Experimental changes to avoid recusrively calling xMutexInit.

FossilOrigin-Name: c9400ff167d9520119081c9b92436794dcd53d22

manifest

@@ -1,5 +1,5 @@
-C Merge\supdates\sfrom\strunk.
-D 2015-09-13T18:43:53.759
+C Experimental\schanges\sto\savoid\srecusrively\scalling\sxMutexInit.
+D 2015-09-13T18:45:50.134
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in f85066ce844a28b671aaeeff320921cd0ce36239
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -314,7 +314,7 @@ F src/mem3.c 61c9d47b792908c532ca3a62b999cf21795c6534
 F src/mem5.c 61eeb90134f9a5be6c2e68d8daae7628b25953fb
 F src/memjournal.c 3eb2c0b51adbd869cb6a44780323f05fa904dc85
 F src/msvc.h d9ba56c6851227ab44b3f228a35f3f5772296495
-F src/mutex.c a5c7d63f595ef4e2c7411fc627f1f6e3e8ee089b
+F src/mutex.c b0fbea2cda9f8e81444f5f1b4b9f07c1a904269e
 F src/mutex.h 779d588e3b7756ec3ecf7d78cde1d84aba414f85
 F src/mutex_noop.c f03e26ba8258399da23b51234f6b6a97197c1900
 F src/mutex_unix.c a72043f2560147d8e85fe48a6aef682896deb3a0
@@ -1386,7 +1386,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P d8051f611acabc2aaf8d23e8707c2a45961be416 786333e05a75406bbd0b5c9c7beb8f16022eabec
-R c5f00344bef9784bebe4d7d63d1f470a
+P b42c2e2076da1a61f667876ff2c18e4ebed50a7f
+R 7600913daf42127c1cd5acb5cae703c1
 U mistachkin
-Z ed5385a43675afcca5c372bcd0fa06ab
+Z e012d74d229ec0f8fc3b071b4b2b7de3

manifest.uuid

@@ -1 +1 @@
-b42c2e2076da1a61f667876ff2c18e4ebed50a7f
+c9400ff167d9520119081c9b92436794dcd53d22

src/mutex.c

@@ -75,6 +75,7 @@ static void mutexCopy(
 ** Initialize the mutex system.
 */
 int sqlite3MutexInit(void){ 
+  static int initPending = 0;
   int rc;
   if( sqlite3CompareAndSwap((void * volatile *)&sqlite3GlobalConfig.pMutex,
                    0, &sqlite3GlobalConfig.mutex)==0 || mutexIsInvalid() ){
@@ -93,8 +94,12 @@ int sqlite3MutexInit(void){
     mutexCopy(&sqlite3GlobalConfig.mutex, pFrom);
     sqlite3MemoryBarrier();
   }
-  assert( sqlite3GlobalConfig.mutex.xMutexInit );
-  rc = sqlite3GlobalConfig.mutex.xMutexInit();
+  if( !initPending ){
+    assert( sqlite3GlobalConfig.mutex.xMutexInit );
+    initPending = 1;
+    rc = sqlite3GlobalConfig.mutex.xMutexInit();
+    initPending = 0;
+  }
 
 #ifdef SQLITE_DEBUG
   GLOBAL(int, mutexIsInit) = 1;