worker.cc

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/*
  Copyright (C) 2012 Paul Davis
  Author: David Robillard

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <stdlib.h>
#include <unistd.h>

#include "ardour/worker.h"
#include "pbd/error.h"

#include <glibmm/timer.h>

namespace ARDOUR {

Worker::Worker(Workee* workee, uint32_t ring_size)
        : _workee(workee)
        , _requests(new RingBuffer<uint8_t>(ring_size))
        , _responses(new RingBuffer<uint8_t>(ring_size))
        , _response((uint8_t*)malloc(ring_size))
        , _sem(0)
        , _exit(false)
        , _thread (Glib::Threads::Thread::create(sigc::mem_fun(*this, &Worker::run)))
{}

Worker::~Worker()
{
        _exit = true;
        _sem.post();
        _thread->join();
}

bool
Worker::schedule(uint32_t size, const void* data)
{
        if (_requests->write_space() < size + sizeof(size)) {
                return false;
        }
        if (_requests->write((const uint8_t*)&size, sizeof(size)) != sizeof(size)) {
                return false;
        }
        if (_requests->write((const uint8_t*)data, size) != size) {
                return false;
        }
        _sem.post();
        return true;
}

bool
Worker::respond(uint32_t size, const void* data)
{
        if (_requests->write_space() < size + sizeof(size)) {
                return false;
        }
        if (_responses->write((const uint8_t*)&size, sizeof(size)) != sizeof(size)) {
                return false;
        }
        if (_responses->write((const uint8_t*)data, size) != size) {
                return false;
        }
        return true;
}

bool
Worker::verify_message_completeness(RingBuffer<uint8_t>* rb)
{
        uint32_t read_space = rb->read_space();
        uint32_t size;
        RingBuffer<uint8_t>::rw_vector vec;
        rb->get_read_vector (&vec);
        if (vec.len[0] + vec.len[1] < sizeof(size)) {
                return false;
        }
        if (vec.len[0] >= sizeof(size)) {
                memcpy (&size, vec.buf[0], sizeof (size));
        } else {
                memcpy (&size, vec.buf[0], vec.len[0]);
                memcpy (&size + vec.len[0], vec.buf[1], sizeof(size) - vec.len[0]);
        }
        if (read_space < size+sizeof(size)) {
                /* message from writer is yet incomplete. respond next cycle */
                return false;
        }
        return true;
}

void
Worker::emit_responses()
{
        uint32_t read_space = _responses->read_space();
        uint32_t size       = 0;
        while (read_space >= sizeof(size)) {
                if (!verify_message_completeness(_responses)) {
                        /* message from writer is yet incomplete. respond next cycle */
                        return;
                }
                /* read and send response */
                _responses->read((uint8_t*)&size, sizeof(size));
                _responses->read(_response, size);
                _workee->work_response(size, _response);
                read_space -= sizeof(size) + size;
        }
}

void
Worker::run()
{
        void*  buf      = NULL;
        size_t buf_size = 0;
        while (true) {
                _sem.wait();
                if (_exit) {
                        if (buf) free(buf);
                        return;
                }

                uint32_t size = _requests->read_space();
                if (size < sizeof(size)) {
                        PBD::error << "Worker: no work-data on ring buffer" << endmsg;
                        continue;
                }
                while (!verify_message_completeness(_requests)) {
                        Glib::usleep(2000);
                        if (_exit) {
                                if (buf) free(buf);
                                return;
                        }
                }
                if (_requests->read((uint8_t*)&size, sizeof(size)) < sizeof(size)) {
                        PBD::error << "Worker: Error reading size from request ring"
                                   << endmsg;
                        continue;
                }

                if (size > buf_size) {
                        buf = realloc(buf, size);
                        if (buf) {
                                buf_size = size;
                        } else {
                                PBD::error << "Worker: Error allocating memory"
                                           << endmsg;
                                buf_size = 0; // TODO: This is probably fatal
                        }
                }

                if (_requests->read((uint8_t*)buf, size) < size) {
                        PBD::error << "Worker: Error reading body from request ring"
                                   << endmsg;
                        continue;  // TODO: This is probably fatal
                }

                _workee->work(size, buf);
        }
}

} // namespace ARDOUR