lazy instantiation of the default isolate

src/v8.cc

 // 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 61 matching lines @@
          i::Isolate::Current());
 
   Isolate* isolate = Isolate::Current();
   if (isolate->IsDead()) return false;
   if (isolate->IsInitialized()) return true;
 
   return isolate->Init(des);
 }
 
 
-void V8::TearDown() {
-  Isolate* isolate = Isolate::Current();
-  ASSERT(isolate->IsDefaultIsolate());
-  if (!isolate->IsInitialized()) return;
+bool V8::TearDown() {
+  Isolate* isolate = Isolate::UncheckedCurrent();
+  if (isolate != NULL) {
+    ASSERT(isolate->IsDefaultIsolate());
+    if (isolate->IsInitialized()) isolate->TearDown();
+    delete isolate;
+  }
 
-  // The isolate has to be torn down before clearing the LOperand
+  // V8 was never initialized, nothing to do.
+  if (Acquire_Load(&init_once) == ONCE_STATE_UNINITIALIZED) return true;
+
+  // TODO(dcarney): Everything below this should be in some sort of mutex...
+  Atomic32 living_isolates = Isolate::GetLivingIsolates();
+
+  // All isolates have to be torn down before clearing the LOperand
   // caches so that the optimizing compiler thread (if running)
   // doesn't see an inconsistent view of the lithium instructions.
-  isolate->TearDown();
-  delete isolate;
+  if (living_isolates != 0) return false;
 
   ElementsAccessor::TearDown();
   LOperand::TearDownCaches();
   ExternalReference::TearDownMathExpData();
   RegisteredExtension::UnregisterAll();
   Isolate::GlobalTearDown();
 
   delete call_completed_callbacks_;
   call_completed_callbacks_ = NULL;
 
   Sampler::TearDown();
+  return true;
 }
 
 
 void V8::SetReturnAddressLocationResolver(
       ReturnAddressLocationResolver resolver) {
   StackFrame::SetReturnAddressLocationResolver(resolver);
 }
 
 
 // Used by JavaScript APIs
@@ skipping 129 matching lines @@
   ExternalReference::SetUp();
   Bootstrapper::InitializeOncePerProcess();
 }
 
 
 void V8::InitializeOncePerProcess() {
   CallOnce(&init_once, &InitializeOncePerProcessImpl);
 }
 
 } }  // namespace v8::internal