common/JackMidiAsyncWaitQueue.h

   1 /*
   2 Copyright (C) 2010 Devin Anderson
   3
   4 This program is free software; you can redistribute it and/or modify
   5 it under the terms of the GNU Lesser General Public License as published by
   6 the Free Software Foundation; either version 2.1 of the License, or
   7 (at your option) any later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU Lesser General Public License for more details.
  13
  14 You should have received a copy of the GNU Lesser General Public License
  15 along with this program; if not, write to the Free Software
  16 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17
  18 */
  19
  20 #ifndef __JackMidiAsyncWaitQueue__
  21 #define __JackMidiAsyncWaitQueue__
  22
  23 #include "JackMidiAsyncQueue.h"
  24
  25 namespace Jack {
  26
  27     /**
  28      * This is an asynchronous wait queue that allows a thread to wait for a
  29      * message, either indefinitely or for a specified time.  This is one
  30      * example of a way that the `JackMidiAsyncQueue` class can be extended so
  31      * that process threads can interact with non-process threads to send MIDI
  32      * events.
  33      *
  34      * XXX: As of right now, this code hasn't been tested.  Also, note the
  35      * warning in the JackMidiAsyncWaitQueue.cpp about semaphore wait
  36      * resolution.
  37      */
  38
  39     class SERVER_EXPORT JackMidiAsyncWaitQueue: public JackMidiAsyncQueue {
  40
  41     private:
  42
  43         JackSynchro semaphore;
  44
  45     public:
  46
  47         using JackMidiAsyncQueue::EnqueueEvent;
  48
  49         /**
  50          * Creates a new asynchronous MIDI wait message queue.  The queue can
  51          * store up to `max_messages` MIDI messages and up to `max_bytes` of
  52          * MIDI data before it starts rejecting messages.
  53          */
  54
  55         JackMidiAsyncWaitQueue(size_t max_bytes=4096,
  56                                size_t max_messages=1024);
  57
  58         ~JackMidiAsyncWaitQueue();
  59
  60         /**
  61          * Dequeues and returns a MIDI event.  Returns '0' if there are no MIDI
  62          * events available right now.
  63          */
  64
  65         jack_midi_event_t *
  66         DequeueEvent();
  67
  68         /**
  69          * Waits a specified time for a MIDI event to be available, or
  70          * indefinitely if the time is negative.  Returns the MIDI event, or
  71          * '0' if time runs out and no MIDI event is available.
  72          */
  73
  74         jack_midi_event_t *
  75         DequeueEvent(long usecs);
  76
  77         /**
  78          * Waits until the specified frame for a MIDI event to be available.
  79          * Returns the MIDI event, or '0' if time runs out and no MIDI event is
  80          * available.
  81          */
  82
  83         jack_midi_event_t *
  84         DequeueEvent(jack_nframes_t frame);
  85
  86         /**
  87          * Enqueues the MIDI event specified by the arguments.  The return
  88          * value indicates whether or not the event was successfully enqueued.
  89          */
  90
  91         EnqueueResult
  92         EnqueueEvent(jack_nframes_t time, size_t size,
  93                      jack_midi_data_t *buffer);
  94
  95     };
  96
  97 }
  98
  99 #endif