Reduce the amount of memory taken up by WAL mmaped regions under Windows.

FossilOrigin-Name: f213e133f6e69b0edd73d96142014bdcab9dfe41

manifest

@@ -1,8 +1,5 @@
------BEGIN PGP SIGNED MESSAGE-----
-Hash: SHA1
-
-C Fix\sa\sdiscrepancy\sbetween\sthe\sdocumented\sbehavior\sof\sSQLITE_DBCONFIG_LOOKASIDE\nand\swhat\sit\sactually\sdoes.\s\sAlso\sadd\sevidence\smarks\son\sthe\sDBCONFIG_LOOKASIDE\nimplementation.
-D 2010-09-03T03:32:47
+C Reduce\sthe\samount\sof\smemory\staken\sup\sby\sWAL\smmaped\sregions\sunder\sWindows.
+D 2010-09-03T04:29:31
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in c599a15d268b1db2aeadea19df2adc3bf2eb6bee
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -161,7 +158,7 @@ F src/os.h 9dbed8c2b9c1f2f2ebabc09e49829d4777c26bf9
 F src/os_common.h a8f95b81eca8a1ab8593d23e94f8a35f35d4078f
 F src/os_os2.c 72d0b2e562952a2464308c4ce5f7913ac10bef3e
 F src/os_unix.c 6152042c3a619fbc390eeb59a8eecafa40afc2e4
-F src/os_win.c 6fb3447ffe56df0dbb2d1ac93f75c9c748e009e1
+F src/os_win.c 2f90f7bdec714fad51cd31b4ecad3cc1b4bb5aad
 F src/pager.c 51d77a9df463f77bf214f32bb2dbc2d0da41fc3e
 F src/pager.h 8167a1e720d0b7a2790079007128e594010220ad
 F src/parse.y 12b7ebd61ea54f0e1b1083ff69cc2c8ce9353d58
@@ -856,14 +853,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P a55842cfb56b659c88832dce9ce7bafb50258211
-R 594e3dfa3a6dc8d6a5c8c27345538f42
-U drh
-Z ee5272a19c79aeac7c1c4ce2730a97f0
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+R fea23b14c42fedda7d16ff1cb4b9cee7
+U shaneh
+Z 0fd3f5ddcf6cc38ff6e323baec639592

manifest.uuid

@@ -1 +1 @@
-f483be441323e1cb91516964cd6ab0edecad4366
+f213e133f6e69b0edd73d96142014bdcab9dfe41

src/os_win.c

@@ -1212,6 +1212,14 @@ static int winDeviceCharacteristics(sqlite3_file *id){
 
 #ifndef SQLITE_OMIT_WAL
 
+/* 
+** Windows will only let you create file view mappings
+** on allocation size granularity boundaries.
+** During sqlite3_os_init() we do a GetSystemInfo()
+** to get the granularity size.
+*/
+SYSTEM_INFO winSysInfo;
+
 /*
 ** Helper functions to obtain and relinquish the global mutex. The
 ** global mutex is used to protect the winLockInfo objects used by 
@@ -1380,6 +1388,7 @@ static int winDelete(sqlite3_vfs *,const char*,int);
 static void winShmPurge(sqlite3_vfs *pVfs, int deleteFlag){
   winShmNode **pp;
   winShmNode *p;
+  BOOL bRc;
   assert( winShmMutexHeld() );
   pp = &winShmNodeList;
   while( (p = *pp)!=0 ){
@@ -1387,8 +1396,14 @@ static void winShmPurge(sqlite3_vfs *pVfs, int deleteFlag){
       int i;
       if( p->mutex ) sqlite3_mutex_free(p->mutex);
       for(i=0; i<p->nRegion; i++){
-        UnmapViewOfFile(p->aRegion[i].pMap);
-        CloseHandle(p->aRegion[i].hMap);
+        bRc = UnmapViewOfFile(p->aRegion[i].pMap);
+        OSTRACE(("SHM-PURGE pid-%d unmap region=%d %s\n",
+                 (int)GetCurrentProcessId(), i,
+                 bRc ? "ok" : "failed"));
+        bRc = CloseHandle(p->aRegion[i].hMap);
+        OSTRACE(("SHM-PURGE pid-%d close region=%d %s\n",
+                 (int)GetCurrentProcessId(), i,
+                 bRc ? "ok" : "failed"));
       }
       if( p->hFile.h != INVALID_HANDLE_VALUE ){
         SimulateIOErrorBenign(1);
@@ -1465,6 +1480,7 @@ static int winOpenSharedMemory(winFile *pDbFd){
       rc = SQLITE_NOMEM;
       goto shm_open_err;
     }
+
     rc = winOpen(pDbFd->pVfs,
                  pShmNode->zFilename,             /* Name of the file (UTF-8) */
                  (sqlite3_file*)&pShmNode->hFile,  /* File handle here */
@@ -1776,10 +1792,18 @@ static int winShmMap(
       hMap = CreateFileMapping(pShmNode->hFile.h, 
           NULL, PAGE_READWRITE, 0, nByte, NULL
       );
+      OSTRACE(("SHM-MAP pid-%d create region=%d nbyte=%d %s\n",
+               (int)GetCurrentProcessId(), pShmNode->nRegion, nByte,
+               hMap ? "ok" : "failed"));
       if( hMap ){
+        int iOffset = pShmNode->nRegion*szRegion;
+        int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
         pMap = MapViewOfFile(hMap, FILE_MAP_WRITE | FILE_MAP_READ,
-            0, 0, nByte
+            0, iOffset - iOffsetShift, szRegion + iOffsetShift
         );
+        OSTRACE(("SHM-MAP pid-%d map region=%d offset=%d size=%d %s\n",
+                 (int)GetCurrentProcessId(), pShmNode->nRegion, iOffset, szRegion,
+                 pMap ? "ok" : "failed"));
       }
       if( !pMap ){
         pShmNode->lastErrno = GetLastError();
@@ -1796,8 +1820,10 @@ static int winShmMap(
 
 shmpage_out:
   if( pShmNode->nRegion>iRegion ){
+    int iOffset = iRegion*szRegion;
+    int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
     char *p = (char *)pShmNode->aRegion[iRegion].pMap;
-    *pp = (void *)&p[iRegion*szRegion];
+    *pp = (void *)&p[iOffsetShift];
   }else{
     *pp = 0;
   }
@@ -2738,6 +2764,13 @@ int sqlite3_os_init(void){
     winCurrentTimeInt64, /* xCurrentTimeInt64 */
   };
 
+#ifndef SQLITE_OMIT_WAL
+  /* get memory map allocation granularity */
+  memset(&winSysInfo, 0, sizeof(SYSTEM_INFO));
+  GetSystemInfo(&winSysInfo);
+  assert(winSysInfo.dwAllocationGranularity > 0);
+#endif
+
   sqlite3_vfs_register(&winVfs, 1);
   return SQLITE_OK; 
 }