Display isolate message queue in Observatory debugger

runtime/vm/message_handler.h

 // Copyright (c) 2011, 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.
 
 #ifndef VM_MESSAGE_HANDLER_H_
 #define VM_MESSAGE_HANDLER_H_
 
 #include "vm/isolate.h"
 #include "vm/message.h"
 #include "vm/os_thread.h"
@@ skipping 78 matching lines @@
   }
 
   void set_pause_on_exit(bool pause_on_exit) {
     pause_on_exit_ = pause_on_exit;
   }
 
   bool paused_on_exit() const {
     return paused_on_exit_;
   }
 
+  class AcquiredQueues : public ValueObject {
+   public:
+    AcquiredQueues();
+
+    ~AcquiredQueues();
+
+    MessageQueue* queue() {
+      if (handler_ == NULL) {
+        return NULL;
+      }
+      return handler_->queue_;
+    }
+
+    MessageQueue* oob_queue() {
+      if (handler_ == NULL) {
+        return NULL;
+      }
+      return handler_->oob_queue_;
+    }
+
+   private:
+    void Reset(MessageHandler* handler);
+
+    MessageHandler* handler_;
+
+    friend class MessageHandler;
+  };
+
+  // Gives temporary ownership of |queue| and |oob_queue|. Calling this
+  // has the side effect that no OOB messages will be handled if a stack
+  // overflow interrupt is delivered.
+  void AcquireQueues(AcquiredQueues* acquired_queue);
 
 #if defined(DEBUG)
   // Check that it is safe to access this message handler.
   //
   // For example, if this MessageHandler is an isolate, then it is
   // only safe to access it when the MessageHandler is the current
   // isolate.
   virtual void CheckAccess();
 #endif
 
@@ skipping 50 matching lines @@
   // messages from the queue_.
   Message* DequeueMessage(Message::Priority min_priority);
 
   // Handles any pending messages.
   bool HandleMessages(bool allow_normal_messages,
                       bool allow_multiple_normal_messages);
 
   Monitor monitor_;  // Protects all fields in MessageHandler.
   MessageQueue* queue_;
   MessageQueue* oob_queue_;
+  // This flag is not thread safe and can only reliably be accessed on a single
+  // thread.
+  bool oob_message_handling_allowed_;
   intptr_t live_ports_;  // The number of open ports, including control ports.
   intptr_t paused_;  // The number of pause messages received.
   bool pause_on_start_;
   bool pause_on_exit_;
   bool paused_on_start_;
   bool paused_on_exit_;
   ThreadPool* pool_;
   ThreadPool::Task* task_;
   StartCallback start_callback_;
   EndCallback end_callback_;
   CallbackData callback_data_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageHandler);
 };
 
 }  // namespace dart
 
 #endif  // VM_MESSAGE_HANDLER_H_