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