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libuv/src/win/core.c  view on Meta::CPAN

int uv_backend_timeout(const uv_loop_t* loop) {
  if (loop->stop_flag != 0)
    return 0;

  if (!uv__has_active_handles(loop) && !uv__has_active_reqs(loop))
    return 0;

  if (loop->pending_reqs_tail)
    return 0;

  if (loop->endgame_handles)
    return 0;

  if (loop->idle_handles)
    return 0;

  return uv__next_timeout(loop);
}


static void uv__poll_wine(uv_loop_t* loop, DWORD timeout) {
  DWORD bytes;
  ULONG_PTR key;
  OVERLAPPED* overlapped;
  uv_req_t* req;
  int repeat;
  uint64_t timeout_time;

  timeout_time = loop->time + timeout;

  for (repeat = 0; ; repeat++) {
    GetQueuedCompletionStatus(loop->iocp,
                              &bytes,
                              &key,
                              &overlapped,
                              timeout);

    if (overlapped) {
      /* Package was dequeued */
      req = uv_overlapped_to_req(overlapped);
      uv_insert_pending_req(loop, req);

      /* Some time might have passed waiting for I/O,
       * so update the loop time here.
       */
      uv_update_time(loop);
    } else if (GetLastError() != WAIT_TIMEOUT) {
      /* Serious error */
      uv_fatal_error(GetLastError(), "GetQueuedCompletionStatus");
    } else if (timeout > 0) {
      /* GetQueuedCompletionStatus can occasionally return a little early.
       * Make sure that the desired timeout target time is reached.
       */
      uv_update_time(loop);
      if (timeout_time > loop->time) {
        timeout = (DWORD)(timeout_time - loop->time);
        /* The first call to GetQueuedCompletionStatus should return very
         * close to the target time and the second should reach it, but
         * this is not stated in the documentation. To make sure a busy
         * loop cannot happen, the timeout is increased exponentially
         * starting on the third round.
         */
        timeout += repeat ? (1 << (repeat - 1)) : 0;
        continue;
      }
    }
    break;
  }
}


static void uv__poll(uv_loop_t* loop, DWORD timeout) {
  BOOL success;
  uv_req_t* req;
  OVERLAPPED_ENTRY overlappeds[128];
  ULONG count;
  ULONG i;
  int repeat;
  uint64_t timeout_time;

  timeout_time = loop->time + timeout;

  for (repeat = 0; ; repeat++) {
    success = GetQueuedCompletionStatusEx(loop->iocp,
                                          overlappeds,
                                          ARRAY_SIZE(overlappeds),
                                          &count,
                                          timeout,
                                          FALSE);

    if (success) {
      for (i = 0; i < count; i++) {
        /* Package was dequeued, but see if it is not a empty package
         * meant only to wake us up.
         */
        if (overlappeds[i].lpOverlapped) {
          req = uv_overlapped_to_req(overlappeds[i].lpOverlapped);
          uv_insert_pending_req(loop, req);
        }
      }

      /* Some time might have passed waiting for I/O,
       * so update the loop time here.
       */
      uv_update_time(loop);
    } else if (GetLastError() != WAIT_TIMEOUT) {
      /* Serious error */
      uv_fatal_error(GetLastError(), "GetQueuedCompletionStatusEx");
    } else if (timeout > 0) {
      /* GetQueuedCompletionStatus can occasionally return a little early.
       * Make sure that the desired timeout target time is reached.
       */
      uv_update_time(loop);
      if (timeout_time > loop->time) {
        timeout = (DWORD)(timeout_time - loop->time);
        /* The first call to GetQueuedCompletionStatus should return very
         * close to the target time and the second should reach it, but
         * this is not stated in the documentation. To make sure a busy
         * loop cannot happen, the timeout is increased exponentially
         * starting on the third round.
         */
        timeout += repeat ? (1 << (repeat - 1)) : 0;
        continue;
      }
    }
    break;
  }
}


static int uv__loop_alive(const uv_loop_t* loop) {
  return uv__has_active_handles(loop) ||
         uv__has_active_reqs(loop) ||
         loop->endgame_handles != NULL;
}


int uv_loop_alive(const uv_loop_t* loop) {
    return uv__loop_alive(loop);
}


int uv_run(uv_loop_t *loop, uv_run_mode mode) {
  DWORD timeout;
  int r;
  int ran_pending;

  r = uv__loop_alive(loop);
  if (!r)
    uv_update_time(loop);

  while (r != 0 && loop->stop_flag == 0) {
    uv_update_time(loop);
    uv__run_timers(loop);

    ran_pending = uv_process_reqs(loop);
    uv_idle_invoke(loop);
    uv_prepare_invoke(loop);

    timeout = 0;
    if ((mode == UV_RUN_ONCE && !ran_pending) || mode == UV_RUN_DEFAULT)
      timeout = uv_backend_timeout(loop);

    if (pGetQueuedCompletionStatusEx)
      uv__poll(loop, timeout);
    else
      uv__poll_wine(loop, timeout);


    uv_check_invoke(loop);
    uv_process_endgames(loop);

    if (mode == UV_RUN_ONCE) {
      /* UV_RUN_ONCE implies forward progress: at least one callback must have
       * been invoked when it returns. uv__io_poll() can return without doing
       * I/O (meaning: no callbacks) when its timeout expires - which means we
       * have pending timers that satisfy the forward progress constraint.
       *