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 #include <unistd.h>
  22
  23 #include "ardour/worker.h"
  24 #include "pbd/error.h"
  25
  26 namespace ARDOUR {
  27
  28 Worker::Worker(Workee* workee, uint32_t ring_size)
  29         : _workee(workee)
  30         , _requests(new RingBuffer<uint8_t>(ring_size))
  31         , _responses(new RingBuffer<uint8_t>(ring_size))
  32         , _response((uint8_t*)malloc(ring_size))
  33         , _sem(0)
  34         , _exit(false)
  35         , _thread (Glib::Threads::Thread::create(sigc::mem_fun(*this, &Worker::run)))
  36 {}
  37
  38 Worker::~Worker()
  39 {
  40         _exit = true;
  41         _sem.post();
  42         _thread->join();
  43 }
  44
  45 bool
  46 Worker::schedule(uint32_t size, const void* data)
  47 {
  48         if (_requests->write_space() < size + sizeof(size)) {
  49                 return false;
  50         }
  51         if (_requests->write((const uint8_t*)&size, sizeof(size)) != sizeof(size)) {
  52                 return false;
  53         }
  54         if (_requests->write((const uint8_t*)data, size) != size) {
  55                 return false;
  56         }
  57         _sem.post();
  58         return true;
  59 }
  60
  61 bool
  62 Worker::respond(uint32_t size, const void* data)
  63 {
  64         if (_requests->write_space() < size + sizeof(size)) {
  65                 return false;
  66         }
  67         if (_responses->write((const uint8_t*)&size, sizeof(size)) != sizeof(size)) {
  68                 return false;
  69         }
  70         if (_responses->write((const uint8_t*)data, size) != size) {
  71                 return false;
  72         }
  73         return true;
  74 }
  75
  76 bool
  77 Worker::verify_message_completeness(RingBuffer<uint8_t>* rb)
  78 {
  79         uint32_t read_space = rb->read_space();
  80         uint32_t size;
  81         RingBuffer<uint8_t>::rw_vector vec;
  82         rb->get_read_vector (&vec);
  83         if (vec.len[0] >= sizeof(size)) {
  84                 memcpy (&size, vec.buf[0], sizeof (size));
  85         } else {
  86                 memcpy (&size, vec.buf[0], vec.len[0]);
  87                 memcpy (&size + vec.len[0], vec.buf[1], sizeof(size) - vec.len[0]);
  88         }
  89         if (read_space < size+sizeof(size)) {
  90                 /* message from writer is yet incomplete. respond next cycle */
  91                 return false;
  92         }
  93         return true;
  94 }
  95
  96 void
  97 Worker::emit_responses()
  98 {
  99         uint32_t read_space = _responses->read_space();
 100         uint32_t size       = 0;
 101         while (read_space >= sizeof(size)) {
 102                 if (!verify_message_completeness(_responses)) {
 103                         /* message from writer is yet incomplete. respond next cycle */
 104                         return;
 105                 }
 106                 /* read and send response */
 107                 _responses->read((uint8_t*)&size, sizeof(size));
 108                 _responses->read(_response, size);
 109                 _workee->work_response(size, _response);
 110                 read_space -= sizeof(size) + size;
 111         }
 112 }
 113
 114 void
 115 Worker::run()
 116 {
 117         void*  buf      = NULL;
 118         size_t buf_size = 0;
 119         while (true) {
 120                 _sem.wait();
 121                 if (_exit) {
 122                         return;
 123                 }
 124
 125                 uint32_t size = _requests->read_space();
 126                 if (size < sizeof(size)) {
 127                         PBD::error << "Worker: no work-data on ring buffer" << endmsg;
 128                         continue;
 129                 }
 130                 while (!verify_message_completeness(_requests)) {
 131                         ::usleep(2000);
 132                         if (_exit) {
 133                                 return;
 134                         }
 135                 }
 136                 if (_requests->read((uint8_t*)&size, sizeof(size)) < sizeof(size)) {
 137                         PBD::error << "Worker: Error reading size from request ring"
 138                                    << endmsg;
 139                         continue;
 140                 }
 141
 142                 if (size > buf_size) {
 143                         buf = realloc(buf, size);
 144                         buf_size = size;
 145                 }
 146
 147                 if (_requests->read((uint8_t*)buf, size) < size) {
 148                         PBD::error << "Worker: Error reading body from request ring"
 149                                    << endmsg;
 150                         continue;  // TODO: This is probably fatal
 151                 }
 152
 153                 _workee->work(size, buf);
 154         }
 155 }
 156
 157 } // namespace ARDOUR