Add uv_pipe_pair for communication between threads

This is only the Unix implementation and test.

include/uv.h

@@ -784,6 +784,13 @@ struct uv_pipe_s {
  */
 UV_EXTERN int uv_pipe_init(uv_loop_t*, uv_pipe_t* handle, int ipc);
 
+/*
+ * Connects two initialized pipes on different loops.
+ * Data written to one pipe will appear on the other side.
+ * This function is thread-safe.
+ */
+UV_EXTERN uv_err_t uv_pipe_pair(uv_pipe_t* a, uv_pipe_t* b);
+
 /*
  * Opens an existing file descriptor or HANDLE as a pipe.
  */

src/unix/pipe.c

@@ -30,6 +30,10 @@
 #include <stdlib.h>
 
 
+static uv_once_t uv__pipe_pair_lock_guard = UV_ONCE_INIT;
+static uv_mutex_t uv__pipe_pair_lock;
+
+
 int uv_pipe_init(uv_loop_t* loop, uv_pipe_t* handle, int ipc) {
   uv__stream_init(loop, (uv_stream_t*)handle, UV_NAMED_PIPE);
   loop->counters.pipe_init++;
@@ -39,6 +43,38 @@ int uv_pipe_init(uv_loop_t* loop, uv_pipe_t* handle, int ipc) {
 }
 
 
+void uv__pipe_pair_lock_init() {
+  uv_mutex_init(&uv__pipe_pair_lock);
+}
+
+
+uv_err_t uv_pipe_pair(uv_pipe_t* a, uv_pipe_t* b) {
+  int fds[2];
+  int r;
+  uv_err_t err;
+
+  /* Make sure that the mutex is only initialized once. */
+  uv_once(&uv__pipe_pair_lock_guard, uv__pipe_pair_lock_init);
+
+  uv_mutex_lock(&uv__pipe_pair_lock);
+
+  r = uv__make_socketpair(fds, UV__F_NONBLOCK | UV__F_IPC);
+
+  if (r) {
+    err = uv__new_sys_error(errno);
+  } else {
+    uv_pipe_open(a, fds[0]);
+    uv_pipe_open(b, fds[1]);
+    err = uv_ok_;
+  }
+
+  uv_mutex_unlock(&uv__pipe_pair_lock);
+
+  return err;
+}
+
+
+
 int uv_pipe_bind(uv_pipe_t* handle, const char* name) {
   struct sockaddr_un saddr;
   const char* pipe_fname;

src/win/pipe.c

@@ -91,6 +91,12 @@ int uv_pipe_init(uv_loop_t* loop, uv_pipe_t* handle, int ipc) {
 }
 
 
+uv_err_t uv_pipe_pair(uv_pipe_t* a, uv_pipe_t* b) {
+  /* Implement me */
+  return uv__new_artificial_error(UV_ENOSYS);
+}
+
+
 static void uv_pipe_connection_init(uv_pipe_t* handle) {
   uv_connection_init((uv_stream_t*) handle);
   handle->read_req.data = handle;

test/test-list.h

@@ -29,6 +29,7 @@ TEST_DECLARE   (tcp_ping_pong_v6)
 TEST_DECLARE   (tcp_ref)
 TEST_DECLARE   (tcp_ref2)
 TEST_DECLARE   (pipe_ping_pong)
+TEST_DECLARE   (pipe_pair)
 TEST_DECLARE   (delayed_accept)
 TEST_DECLARE   (multiple_listen)
 TEST_DECLARE   (tcp_writealot)
@@ -163,6 +164,8 @@ TASK_LIST_START
   TEST_ENTRY  (pipe_ping_pong)
   TEST_HELPER (pipe_ping_pong, pipe_echo_server)
 
+  TEST_ENTRY  (pipe_pair)
+
   TEST_ENTRY  (delayed_accept)
   TEST_ENTRY  (multiple_listen)
 

test/test-pipe-pair.c

@@ -0,0 +1,137 @@
+/* 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.
+ */
+
+#include "uv.h"
+#include "task.h"
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#define PING "PING"
+
+static uv_pipe_t a;
+static uv_pipe_t b;
+static uv_write_t req;
+static uv_buf_t buf;
+static enum {
+  STATE_MAIN_START,
+  STATE_THREAD_START,
+  STATE_MAIN_CLOSE,
+  STATE_THREAD_CLOSE,
+} state;
+
+
+static void pinger_read_cb(uv_stream_t* stream, ssize_t nread, uv_buf_t buf) {
+  ASSERT(state == STATE_MAIN_CLOSE);
+  state = STATE_THREAD_CLOSE;
+
+  ASSERT((uv_pipe_t*)stream == &b);
+
+  ASSERT(nread < 0);
+  ASSERT(uv_last_error(stream->loop).code == UV_EOF);
+
+  free(buf.base);
+
+  uv_close((uv_handle_t*)stream, NULL);
+}
+
+
+static void main_thread_read_cb(uv_stream_t* stream, ssize_t nread,
+    uv_buf_t buf) {
+  ASSERT(state == STATE_THREAD_START);
+  state = STATE_MAIN_CLOSE;
+
+  ASSERT((uv_pipe_t*)stream == &a);
+  ASSERT(stream->loop == uv_default_loop());
+
+  if (nread > 0) {
+    ASSERT(strcmp(buf.base, PING) == 0);
+    uv_close((uv_handle_t*)stream, NULL);
+  }
+
+  free(buf.base);
+}
+
+
+static uv_buf_t alloc_cb(uv_handle_t* handle, size_t size) {
+  uv_buf_t buf;
+  buf.base = (char*)malloc(size);
+  buf.len = size;
+  return buf;
+}
+
+
+void start(void* data) {
+  uv_loop_t* loop;
+  int r;
+
+  ASSERT(state == STATE_MAIN_START);
+  state = STATE_THREAD_START;
+
+  loop = data;
+
+  buf = uv_buf_init(PING, strlen(PING));
+
+  if (uv_write(&req, (uv_stream_t*)&b, &buf, 1, NULL)) {
+    FATAL("uv_write failed");
+  }
+
+  uv_read_start((uv_stream_t*)&b, alloc_cb, pinger_read_cb);
+
+  uv_run(loop);
+
+  ASSERT(state == STATE_THREAD_CLOSE);
+}
+
+
+TEST_IMPL(pipe_pair) {
+  int r;
+  uv_err_t err;
+  uv_thread_t tid;
+  uv_loop_t* loop;
+
+  state = STATE_MAIN_START;
+
+  r = uv_pipe_init(uv_default_loop(), &a, 1);
+  ASSERT(r == 0);
+
+  loop = uv_loop_new();
+  ASSERT(loop);
+
+  r = uv_pipe_init(loop, &b, 1);
+  ASSERT(r == 0);
+
+  err = uv_pipe_pair(&a, &b);
+  ASSERT(err.code == UV_OK);
+
+  r = uv_thread_create(&tid, start, loop);
+  ASSERT(r == 0);
+
+  uv_read_start((uv_stream_t*)&a, alloc_cb, main_thread_read_cb);
+
+  uv_run(uv_default_loop());
+  uv_thread_join(&tid);
+
+  ASSERT(state == STATE_THREAD_CLOSE);
+
+  return 0;
+}

uv.gyp

@@ -302,6 +302,7 @@
         'test/test-ping-pong.c',
         'test/test-pipe-bind-error.c',
         'test/test-pipe-connect-error.c',
+        'test/test-pipe-pair.c',
         'test/test-platform-output.c',
         'test/test-process-title.c',
         'test/test-ref.c',