From 08cafd091ba408cc339a9ea20a60260ac582f091 Mon Sep 17 00:00:00 2001
From: Fedor Indutny <fedor.indutny@gmail.com>
Date: Sat, 21 Dec 2013 01:16:17 +0400
Subject: [PATCH] stream: fix uv__stream_osx_select

Relying on `readable`/`writable` when polling will lead to the select
thread spinning in the loop and calling `uv_async_send()`, because
stream may never become not `readable`/`writable`.

We should rely on `uv__io_active()` instead and interruprt select thread
every time it changes.
---
 src/unix/stream.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/src/unix/stream.c b/src/unix/stream.c
index ee3ea75f..f4e9bf75 100644
--- a/src/unix/stream.c
+++ b/src/unix/stream.c
@@ -168,9 +168,9 @@ static void uv__stream_osx_select(void* arg) {
     FD_ZERO(&sread);
     FD_ZERO(&swrite);
 
-    if (uv_is_readable(stream))
+    if (uv__io_active(&stream->io_watcher, UV__POLLIN))
       FD_SET(fd, &sread);
-    if (uv_is_writable(stream))
+    if (uv__io_active(&stream->io_watcher, UV__POLLOUT))
       FD_SET(fd, &swrite);
     FD_SET(s->int_fd, &sread);
 
@@ -230,11 +230,14 @@ static void uv__stream_osx_select(void* arg) {
 
 
 static void uv__stream_osx_interrupt_select(uv_stream_t* stream) {
+#if defined(__APPLE__)
   /* Notify select() thread about state change */
   uv__stream_select_t* s;
   int r;
 
   s = stream->select;
+  if (s == NULL)
+    return;
 
   /* Interrupt select() loop
    * NOTE: fake_fd and int_fd are socketpair(), thus writing to one will
@@ -245,6 +248,9 @@ static void uv__stream_osx_interrupt_select(uv_stream_t* stream) {
   while (r == -1 && errno == EINTR);
 
   assert(r == 1);
+#else  /* !defined(__APPLE__) */
+  /* No-op on any other platform */
+#endif  /* !defined(__APPLE__) */
 }
 
 
@@ -622,6 +628,7 @@ static void uv__drain(uv_stream_t* stream) {
 
   assert(QUEUE_EMPTY(&stream->write_queue));
   uv__io_stop(stream->loop, &stream->io_watcher, UV__POLLOUT);
+  uv__stream_osx_interrupt_select(stream);
 
   /* Shutdown? */
   if ((stream->flags & UV_STREAM_SHUTTING) &&
@@ -802,6 +809,7 @@ start:
       uv__io_stop(stream->loop, &stream->io_watcher, UV__POLLOUT);
       if (!uv__io_active(&stream->io_watcher, UV__POLLIN))
         uv__handle_stop(stream);
+      uv__stream_osx_interrupt_select(stream);
       return;
     } else if (stream->flags & UV_STREAM_BLOCKING) {
       /* If this is a blocking stream, try again. */
@@ -863,6 +871,9 @@ start:
 
   /* We're not done. */
   uv__io_start(stream->loop, &stream->io_watcher, UV__POLLOUT);
+
+  /* Notify select() thread about state change */
+  uv__stream_osx_interrupt_select(stream);
 }
 
 
@@ -947,6 +958,7 @@ static void uv__stream_eof(uv_stream_t* stream, const uv_buf_t* buf) {
   uv__io_stop(stream->loop, &stream->io_watcher, UV__POLLIN);
   if (!uv__io_active(&stream->io_watcher, UV__POLLOUT))
     uv__handle_stop(stream);
+  uv__stream_osx_interrupt_select(stream);
   uv__stream_read_cb(stream, UV_EOF, buf, UV_UNKNOWN_HANDLE);
 }
 
@@ -1013,6 +1025,7 @@ static void uv__read(uv_stream_t* stream) {
         /* Wait for the next one. */
         if (stream->flags & UV_STREAM_READING) {
           uv__io_start(stream->loop, &stream->io_watcher, UV__POLLIN);
+          uv__stream_osx_interrupt_select(stream);
         }
         uv__stream_read_cb(stream, 0, &buf, UV_UNKNOWN_HANDLE);
       } else {
@@ -1105,6 +1118,7 @@ int uv_shutdown(uv_shutdown_t* req, uv_stream_t* stream, uv_shutdown_cb cb) {
   stream->flags |= UV_STREAM_SHUTTING;
 
   uv__io_start(stream->loop, &stream->io_watcher, UV__POLLOUT);
+  uv__stream_osx_interrupt_select(stream);
 
   return 0;
 }
@@ -1281,6 +1295,7 @@ int uv_write2(uv_write_t* req,
      */
     assert(!(stream->flags & UV_STREAM_BLOCKING));
     uv__io_start(stream->loop, &stream->io_watcher, UV__POLLOUT);
+    uv__stream_osx_interrupt_select(stream);
   }
 
   return 0;
@@ -1341,8 +1356,10 @@ int uv_try_write(uv_stream_t* stream,
   req.bufs = NULL;
 
   /* Do not poll for writable, if we wasn't before calling this */
-  if (!has_pollout)
+  if (!has_pollout) {
     uv__io_stop(stream->loop, &stream->io_watcher, UV__POLLOUT);
+    uv__stream_osx_interrupt_select(stream);
+  }
 
   return (int) written;
 }
@@ -1363,12 +1380,6 @@ static int uv__read_start_common(uv_stream_t* stream,
    */
   stream->flags |= UV_STREAM_READING;
 
-#if defined(__APPLE__)
-  /* Notify select() thread about state change */
-  if (stream->select != NULL)
-    uv__stream_osx_interrupt_select(stream);
-#endif /* defined(__APPLE__) */
-
   /* TODO: try to do the read inline? */
   /* TODO: keep track of tcp state. If we've gotten a EOF then we should
    * not start the IO watcher.
@@ -1382,6 +1393,7 @@ static int uv__read_start_common(uv_stream_t* stream,
 
   uv__io_start(stream->loop, &stream->io_watcher, UV__POLLIN);
   uv__handle_start(stream);
+  uv__stream_osx_interrupt_select(stream);
 
   return 0;
 }
@@ -1414,12 +1426,7 @@ int uv_read_stop(uv_stream_t* stream) {
   uv__io_stop(stream->loop, &stream->io_watcher, UV__POLLIN);
   if (!uv__io_active(&stream->io_watcher, UV__POLLOUT))
     uv__handle_stop(stream);
-
-#if defined(__APPLE__)
-  /* Notify select() thread about state change */
-  if (stream->select != NULL)
-    uv__stream_osx_interrupt_select(stream);
-#endif /* defined(__APPLE__) */
+  uv__stream_osx_interrupt_select(stream);
 
   stream->read_cb = NULL;
   stream->read2_cb = NULL;