From: drh <drh@noemail.net>
Date: Thu, 3 Sep 2015 17:54:32 +0000 (+0000)
Subject: Change the Pager.hasBeenUsed flag into Pager.hasHeldSharedLock in order to
X-Git-Tag: version-3.9.0~157
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c98a4cc8b6a2fd2a54d6281279f46ccb14ec2e81;p=thirdparty%2Fsqlite.git

Change the Pager.hasBeenUsed flag into Pager.hasHeldSharedLock in order to
take it off the critical path in sqlite3PagerAcquire().

FossilOrigin-Name: b79096be7cb02aae2f303db33a8bf19e69204374
---

diff --git a/manifest b/manifest
index 5e842820c7..9427db7679 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\sthe\ssqlite3VdbeLoadString()\sand\ssqlite3VdbeMultiLoad()\sroutines\sto\shelp\nwith\scode\sgeneration,\sespecially\son\sPRAGMAs.\s\sRename\ssqlite3VdbeAddGoto()\nto\sjust\ssqlite3VdbeGoto().
-D 2015-09-03T13:46:12.406
+C Change\sthe\sPager.hasBeenUsed\sflag\sinto\sPager.hasHeldSharedLock\sin\sorder\sto\ntake\sit\soff\sthe\scritical\spath\sin\ssqlite3PagerAcquire().
+D 2015-09-03T17:54:32.014
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in f85066ce844a28b671aaeeff320921cd0ce36239
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -324,7 +324,7 @@ F src/os_setup.h c9d4553b5aaa6f73391448b265b89bed0b890faa
 F src/os_unix.c 76f493ed71c4154338049dee1bf6e47f69c74a55
 F src/os_win.c 40b3af7a47eb1107d0d69e592bec345a3b7b798a
 F src/os_win.h eb7a47aa17b26b77eb97e4823f20a00b8bda12ca
-F src/pager.c aa916ca28606ccf4b6877dfc2b643ccbca86589f
+F src/pager.c 2a9d77ac483a684c4187ec9ca786b551d3adfda5
 F src/pager.h 6d435f563b3f7fcae4b84433b76a6ac2730036e2
 F src/parse.y f599aa5e871a493330d567ced93de696f61f48f7
 F src/pcache.c cde06aa50962595e412d497e22fd2e07878ba1f0
@@ -1380,7 +1380,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P d7f4bdf594e93c848f46901637861c8eed4c34df
-R 87d27a58ce6d4a6cd03f169f2370f2fe
+P 847387ec8e6fef283899578fb232b2c23b00ee5b
+R 530c1d1d05feba269ca8969115207173
 U drh
-Z bdbaccc5e83ea81c60c1b2c883af5b3e
+Z e28985417ac4a7094ed6187f7e395585
diff --git a/manifest.uuid b/manifest.uuid
index 3428834616..eaef64ee94 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-847387ec8e6fef283899578fb232b2c23b00ee5b
\ No newline at end of file
+b79096be7cb02aae2f303db33a8bf19e69204374
\ No newline at end of file
diff --git a/src/pager.c b/src/pager.c
index 060edb8d1d..f4e27f36ca 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -647,7 +647,7 @@ struct Pager {
   u8 doNotSpill;              /* Do not spill the cache when non-zero */
   u8 subjInMemory;            /* True to use in-memory sub-journals */
   u8 bUseFetch;               /* True to use xFetch() */
-  u8 hasBeenUsed;             /* True if any content previously read */
+  u8 hasHeldSharedLock;       /* True if a shared lock has ever been held */
   Pgno dbSize;                /* Number of pages in the database */
   Pgno dbOrigSize;            /* dbSize before the current transaction */
   Pgno dbFileSize;            /* Number of pages in the database file */
@@ -5097,10 +5097,10 @@ int sqlite3PagerSharedLock(Pager *pPager){
       );
     }
 
-    if( !pPager->tempFile && pPager->hasBeenUsed ){
+    if( !pPager->tempFile && pPager->hasHeldSharedLock ){
       /* The shared-lock has just been acquired then check to
       ** see if the database has been modified.  If the database has changed,
-      ** flush the cache.  The pPager->hasBeenUsed flag prevents this from
+      ** flush the cache.  The hasHeldSharedLock flag prevents this from
       ** occurring on the very first access to a file, in order to save a
       ** single unnecessary sqlite3OsRead() call at the start-up.
       **
@@ -5170,6 +5170,7 @@ int sqlite3PagerSharedLock(Pager *pPager){
     assert( pPager->eState==PAGER_OPEN );
   }else{
     pPager->eState = PAGER_READER;
+    pPager->hasHeldSharedLock = 1;
   }
   return rc;
 }
@@ -5267,7 +5268,7 @@ int sqlite3PagerAcquire(
   if( pgno==0 ){
     return SQLITE_CORRUPT_BKPT;
   }
-  pPager->hasBeenUsed = 1;
+  assert( pPager->hasHeldSharedLock==1 );
 
   /* If the pager is in the error state, return an error immediately. 
   ** Otherwise, request the page from the PCache layer. */
@@ -5422,7 +5423,7 @@ DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
   assert( pgno!=0 );
   assert( pPager->pPCache!=0 );
   pPage = sqlite3PcacheFetch(pPager->pPCache, pgno, 0);
-  assert( pPage==0 || pPager->hasBeenUsed );
+  assert( pPage==0 || pPager->hasHeldSharedLock );
   if( pPage==0 ) return 0;
   return sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pPage);
 }