Cache vectors to avoid heap allocations on each message pump iteration.

mojo/common/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_COMMON_MESSAGE_PUMP_MOJO_H_
 #define MOJO_COMMON_MESSAGE_PUMP_MOJO_H_
 
 #include <map>
+#include <utility>
+#include <vector>
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_pump.h"
 #include "base/observer_list.h"
 #include "base/synchronization/lock.h"
 #include "base/time/time.h"
 #include "mojo/public/cpp/system/core.h"
 
 namespace mojo {
@@ skipping 55 matching lines @@
     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;
+  typedef std::vector<std::pair<Handle, Handler>> HandleToHandlerList;
 
   // 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);
 
   // Removes the given invalid handle. This is called if MojoWaitMany finds an
   // invalid handle.
   void RemoveInvalidHandle(const WaitState& wait_state,
                            MojoResult result,
                            uint32_t result_index);
 
   void SignalControlPipe(const RunState& run_state);
 
-  WaitState GetWaitState(const RunState& run_state) const;
+  void GetWaitState(const RunState& run_state, WaitState* wait_state) const;
 
   // Returns the deadline for the call to MojoWaitMany().
   MojoDeadline GetDeadlineForWait(const RunState& run_state) const;
 
   void WillSignalHandler();
   void DidSignalHandler();
 
   // If non-NULL we're running (inside Run()). Member is reference to value on
   // stack.
   RunState* run_state_;
@@ skipping 14 matching lines @@
 
   ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePumpMojo);
 };
 
 }  // namespace common
 }  // namespace mojo
 
 #endif  // MOJO_COMMON_MESSAGE_PUMP_MOJO_H_