Instead of transitioning to RECOVER state from CHECKPOINT when a reco…

…very is required, perform the recovery while holding the CHECKPOINT lock.
shiyezheng · May 6, 2010 · 56be9f4 · 56be9f4
1 parent ef22e7f
commit 56be9f4
Show file tree

Hide file tree

Showing 4 changed files with 14 additions and 17 deletions.
diff --git a/doc/vfs-shm.txt b/doc/vfs-shm.txt
@@ -113,9 +113,7 @@ The following are the allowed lock transitions:
 (11l)  PENDING            UNLOCK          UNLOCK
 (11m)  PENDING            CHECKPOINT      CHECKPOINT
 (11n)  CHECKPOINT         UNLOCK          UNLOCK
-(11o)  CHECKPOINT         RECOVER         RECOVER
-(11p)  RECOVER            READ            READ
-(11q)  RECOVER            CHECKPOINT      CHECKPOINT
+(11o)  RECOVER            READ            READ
 
 These 17 transitions are all that needs to be supported.  The lock
 manager implementation can assert that fact.  The other 25 possible

diff --git a/src/os_unix.c b/src/os_unix.c
@@ -5339,12 +5339,7 @@ static int unixShmLock(
     case SQLITE_SHM_CHECKPOINT: {
       assert( p->lockState==SQLITE_SHM_UNLOCK
            || p->lockState==SQLITE_SHM_PENDING
-           || p->lockState==SQLITE_SHM_RECOVER );
-      if( p->lockState==SQLITE_SHM_RECOVER ){
-        unixShmUnlock(pFile, p, UNIX_SHM_C);
-        p->lockState = SQLITE_SHM_CHECKPOINT;
-        rc = SQLITE_OK;
-      }
+      );
       if( p->lockState==SQLITE_SHM_UNLOCK ){
         rc = unixShmExclusiveLock(pFile, p, UNIX_SHM_B|UNIX_SHM_C);
         if( rc==SQLITE_OK ){
@@ -5363,7 +5358,7 @@ static int unixShmLock(
       assert( desiredLock==SQLITE_SHM_RECOVER );
       assert( p->lockState==SQLITE_SHM_READ
            || p->lockState==SQLITE_SHM_READ_FULL
-           || p->lockState==SQLITE_SHM_CHECKPOINT );
+      );
       assert( sqlite3_mutex_held(pFile->mutexBuf) );
       rc = unixShmExclusiveLock(pFile, p, UNIX_SHM_C);
       if( rc==SQLITE_OK ){

diff --git a/src/wal.c b/src/wal.c
@@ -501,7 +501,7 @@ static int walIndexRecover(Wal *pWal){
   i64 nSize;                      /* Size of log file */
   WalIndexHdr hdr;              /* Recovered wal-index header */
 
-  assert( pWal->lockState==SQLITE_SHM_RECOVER );
+  assert( pWal->lockState>SQLITE_SHM_READ );
   memset(&hdr, 0, sizeof(hdr));
 
   rc = sqlite3OsFileSize(pWal->pFd, &nSize);
@@ -941,7 +941,9 @@ static int walIndexReadHdr(Wal *pWal, int *pChanged){
   ** time as well, run log recovery.
   */
   lockState = pWal->lockState;
-  if( SQLITE_OK==(rc = walSetLock(pWal, SQLITE_SHM_RECOVER)) ){
+  if( lockState>SQLITE_SHM_READ
+   || SQLITE_OK==(rc = walSetLock(pWal, SQLITE_SHM_RECOVER)) 
+  ){
     /* This call to walIndexTryHdr() may not return an error code, as the
     ** wal-index is already mapped. It may find that the header is invalid,
     ** but there is no chance of hitting an actual error.  */
@@ -952,7 +954,9 @@ static int walIndexReadHdr(Wal *pWal, int *pChanged){
       *pChanged = 1;
       rc = walIndexRecover(pWal);
     }
-    walSetLock(pWal, lockState);
+    if( lockState==SQLITE_SHM_READ ){
+      walSetLock(pWal, SQLITE_SHM_READ);
+    }
   }
 
   return rc;

diff --git a/test/wal2.test b/test/wal2.test
@@ -338,8 +338,7 @@ tvfs delete
 
 #-------------------------------------------------------------------------
 # Test that if a database connection is forced to run recovery before it
-# can perform a checkpoint, it transistions from RECOVERY->CHECKPOINT
-# before doing so.
+# can perform a checkpoint, it does not transition into RECOVER state.
 #
 do_test wal2-5.1 {
   proc tvfs_cb {method args} {
@@ -362,8 +361,9 @@ do_test wal2-5.1 {
   set ::locks [list]
   execsql { PRAGMA wal_checkpoint }
   set ::locks
-} {CHECKPOINT RECOVER CHECKPOINT UNLOCK}
-
+} {CHECKPOINT UNLOCK}
 
+db close
+tvfs delete
 
 finish_test