upgrade to 14.4.1upstream/14.4.1

1 files changed, 96 insertions, 0 deletions

diff --git a/examples/eventloop/asyncweb.py b/examples/eventloop/asyncweb.py
new file mode 100644
index 0000000..06b03f3
--- /dev/null
+++ b/examples/eventloop/asyncweb.py
@@ -0,0 +1,96 @@
+"""Async web request example with tornado.
+
+Requests to localhost:8888 will be relayed via 0MQ to a slow responder,
+who will take 1-5 seconds to respond.  The tornado app will remain responsive
+duriung this time, and when the worker replies, the web request will finish.
+
+A '.' is printed every 100ms to demonstrate that the zmq request is not blocking
+the event loop.
+"""
+
+
+import sys
+import random
+import threading
+import time
+
+import zmq
+from zmq.eventloop import ioloop, zmqstream
+
+"""
+ioloop.install() must be called prior to instantiating *any* tornado objects,
+and ideally before importing anything from tornado, just to be safe.
+
+install() sets the singleton instance of tornado.ioloop.IOLoop with zmq's
+IOLoop. If this is not done properly, multiple IOLoop instances may be
+created, which will have the effect of some subset of handlers never being
+called, because only one loop will be running.
+"""
+
+ioloop.install()
+
+import tornado
+from tornado import web
+
+
+def slow_responder():
+    """thread for slowly responding to replies."""
+    ctx = zmq.Context.instance()
+    socket = ctx.socket(zmq.REP)
+    socket.linger = 0
+    socket.bind('tcp://127.0.0.1:5555')
+    i=0
+    while True:
+        msg = socket.recv()
+        print "\nworker received %r\n" % msg
+        time.sleep(random.randint(1,5))
+        socket.send(msg + " to you too, #%i" % i)
+        i+=1
+
+def dot():
+    """callback for showing that IOLoop is still responsive while we wait"""
+    sys.stdout.write('.')
+    sys.stdout.flush()
+
+def printer(msg):
+    print (msg)
+
+class TestHandler(web.RequestHandler):
+    
+    @web.asynchronous
+    def get(self):
+        ctx = zmq.Context.instance()
+        s = ctx.socket(zmq.REQ)
+        s.connect('tcp://127.0.0.1:5555')
+        # send request to worker
+        s.send('hello')
+        loop = ioloop.IOLoop.instance()
+        self.stream = zmqstream.ZMQStream(s)
+        self.stream.on_recv(self.handle_reply)
+    
+    def handle_reply(self, msg):
+        # finish web request with worker's reply
+        reply = msg[0]
+        print "\nfinishing with %r\n" % reply,
+        self.stream.close()
+        self.write(reply)
+        self.finish()
+
+def main():
+    worker = threading.Thread(target=slow_responder)
+    worker.daemon=True
+    worker.start()
+    
+    application = web.Application([(r"/", TestHandler)])
+    beat = ioloop.PeriodicCallback(dot, 100)
+    beat.start()
+    application.listen(8888)
+    try:
+        ioloop.IOLoop.instance().start()
+    except KeyboardInterrupt:
+        print ' Interrupted'
+    
+    
+if __name__ == "__main__":
+    main()
+