Merge pull request #23539 from QuLogic/webagg-examplar

tacaswell · web-flow · commit 1cedc976dfe0 · 2022-08-03T14:13:40.000-04:00
DOC: Small improvements to WebAgg example
diff --git a/examples/user_interfaces/embedding_webagg_sgskip.py b/examples/user_interfaces/embedding_webagg_sgskip.py
@@ -11,10 +11,13 @@
 The framework being used must support web sockets.
 """
 
+import argparse
 import io
 import json
 import mimetypes
 from pathlib import Path
+import signal
+import socket
 
 try:
     import tornado
@@ -238,13 +241,36 @@ def __init__(self, figure):
 
 
 if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-p', '--port', type=int, default=8080,
+                        help='Port to listen on (0 for a random port).')
+    args = parser.parse_args()
+
     figure = create_figure()
     application = MyApplication(figure)
 
     http_server = tornado.httpserver.HTTPServer(application)
-    http_server.listen(8080)
-
-    print("http://127.0.0.1:8080/")
+    sockets = tornado.netutil.bind_sockets(args.port, '')
+    http_server.add_sockets(sockets)
+
+    for s in sockets:
+        addr, port = s.getsockname()[:2]
+        if s.family is socket.AF_INET6:
+            addr = f'[{addr}]'
+        print(f"Listening on http://{addr}:{port}/")
     print("Press Ctrl+C to quit")
 
-    tornado.ioloop.IOLoop.instance().start()
+    ioloop = tornado.ioloop.IOLoop.instance()
+
+    def shutdown():
+        ioloop.stop()
+        print("Server stopped")
+
+    old_handler = signal.signal(
+        signal.SIGINT,
+        lambda sig, frame: ioloop.add_callback_from_signal(shutdown))
+
+    try:
+        ioloop.start()
+    finally:
+        signal.signal(signal.SIGINT, old_handler)
