src/lib/butler.cc

   1 /*
   2     Copyright (C) 2016-2017 Carl Hetherington <cth@carlh.net>
   3
   4     This file is part of DCP-o-matic.
   5
   6     DCP-o-matic is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     DCP-o-matic is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.
  18
  19 */
  20
  21 #include "butler.h"
  22 #include "player.h"
  23 #include <boost/weak_ptr.hpp>
  24 #include <boost/shared_ptr.hpp>
  25
  26 using std::cout;
  27 using std::pair;
  28 using std::make_pair;
  29 using boost::weak_ptr;
  30 using boost::shared_ptr;
  31 using boost::bind;
  32 using boost::optional;
  33
  34 /** Video readahead in frames */
  35 #define VIDEO_READAHEAD 10
  36
  37 Butler::Butler (weak_ptr<const Film> film, shared_ptr<Player> player)
  38         : _film (film)
  39         , _player (player)
  40         , _pending_seek_accurate (false)
  41         , _finished (false)
  42 {
  43         _player_video_connection = _player->Video.connect (bind (&Butler::video, this, _1, _2));
  44         _player_changed_connection = _player->Changed.connect (bind (&Butler::player_changed, this));
  45         _thread = new boost::thread (bind (&Butler::thread, this));
  46 }
  47
  48 Butler::~Butler ()
  49 {
  50         _thread->interrupt ();
  51         try {
  52                 _thread->join ();
  53         } catch (boost::thread_interrupted& e) {
  54                 /* No problem */
  55         }
  56         delete _thread;
  57 }
  58
  59 void
  60 Butler::thread ()
  61 {
  62         while (true) {
  63                 boost::mutex::scoped_lock lm (_mutex);
  64
  65                 /* Wait until we have something to do */
  66                 while (_video.size() >= VIDEO_READAHEAD && !_pending_seek_position) {
  67                         _summon.wait (lm);
  68                 }
  69
  70                 /* Do any seek that has been requested */
  71                 if (_pending_seek_position) {
  72                         _player->seek (*_pending_seek_position, _pending_seek_accurate);
  73                         _pending_seek_position = optional<DCPTime> ();
  74                 }
  75
  76                 /* Fill _video.  Don't try to carry on if a pending seek appears
  77                    while lm is unlocked, as in that state nothing will be added to
  78                    _video.
  79                 */
  80                 while (_video.size() < VIDEO_READAHEAD && !_pending_seek_position) {
  81                         lm.unlock ();
  82                         if (_player->pass ()) {
  83                                 _finished = true;
  84                                 _arrived.notify_all ();
  85                                 break;
  86                         }
  87                         lm.lock ();
  88                         _arrived.notify_all ();
  89                 }
  90         }
  91 }
  92
  93 pair<shared_ptr<PlayerVideo>, DCPTime>
  94 Butler::get_video ()
  95 {
  96         boost::mutex::scoped_lock lm (_mutex);
  97
  98         /* Wait for data if we have none */
  99         while (_video.empty() && !_finished) {
 100                 _arrived.wait (lm);
 101         }
 102
 103         if (_finished) {
 104                 return make_pair (shared_ptr<PlayerVideo>(), DCPTime());
 105         }
 106
 107         pair<shared_ptr<PlayerVideo>, DCPTime> const r = _video.get ();
 108         _summon.notify_all ();
 109         return r;
 110 }
 111
 112 void
 113 Butler::seek (DCPTime position, bool accurate)
 114 {
 115         boost::mutex::scoped_lock lm (_mutex);
 116         _video.clear ();
 117         _finished = false;
 118         _pending_seek_position = position;
 119         _pending_seek_accurate = accurate;
 120         _summon.notify_all ();
 121 }
 122
 123 void
 124 Butler::video (shared_ptr<PlayerVideo> video, DCPTime time)
 125 {
 126         {
 127                 boost::mutex::scoped_lock lm (_mutex);
 128                 if (_pending_seek_position) {
 129                         /* Don't store any video while a seek is pending */
 130                         return;
 131                 }
 132         }
 133
 134         _video.put (video, time);
 135 }
 136
 137 void
 138 Butler::player_changed ()
 139 {
 140         optional<DCPTime> t;
 141
 142         {
 143                 boost::mutex::scoped_lock lm (_mutex);
 144                 t = _video.earliest ();
 145         }
 146
 147         if (t) {
 148                 seek (*t, true);
 149         }
 150 }