Bug 529134: Initialize tracemalloc in NS_LogInit() to ensure that tracemalloc is always thread safe. r=bsmedberg r=dbaron

tools/trace-malloc/lib/nsTraceMalloc.c

@@ -1477,6 +1477,12 @@ NS_TraceMallocStartupArgs(int argc, char **argv)
     return argc;
 }
 
+PR_IMPLEMENT(PRBool)
+NS_TraceMallocHasStarted(void)
+{
+    return tmlock ? PR_TRUE : PR_FALSE;
+}
+
 PR_IMPLEMENT(void)
 NS_TraceMallocShutdown(void)
 {

tools/trace-malloc/lib/nsTraceMalloc.h

@@ -164,6 +164,11 @@ PR_EXTERN(void) NS_TraceMallocStartup(int logfd);
  */
 PR_EXTERN(int) NS_TraceMallocStartupArgs(int argc, char* argv[]);
 
+/**
+ * Return PR_TRUE iff |NS_TraceMallocStartup[Args]| has been successfully called.
+ */
+PR_EXTERN(PRBool) NS_TraceMallocHasStarted(void);
+
 /**
  * Stop all malloc tracing, flushing any buffered events to the logfile.
  */

xpcom/base/nsTraceRefcntImpl.cpp

@@ -61,6 +61,10 @@
 #endif
 #endif
 
+#ifdef NS_TRACE_MALLOC
+#include "nsTraceMalloc.h"
+#endif
+
 #ifdef HAVE_LIBDL
 #include <dlfcn.h>
 #endif
@@ -900,6 +904,13 @@ NS_LogInit()
   if (++gInitCount)
     nsTraceRefcntImpl::SetActivityIsLegal(PR_TRUE);
 #endif
+
+#ifdef NS_TRACE_MALLOC
+  // XXX we don't have to worry about shutting down trace-malloc; it
+  // handles this itself, through an atexit() callback.
+  if (!NS_TraceMallocHasStarted())
+    NS_TraceMallocStartup(-1);  // -1 == no logging
+#endif
 }
 
 EXPORT_XPCOM_API(void)