unix: guarantee write queue cb execution order in streams

The problem was that the canceled write callbacks
were being called before the already written callbacks, even
though they were queued after them.

Makefile.am

@@ -196,6 +196,7 @@ test_run_tests_SOURCES = test/blackhole-server.c \
                          test/test-tcp-write-to-half-open-connection.c \
                          test/test-tcp-writealot.c \
                          test/test-tcp-try-write.c \
+                         test/test-tcp-write-queue-order.c \
                          test/test-thread.c \
                          test/test-threadpool-cancel.c \
                          test/test-threadpool.c \

src/unix/stream.c

@@ -60,6 +60,7 @@ static void uv__stream_connect(uv_stream_t*);
 static void uv__write(uv_stream_t* stream);
 static void uv__read(uv_stream_t* stream);
 static void uv__stream_io(uv_loop_t* loop, uv__io_t* w, unsigned int events);
+static void uv__write_callbacks(uv_stream_t* stream);
 static size_t uv__write_req_size(uv_write_t* req);
 
 
@@ -378,33 +379,12 @@ void uv__stream_destroy(uv_stream_t* stream) {
     QUEUE_REMOVE(q);
 
     req = QUEUE_DATA(q, uv_write_t, queue);
-    uv__req_unregister(stream->loop, req);
+    req->error = -ECANCELED;
 
-    if (req->bufs != req->bufsml)
+    QUEUE_INSERT_TAIL(&stream->write_completed_queue, &req->queue);
-      free(req->bufs);
-    req->bufs = NULL;
-
-    if (req->cb != NULL)
-      req->cb(req, -ECANCELED);
   }
 
-  while (!QUEUE_EMPTY(&stream->write_completed_queue)) {
+  uv__write_callbacks(stream);
-    q = QUEUE_HEAD(&stream->write_completed_queue);
-    QUEUE_REMOVE(q);
-
-    req = QUEUE_DATA(q, uv_write_t, queue);
-    uv__req_unregister(stream->loop, req);
-
-    if (req->bufs != NULL) {
-      stream->write_queue_size -= uv__write_req_size(req);
-      if (req->bufs != req->bufsml)
-        free(req->bufs);
-      req->bufs = NULL;
-    }
-
-    if (req->cb)
-      req->cb(req, req->error);
-  }
 
   if (stream->shutdown_req) {
     /* The ECANCELED error code is a lie, the shutdown(2) syscall is a
@@ -416,6 +396,8 @@ void uv__stream_destroy(uv_stream_t* stream) {
     stream->shutdown_req->cb(stream->shutdown_req, -ECANCELED);
     stream->shutdown_req = NULL;
   }
+
+  assert(stream->write_queue_size == 0);
 }
 
 
@@ -891,10 +873,6 @@ static void uv__write_callbacks(uv_stream_t* stream) {
   }
 
   assert(QUEUE_EMPTY(&stream->write_completed_queue));
-
-  /* Write queue drained. */
-  if (QUEUE_EMPTY(&stream->write_queue))
-    uv__drain(stream);
 }
 
 
@@ -1211,6 +1189,10 @@ static void uv__stream_io(uv_loop_t* loop, uv__io_t* w, unsigned int events) {
   if (events & (UV__POLLOUT | UV__POLLERR | UV__POLLHUP)) {
     uv__write(stream);
     uv__write_callbacks(stream);
+
+    /* Write queue drained. */
+    if (QUEUE_EMPTY(&stream->write_queue))
+      uv__drain(stream);
   }
 }
 

test/test-list.h

@@ -56,6 +56,7 @@ TEST_DECLARE   (delayed_accept)
 TEST_DECLARE   (multiple_listen)
 TEST_DECLARE   (tcp_writealot)
 TEST_DECLARE   (tcp_try_write)
+TEST_DECLARE   (tcp_write_queue_order)
 TEST_DECLARE   (tcp_open)
 TEST_DECLARE   (tcp_connect_error_after_write)
 TEST_DECLARE   (tcp_shutdown_after_write)
@@ -332,6 +333,8 @@ TASK_LIST_START
 
   TEST_ENTRY  (tcp_try_write)
 
+  TEST_ENTRY  (tcp_write_queue_order)
+
   TEST_ENTRY  (tcp_open)
   TEST_HELPER (tcp_open, tcp4_echo_server)
 

test/test-tcp-write-queue-order.c

@@ -0,0 +1,140 @@
+/* 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "uv.h"
+#include "task.h"
+
+#define REQ_COUNT 100000
+
+static uv_timer_t timer;
+static uv_tcp_t server;
+static uv_tcp_t client;
+static uv_tcp_t incoming;
+static int connect_cb_called;
+static int close_cb_called;
+static int connection_cb_called;
+static int write_callbacks;
+static int write_cancelled_callbacks;
+static int write_error_callbacks;
+
+static uv_write_t write_requests[REQ_COUNT];
+
+
+static void close_cb(uv_handle_t* handle) {
+  close_cb_called++;
+}
+
+void timer_cb(uv_timer_t* handle) {
+  uv_close((uv_handle_t*) &client, close_cb);
+  uv_close((uv_handle_t*) &server, close_cb);
+  uv_close((uv_handle_t*) &incoming, close_cb);
+}
+
+void write_cb(uv_write_t* req, int status) {
+  if (status == 0)
+    write_callbacks++;
+  else if (status == UV_ECANCELED)
+    write_cancelled_callbacks++;
+  else
+    write_error_callbacks++;
+}
+
+static void connect_cb(uv_connect_t* req, int status) {
+  static char base[1024];
+  int r;
+  int i;
+  uv_buf_t buf;
+
+  ASSERT(status == 0);
+  connect_cb_called++;
+
+  buf = uv_buf_init(base, sizeof(base));
+
+  for (i = 0; i < REQ_COUNT; i++) {
+    r = uv_write(&write_requests[i],
+                 req->handle,
+                 &buf,
+                 1,
+                 write_cb);
+    ASSERT(r == 0);
+  }
+}
+
+
+static void connection_cb(uv_stream_t* tcp, int status) {
+  ASSERT(status == 0);
+
+  ASSERT(0 == uv_tcp_init(tcp->loop, &incoming));
+  ASSERT(0 == uv_accept(tcp, (uv_stream_t*) &incoming));
+
+  connection_cb_called++;
+}
+
+
+static void start_server(void) {
+  struct sockaddr_in addr;
+
+  ASSERT(0 == uv_ip4_addr("0.0.0.0", TEST_PORT, &addr));
+
+  ASSERT(0 == uv_tcp_init(uv_default_loop(), &server));
+  ASSERT(0 == uv_tcp_bind(&server, (struct sockaddr*) &addr, 0));
+  ASSERT(0 == uv_listen((uv_stream_t*) &server, 128, connection_cb));
+}
+
+
+TEST_IMPL(tcp_write_queue_order) {
+  uv_connect_t connect_req;
+  struct sockaddr_in addr;
+
+  start_server();
+
+  ASSERT(0 == uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+
+  ASSERT(0 == uv_tcp_init(uv_default_loop(), &client));
+  ASSERT(0 == uv_tcp_connect(&connect_req,
+                             &client,
+                             (struct sockaddr*) &addr,
+                             connect_cb));
+
+  ASSERT(0 == uv_timer_init(uv_default_loop(), &timer));
+  ASSERT(0 == uv_timer_start(&timer, timer_cb, 100, 0));
+
+  ASSERT(0 == uv_run(uv_default_loop(), UV_RUN_DEFAULT));
+
+  ASSERT(connect_cb_called == 1);
+  ASSERT(connection_cb_called == 1);
+  ASSERT(write_callbacks > 0);
+#ifndef _WIN32
+  /* on Windows we never get ECANCELED */
+  ASSERT(write_cancelled_callbacks > 0);
+#endif
+  ASSERT(write_callbacks +
+         write_error_callbacks +
+         write_cancelled_callbacks == REQ_COUNT);
+  ASSERT(close_cb_called == 3);
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}

uv.gyp

@@ -378,6 +378,7 @@
         'test/test-tcp-try-write.c',
         'test/test-tcp-unexpected-read.c',
         'test/test-tcp-read-stop.c',
+        'test/test-tcp-write-queue-order.c',
         'test/test-threadpool.c',
         'test/test-threadpool-cancel.c',
         'test/test-mutexes.c',