Add experimental feature to detect threading bugs in apps that use

SQLITE_CONFIG_MULTITHREADED. Enabled at compile time using
SQLITE_ENABLE_MULTITHREADED_CHECKS.

FossilOrigin-Name: 40b598c8392f030f6ed8c63ce81cb0426bb3984397c19c756215f6a569a40164

manifest

@@ -1,5 +1,5 @@
-C Update\stests\sto\sdeal\swith\sSQLITE_FAST_SECURE_DELETE.
-D 2017-11-28T00:52:14.148
+C Add\sexperimental\sfeature\sto\sdetect\sthreading\sbugs\sin\sapps\sthat\suse\nSQLITE_CONFIG_MULTITHREADED.\sEnabled\sat\scompile\stime\susing\nSQLITE_ENABLE_MULTITHREADED_CHECKS.
+D 2017-11-28T07:52:00.416
 F Makefile.in 6a879cbf01e37f9eac131414955f71774b566502d9a57ded1b8585b507503cb8
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc e5d7606238f55816da99f719969598df5b091aa2e9a6935c9412fcae8f53fc44
@@ -436,7 +436,7 @@ F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c cb67cc56ef2ddd13e6944b2c0dd08a920bcd9503230adef8b9928d338097c722
 F src/legacy.c 134ab3e3fae00a0f67a5187981d6935b24b337bcf0f4b3e5c9fa5763da95bf4e
 F src/loadext.c 20865b183bb8a3723d59cf1efffc3c50217eb452c1021d077b908c94da26b0b2
-F src/main.c 99ed3d45e315afb2ada049991db7944b1210663bb30bfd0b63103537c1ac25d0
+F src/main.c 6a0cc1c7b8ab92374effecdd7b92792b3273a255c70575b7d67bd9a4315e6d3a
 F src/malloc.c a02c9e69bc76bee0f639416b947a946412890b606301454727feadcb313536d6
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c c12a42539b1ba105e3707d0e628ad70e611040d8f5e38cf942cee30c867083de
@@ -445,7 +445,7 @@ F src/mem3.c 8768ac94694f31ffaf8b4d0ea5dc08af7010a35a
 F src/mem5.c 9bf955937b07f8c32541c8a9991f33ce3173d944
 F src/memjournal.c 6f3d36a0a8f72f48f6c3c722f04301ac64f2515435fa42924293e46fc7994661
 F src/msvc.h 4942752b6a253116baaa8de75256c51a459a5e81
-F src/mutex.c 8e45800ee78e0cd1f1f3fe8e398853307f4a085c
+F src/mutex.c 20172f2cc43c4542f7860ab6bafdd16965822c4e56650d62628059a48c7f43c4
 F src/mutex.h 779d588e3b7756ec3ecf7d78cde1d84aba414f85
 F src/mutex_noop.c 9d4309c075ba9cc7249e19412d3d62f7f94839c4
 F src/mutex_unix.c 27bb6cc49485ee46711a6580ab7b3f1402211d23
@@ -476,7 +476,7 @@ F src/shell.c.in c441d7ddfbb8120cd8a7cde838ca5c9167311a7e400b1077c3ae6090aa420be
 F src/sqlite.h.in 8fd97993d48b50b9bade38c52f12d175942c9497c960905610c7b03a3e4b5818
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h c02d628cca67f3889c689d82d25c3eb45e2c155db08e4c6089b5840d64687d34
-F src/sqliteInt.h 9b26fbab75ef426efae70d88ab535844d59de8954542b122c1d49af580a76f58
+F src/sqliteInt.h 4c910d9c0d88a90e8639a4f83ef05f701ccfe731cf593e757444074f01df4964
 F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
 F src/status.c 9737ed017279a9e0c5da748701c3c7bf1e8ae0dae459aad20dd64fcff97a7e35
 F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@ -1678,7 +1678,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 465350e55ddaf30cfba7874653301de7238a9dc2bc5e1f800fc95de9360679f6
-R 5c3698b136ad7029a7e22749e9f1a061
-U drh
-Z 455c99a49ae132932748abfe00c111c4
+P e6b89304695be371978e65dddd710c8bd563c66b9c94d23165142b6c235c82e1 12a23c0a66fac5c9674120b390f6abaeaba3f7ff04693b281af1eefb93d6f47c
+R dd8aff31239aebcaa5e5379a4673912d
+T +closed 12a23c0a66fac5c9674120b390f6abaeaba3f7ff04693b281af1eefb93d6f47c
+U dan
+Z bdded6a608898929c58df7d45769809f

manifest.uuid

@@ -1 +1 @@
-e6b89304695be371978e65dddd710c8bd563c66b9c94d23165142b6c235c82e1
+40b598c8392f030f6ed8c63ce81cb0426bb3984397c19c756215f6a569a40164

src/main.c

@@ -2822,6 +2822,7 @@ static int openDatabase(
   }else{
     isThreadsafe = sqlite3GlobalConfig.bFullMutex;
   }
+
   if( flags & SQLITE_OPEN_PRIVATECACHE ){
     flags &= ~SQLITE_OPEN_SHAREDCACHE;
   }else if( sqlite3GlobalConfig.sharedCacheEnabled ){
@@ -2854,13 +2855,20 @@ static int openDatabase(
   /* Allocate the sqlite data structure */
   db = sqlite3MallocZero( sizeof(sqlite3) );
   if( db==0 ) goto opendb_out;
-  if( isThreadsafe ){
+  if( isThreadsafe 
+#ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS
+   || sqlite3GlobalConfig.bCoreMutex
+#endif
+  ){
     db->mutex = sqlite3MutexAlloc(SQLITE_MUTEX_RECURSIVE);
     if( db->mutex==0 ){
       sqlite3_free(db);
       db = 0;
       goto opendb_out;
     }
+    if( isThreadsafe==0 ){
+      sqlite3MutexWarnOnContention(db->mutex);
+    }
   }
   sqlite3_mutex_enter(db->mutex);
   db->errMask = 0xff;

src/mutex.c

@@ -26,6 +26,193 @@ static SQLITE_WSD int mutexIsInit = 0;
 
 
 #ifndef SQLITE_MUTEX_OMIT
+
+#ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS
+/*
+** This block (enclosed by SQLITE_ENABLE_MULTITHREADED_CHECKS) contains
+** the implementation of a wrapper around the system default mutex
+** implementation (sqlite3DefaultMutex()). 
+**
+** Most calls are passed directly through to the underlying default
+** mutex implementation. Except, if a mutex is configured by calling
+** sqlite3MutexWarnOnContention() on it, then if contention is ever
+** encountered within xMutexEnter() a warning is emitted via sqlite3_log().
+**
+** This type of mutex is used as the database handle mutex when testing
+** apps that usually use SQLITE_CONFIG_MULTITHREAD mode.
+*/
+
+/* 
+** Type for all mutexes used when SQLITE_ENABLE_MULTITHREADED_CHECKS
+** is defined. Variable CheckMutex.mutex is a pointer to the real mutex
+** allocated by the system mutex implementation. Variable iType is usually set
+** to the type of mutex requested - SQLITE_MUTEX_RECURSIVE, SQLITE_MUTEX_FAST
+** or one of the static mutex identifiers. Or, if this is a recursive mutex
+** that has been configured using sqlite3MutexWarnOnContention(), it is
+** set to SQLITE_MUTEX_WARNONCONTENTION.
+*/
+typedef struct CheckMutex CheckMutex;
+struct CheckMutex {
+  int iType;
+  sqlite3_mutex *mutex;
+};
+
+#define SQLITE_MUTEX_WARNONCONTENTION  (-1)
+
+/* 
+** Pointer to real mutex methods object used by the CheckMutex
+** implementation. Set by checkMutexInit(). 
+*/
+static SQLITE_WSD const sqlite3_mutex_methods *pGlobalMutexMethods;
+
+#ifdef SQLITE_DEBUG
+static int checkMutexHeld(sqlite3_mutex *p){
+  return pGlobalMutexMethods->xMutexHeld(((CheckMutex*)p)->mutex);
+}
+static int checkMutexNotheld(sqlite3_mutex *p){
+  return pGlobalMutexMethods->xMutexNotheld(((CheckMutex*)p)->mutex);
+}
+#endif
+
+/*
+** Initialize and deinitialize the mutex subsystem.
+*/
+static int checkMutexInit(void){ 
+  pGlobalMutexMethods = sqlite3DefaultMutex();
+  return SQLITE_OK; 
+}
+static int checkMutexEnd(void){ 
+  pGlobalMutexMethods = 0;
+  return SQLITE_OK; 
+}
+
+/*
+** Allocate a mutex.
+*/
+static sqlite3_mutex *checkMutexAlloc(int iType){
+  static CheckMutex staticMutexes[] = {
+    {2, 0}, {3, 0}, {4, 0}, {5, 0},
+    {6, 0}, {7, 0}, {8, 0}, {9, 0},
+    {10, 0}, {11, 0}, {12, 0}, {13, 0}
+  };
+  CheckMutex *p = 0;
+
+  assert( SQLITE_MUTEX_RECURSIVE==1 && SQLITE_MUTEX_FAST==0 );
+  if( iType<2 ){
+    p = sqlite3MallocZero(sizeof(CheckMutex));
+    if( p==0 ) return 0;
+    p->iType = iType;
+  }else{
+#ifdef SQLITE_ENABLE_API_ARMOR
+    if( iType-2>=ArraySize(staticMutexes) ){
+      (void)SQLITE_MISUSE_BKPT;
+      return 0;
+    }
+#endif
+    p = &staticMutexes[iType-2];
+  }
+
+  if( p->mutex==0 ){
+    p->mutex = pGlobalMutexMethods->xMutexAlloc(iType);
+    if( p->mutex==0 ){
+      if( iType<2 ){
+        sqlite3_free(p);
+      }
+      p = 0;
+    }
+  }
+
+  return (sqlite3_mutex*)p;
+}
+
+/*
+** Free a mutex.
+*/
+static void checkMutexFree(sqlite3_mutex *p){
+  assert( SQLITE_MUTEX_RECURSIVE<2 );
+  assert( SQLITE_MUTEX_FAST<2 );
+  assert( SQLITE_MUTEX_WARNONCONTENTION<2 );
+
+#if SQLITE_ENABLE_API_ARMOR
+  if( p->iType<2 ){
+#endif
+  {
+    CheckMutex *pCheck = (CheckMutex*)p;
+    pGlobalMutexMethods->xMutexFree(pCheck->mutex);
+    sqlite3_free(pCheck);
+  }
+#ifdef SQLITE_ENABLE_API_ARMOR
+  else{
+    (void)SQLITE_MISUSE_BKPT;
+  }
+#endif
+}
+
+/*
+** Enter the mutex.
+*/
+static void checkMutexEnter(sqlite3_mutex *p){
+  CheckMutex *pCheck = (CheckMutex*)p;
+  if( pCheck->iType==SQLITE_MUTEX_WARNONCONTENTION ){
+    if( SQLITE_OK==pGlobalMutexMethods->xMutexTry(pCheck->mutex) ){
+      return;
+    }
+    sqlite3_log(SQLITE_MISUSE, 
+        "illegal multi-threaded access to database connection"
+    );
+  }
+  pGlobalMutexMethods->xMutexEnter(pCheck->mutex);
+}
+
+/*
+** Enter the mutex (do not block).
+*/
+static int checkMutexTry(sqlite3_mutex *p){
+  CheckMutex *pCheck = (CheckMutex*)p;
+  return pGlobalMutexMethods->xMutexTry(pCheck->mutex);
+}
+
+/*
+** Leave the mutex.
+*/
+static void checkMutexLeave(sqlite3_mutex *p){
+  CheckMutex *pCheck = (CheckMutex*)p;
+  pGlobalMutexMethods->xMutexLeave(pCheck->mutex);
+}
+
+sqlite3_mutex_methods const *multiThreadedCheckMutex(void){
+  static const sqlite3_mutex_methods sMutex = {
+    checkMutexInit,
+    checkMutexEnd,
+    checkMutexAlloc,
+    checkMutexFree,
+    checkMutexEnter,
+    checkMutexTry,
+    checkMutexLeave,
+#ifdef SQLITE_DEBUG
+    checkMutexHeld,
+    checkMutexNotheld
+#else
+    0,
+    0
+#endif
+  };
+  return &sMutex;
+}
+
+/*
+** Mark the SQLITE_MUTEX_RECURSIVE mutex passed as the only argument as
+** one on which there should be no contention.
+*/
+void sqlite3MutexWarnOnContention(sqlite3_mutex *p){
+  if( sqlite3GlobalConfig.mutex.xMutexAlloc==checkMutexAlloc ){
+    CheckMutex *pCheck = (CheckMutex*)p;
+    assert( pCheck->iType==SQLITE_MUTEX_RECURSIVE );
+    pCheck->iType = SQLITE_MUTEX_WARNONCONTENTION;
+  }
+}
+#endif   /* ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS */
+
 /*
 ** Initialize the mutex system.
 */
@@ -41,7 +228,11 @@ int sqlite3MutexInit(void){
     sqlite3_mutex_methods *pTo = &sqlite3GlobalConfig.mutex;
 
     if( sqlite3GlobalConfig.bCoreMutex ){
+#ifdef SQLITE_ENABLE_MULTITHREADED_CHECKS
+      pFrom = multiThreadedCheckMutex();
+#else
       pFrom = sqlite3DefaultMutex();
+#endif
     }else{
       pFrom = sqlite3NoopMutex();
     }
@@ -167,3 +358,4 @@ int sqlite3_mutex_notheld(sqlite3_mutex *p){
 #endif
 
 #endif /* !defined(SQLITE_MUTEX_OMIT) */
+

src/sqliteInt.h

@@ -3590,6 +3590,12 @@ int sqlite3LookasideUsed(sqlite3*,int*);
 sqlite3_mutex *sqlite3Pcache1Mutex(void);
 sqlite3_mutex *sqlite3MallocMutex(void);
 
+#if defined(SQLITE_ENABLE_MULTITHREADED_CHECKS) && !defined(SQLITE_MUTEX_OMIT)
+void sqlite3MutexWarnOnContention(sqlite3_mutex*);
+#else
+# define sqlite3MutexWarnOnContention(x)
+#endif
+
 #ifndef SQLITE_OMIT_FLOATING_POINT
   int sqlite3IsNaN(double);
 #else