Implement MessagePumpMojo using WaitSet.

mojo/message_pump/message_pump_mojo.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_MESSAGE_PUMP_MESSAGE_PUMP_MOJO_H_
 #define MOJO_MESSAGE_PUMP_MESSAGE_PUMP_MOJO_H_
 
 #include <map>
 #include <set>
 
@@ skipping 51 matching lines @@
   void RemoveObserver(Observer*);
 
   // MessagePump:
   void Run(Delegate* delegate) override;
   void Quit() override;
   void ScheduleWork() override;
   void ScheduleDelayedWork(const base::TimeTicks& delayed_work_time) override;
 
  private:
   struct RunState;
-  struct WaitState;
 
   // Contains the data needed to track a request to AddHandler().
   struct Handler {
     Handler() : handler(NULL), wait_signals(MOJO_HANDLE_SIGNAL_NONE), id(0) {}
 
     MessagePumpMojoHandler* handler;
     MojoHandleSignals wait_signals;
     base::TimeTicks deadline;
     // See description of |MessagePumpMojo::next_handler_id_| for details.
     int id;
   };
 
   typedef std::map<Handle, Handler> HandleToHandler;
 
   // Implementation of Run().
   void DoRunLoop(RunState* run_state, Delegate* delegate);
 
   // Services the set of handles ready. If |block| is true this waits for a
   // handle to become ready, otherwise this does not block. Returns |true| if a
   // handle has become ready, |false| otherwise.
   bool DoInternalWork(const RunState& run_state, bool block);
 
+  // Waits for handles in the wait set to become ready. Returns |true| if ready
+  // handles may be available, or |false| if the wait's deadline was exceeded.
+  // Note, ready handles may be unavailable, even though |true| was returned.
+  bool WaitForReadyHandles(const RunState& run_state) const;
+
+  // Retrieves any 'ready' handles from the wait set, and runs the handler's
+  // OnHandleReady() or OnHandleError() functions as necessary. Returns |true|
+  // if any handles were ready and processed.
+  bool ProcessReadyHandles();
+
   // Removes the given invalid handle. This is called if MojoWaitMany finds an

[yzshen1, 2016/01/05 17:41:05]

nit: please update the comment.

[Anand Mistry (off Chromium), 2016/01/05 23:29:52]

Done.

   // invalid handle.
-  void RemoveInvalidHandle(const WaitState& wait_state,
-                           MojoResult result,
-                           uint32_t result_index);
+  void RemoveInvalidHandle(MojoResult result, Handle handle);
+
+  // Removes any handles that have expired their deadline. Runs the handler's
+  // OnHandleError() function with |MOJO_RESULT_DEADLINE_EXCEEDED| as the
+  // result. Returns |true| if any handles were removed.
+  bool RemoveExpiredHandles();
 
   void SignalControlPipe();
 
-  WaitState GetWaitState() const;
+  // Returns the deadline for the call to MojoWait().
+  MojoDeadline GetDeadlineForWait(const RunState& run_state) const;
 
-  // Returns the deadline for the call to MojoWaitMany().
-  MojoDeadline GetDeadlineForWait(const RunState& run_state) const;
+  // Run |OnHandleReady()| for the handler registered with |handle|. |handle|
+  // must be registered.
+  void SignalHandleReady(Handle handle);
 
   void WillSignalHandler();
   void DidSignalHandler();
 
   // If non-NULL we're running (inside Run()). Member is reference to value on
   // stack.
   RunState* run_state_;
 
   // Lock for accessing |run_state_|. In general the only method that we have to
   // worry about is ScheduleWork(). All other methods are invoked on the same
   // thread.
   base::Lock run_state_lock_;
 
   HandleToHandler handlers_;
   // Set of handles that have a deadline set. Avoids iterating over all elements
   // in |handles_| in the common case (no deadline set).
   // TODO(amistry): Make this better and avoid special-casing deadlines.
   std::set<Handle> deadline_handles_;
 
   // An ever increasing value assigned to each Handler::id. Used to detect
   // uniqueness while notifying. That is, while notifying expired timers we copy
   // |handlers_| and only notify handlers whose id match. If the id does not
   // match it means the handler was removed then added so that we shouldn't
   // notify it.
   int next_handler_id_;
 
   base::ObserverList<Observer> observers_;
 
+  // Mojo handle for the wait set.
+  ScopedHandle wait_set_handle_;
   // Used to wake up run loop from |SignalControlPipe()|.
   ScopedMessagePipeHandle read_handle_;
   ScopedMessagePipeHandle write_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePumpMojo);
 };
 
 }  // namespace common
 }  // namespace mojo
 
 #endif  // MOJO_MESSAGE_PUMP_MESSAGE_PUMP_MOJO_H_