Method lock

src/app/document.cpp:434–477

// Multi-threading ("sprite wrappers" use this)

bool Document::lock(LockType lockType, int timeout)
{
  while (timeout >= 0) {
    {
      scoped_lock lock(m_mutex);
      switch (lockType) {

        case ReadLock:
          // If no body is writting the sprite...
          if (!m_write_lock) {
            // We can read it
            ++m_read_locks;
            return true;
          }
          break;

        case WriteLock:
          // If no body is reading and writting...
          if (m_read_locks == 0 && !m_write_lock) {
            // We can start writting the sprite...
            m_write_lock = true;
            TRACE("Document::lock: Locked <%d> to write\n", id());
            return true;
          }
          break;

      }
    }

    if (timeout > 0) {
      int delay = MIN(100, timeout);
      timeout -= delay;

      TRACE("Document::lock: wait 100 msecs for <%d>\n", id());
      base::this_thread::sleep_for(double(delay) / 1000.0);
    }
    else
      break;
  }

  TRACE("Document::lock: Cannot lock <%d> to %s (has %d read locks and %d write locks)\n",
    id(), (lockType == ReadLock ? "read": "write"), m_read_locks, m_write_lock);
  return false;
}

bool Document::lockToWrite(int timeout)
{