
     p->isBulkLocal = 0;
     p->isAnchor = 0;
   }
-  if( pCache->bPurgeable ){
-    pCache->pGroup->nCurrentPage++;
-  }
+  (*pCache->pnPurgeable)++;
   return p;
 }
 
@@ -466,9 +466,7 @@ static void pcache1FreePage(PgHdr1 *p){
     sqlite3_free(p);
 #endif
   }
-  if( pCache->bPurgeable ){
-    pCache->pGroup->nCurrentPage--;
-  }
+  (*pCache->pnPurgeable)--;
 }
 
 /*
@@ -608,7 +606,7 @@ static void pcache1EnforceMaxPage(PCache1 *pCache){
   PGroup *pGroup = pCache->pGroup;
   PgHdr1 *p;
   assert( sqlite3_mutex_held(pGroup->mutex) );
-  while( pGroup->nCurrentPage>pGroup->nMaxPage
+  while( pGroup->nPurgeable>pGroup->nMaxPage
       && (p=pGroup->lru.pLruPrev)->isAnchor==0
   ){
     assert( p->pCache->pGroup==pGroup );
@@ -779,6 +777,10 @@ static sqlite3_pcache *pcache1Create(int szPage, int szExtra, int bPurgeable){
       pCache->nMin = 10;
       pGroup->nMinPage += pCache->nMin;
       pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
+      pCache->pnPurgeable = &pGroup->nPurgeable;
+    }else{
+      static unsigned int dummyCurrentPage;
+      pCache->pnPurgeable = &dummyCurrentPage;
     }
     pcache1LeaveMutex(pGroup);
     if( pCache->nHash==0 ){
@@ -888,7 +890,7 @@ static SQLITE_NOINLINE PgHdr1 *pcache1FetchStage2(
       pcache1FreePage(pPage);
       pPage = 0;
     }else{
-      pGroup->nCurrentPage -= (pOther->bPurgeable - pCache->bPurgeable);
+      pGroup->nPurgeable -= (pOther->bPurgeable - pCache->bPurgeable);
     }
   }
 
@@ -1069,7 +1071,7 @@ static void pcache1Unpin(
   assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
   assert( PAGE_IS_PINNED(pPage) );
 
-  if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){
+  if( reuseUnlikely || pGroup->nPurgeable>pGroup->nMaxPage ){
     pcache1RemoveFromHash(pPage, 1);
   }else{
     /* Add the page to the PGroup LRU list. */
@@ -1248,7 +1250,7 @@ void sqlite3PcacheStats(
     assert( PAGE_IS_UNPINNED(p) );
     nRecyclable++;
   }
-  *pnCurrent = pcache1.grp.nCurrentPage;
+  *pnCurrent = pcache1.grp.nPurgeable;
   *pnMax = (int)pcache1.grp.nMaxPage;
   *pnMin = (int)pcache1.grp.nMinPage;
   *pnRecyclable = nRecyclable;