Remove the mutex counter and the logic that attempts to verify that btree

mutexes are held continuously.  We are not making that assumption at this
time.

FossilOrigin-Name: 242ce7cff416a87d57d4eb624cb79fa4e2215559

manifest

@@ -1,5 +1,5 @@
-C When\scommitting\sa\sWAL\stransaction,\sdo\snot\swrite\sany\spages\sto\sthe\sWAL\sfile\swith\spage\snumbers\sgreater\sthan\sthe\ssize\sof\sthe\sdatabase\simage\sin\spages.
-D 2011-04-05T16:09:08.127
+C Remove\sthe\smutex\scounter\sand\sthe\slogic\sthat\sattempts\sto\sverify\sthat\sbtree\nmutexes\sare\sheld\scontinuously.\s\sWe\sare\snot\smaking\sthat\sassumption\sat\sthis\ntime.
+D 2011-04-05T17:31:56.106
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 7a4d9524721d40ef9ee26f93f9bd6a51dba106f2
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -120,10 +120,10 @@ F src/attach.c 7cae2cf0c14762ce14c074a860ec52890a973a56
 F src/auth.c 523da7fb4979469955d822ff9298352d6b31de34
 F src/backup.c b7529a6691f0fd534ae8ff622203c46a7f1b626b
 F src/bitvec.c af50f1c8c0ff54d6bdb7a80e2fceca5a93670bef
-F src/btmutex.c b81062220a4f91b0bd785d13d57205d68449be88
+F src/btmutex.c 1f951523accdfa1d204b06150e016b5b69529b8a
 F src/btree.c 107723ed4f9bdb55213ba6164c30c49af75f4bf9
-F src/btree.h c0e0ff5c85effe9fc757e3085bbdded6d1cca000
-F src/btreeInt.h 6714ce2f5e879eb9a904a6a4575dc4faa4f29991
+F src/btree.h 221e186cd64127088890a878aaab154344380fe8
+F src/btreeInt.h b5e339df994d12bcd9067d04f9125c8792de51ac
 F src/build.c d809f57250b10e83586bc23921de02055890b239
 F src/callback.c 0425c6320730e6d3981acfb9202c1bed9016ad1a
 F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
@@ -235,11 +235,11 @@ F src/update.c 81911be16ece3c3e7716aa18565b4814ec41f8b9
 F src/utf.c d83650c3ea08f7407bd9d0839d9885241c209c60
 F src/util.c cd997077bad039efc0597eb027c929658f93c018
 F src/vacuum.c 05513dca036a1e7848fe18d5ed1265ac0b32365e
-F src/vdbe.c 0140a57f9cbd50351219bfc4e44ef3de64bd65b8
+F src/vdbe.c b239d70f6862f1d0d3896c96efe7d6fabae1c56c
 F src/vdbe.h 8a675fefdf7119441fe817c800a9a52440c2e797
-F src/vdbeInt.h 7e2f028ecc1a9faa6f253e7aa8d89cae03662bae
+F src/vdbeInt.h 53dfcaf5b83297c24f537c4a54c1f35fd655b0a2
 F src/vdbeapi.c a09ad9164cafc505250d5dd6b69660c960f1308c
-F src/vdbeaux.c e1ea6edc07b4f33a339cc45a2fbe0a36067d2d8b
+F src/vdbeaux.c 64304e50c6d4ccca586410184927baa9faca6ecc
 F src/vdbeblob.c c3ccb7c8732858c680f442932e66ad06bb036562
 F src/vdbemem.c 0498796b6ffbe45e32960d6a1f5adfb6e419883b
 F src/vdbetrace.c 3ba13bc32bdf16d2bdea523245fd16736bed67b5
@@ -926,7 +926,7 @@ F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/split-sqlite3c.tcl d9be87f1c340285a3e081eb19b4a247981ed290c
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P d25c17ef6e2b916923489dccaaa018a2d6525401
-R c888a09e2325a742237e83457c23e497
-U dan
-Z 881050430264f599344995b52c518cce
+P 311d0b613d9cfa2dbcbb9ef2450041b1fd48770a
+R f2efb954b9e1d86872be6fb2ad3e5711
+U drh
+Z c70542c8d51f5c49bbcf63ab42aa4a3a

manifest.uuid

@@ -1 +1 @@
-311d0b613d9cfa2dbcbb9ef2450041b1fd48770a
+242ce7cff416a87d57d4eb624cb79fa4e2215559

src/btmutex.c

@@ -45,28 +45,10 @@ static void unlockBtreeMutex(Btree *p){
   assert( sqlite3_mutex_held(p->db->mutex) );
   assert( p->db==pBt->db );
 
-  pBt->iMutexCounter++;
   sqlite3_mutex_leave(pBt->mutex);
   p->locked = 0;
 }
 
-#ifdef SQLITE_DEBUG
-/*
-** Return the number of times that the mutex has been exited for
-** the given btree.
-**
-** This is a small circular counter that wraps around to zero on
-** overflow.  It is used only for sanity checking - to verify that
-** mutexes are held continously by asserting that the value of
-** this counter at the beginning of a region is the same as at
-** the end.
-*/
-u32 sqlite3BtreeMutexCounter(Btree *p){
-  assert( p->locked==1 || p->sharable==0 );
-  return p->pBt->iMutexCounter;
-}
-#endif
-
 /*
 ** Enter a mutex on the given BTree object.
 **
@@ -111,24 +93,6 @@ void sqlite3BtreeEnter(Btree *p){
   p->wantToLock++;
   if( p->locked ) return;
 
-  /* Increment the mutex counter on all locked btrees in the same
-  ** database connection.  This simulates the unlocking that would
-  ** occur on a worst-case mutex dead-lock avoidance scenario.
-  */
-#ifdef SQLITE_DEBUG
-  {
-    int ii;
-    sqlite3 *db = p->db;
-    Btree *pOther;
-    for(ii=0; ii<db->nDb; ii++){
-      if( ii==1 ) continue;
-      pOther = db->aDb[ii].pBt;
-      if( pOther==0 || pOther->sharable==0 || pOther->locked==0 ) continue;
-      pOther->pBt->iMutexCounter++;
-    }
-  }
-#endif
-
   /* In most cases, we should be able to acquire the lock we
   ** want without having to go throught the ascending lock
   ** procedure that follows.  Just be sure not to block.

src/btree.h

@@ -221,19 +221,17 @@ void sqlite3BtreeCursorList(Btree*);
   int sqlite3BtreeHoldsMutex(Btree*);
   int sqlite3BtreeHoldsAllMutexes(sqlite3*);
   int sqlite3SchemaMutexHeld(sqlite3*,int,Schema*);
-  u32 sqlite3BtreeMutexCounter(Btree*);
 #endif
 #else
 
 # define sqlite3BtreeLeave(X)
-# define sqlite3BtreeMutexCounter(X) 0
 # define sqlite3BtreeEnterCursor(X)
 # define sqlite3BtreeLeaveCursor(X)
 # define sqlite3BtreeLeaveAll(X)
 
 # define sqlite3BtreeHoldsMutex(X) 1
 # define sqlite3BtreeHoldsAllMutexes(X) 1
-# define sqlite3BtreeSchemaMutexHeld(X,Y) 1
+# define sqlite3SchemaMutexHeld(X,Y,Z) 1
 #endif
 
 

src/btreeInt.h

@@ -435,7 +435,6 @@ struct BtShared {
   Btree *pWriter;       /* Btree with currently open write transaction */
   u8 isExclusive;       /* True if pWriter has an EXCLUSIVE lock on the db */
   u8 isPending;         /* If waiting for read-locks to clear */
-  u16 iMutexCounter;    /* The number of mutex_leave(mutex) calls */
 #endif
   u8 *pTmpSpace;        /* BtShared.pageSize bytes of space for tmp use */
 };

src/vdbe.c

@@ -1394,7 +1394,6 @@ case OP_Function: {
     ctx.pColl = pOp[-1].p4.pColl;
   }
   (*ctx.pFunc->xFunc)(&ctx, n, apVal); /* IMP: R-24505-23230 */
-  sqlite3VdbeMutexResync(p);
   if( db->mallocFailed ){
     /* Even though a malloc() has failed, the implementation of the
     ** user function may have called an sqlite3_result_XXX() function
@@ -2660,7 +2659,6 @@ case OP_Savepoint: {
         if( p1==SAVEPOINT_ROLLBACK && (db->flags&SQLITE_InternChanges)!=0 ){
           sqlite3ExpirePreparedStatements(db);
           sqlite3ResetInternalSchema(db, -1);
-          sqlite3VdbeMutexResync(p);
           db->flags = (db->flags | SQLITE_InternChanges);
         }
       }
@@ -5198,23 +5196,11 @@ case OP_AggStep: {
     ctx.pColl = pOp[-1].p4.pColl;
   }
   (ctx.pFunc->xStep)(&ctx, n, apVal); /* IMP: R-24505-23230 */
-  sqlite3VdbeMutexResync(p);
   if( ctx.isError ){
     sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(&ctx.s));
     rc = ctx.isError;
   }
 
-  /* The app-defined function has done something that as caused this
-  ** statement to expire.  (Perhaps the function called sqlite3_exec()
-  ** with a CREATE TABLE statement.)
-  */
-#if 0
-  if( p->expired ){
-    rc = SQLITE_ABORT;
-    break;
-  }
-#endif
-
   sqlite3VdbeMemRelease(&ctx.s);
 
   break;
@@ -5238,11 +5224,8 @@ case OP_AggFinal: {
   pMem = &aMem[pOp->p1];
   assert( (pMem->flags & ~(MEM_Null|MEM_Agg))==0 );
   rc = sqlite3VdbeMemFinalize(pMem, pOp->p4.pFunc);
-  sqlite3VdbeMutexResync(p);
   if( rc ){
     sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(pMem));
-  }else if( p->expired ){
-    rc = SQLITE_ABORT;
   }
   sqlite3VdbeChangeEncoding(pMem, encoding);
   UPDATE_MAX_BLOBSIZE(pMem);

src/vdbeInt.h

@@ -303,7 +303,6 @@ struct Vdbe {
   u8 isPrepareV2;         /* True if prepared with prepare_v2() */
   int nChange;            /* Number of db changes made since last reset */
   yDbMask btreeMask;      /* Bitmask of db->aDb[] entries referenced */
-  u32 iMutexCounter;      /* Mutex counter upon sqlite3VdbeEnter() */
   int iStatement;         /* Statement number (or 0 if has not opened stmt) */
   int aCounter[3];        /* Counters used by sqlite3_stmt_status() */
 #ifndef SQLITE_OMIT_TRACE
@@ -387,9 +386,14 @@ int sqlite3VdbeCloseStatement(Vdbe *, int);
 void sqlite3VdbeFrameDelete(VdbeFrame*);
 int sqlite3VdbeFrameRestore(VdbeFrame *);
 void sqlite3VdbeMemStoreType(Mem *pMem);
-void sqlite3VdbeEnter(Vdbe*);
-void sqlite3VdbeLeave(Vdbe*);
-void sqlite3VdbeMutexResync(Vdbe*);
+
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
+  void sqlite3VdbeEnter(Vdbe*);
+  void sqlite3VdbeLeave(Vdbe*);
+#else
+# define sqlite3VdbeEnter(X)
+# define sqlite3VdbeLeave(X)
+#endif
 
 #ifdef SQLITE_DEBUG
 void sqlite3VdbeMemPrepareToChange(Vdbe*,Mem*);

src/vdbeaux.c

@@ -960,31 +960,7 @@ void sqlite3VdbeUsesBtree(Vdbe *p, int i){
   p->btreeMask |= ((yDbMask)1)<<i;
 }
 
-/*
-** Compute the sum of all mutex counters for all btrees in the
-** given prepared statement.
-*/
-#ifndef SQLITE_OMIT_SHARED_CACHE
-static u32 mutexCounterSum(Vdbe *p){
-  u32 cntSum = 0;
-#ifdef SQLITE_DEBUG
-  int i;
-  yDbMask mask;
-  sqlite3 *db = p->db;
-  Db *aDb = db->aDb;
-  int nDb = db->nDb;
-  for(i=0, mask=1; i<nDb; i++, mask += mask){
-    if( i!=1 && (mask & p->btreeMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
-      cntSum += sqlite3BtreeMutexCounter(aDb[i].pBt);
-    }
-  }
-#else
-  UNUSED_PARAMETER(p);
-#endif
-  return cntSum;
-}
-#endif
-
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
 /*
 ** If SQLite is compiled to support shared-cache mode and to be threadsafe,
 ** this routine obtains the mutex associated with each BtShared structure
@@ -1007,7 +983,6 @@ static u32 mutexCounterSum(Vdbe *p){
 ** be a problem.
 */
 void sqlite3VdbeEnter(Vdbe *p){
-#ifndef SQLITE_OMIT_SHARED_CACHE
   int i;
   yDbMask mask;
   sqlite3 *db = p->db;
@@ -1018,63 +993,27 @@ void sqlite3VdbeEnter(Vdbe *p){
       sqlite3BtreeEnter(aDb[i].pBt);
     }
   }
-  p->iMutexCounter = mutexCounterSum(p);
-#else
-  UNUSED_PARAMETER(p);
-#endif
 }
+#endif
 
+#if !defined(SQLITE_OMIT_SHARED_CACHE) && SQLITE_THREADSAFE>0
 /*
 ** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
 */
 void sqlite3VdbeLeave(Vdbe *p){
-#ifndef SQLITE_OMIT_SHARED_CACHE
   int i;
   yDbMask mask;
   sqlite3 *db = p->db;
   Db *aDb = db->aDb;
   int nDb = db->nDb;
 
-  /* Assert that the all mutexes have been held continously since
-  ** the most recent sqlite3VdbeEnter() or sqlite3VdbeMutexResync().
-  */
-  assert( mutexCounterSum(p) == p->iMutexCounter );
-
   for(i=0, mask=1; i<nDb; i++, mask += mask){
     if( i!=1 && (mask & p->btreeMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
       sqlite3BtreeLeave(aDb[i].pBt);
     }
   }
-#else
-  UNUSED_PARAMETER(p);
-#endif
 }
-
-/*
-** Recompute the sum of the mutex counters on all btrees used by the
-** prepared statement p.
-**
-** Call this routine while holding a sqlite3VdbeEnter() after doing something
-** that might cause one or more of the individual mutexes held by the
-** prepared statement to be released.  Calling sqlite3BtreeEnter() on 
-** any BtShared mutex which is not used by the prepared statement is one
-** way to cause one or more of the mutexes in the prepared statement
-** to be temporarily released.  The anti-deadlocking logic in
-** sqlite3BtreeEnter() can cause mutexes to be released temporarily then
-** reacquired.
-**
-** Calling this routine is an acknowledgement that some of the individual
-** mutexes in the prepared statement might have been released and reacquired.
-** So checks to verify that mutex-protected content did not change
-** unexpectedly should accompany any call to this routine.
-*/
-void sqlite3VdbeMutexResync(Vdbe *p){
-#if !defined(SQLITE_OMIT_SHARED_CACHE) && defined(SQLITE_DEBUG)
-  p->iMutexCounter = mutexCounterSum(p);
-#else
-  UNUSED_PARAMETER(p);
 #endif
-}
 
 #if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
 /*
@@ -2283,7 +2222,6 @@ int sqlite3VdbeHalt(Vdbe *p){
     }
 
     /* Release the locks */
-    sqlite3VdbeMutexResync(p);
     sqlite3VdbeLeave(p);
   }