unix: fix event loop stall

Stop libev from entering the epoll_wait/kevent/port_getn/etc. syscall when
there are no active handles left, that will block indefinitely.

src/unix/core.c

@@ -604,6 +604,13 @@ static void uv__io_rw(struct ev_loop* ev, ev_io* w, int events) {
   uv__io_t* handle = container_of(w, uv__io_t, io_watcher);
   u.data = handle->io_watcher.data;
   u.cb(loop, handle, events & (EV_READ|EV_WRITE|EV_ERROR));
+
+  /* The callback may have closed all active handles. Stop libev from entering
+   * the epoll_wait/kevent/port_getn/etc. syscall if that's the case, it would
+   * hang indefinitely.
+   */
+  if (loop->active_handles == 0)
+    ev_break(loop->ev, EVBREAK_ONE);
 }
 
 

test/test-list.h

@@ -41,6 +41,7 @@ TEST_DECLARE   (delayed_accept)
 TEST_DECLARE   (multiple_listen)
 TEST_DECLARE   (tcp_writealot)
 TEST_DECLARE   (tcp_connect_error_after_write)
+TEST_DECLARE   (tcp_shutdown_after_write)
 TEST_DECLARE   (tcp_bind_error_addrinuse)
 TEST_DECLARE   (tcp_bind_error_addrnotavail_1)
 TEST_DECLARE   (tcp_bind_error_addrnotavail_2)
@@ -229,6 +230,9 @@ TASK_LIST_START
   TEST_ENTRY  (tcp_writealot)
   TEST_HELPER (tcp_writealot, tcp4_echo_server)
 
+  TEST_ENTRY  (tcp_shutdown_after_write)
+  TEST_HELPER (tcp_shutdown_after_write, tcp4_echo_server)
+
   TEST_ENTRY  (tcp_connect_error_after_write)
   TEST_ENTRY  (tcp_bind_error_addrinuse)
   TEST_ENTRY  (tcp_bind_error_addrnotavail_1)

test/test-tcp-shutdown-after-write.c

@@ -0,0 +1,129 @@
+/* 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"
+
+static void write_cb(uv_write_t* req, int status);
+static void shutdown_cb(uv_shutdown_t* req, int status);
+
+static uv_tcp_t conn;
+static uv_timer_t timer;
+static uv_connect_t connect_req;
+static uv_write_t write_req;
+static uv_shutdown_t shutdown_req;
+
+static int connect_cb_called;
+static int write_cb_called;
+static int shutdown_cb_called;
+
+static int conn_close_cb_called;
+static int timer_close_cb_called;
+
+
+static void close_cb(uv_handle_t* handle) {
+  if (handle == (uv_handle_t*)&conn)
+    conn_close_cb_called++;
+  else if (handle == (uv_handle_t*)&timer)
+    timer_close_cb_called++;
+  else
+    ASSERT(0 && "bad handle in close_cb");
+}
+
+
+static uv_buf_t alloc_cb(uv_handle_t* handle, size_t suggested_size) {
+  static char slab[64];
+  return uv_buf_init(slab, sizeof(slab));
+}
+
+
+static void timer_cb(uv_timer_t* handle, int status) {
+  uv_buf_t buf;
+  int r;
+
+  uv_close((uv_handle_t*)handle, close_cb);
+
+  buf = uv_buf_init("TEST", 4);
+  r = uv_write(&write_req, (uv_stream_t*)&conn, &buf, 1, write_cb);
+  ASSERT(r == 0);
+
+  r = uv_shutdown(&shutdown_req, (uv_stream_t*)&conn, shutdown_cb);
+  ASSERT(r == 0);
+}
+
+
+static void connect_cb(uv_connect_t* req, int status) {
+  ASSERT(status == 0);
+  connect_cb_called++;
+}
+
+
+static void read_cb(uv_stream_t* handle, ssize_t nread, uv_buf_t buf) {
+}
+
+
+static void write_cb(uv_write_t* req, int status) {
+  ASSERT(status == 0);
+  write_cb_called++;
+}
+
+
+static void shutdown_cb(uv_shutdown_t* req, int status) {
+  ASSERT(status == 0);
+  shutdown_cb_called++;
+  uv_close((uv_handle_t*)&conn, close_cb);
+}
+
+
+TEST_IMPL(tcp_shutdown_after_write) {
+  struct sockaddr_in addr;
+  uv_loop_t* loop;
+  int r;
+
+  addr = uv_ip4_addr("127.0.0.1", TEST_PORT);
+  loop = uv_default_loop();
+
+  r = uv_timer_init(loop, &timer);
+  ASSERT(r == 0);
+
+  r = uv_timer_start(&timer, timer_cb, 125, 0);
+  ASSERT(r == 0);
+
+  r = uv_tcp_init(loop, &conn);
+  ASSERT(r == 0);
+
+  r = uv_tcp_connect(&connect_req, &conn, addr, connect_cb);
+  ASSERT(r == 0);
+
+  r = uv_read_start((uv_stream_t*)&conn, alloc_cb, read_cb);
+  ASSERT(r == 0);
+
+  r = uv_run(loop);
+  ASSERT(r == 0);
+
+  ASSERT(connect_cb_called == 1);
+  ASSERT(write_cb_called == 1);
+  ASSERT(shutdown_cb_called == 1);
+  ASSERT(conn_close_cb_called == 1);
+  ASSERT(timer_close_cb_called == 1);
+
+  return 0;
+}

uv.gyp

@@ -343,6 +343,7 @@
         'test/test-tcp-bind6-error.c',
         'test/test-tcp-close.c',
         'test/test-tcp-connect-error-after-write.c',
+        'test/test-tcp-shutdown-after-write.c',
         'test/test-tcp-flags.c',
         'test/test-tcp-connect-error.c',
         'test/test-tcp-connect-timeout.c',