From 39e8a2b99fd2bf4166ccfe23ab04bea6a7a6ff2d Mon Sep 17 00:00:00 2001
From: Hyunjun Kim <khj@linecorp.com>
Date: Wed, 11 Jan 2017 17:20:48 +0900
Subject: [PATCH] Signaling support with Blinker integration

---
 docs/signals.md  | 27 +++++++++++++++++++++++++++
 requirements.txt |  2 ++
 sanic/sanic.py   |  4 ++++
 sanic/signals.py | 10 ++++++++++
 4 files changed, 43 insertions(+)
 create mode 100644 docs/signals.md
 create mode 100644 sanic/signals.py

diff --git a/docs/signals.md b/docs/signals.md
new file mode 100644
index 00000000..899d98c0
--- /dev/null
+++ b/docs/signals.md
@@ -0,0 +1,27 @@
+# Signals
+
+Signals allow you to send notifications to multiple subscribers when the specific event occured.
+Signaling is provided by [Blinker](http://pythonhosted.org/blinker/) library and
+Sanic has few built-in signals:
+
+* `request_started`: Sent when the request processing has started.
+* `request_finished`: Sent when the request processing has finished.
+
+## Examples
+
+```python
+from sanic.signals import request_started
+import my_realtime_stat
+
+app = Sanic(__name__)
+
+@request_started.connect
+def collect_stats(request):
+    my_realtime_stat.incoming_requests.incr(request.url)
+
+
+@request_finished.connect
+def count_errors(response):
+    if response.status != 200:
+        my_realtime_stat.error_responses.incr(response.status)
+```
diff --git a/requirements.txt b/requirements.txt
index cef8660e..41799297 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,3 +2,5 @@ httptools
 ujson
 uvloop
 aiofiles
+multidict
+blinker
diff --git a/sanic/sanic.py b/sanic/sanic.py
index 018ed720..b6f9f99e 100644
--- a/sanic/sanic.py
+++ b/sanic/sanic.py
@@ -13,6 +13,7 @@ from .log import log
 from .response import HTTPResponse
 from .router import Router
 from .server import serve, HttpProtocol
+from .signals import request_started, request_finished
 from .static import register as static_register
 from .exceptions import ServerError
 from socket import socket, SOL_SOCKET, SO_REUSEADDR
@@ -176,6 +177,8 @@ class Sanic:
         :return: Nothing
         """
         try:
+            request_started.send(request)
+
             # -------------------------------------------- #
             # Request Middleware
             # -------------------------------------------- #
@@ -239,6 +242,7 @@ class Sanic:
                     response = HTTPResponse(
                         "An error occurred while handling an error")
 
+        request_finished.send(response)
         response_callback(response)
 
     # -------------------------------------------------------------------- #
diff --git a/sanic/signals.py b/sanic/signals.py
new file mode 100644
index 00000000..82bbefda
--- /dev/null
+++ b/sanic/signals.py
@@ -0,0 +1,10 @@
+from blinker import Namespace
+
+__all__ = ('request_started', 'request_finished')
+
+_signals = Namespace()
+signal = _signals.signal
+
+
+request_started = signal('request-started')
+request_finished = signal('request-finished')