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/midi/midi_export.h"
  16 #include "media/midi/midi_port_info.h"
  17 #include "media/midi/result.h"
  18
  19 namespace base {
  20 class SingleThreadTaskRunner;
  21 }  // namespace base
  22
  23 namespace media {
  24 namespace midi {
  25
  26 // A MidiManagerClient registers with the MidiManager to receive MIDI data.
  27 // See MidiManager::RequestAccess() and MidiManager::ReleaseAccess()
  28 // for details.
  29 class MIDI_EXPORT MidiManagerClient {
  30  public:
  31   virtual ~MidiManagerClient() {}
  32
  33   // AddInputPort() and AddOutputPort() are called before CompleteStartSession()
  34   // is called to notify existing MIDI ports, and also called after that to
  35   // notify new MIDI ports are added.
  36   virtual void AddInputPort(const MidiPortInfo& info) = 0;
  37   virtual void AddOutputPort(const MidiPortInfo& info) = 0;
  38
  39   // SetInputPortState() and SetOutputPortState() are called to notify a known
  40   // device gets disconnected, or connected again.
  41   virtual void SetInputPortState(uint32 port_index, MidiPortState state) = 0;
  42   virtual void SetOutputPortState(uint32 port_index, MidiPortState state) = 0;
  43
  44   // CompleteStartSession() is called when platform dependent preparation is
  45   // finished.
  46   virtual void CompleteStartSession(Result result) = 0;
  47
  48   // ReceiveMidiData() is called when MIDI data has been received from the
  49   // MIDI system.
  50   // |port_index| represents the specific input port from input_ports().
  51   // |data| represents a series of bytes encoding one or more MIDI messages.
  52   // |length| is the number of bytes in |data|.
  53   // |timestamp| is the time the data was received, in seconds.
  54   virtual void ReceiveMidiData(uint32 port_index,
  55                                const uint8* data,
  56                                size_t length,
  57                                double timestamp) = 0;
  58
  59   // AccumulateMidiBytesSent() is called to acknowledge when bytes have
  60   // successfully been sent to the hardware.
  61   // This happens as a result of the client having previously called
  62   // MidiManager::DispatchSendMidiData().
  63   virtual void AccumulateMidiBytesSent(size_t n) = 0;
  64 };
  65
  66 // Manages access to all MIDI hardware.
  67 class MIDI_EXPORT MidiManager {
  68  public:
  69   static const size_t kMaxPendingClientCount = 128;
  70
  71   MidiManager();
  72   virtual ~MidiManager();
  73
  74   // The constructor and the destructor will be called on the CrBrowserMain
  75   // thread.
  76   static MidiManager* Create();
  77
  78   // A client calls StartSession() to receive and send MIDI data.
  79   // If the session is ready to start, the MIDI system is lazily initialized
  80   // and the client is registered to receive MIDI data.
  81   // CompleteStartSession() is called with Result::OK if the session is started.
  82   // Otherwise CompleteStartSession() is called with proper Result code.
  83   // StartSession() and EndSession() can be called on the Chrome_IOThread.
  84   // CompleteStartSession() will be invoked on the same Chrome_IOThread.
  85   void StartSession(MidiManagerClient* client);
  86
  87   // A client calls EndSession() to stop receiving MIDI data.
  88   void EndSession(MidiManagerClient* client);
  89
  90   // Invoke AccumulateMidiBytesSent() for |client| safely. If the session was
  91   // already closed, do nothing.
  92   void AccumulateMidiBytesSent(MidiManagerClient* client, size_t n);
  93
  94   // DispatchSendMidiData() is called when MIDI data should be sent to the MIDI
  95   // system.
  96   // This method is supposed to return immediately and should not block.
  97   // |port_index| represents the specific output port from output_ports().
  98   // |data| represents a series of bytes encoding one or more MIDI messages.
  99   // |length| is the number of bytes in |data|.
 100   // |timestamp| is the time to send the data, in seconds. A value of 0
 101   // means send "now" or as soon as possible.
 102   // The default implementation is for unsupported platforms.
 103   virtual void DispatchSendMidiData(MidiManagerClient* client,
 104                                     uint32 port_index,
 105                                     const std::vector<uint8>& data,
 106                                     double timestamp);
 107
 108  protected:
 109   friend class MidiManagerUsb;
 110
 111   // Initializes the platform dependent MIDI system. MidiManager class has a
 112   // default implementation that synchronously calls CompleteInitialization()
 113   // with Result::NOT_SUPPORTED on the caller thread. A derived class for a
 114   // specific platform should override this method correctly.
 115   // This method is called on Chrome_IOThread thread inside StartSession().
 116   // Platform dependent initialization can be processed synchronously or
 117   // asynchronously. When the initialization is completed,
 118   // CompleteInitialization() should be called with |result|.
 119   // |result| should be Result::OK on success, otherwise a proper Result.
 120   virtual void StartInitialization();
 121
 122   // Called from a platform dependent implementation of StartInitialization().
 123   // It invokes CompleteInitializationInternal() on the thread that calls
 124   // StartSession() and distributes |result| to MIDIManagerClient objects in
 125   // |pending_clients_|.
 126   void CompleteInitialization(Result result);
 127
 128   void AddInputPort(const MidiPortInfo& info);
 129   void AddOutputPort(const MidiPortInfo& info);
 130   void SetInputPortState(uint32 port_index, MidiPortState state);
 131   void SetOutputPortState(uint32 port_index, MidiPortState state);
 132
 133   // Dispatches to all clients.
 134   // TODO(toyoshim): Fix the mac implementation to use
 135   // |ReceiveMidiData(..., base::TimeTicks)|.
 136   void ReceiveMidiData(uint32 port_index,
 137                        const uint8* data,
 138                        size_t length,
 139                        double timestamp);
 140
 141   void ReceiveMidiData(uint32 port_index,
 142                        const uint8* data,
 143                        size_t length,
 144                        base::TimeTicks time) {
 145     ReceiveMidiData(port_index, data, length,
 146                     (time - base::TimeTicks()).InSecondsF());
 147   }
 148
 149   size_t clients_size_for_testing() const { return clients_.size(); }
 150   size_t pending_clients_size_for_testing() const {
 151     return pending_clients_.size();
 152   }
 153
 154  private:
 155   void CompleteInitializationInternal(Result result);
 156   void AddInitialPorts(MidiManagerClient* client);
 157
 158   // Keeps track of all clients who wish to receive MIDI data.
 159   typedef std::set<MidiManagerClient*> ClientSet;
 160   ClientSet clients_;
 161
 162   // Keeps track of all clients who are waiting for CompleteStartSession().
 163   ClientSet pending_clients_;
 164
 165   // Keeps a SingleThreadTaskRunner of the thread that calls StartSession in
 166   // order to invoke CompleteStartSession() on the thread.
 167   scoped_refptr<base::SingleThreadTaskRunner> session_thread_runner_;
 168
 169   // Keeps true if platform dependent initialization is already completed.
 170   bool initialized_;
 171
 172   // Keeps the platform dependent initialization result if initialization is
 173   // completed. Otherwise keeps Result::NOT_INITIALIZED.
 174   Result result_;
 175
 176   // Keeps all MidiPortInfo.
 177   MidiPortInfoList input_ports_;
 178   MidiPortInfoList output_ports_;
 179
 180   // Protects access to |clients_|, |pending_clients_|, |initialized_|,
 181   // |result_|, |input_ports_| and |output_ports_|.
 182   base::Lock lock_;
 183
 184   DISALLOW_COPY_AND_ASSIGN(MidiManager);
 185 };
 186
 187 }  // namespace midi
 188 }  // namespace media
 189
 190 #endif  // MEDIA_MIDI_MIDI_MANAGER_H_