Add 'drain' event to tcp.Connection

deps/evcom/evcom.c

@@ -306,6 +306,10 @@ stream_recv__close (evcom_stream *stream)
 static int
 stream_send__drain (evcom_stream *stream)
 {
+  if (stream->on_drain) {
+    stream->on_drain(stream);
+  }
+
   if (!GOT_CLOSE(stream)) {
     stream->send_action = stream_send__wait_for_buf;
     return OKAY;
@@ -1094,6 +1098,7 @@ evcom_stream_init (evcom_stream *stream)
   stream->on_connect = NULL;
   stream->on_timeout = NULL;
   stream->on_read = NULL;
+  stream->on_drain = NULL;
   stream->on_close = NULL;
 }
 

deps/evcom/evcom.h

@@ -144,6 +144,7 @@ typedef struct evcom_stream {
   void (*on_connect) (struct evcom_stream *);
   void (*on_timeout) (struct evcom_stream *);
   void (*on_read)    (struct evcom_stream *, const void* buf, size_t len);
+  void (*on_drain)   (struct evcom_stream *);
   void (*on_close)   (struct evcom_stream *);
   void *data;
 } evcom_stream;

doc/api.txt

@@ -1172,6 +1172,8 @@ socket for +tcp.Server+.
 |+"timeout"+     |              | Emitted if the connection times out from
                                   inactivity. The +"close"+ event will be 
                                   emitted immediately following this event. 
+|+"drain"+       |              | Emitted when the write buffer becomes
+                                  empty. Can be used to throttle uploads.
 |+"close"+       | +had_error+  | Emitted once the connection is fully
                                   closed. The argument +had_error+
                                   is a boolean which says if the connection

src/node_net.cc

@@ -144,6 +144,7 @@ void Connection::Init() {
   stream_.on_read    = Connection::on_read;
   stream_.on_close   = Connection::on_close;
   stream_.on_timeout = Connection::on_timeout;
+  stream_.on_drain   = Connection::on_drain;
   stream_.data = this;
 }
 
@@ -469,6 +470,11 @@ void Connection::OnTimeout() {
   Emit("timeout", 0, NULL);
 }
 
+void Connection::OnDrain() {
+  HandleScope scope;
+  Emit("drain", 0, NULL);
+}
+
 void Connection::OnEOF() {
   HandleScope scope;
   Emit("eof", 0, NULL);

src/node_net.h

@@ -82,6 +82,7 @@ class Connection : public EventEmitter {
   virtual void OnEOF();
   virtual void OnClose();
   virtual void OnTimeout();
+  virtual void OnDrain();
 
   v8::Local<v8::Object> GetProtocol();
 
@@ -129,6 +130,11 @@ class Connection : public EventEmitter {
     connection->OnTimeout();
   }
 
+  static void on_drain(evcom_stream *s) {
+    Connection *connection = static_cast<Connection*>(s->data);
+    connection->OnDrain();
+  }
+
   void Init();  // constructor helper.
 
   static int Resolve(eio_req *req);