Add Isolate::DiscardThreadSpecificMetadata method to embedder API.

test/cctest/test-lockers.cc

 // Copyright 2007-2011 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 329 matching lines @@
 };
 
 class LockerUnlockerThread : public JoinableThread {
  public:
   explicit LockerUnlockerThread(v8::Isolate* isolate)
     : JoinableThread("LockerUnlockerThread"),
       isolate_(isolate) {
   }
 
   virtual void Run() {
-    v8::Locker lock(isolate_);
-    v8::Isolate::Scope isolate_scope(isolate_);
-    v8::HandleScope handle_scope(isolate_);
-    v8::Local<v8::Context> context = v8::Context::New(isolate_);
+    isolate_->DiscardThreadSpecificMetadata();  // No-op
     {
-      v8::Context::Scope context_scope(context);
-      CalcFibAndCheck(context);
+      v8::Locker lock(isolate_);
+      v8::Isolate::Scope isolate_scope(isolate_);
+      v8::HandleScope handle_scope(isolate_);
+      v8::Local<v8::Context> context = v8::Context::New(isolate_);
+      {
+        v8::Context::Scope context_scope(context);
+        CalcFibAndCheck(context);
+      }
+      {
+        LockIsolateAndCalculateFibSharedContextThread thread(isolate_, context);
+        isolate_->Exit();
+        v8::Unlocker unlocker(isolate_);
+        thread.Start();
+        thread.Join();
+      }
+      isolate_->Enter();
+      {
+        v8::Context::Scope context_scope(context);
+        CalcFibAndCheck(context);
+      }
     }
-    {
-      LockIsolateAndCalculateFibSharedContextThread thread(isolate_, context);
-      isolate_->Exit();
-      v8::Unlocker unlocker(isolate_);
-      thread.Start();
-      thread.Join();
-    }
-    isolate_->Enter();
-    {
-      v8::Context::Scope context_scope(context);
-      CalcFibAndCheck(context);
-    }
+    isolate_->DiscardThreadSpecificMetadata();
+    isolate_->DiscardThreadSpecificMetadata();  // No-op
   }
 
  private:
   v8::Isolate* isolate_;
 };
 
 
 // Use unlocker inside of a Locker, multiple threads.
 TEST(LockerUnlocker) {
   i::FLAG_always_opt = false;
@@ skipping 346 matching lines @@
                                           kSimpleExtensionSource));
   const char* extension_names[] = { "test0", "test1",
                                     "test2", "test3", "test4",
                                     "test5", "test6", "test7" };
   i::List<JoinableThread*> threads(kNThreads);
   for (int i = 0; i < kNThreads; i++) {
     threads.Add(new IsolateGenesisThread(8, extension_names));
   }
   StartJoinAndDeleteThreads(threads);
 }