Fast path for ThreadSpecific for main thread on TLS-slow platforms

third_party/WebKit/Source/wtf/WTF.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "wtf/WTF.h"
 
 #include "wtf/Assertions.h"
 #include "wtf/Functional.h"
 #include "wtf/Threading.h"
+#include "wtf/WTFThreadData.h"
 #include "wtf/allocator/Partitions.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/StringStatics.h"
 #include "wtf/typed_arrays/ArrayBufferContents.h"
 
 namespace WTF {
 
 extern void initializeThreading();
 
 bool s_initialized;
 bool s_shutdown;
 void (*s_callOnMainThreadFunction)(MainThreadFunction, void*);
-ThreadIdentifier s_mainThreadIdentifier;
 
 namespace internal {
 
 void callOnMainThread(MainThreadFunction* function, void* context) {
   (*s_callOnMainThreadFunction)(function, context);
 }
 
 }  // namespace internal
 
 bool isMainThread() {
-  return currentThread() == s_mainThreadIdentifier;
+  return WTFThreadData::isMainThread();
 }
 
 void initialize(void (*callOnMainThreadFunction)(MainThreadFunction, void*)) {
   // WTF, and Blink in general, cannot handle being re-initialized, even if
   // shutdown first.  Make that explicit here.
   RELEASE_ASSERT(!s_initialized);
   RELEASE_ASSERT(!s_shutdown);
   s_initialized = true;
   initializeThreading();
 
   s_callOnMainThreadFunction = callOnMainThreadFunction;
-  s_mainThreadIdentifier = currentThread();
   AtomicString::init();
   StringStatics::init();
 }
 
 void shutdown() {
   RELEASE_ASSERT(s_initialized);
   RELEASE_ASSERT(!s_shutdown);
   s_shutdown = true;
 }
 
 bool isShutdown() {
   return s_shutdown;
 }
 
 }  // namespace WTF