Addresses #2121 refs[t:2121] toku_ydb_lock_destroy(): After freeing...

Addresses #2121 refs[t:2121] toku_ydb_lock_destroy(): After freeing thread-specific memory for ydbtime struct, 
set thread-specific storage to NULL to prevent destructor (toku_free) from being called twice,
just in case the thread that calls toku_ydb_lock_destroy() is not the same thread that called 
toku_ydb_lock_init().


git-svn-id: file:///svn/toku/tokudb@15976 c7de825b-a66e-492c-adef-691d508d4ae1

src/elocks.c

@@ -107,8 +107,15 @@ toku_ydb_lock_destroy(void) {
     int r;
     r = toku_pthread_mutex_destroy(&ydb_big_lock.lock); assert(r == 0);
 #if YDB_LOCK_MISS_TIME
+    // If main thread calls here, free memory allocated to main thread
+    // because destructor would not be called on thread exit.
     void * last_ydbtime = toku_pthread_getspecific(ydb_big_lock.time_key);
     if (last_ydbtime) toku_free(last_ydbtime);
+
+    // If some other thread (not main thread) calls here
+    // set the value to NULL so destructor is not called twice
+    r = toku_pthread_setspecific(ydb_big_lock.time_key, NULL); assert(r==0);
+
     r = toku_pthread_key_delete(ydb_big_lock.time_key); assert(r == 0);
 #endif
     return r;