deps/uv/src/unix/uv-eio.c

/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

/* This file integrates the libuv event loop with the libeio thread pool */

#include "uv.h"
#include "eio.h"

#include <assert.h>
#include <stdio.h>


static uv_once_t uv__eio_init_once_guard = UV_ONCE_INIT;


static void uv_eio_do_poll(uv_idle_t* watcher, int status) {
  uv_loop_t* loop = watcher->loop;
  assert(watcher == &loop->uv_eio_poller);
  if (eio_poll(&loop->uv_eio_channel) != -1)
    uv_idle_stop(watcher);
}


/* Called from the main thread. */
static void uv_eio_want_poll_notifier_cb(uv_async_t* watcher, int status) {
  uv_loop_t* loop = watcher->loop;
  assert(watcher == &loop->uv_eio_want_poll_notifier);
  if (eio_poll(&loop->uv_eio_channel) == -1)
    uv_idle_start(&loop->uv_eio_poller, uv_eio_do_poll);
}


static void uv_eio_done_poll_notifier_cb(uv_async_t* watcher, int revents) {
  uv_loop_t* loop = watcher->loop;
  assert(watcher == &loop->uv_eio_done_poll_notifier);
  if (eio_poll(&loop->uv_eio_channel) != -1)
    uv_idle_stop(&loop->uv_eio_poller);
}


/*
 * uv_eio_want_poll() is called from the EIO thread pool each time an EIO
 * request (that is, one of the node.fs.* functions) has completed.
 */
static void uv_eio_want_poll(eio_channel *channel) {
  /* Signal the main thread that eio_poll need to be processed. */
  uv_loop_t* loop = channel->data;
  uv_async_send(&loop->uv_eio_want_poll_notifier);
}


static void uv_eio_done_poll(eio_channel *channel) {
  /*
   * Signal the main thread that we should stop calling eio_poll().
   * from the idle watcher.
   */
  uv_loop_t* loop = channel->data;
  uv_async_send(&loop->uv_eio_done_poll_notifier);
}


static void uv__eio_init(void) {
  eio_init(uv_eio_want_poll, uv_eio_done_poll);
}


void uv_eio_init(uv_loop_t* loop) {
  if (loop->counters.eio_init) return;
  loop->counters.eio_init = 1;

  uv_idle_init(loop, &loop->uv_eio_poller);
  uv_idle_start(&loop->uv_eio_poller, uv_eio_do_poll);

  loop->uv_eio_want_poll_notifier.data = loop;
  uv_async_init(loop, &loop->uv_eio_want_poll_notifier,
      uv_eio_want_poll_notifier_cb);

  uv_async_init(loop, &loop->uv_eio_done_poll_notifier,
      uv_eio_done_poll_notifier_cb);

  uv_once(&uv__eio_init_once_guard, uv__eio_init);
}