Always use isolate creation callback passed to Dart_Initialize for service isolate startup

runtime/vm/service.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/service.h"
 
 #include "include/dart_api.h"
 #include "platform/globals.h"
 
 #include "vm/compiler.h"
@@ skipping 479 matching lines @@
   for (intptr_t i = 0; i < n; i++) {
     VmServiceNativeEntry entry = _VmServiceNativeEntries[i];
     if ((strcmp(function_name, entry.name) == 0) &&
         (num_arguments == entry.num_arguments)) {
       return entry.function;
     }
   }
   return NULL;
 }
 
-const char* Service::kServiceIsolateName = "vm-service";
+const char* Service::kIsolateName = "vm-service";
 EmbedderServiceHandler* Service::isolate_service_handler_head_ = NULL;
 EmbedderServiceHandler* Service::root_service_handler_head_ = NULL;
 Isolate* Service::service_isolate_ = NULL;
 Dart_Port Service::service_port_ = ILLEGAL_PORT;
 Dart_Port Service::load_port_ = ILLEGAL_PORT;
+Dart_IsolateCreateCallback Service::create_callback_ = NULL;
 Monitor* Service::monitor_ = NULL;
 bool Service::initializing_ = true;
 uint32_t Service::event_mask_ = 0;
 
 
 bool Service::IsServiceIsolateName(const char* name) {
   ASSERT(name != NULL);
-  return strcmp(name, kServiceIsolateName) == 0;
+  return strcmp(name, kIsolateName) == 0;
 }
 
 
 bool Service::SendIsolateStartupMessage() {
   if (!IsRunning()) {
     return false;
   }
   Isolate* isolate = Isolate::Current();
   if (IsServiceIsolate(isolate)) {
     return false;
@@ skipping 186 matching lines @@
 }
 
 
 class RunServiceTask : public ThreadPool::Task {
  public:
   virtual void Run() {
     ASSERT(Isolate::Current() == NULL);
     char* error = NULL;
     Isolate* isolate = NULL;
 
-    Dart_IsolateCreateCallback create_callback = Isolate::CreateCallback();
+    Dart_IsolateCreateCallback create_callback = Service::create_callback();
+    // TODO(johnmccutchan): Support starting up service isolate without embedder
+    // provided isolate creation callback.
     if (create_callback == NULL) {
       Service::FinishedInitializing();
       return;
     }
 
     isolate =
-        reinterpret_cast<Isolate*>(create_callback(Service::kServiceIsolateName,
+        reinterpret_cast<Isolate*>(create_callback(Service::kIsolateName,
                                                    NULL,
                                                    NULL,
                                                    NULL,
                                                    &error));
-    Isolate::SetCurrent(NULL);
-
     if (isolate == NULL) {
       OS::PrintErr("vm-service: Isolate creation error: %s\n", error);
       Service::FinishedInitializing();
       return;
     }
 
+    Isolate::SetCurrent(NULL);
+
     RunMain(isolate);
 
     Service::FinishedInitializing();
 
     isolate->message_handler()->Run(Dart::thread_pool(),
                                     NULL,
                                     ShutdownIsolate,
                                     reinterpret_cast<uword>(isolate));
   }
 
@@ skipping 44 matching lines @@
     const ReceivePort& rp = ReceivePort::Cast(result);
     Service::SetLoadPort(rp.Id());
   }
 };
 
 
 void Service::RunService() {
   ASSERT(monitor_ == NULL);
   monitor_ = new Monitor();
   ASSERT(monitor_ != NULL);
+  // Grab the isolate create callback here to avoid race conditions with tests
+  // that change this after Dart_Initialize returns.
+  create_callback_ = Isolate::CreateCallback();
   Dart::thread_pool()->Run(new RunServiceTask());
 }
 
 // A handler for a per-isolate request.
 //
 // If a handler returns true, the reply is complete and ready to be
 // posted.  If a handler returns false, then it is responsible for
 // posting the reply (this can be used for asynchronous delegation of
 // the response handling).
 typedef bool (*IsolateMessageHandler)(Isolate* isolate, JSONStream* stream);
@@ skipping 2177 matching lines @@
   while (current != NULL) {
     if (strcmp(name, current->name()) == 0) {
       return current;
     }
     current = current->next();
   }
   return NULL;
 }
 
 }  // namespace dart