Add necessary support functions so that embedders can implemented pause on start and exit

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 38 matching lines @@
            EndCallback end_callback,
            CallbackData data);
 
   // Handles the next message for this message handler.  Should only
   // be used when not running the handler on the thread pool (via Run
   // or RunBlocking).
   //
   // Returns true on success.
   MessageStatus HandleNextMessage();
 
+  // Handles all messages for this message handler.  Should only
+  // be used when not running the handler on the thread pool (via Run
+  // or RunBlocking).
+  //
+  // Returns true on success.
+  MessageStatus HandleAllMessages();
+
   // Handles any OOB messages for this message handler.  Can be used
   // even if the message handler is running on the thread pool.
   //
   // Returns true on success.
   MessageStatus HandleOOBMessages();
 
   // Returns true if there are pending OOB messages for this message
   // handler.
   bool HasOOBMessages();
 
   // A message handler tracks how many live ports it has.
   bool HasLivePorts() const { return live_ports_ > 0; }
 
   intptr_t live_ports() const {
     return live_ports_;
   }
 
   bool paused() const { return paused_ > 0; }
 
   void increment_paused() { paused_++; }
   void decrement_paused() { ASSERT(paused_ > 0); paused_--; }
 
-  bool pause_on_start() const {
-    return pause_on_start_;
+  bool ShouldPauseOnStart(MessageStatus status) const;
+  bool should_pause_on_start() const {
+    return should_pause_on_start_;
   }
 
-  void set_pause_on_start(bool pause_on_start) {
-    pause_on_start_ = pause_on_start;
+  void set_should_pause_on_start(bool should_pause_on_start) {
+    should_pause_on_start_ = should_pause_on_start;
   }
 
-  bool paused_on_start() const {
-    // If pause_on_start_ is still set, tell the user we are paused,
-    // even if we haven't hit the pause point yet.
-    return paused_on_start_;
+  bool is_paused_on_start() const {
+    return is_paused_on_start_;
   }
 
-  bool pause_on_exit() const {
-    return pause_on_exit_;
+  bool ShouldPauseOnExit(MessageStatus status) const;
+  bool should_pause_on_exit() const {
+    return should_pause_on_exit_;
   }
 
-  void set_pause_on_exit(bool pause_on_exit) {
-    pause_on_exit_ = pause_on_exit;
+  void set_should_pause_on_exit(bool should_pause_on_exit) {
+    should_pause_on_exit_ = should_pause_on_exit;
   }
 
-  bool paused_on_exit() const {
-    return paused_on_exit_;
+  bool is_paused_on_exit() const {
+    return is_paused_on_exit_;
   }
 
   // Timestamp of the paused on start or paused on exit.
   int64_t paused_timestamp() const {
     return paused_timestamp_;
   }
 
+  void PausedOnStart(bool paused);
+  void PausedOnExit(bool paused);
+
   class AcquiredQueues : public ValueObject {
    public:
     AcquiredQueues();
 
     ~AcquiredQueues();
 
     MessageQueue* queue() {
       if (handler_ == NULL) {
         return NULL;
       }
@@ skipping 74 matching lines @@
   Thread* thread() const { return Thread::Current(); }
 
  private:
   friend class PortMap;
   friend class MessageHandlerTestPeer;
   friend class MessageHandlerTask;
 
   // Called by MessageHandlerTask to process our task queue.
   void TaskCallback();
 
+  // NOTE: These two functions release and reacquire the monitor, you may
+  // need to call HandleMessages to ensure all pending messages are handled.
+  void PausedOnStartLocked(bool paused);
+  void PausedOnExitLocked(bool paused);
+
   // Dequeue the next message.  Prefer messages from the oob_queue_ to
   // messages from the queue_.
   Message* DequeueMessage(Message::Priority min_priority);
 
   void ClearOOBQueue();
 
   // Handles any pending messages.
   MessageStatus 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_;
+  bool should_pause_on_start_;
+  bool should_pause_on_exit_;
+  bool is_paused_on_start_;
+  bool is_paused_on_exit_;
   int64_t paused_timestamp_;
   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_