Web MIDI: fix multi-threading problem around message buffer handling

media/midi/midi_manager.h

 // Copyright (c) 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 MEDIA_MIDI_MIDI_MANAGER_H_
 #define MEDIA_MIDI_MIDI_MANAGER_H_
 
 #include <set>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/synchronization/lock.h"
 #include "media/base/media_export.h"
 #include "media/midi/midi_port_info.h"
 
 namespace base {
 class Thread;
@@ skipping 44 matching lines @@
   void EndSession(MIDIManagerClient* client);
 
   // DispatchSendMIDIData() schedules one or more messages to be sent
   // at the given time on a dedicated thread.
   // |port_index| represents the specific output port from output_ports().
   // |data| represents a series of bytes encoding one or more MIDI messages.
   // |length| is the number of bytes in |data|.
   // |timestamp| is the time to send the data, in seconds. A value of 0
   // means send "now" or as soon as possible.
   void DispatchSendMIDIData(MIDIManagerClient* client,
-                            int port_index,
-                            const uint8* data,
-                            size_t length,
+                            size_t port_index,
+                            const std::vector<uint8>& data,
                             double timestamp);
 
   // input_ports() is a list of MIDI ports for receiving MIDI data.
   // Each individual port in this list can be identified by its
   // integer index into this list.
   const MIDIPortInfoList& input_ports() { return input_ports_; }
 
   // output_ports() is a list of MIDI ports for sending MIDI data.
   // Each individual port in this list can be identified by its
   // integer index into this list.
   const MIDIPortInfoList& output_ports() { return output_ports_; }
 
  protected:
   // Initializes the MIDI system, returning |true| on success.
   virtual bool Initialize() = 0;
 
   // Implements the platform-specific details of sending MIDI data.
+  // This function runs on MIDISendThread.
   virtual void SendMIDIData(MIDIManagerClient* client,
-                            int port_index,
-                            const uint8* data,
-                            size_t length,
+                            size_t port_index,
+                            const std::vector<uint8>& data,
                             double timestamp) = 0;
 
   void AddInputPort(const MIDIPortInfo& info);
   void AddOutputPort(const MIDIPortInfo& info);
 
   // Dispatches to all clients.
-  void ReceiveMIDIData(
-      int port_index,
-      const uint8* data,
-      size_t length,
-      double timestamp);
+  // TODO(toyoshim): Make |port_index| size_t to be consistent with send side.

[palmer, 2013/08/26 17:43:25]

uint32_t. And, why not do it now?

[Takashi Toyoshima, 2013/08/27 07:14:33]

Maybe I should split all type related changes to another CL since this original
change focus on a use after free bug in browser process. Also receiving side has
another nits I want to fix them together. Anyway I'll fix them too in this CL.

+  void ReceiveMIDIData(int port_index,
+                       const uint8* data,
+                       size_t length,
+                       double timestamp);
+
+  // Checks if current thread is MIDISendThread.
+  bool CurrentlyOnMIDISendThread();
 
   bool initialized_;
 
   // Keeps track of all clients who wish to receive MIDI data.
   typedef std::set<MIDIManagerClient*> ClientList;
   ClientList clients_;
 
   // Protects access to our clients.
   base::Lock clients_lock_;
 
   MIDIPortInfoList input_ports_;
   MIDIPortInfoList output_ports_;
 
   // |send_thread_| is used to send MIDI data by calling the platform-specific
   // API.
   scoped_ptr<base::Thread> send_thread_;
   scoped_refptr<base::MessageLoopProxy> send_message_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(MIDIManager);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_MIDI_MIDI_MANAGER_H_