media/midi/midi_manager.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_MIDI_MIDI_MANAGER_H_
   6 #define MEDIA_MIDI_MIDI_MANAGER_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <vector>
  11
  12 #include "base/basictypes.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/synchronization/lock.h"
  15 #include "base/time/time.h"
  16 #include "media/base/media_export.h"
  17 #include "media/midi/midi_port_info.h"
  18 #include "media/midi/midi_result.h"
  19
  20 namespace base {
  21 class SingleThreadTaskRunner;
  22 }  // namespace base
  23
  24 namespace media {
  25
  26 // A MidiManagerClient registers with the MidiManager to receive MIDI data.
  27 // See MidiManager::RequestAccess() and MidiManager::ReleaseAccess()
  28 // for details.
  29 class MEDIA_EXPORT MidiManagerClient {
  30  public:
  31   virtual ~MidiManagerClient() {}
  32
  33   // CompleteStartSession() is called when platform dependent preparation is
  34   // finished.
  35   virtual void CompleteStartSession(int client_id, MidiResult result) = 0;
  36
  37   // ReceiveMidiData() is called when MIDI data has been received from the
  38   // MIDI system.
  39   // |port_index| represents the specific input port from input_ports().
  40   // |data| represents a series of bytes encoding one or more MIDI messages.
  41   // |length| is the number of bytes in |data|.
  42   // |timestamp| is the time the data was received, in seconds.
  43   virtual void ReceiveMidiData(uint32 port_index,
  44                                const uint8* data,
  45                                size_t length,
  46                                double timestamp) = 0;
  47
  48   // AccumulateMidiBytesSent() is called to acknowledge when bytes have
  49   // successfully been sent to the hardware.
  50   // This happens as a result of the client having previously called
  51   // MidiManager::DispatchSendMidiData().
  52   virtual void AccumulateMidiBytesSent(size_t n) = 0;
  53 };
  54
  55 // Manages access to all MIDI hardware.
  56 class MEDIA_EXPORT MidiManager {
  57  public:
  58   static const size_t kMaxPendingClientCount = 128;
  59
  60   MidiManager();
  61   virtual ~MidiManager();
  62
  63   // The constructor and the destructor will be called on the CrBrowserMain
  64   // thread.
  65   static MidiManager* Create();
  66
  67   // A client calls StartSession() to receive and send MIDI data.
  68   // If the session is ready to start, the MIDI system is lazily initialized
  69   // and the client is registered to receive MIDI data.
  70   // CompleteStartSession() is called with MIDI_OK if the session is started.
  71   // Otherwise CompleteStartSession() is called with proper MidiResult code.
  72   // StartSession() and EndSession() can be called on the Chrome_IOThread.
  73   // CompleteStartSession() will be invoked on the same Chrome_IOThread.
  74   void StartSession(MidiManagerClient* client, int client_id);
  75
  76   // A client calls EndSession() to stop receiving MIDI data.
  77   void EndSession(MidiManagerClient* client);
  78
  79   // DispatchSendMidiData() is called when MIDI data should be sent to the MIDI
  80   // system.
  81   // This method is supposed to return immediately and should not block.
  82   // |port_index| represents the specific output port from output_ports().
  83   // |data| represents a series of bytes encoding one or more MIDI messages.
  84   // |length| is the number of bytes in |data|.
  85   // |timestamp| is the time to send the data, in seconds. A value of 0
  86   // means send "now" or as soon as possible.
  87   // The default implementation is for unsupported platforms.
  88   virtual void DispatchSendMidiData(MidiManagerClient* client,
  89                                     uint32 port_index,
  90                                     const std::vector<uint8>& data,
  91                                     double timestamp);
  92
  93   // input_ports() is a list of MIDI ports for receiving MIDI data.
  94   // Each individual port in this list can be identified by its
  95   // integer index into this list.
  96   const MidiPortInfoList& input_ports() const { return input_ports_; }
  97
  98   // output_ports() is a list of MIDI ports for sending MIDI data.
  99   // Each individual port in this list can be identified by its
 100   // integer index into this list.
 101   const MidiPortInfoList& output_ports() const { return output_ports_; }
 102
 103  protected:
 104   friend class MidiManagerUsb;
 105
 106   // Initializes the platform dependent MIDI system. MidiManager class has a
 107   // default implementation that synchronously calls CompleteInitialization()
 108   // with MIDI_NOT_SUPPORTED on the caller thread. A derived class for a
 109   // specific platform should override this method correctly.
 110   // This method is called on Chrome_IOThread thread inside StartSession().
 111   // Platform dependent initialization can be processed synchronously or
 112   // asynchronously. When the initialization is completed,
 113   // CompleteInitialization() should be called with |result|.
 114   // |result| should be MIDI_OK on success, otherwise a proper MidiResult.
 115   virtual void StartInitialization();
 116
 117   // Called from a platform dependent implementation of StartInitialization().
 118   // It invokes CompleteInitializationInternal() on the thread that calls
 119   // StartSession() and distributes |result| to MIDIManagerClient objects in
 120   // |pending_clients_|.
 121   void CompleteInitialization(MidiResult result);
 122
 123   void AddInputPort(const MidiPortInfo& info);
 124   void AddOutputPort(const MidiPortInfo& info);
 125
 126   // Dispatches to all clients.
 127   // TODO(toyoshim): Fix the mac implementation to use
 128   // |ReceiveMidiData(..., base::TimeTicks)|.
 129   void ReceiveMidiData(uint32 port_index,
 130                        const uint8* data,
 131                        size_t length,
 132                        double timestamp);
 133
 134   void ReceiveMidiData(uint32 port_index,
 135                        const uint8* data,
 136                        size_t length,
 137                        base::TimeTicks time) {
 138     ReceiveMidiData(port_index, data, length,
 139                     (time - base::TimeTicks()).InSecondsF());
 140   }
 141
 142   size_t clients_size_for_testing() const { return clients_.size(); }
 143   size_t pending_clients_size_for_testing() const {
 144     return pending_clients_.size();
 145   }
 146
 147  private:
 148   void CompleteInitializationInternal(MidiResult result);
 149
 150   // Keeps track of all clients who wish to receive MIDI data.
 151   typedef std::set<MidiManagerClient*> ClientList;
 152   ClientList clients_;
 153
 154   // Keeps track of all clients who are waiting for CompleteStartSession().
 155   typedef std::map<int, MidiManagerClient*> PendingClientMap;
 156   PendingClientMap pending_clients_;
 157
 158   // Keeps a SingleThreadTaskRunner of the thread that calls StartSession in
 159   // order to invoke CompleteStartSession() on the thread.
 160   scoped_refptr<base::SingleThreadTaskRunner> session_thread_runner_;
 161
 162   // Keeps true if platform dependent initialization is already completed.
 163   bool initialized_;
 164
 165   // Keeps the platform dependent initialization result if initialization is
 166   // completed. Otherwise keeps MIDI_NOT_SUPPORTED.
 167   MidiResult result_;
 168
 169   // Protects access to |clients_|, |pending_clients_|, |initialized_|, and
 170   // |result_|.
 171   base::Lock lock_;
 172
 173   MidiPortInfoList input_ports_;
 174   MidiPortInfoList output_ports_;
 175
 176   DISALLOW_COPY_AND_ASSIGN(MidiManager);
 177 };
 178
 179 }  // namespace media
 180
 181 #endif  // MEDIA_MIDI_MIDI_MANAGER_H_