/* 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 contains both the uv__async internal infrastructure and the
* user-facing uv_async_t functions.
*/
#include "uv.h"
#include "internal.h"
#include "atomic-ops.h"
#include <errno.h>
#include <stdio.h> /* snprintf() */
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static void uv__async_send(uv_loop_t* loop);
static int uv__async_start(uv_loop_t* loop);
static int uv__async_eventfd(void);
int uv_async_init(uv_loop_t* loop, uv_async_t* handle, uv_async_cb async_cb) {
int err;
err = uv__async_start(loop);
if (err)
return err;
uv__handle_init(loop, (uv_handle_t*)handle, UV_ASYNC);
handle->async_cb = async_cb;
handle->pending = 0;
QUEUE_INSERT_TAIL(&loop->async_handles, &handle->queue);
uv__handle_start(handle);
return 0;
}
int uv_async_send(uv_async_t* handle) {
/* Do a cheap read first. */
if (ACCESS_ONCE(int, handle->pending) != 0)
return 0;
if (cmpxchgi(&handle->pending, 0, 1) == 0)
uv__async_send(handle->loop);
return 0;
}
void uv__async_close(uv_async_t* handle) {
QUEUE_REMOVE(&handle->queue);
uv__handle_stop(handle);
}
static void uv__async_io(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
char buf[1024];
ssize_t r;
QUEUE queue;
QUEUE* q;
uv_async_t* h;
assert(w == &loop->async_io_watcher);
for (;;) {
r = read(w->fd, buf, sizeof(buf));
if (r == sizeof(buf))
continue;
if (r != -1)
break;
if (errno == EAGAIN || errno == EWOULDBLOCK)
break;
if (errno == EINTR)
continue;
abort();
}
QUEUE_MOVE(&loop->async_handles, &queue);
while (!QUEUE_EMPTY(&queue)) {
q = QUEUE_HEAD(&queue);
h = QUEUE_DATA(q, uv_async_t, queue);
QUEUE_REMOVE(q);
QUEUE_INSERT_TAIL(&loop->async_handles, q);
if (cmpxchgi(&h->pending, 1, 0) == 0)
continue;
if (h->async_cb == NULL)
continue;
h->async_cb(h);
}
}
static void uv__async_send(uv_loop_t* loop) {
const void* buf;
ssize_t len;
int fd;
int r;
buf = "";
len = 1;
fd = loop->async_wfd;
#if defined(__linux__)
if (fd == -1) {
static const uint64_t val = 1;
buf = &val;
len = sizeof(val);
fd = loop->async_io_watcher.fd; /* eventfd */
}
#endif
do
r = write(fd, buf, len);
while (r == -1 && errno == EINTR);
if (r == len)
return;
if (r == -1)
if (errno == EAGAIN || errno == EWOULDBLOCK)
return;
abort();
}
static int uv__async_start(uv_loop_t* loop) {
int pipefd[2];
int err;
if (loop->async_io_watcher.fd != -1)
return 0;
err = uv__async_eventfd();
if (err >= 0) {
pipefd[0] = err;
pipefd[1] = -1;
}
else if (err == UV_ENOSYS) {
err = uv__make_pipe(pipefd, UV__F_NONBLOCK);
#if defined(__linux__)
/* Save a file descriptor by opening one of the pipe descriptors as
* read/write through the procfs. That file descriptor can then
* function as both ends of the pipe.
*/
if (err == 0) {
char buf[32];
int fd;
snprintf(buf, sizeof(buf), "/proc/self/fd/%d", pipefd[0]);
fd = uv__open_cloexec(buf, O_RDWR);
if (fd >= 0) {
uv__close(pipefd[0]);
uv__close(pipefd[1]);
pipefd[0] = fd;
pipefd[1] = fd;
}
}
#endif
}
if (err < 0)
return err;
uv__io_init(&loop->async_io_watcher, uv__async_io, pipefd[0]);
uv__io_start(loop, &loop->async_io_watcher, POLLIN);
loop->async_wfd = pipefd[1];
return 0;
}
int uv__async_fork(uv_loop_t* loop) {
if (loop->async_io_watcher.fd == -1) /* never started */
return 0;
uv__async_stop(loop);
return uv__async_start(loop);
}
void uv__async_stop(uv_loop_t* loop) {
if (loop->async_io_watcher.fd == -1)
return;
if (loop->async_wfd != -1) {
if (loop->async_wfd != loop->async_io_watcher.fd)
uv__close(loop->async_wfd);
loop->async_wfd = -1;
}
uv__io_stop(loop, &loop->async_io_watcher, POLLIN);
uv__close(loop->async_io_watcher.fd);
loop->async_io_watcher.fd = -1;
}
static int uv__async_eventfd(void) {
#if defined(__linux__)
static int no_eventfd2;
static int no_eventfd;
int fd;
if (no_eventfd2)
goto skip_eventfd2;
fd = uv__eventfd2(0, UV__EFD_CLOEXEC | UV__EFD_NONBLOCK);
if (fd != -1)
return fd;
if (errno != ENOSYS)
return UV__ERR(errno);
no_eventfd2 = 1;
skip_eventfd2:
if (no_eventfd)
goto skip_eventfd;
fd = uv__eventfd(0);
if (fd != -1) {
uv__cloexec(fd, 1);
uv__nonblock(fd, 1);
return fd;
}
if (errno != ENOSYS)
return UV__ERR(errno);
no_eventfd = 1;
skip_eventfd:
#endif
return UV_ENOSYS;
}