libs/ardour/worker.cc

   1 /*
   2   Copyright (C) 2012 Paul Davis
   3   Author: David Robillard
   4
   5   This program is free software; you can redistribute it and/or modify
   6   it under the terms of the GNU General Public License as published by
   7   the Free Software Foundation; either version 2 of the License, or
   8   (at your option) any later version.
   9
  10   This program is distributed in the hope that it will be useful,
  11   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13   GNU General Public License for more details.
  14
  15   You should have received a copy of the GNU General Public License
  16   along with this program; if not, write to the Free Software
  17   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18 */
  19
  20 #include <stdlib.h>
  21
  22 #include "ardour/worker.h"
  23 #include "pbd/error.h"
  24
  25 namespace ARDOUR {
  26
  27 Worker::Worker(Workee* workee, uint32_t ring_size)
  28         : _workee(workee)
  29         , _requests(new RingBuffer<uint8_t>(ring_size))
  30         , _responses(new RingBuffer<uint8_t>(ring_size))
  31         , _response((uint8_t*)malloc(ring_size))
  32         , _sem(0)
  33         , _exit(false)
  34         , _thread (Glib::Threads::Thread::create(sigc::mem_fun(*this, &Worker::run)))
  35 {}
  36
  37 Worker::~Worker()
  38 {
  39         _exit = true;
  40         _sem.post();
  41         _thread->join();
  42 }
  43
  44 bool
  45 Worker::schedule(uint32_t size, const void* data)
  46 {
  47         if (_requests->write_space() < size + sizeof(size)) {
  48                 return false;
  49         }
  50         if (_requests->write((const uint8_t*)&size, sizeof(size)) != sizeof(size)) {
  51                 return false;
  52         }
  53         if (_requests->write((const uint8_t*)data, size) != size) {
  54                 return false;
  55         }
  56         _sem.post();
  57         return true;
  58 }
  59
  60 bool
  61 Worker::respond(uint32_t size, const void* data)
  62 {
  63         if (_requests->write_space() < size + sizeof(size)) {
  64                 return false;
  65         }
  66         if (_responses->write((const uint8_t*)&size, sizeof(size)) != sizeof(size)) {
  67                 return false;
  68         }
  69         if (_responses->write((const uint8_t*)data, size) != size) {
  70                 return false;
  71         }
  72         return true;
  73 }
  74
  75 bool
  76 Worker::verify_message_completeness(RingBuffer<uint8_t>* rb)
  77 {
  78         uint32_t read_space = rb->read_space();
  79         uint32_t size;
  80         RingBuffer<uint8_t>::rw_vector vec;
  81         rb->get_read_vector (&vec);
  82         if (vec.len[0] >= sizeof(size)) {
  83                 memcpy (&size, vec.buf[0], sizeof (size));
  84         } else {
  85                 memcpy (&size, vec.buf[0], vec.len[0]);
  86                 memcpy (&size + vec.len[0], vec.buf[1], sizeof(size) - vec.len[0]);
  87         }
  88         if (read_space < size+sizeof(size)) {
  89                 /* message from writer is yet incomplete. respond next cycle */
  90                 return false;
  91         }
  92         return true;
  93 }
  94
  95 void
  96 Worker::emit_responses()
  97 {
  98         uint32_t read_space = _responses->read_space();
  99         uint32_t size       = 0;
 100         while (read_space >= sizeof(size)) {
 101                 if (!verify_message_completeness(_responses)) {
 102                         /* message from writer is yet incomplete. respond next cycle */
 103                         return;
 104                 }
 105                 /* read and send response */
 106                 _responses->read((uint8_t*)&size, sizeof(size));
 107                 _responses->read(_response, size);
 108                 _workee->work_response(size, _response);
 109                 read_space -= sizeof(size) + size;
 110         }
 111 }
 112
 113 void
 114 Worker::run()
 115 {
 116         void*  buf      = NULL;
 117         size_t buf_size = 0;
 118         while (true) {
 119                 _sem.wait();
 120                 if (_exit) {
 121                         return;
 122                 }
 123
 124                 uint32_t size = _requests->read_space();
 125                 if (size < sizeof(size)) {
 126                         PBD::error << "Worker: no work-data on ring buffer" << endmsg;
 127                         continue;
 128                 }
 129                 while (!verify_message_completeness(_requests)) {
 130                         ::usleep(2000);
 131                         if (_exit) {
 132                                 return;
 133                         }
 134                 }
 135                 if (_requests->read((uint8_t*)&size, sizeof(size)) < sizeof(size)) {
 136                         PBD::error << "Worker: Error reading size from request ring"
 137                                    << endmsg;
 138                         continue;
 139                 }
 140
 141                 if (size > buf_size) {
 142                         buf = realloc(buf, size);
 143                         buf_size = size;
 144                 }
 145
 146                 if (_requests->read((uint8_t*)buf, size) < size) {
 147                         PBD::error << "Worker: Error reading body from request ring"
 148                                    << endmsg;
 149                         continue;  // TODO: This is probably fatal
 150                 }
 151
 152                 _workee->work(size, buf);
 153         }
 154 }
 155
 156 } // namespace ARDOUR