Merge commit 'a302c65dc65896776d6cb9e2c89a6ccc77ada530' as 'third-party/libuv'

1 files changed, 290 insertions, 0 deletions

diff --git a/third-party/libuv/src/unix/async.c b/third-party/libuv/src/unix/async.c
new file mode 100644
index 0000000000..3c23e1d7fd
--- /dev/null
+++ b/third-party/libuv/src/unix/async.c
@@ -0,0 +1,290 @@
+/* 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 <errno.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static void uv__async_event(uv_loop_t* loop,
+                            struct uv__async* w,
+                            unsigned int nevents);
+static int uv__async_make_pending(int* pending);
+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, &loop->async_watcher, uv__async_event);
+  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) {
+  if (uv__async_make_pending(&handle->pending) == 0)
+    uv__async_send(&handle->loop->async_watcher);
+
+  return 0;
+}
+
+
+void uv__async_close(uv_async_t* handle) {
+  QUEUE_REMOVE(&handle->queue);
+  uv__handle_stop(handle);
+}
+
+
+static void uv__async_event(uv_loop_t* loop,
+                            struct uv__async* w,
+                            unsigned int nevents) {
+  QUEUE* q;
+  uv_async_t* h;
+
+  QUEUE_FOREACH(q, &loop->async_handles) {
+    h = QUEUE_DATA(q, uv_async_t, queue);
+
+    if (h->pending == 0)
+      continue;
+    h->pending = 0;
+
+    if (h->async_cb == NULL)
+      continue;
+    h->async_cb(h, 0);
+  }
+}
+
+
+static int uv__async_make_pending(int* pending) {
+  /* Do a cheap read first. */
+  if (ACCESS_ONCE(int, *pending) != 0)
+    return 1;
+
+  /* Micro-optimization: use atomic memory operations to detect if we've been
+   * preempted by another thread and don't have to make an expensive syscall.
+   * This speeds up the heavily contended case by about 1-2% and has little
+   * if any impact on the non-contended case.
+   *
+   * Use XCHG instead of the CMPXCHG that __sync_val_compare_and_swap() emits
+   * on x86, it's about 4x faster. It probably makes zero difference in the
+   * grand scheme of things but I'm OCD enough not to let this one pass.
+   */
+#if defined(__i386__) || defined(__x86_64__)
+  {
+    unsigned int val = 1;
+    __asm__ __volatile__ ("xchgl %0, %1"
+                         : "+r" (val)
+                         : "m"  (*pending));
+    return val != 0;
+  }
+#elif defined(__GNUC__) && (__GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ > 0)
+  return __sync_val_compare_and_swap(pending, 0, 1) != 0;
+#else
+  ACCESS_ONCE(int, *pending) = 1;
+  return 0;
+#endif
+}
+
+
+static void uv__async_io(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
+  struct uv__async* wa;
+  char buf[1024];
+  unsigned n;
+  ssize_t r;
+
+  n = 0;
+  for (;;) {
+    r = read(w->fd, buf, sizeof(buf));
+
+    if (r > 0)
+      n += r;
+
+    if (r == sizeof(buf))
+      continue;
+
+    if (r != -1)
+      break;
+
+    if (errno == EAGAIN || errno == EWOULDBLOCK)
+      break;
+
+    if (errno == EINTR)
+      continue;
+
+    abort();
+  }
+
+  wa = container_of(w, struct uv__async, io_watcher);
+
+#if defined(__linux__)
+  if (wa->wfd == -1) {
+    uint64_t val;
+    assert(n == sizeof(val));
+    memcpy(&val, buf, sizeof(val));  /* Avoid alignment issues. */
+    wa->cb(loop, wa, val);
+    return;
+  }
+#endif
+
+  wa->cb(loop, wa, n);
+}
+
+
+void uv__async_send(struct uv__async* wa) {
+  const void* buf;
+  ssize_t len;
+  int fd;
+  int r;
+
+  buf = "";
+  len = 1;
+  fd = wa->wfd;
+
+#if defined(__linux__)
+  if (fd == -1) {
+    static const uint64_t val = 1;
+    buf = &val;
+    len = sizeof(val);
+    fd = wa->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();
+}
+
+
+void uv__async_init(struct uv__async* wa) {
+  wa->io_watcher.fd = -1;
+  wa->wfd = -1;
+}
+
+
+int uv__async_start(uv_loop_t* loop, struct uv__async* wa, uv__async_cb cb) {
+  int pipefd[2];
+  int err;
+
+  if (wa->io_watcher.fd != -1)
+    return 0;
+
+  err = uv__async_eventfd();
+  if (err >= 0) {
+    pipefd[0] = err;
+    pipefd[1] = -1;
+  }
+  else if (err == -ENOSYS)
+    err = uv__make_pipe(pipefd, UV__F_NONBLOCK);
+
+  if (err < 0)
+    return err;
+
+  uv__io_init(&wa->io_watcher, uv__async_io, pipefd[0]);
+  uv__io_start(loop, &wa->io_watcher, UV__POLLIN);
+  wa->wfd = pipefd[1];
+  wa->cb = cb;
+
+  return 0;
+}
+
+
+void uv__async_stop(uv_loop_t* loop, struct uv__async* wa) {
+  if (wa->io_watcher.fd == -1)
+    return;
+
+  uv__io_stop(loop, &wa->io_watcher, UV__POLLIN);
+  uv__close(wa->io_watcher.fd);
+  wa->io_watcher.fd = -1;
+
+  if (wa->wfd != -1) {
+    uv__close(wa->wfd);
+    wa->wfd = -1;
+  }
+}
+
+
+static int uv__async_eventfd() {
+#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 -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 -errno;
+
+  no_eventfd = 1;
+
+skip_eventfd:
+
+#endif
+
+  return -ENOSYS;
+}