Fix performance regressions due to lazy initialization.

src/isolate.h

 // Copyright 2012 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 412 matching lines @@
 #define DECLARE_ENUM(CamelName, hacker_name) k##CamelName##Address,
     FOR_EACH_ISOLATE_ADDRESS_NAME(DECLARE_ENUM)
 #undef C
     kIsolateAddressCount
   };
 
   // Returns the PerIsolateThreadData for the current thread (or NULL if one is
   // not currently set).
   static PerIsolateThreadData* CurrentPerIsolateThreadData() {
     return reinterpret_cast<PerIsolateThreadData*>(
-        Thread::GetThreadLocal(per_isolate_thread_data_key()));
+        Thread::GetThreadLocal(per_isolate_thread_data_key_));
   }
 
   // Returns the isolate inside which the current thread is running.
   INLINE(static Isolate* Current()) {
-    const Thread::LocalStorageKey key = isolate_key();
     Isolate* isolate = reinterpret_cast<Isolate*>(
-        Thread::GetExistingThreadLocal(key));
-    if (!isolate) {
-      EnsureDefaultIsolate();
-      isolate = reinterpret_cast<Isolate*>(
-          Thread::GetExistingThreadLocal(key));
-    }
+        Thread::GetExistingThreadLocal(isolate_key_));
     ASSERT(isolate != NULL);
     return isolate;
   }
 
   INLINE(static Isolate* UncheckedCurrent()) {
-    return reinterpret_cast<Isolate*>(Thread::GetThreadLocal(isolate_key()));
+    return reinterpret_cast<Isolate*>(Thread::GetThreadLocal(isolate_key_));
   }
 
   // Usually called by Init(), but can be called early e.g. to allow
   // testing components that require logging but not the whole
   // isolate.
   //
   // Safe to call more than once.
   void InitializeLoggingAndCounters();
 
   bool Init(Deserializer* des);
 
   bool IsInitialized() { return state_ == INITIALIZED; }
 
   // True if at least one thread Enter'ed this isolate.
   bool IsInUse() { return entry_stack_ != NULL; }
 
   // Destroys the non-default isolates.
   // Sets default isolate into "has_been_disposed" state rather then destroying,
   // for legacy API reasons.
   void TearDown();
 
-  bool IsDefaultIsolate() const;
+  bool IsDefaultIsolate() const { return this == default_isolate_; }
 
   // Ensures that process-wide resources and the default isolate have been
   // allocated. It is only necessary to call this method in rare cases, for
   // example if you are using V8 from within the body of a static initializer.
   // Safe to call multiple times.
   static void EnsureDefaultIsolate();
 
   // Find the PerThread for this particular (isolate, thread) combination
   // If one does not yet exist, return null.
   PerIsolateThreadData* FindPerThreadDataForThisThread();
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
   // Get the debugger from the default isolate. Preinitializes the
   // default isolate if needed.
   static Debugger* GetDefaultIsolateDebugger();
 #endif
 
   // Get the stack guard from the default isolate. Preinitializes the
   // default isolate if needed.
   static StackGuard* GetDefaultIsolateStackGuard();
 
   // Returns the key used to store the pointer to the current isolate.
   // Used internally for V8 threads that do not execute JavaScript but still
   // are part of the domain of an isolate (like the context switcher).
-  static Thread::LocalStorageKey isolate_key();
+  static Thread::LocalStorageKey isolate_key() {
+    return isolate_key_;
+  }
 
   // Returns the key used to store process-wide thread IDs.
-  static Thread::LocalStorageKey thread_id_key();
+  static Thread::LocalStorageKey thread_id_key() {
+    return thread_id_key_;
+  }
 
   static Thread::LocalStorageKey per_isolate_thread_data_key();
 
   // If a client attempts to create a Locker without specifying an isolate,
   // we assume that the client is using legacy behavior. Set up the current
   // thread to be inside the implicit isolate (or fail a check if we have
   // switched to non-legacy behavior).
   static void EnterDefaultIsolate();
 
   // Mutex for serializing access to break control structures.
@@ skipping 563 matching lines @@
 
     int entry_count;
     PerIsolateThreadData* previous_thread_data;
     Isolate* previous_isolate;
     EntryStackItem* previous_item;
 
    private:
     DISALLOW_COPY_AND_ASSIGN(EntryStackItem);
   };
 
+  // This mutex protects highest_thread_id_, thread_data_table_ and
+  // default_isolate_.
+  static Mutex* process_wide_mutex_;
+
+  static Thread::LocalStorageKey per_isolate_thread_data_key_;
+  static Thread::LocalStorageKey isolate_key_;
+  static Thread::LocalStorageKey thread_id_key_;
+  static Isolate* default_isolate_;
+  static ThreadDataTable* thread_data_table_;
+
   void Deinit();
 
   static void SetIsolateThreadLocals(Isolate* isolate,
                                      PerIsolateThreadData* data);
 
   enum State {
     UNINITIALIZED,    // Some components may not have been allocated.
     INITIALIZED       // All components are fully initialized.
   };
 
@@ skipping 303 matching lines @@
 
 // Mark the global context with out of memory.
 inline void Context::mark_out_of_memory() {
   global_context()->set_out_of_memory(HEAP->true_value());
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ISOLATE_H_