send a ping frame as feedback when publishing a message through websocket connection

misc/spec/subscriber/websocket_spec.rb

@@ -308,6 +308,13 @@ describe "Subscriber WebSocket" do
       headers, body = read_response_on_socket(socket)
       socket.print(frame)
 
+      body, dummy = read_response_on_socket(socket)
+      body.should eql("\211\000")
+
+      body, dummy = read_response_on_socket(socket)
+      body.should eql("\x81N{\"channel\":\"ch_test_publish_message_same_stream\", \"id\":\"1\", \"message\":\"hello\"}")
+
+
       EventMachine.run do
         pub = EventMachine::HttpRequest.new(nginx_address + '/channels-stats?id=' + channel.to_s).get :timeout => 30
         pub.callback do

src/ngx_http_push_stream_module_websocket.c

@@ -281,6 +281,8 @@ ngx_http_push_stream_websocket_reading(ngx_http_request_t *r)
                 ngx_http_finalize_request(r, NGX_OK);
                 ngx_destroy_pool(temp_pool);
                 return;
+            } else {
+                ngx_http_push_stream_send_response_text(r, NGX_HTTP_PUSH_STREAM_WEBSOCKET_PING_LAST_FRAME_BYTE, sizeof(NGX_HTTP_PUSH_STREAM_WEBSOCKET_PING_LAST_FRAME_BYTE), 1);
             }
         }