Upgrade Tornado to v6, and fix servers accordingly. (google#1181)

Also updated the README for web_gui development

openhtf/output/servers/station_server.py

@@ -19,6 +19,7 @@
 aggregate info from multiple station servers with a single frontend.
 """
 
+import asyncio
 import contextlib
 import itertools
 import json
@@ -166,6 +167,7 @@ def __init__(self, update_callback):
 
   def run(self):
     """Call self._poll_for_update() in a loop and handle errors."""
+    asyncio.set_event_loop(asyncio.new_event_loop())
     while True:
       try:
         self._poll_for_update()

openhtf/output/servers/web_gui_server.py

@@ -13,9 +13,9 @@
 # limitations under the License.
 """Extensible HTTP server serving the OpenHTF Angular frontend."""
 
+import asyncio
 import os
 import threading
-import time
 
 import tornado.httpclient
 import tornado.httpserver
@@ -112,6 +112,8 @@ class WebGuiServer(threading.Thread):
 
   def __init__(self, additional_routes, port, sockets=None):
     super(WebGuiServer, self).__init__(name=type(self).__name__)
+    self.ts_event = threading.Event()
+    self._running = asyncio.Event()
 
     # Set up routes.
     routes = [
@@ -121,24 +123,17 @@ def __init__(self, additional_routes, port, sockets=None):
         }),
     ]
     routes.extend(additional_routes)
-
-    if sockets is None:
-      sockets, self.port = bind_port(port)
-    else:
-      if not port:
-        raise ValueError('When sockets are passed to the server, port must be '
-                         'specified and nonzero.')
-      self.port = port
+    self._sockets = sockets
+    self.port = port
+    self._loop = None
 
     # Configure the Tornado application.
-    application = tornado.web.Application(
+    self.application = tornado.web.Application(
         routes,
         default_handler_class=DefaultHandler,
         template_loader=TemplateLoader(STATIC_FILES_ROOT),
         static_path=STATIC_FILES_ROOT,
     )
-    self.server = tornado.httpserver.HTTPServer(application)
-    self.server.add_sockets(sockets)
 
   def __enter__(self):
     self.start()
@@ -147,14 +142,38 @@ def __enter__(self):
   def __exit__(self, *unused_args):
     self.stop()
 
+  async def run_app(self):
+    """Runs the station server application."""
+    self.ts_watchdog_task = asyncio.create_task(self._stop_threadsafe())
+    if self._sockets is None:
+      self._sockets, self.port = bind_port(self.port)
+    else:
+      if not self.port:
+        raise ValueError(
+            'When sockets are passed to the server, port must be '
+            'specified and nonzero.'
+        )
+    self.server = tornado.httpserver.HTTPServer(self.application)
+    self.server.add_sockets(self._sockets)
+    await self._running.wait()
+    await self.ts_watchdog_task
+    await self.server.close_all_connections()
+
+  async def _stop_threadsafe(self):
+    """Handles stopping the server in a threadsafe manner."""
+    while not self.ts_event.is_set():
+      await asyncio.sleep(0.1)
+    self._running.set()
+
   def _get_config(self):
     """Override this to configure the Angular app."""
     return {}
 
   def run(self):
-    tornado.ioloop.IOLoop.instance().start()  # Blocking IO loop.
+    """Runs the station server."""
+    asyncio.run(self.run_app())
 
   def stop(self):
-    self.server.stop()
-    ioloop = tornado.ioloop.IOLoop.instance()
-    ioloop.add_timeout(time.time() + _SERVER_SHUTDOWN_BUFFER_S, ioloop.stop)
+    """Stops the station server. Method is threadsafe."""
+    self.ts_event.set()
+

openhtf/output/web_gui/README.md

@@ -1,8 +1,13 @@
 # OpenHTF web GUI client
 
+## Prerequisites
+
+Follow the steps from [CONTRIBUTING.md](../../../CONTRIBUTING.md) to set up
+the Python virtual environment. Make sure you have done an "editable" install.
+
 ## Development
 
-First, start the dashboard server on the default port by running the following
+Start the dashboard server on the default port by running the following
 from the project root directory:
 
 ```
@@ -22,4 +27,10 @@ the dashboard server and should reload automatically when changes are made to
 frontend files.
 
 With the dashboard running, you can run OpenHTF tests separately, and they
-should be picked up over multicast and appear on the dashboard.
+should be picked up over multicast and appear on the dashboard. To test things
+out, you can run the frontend example test:
+
+```
+python3 examples/frontend_example.py
+```
+

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "openhtf"
-version = "1.6.0"
+version = "1.6.1"
 authors = [
   { name="The OpenHTF Authors"},
 ]
@@ -23,7 +23,7 @@ dependencies = [
     "pyOpenSSL>=17.1.0",
     "requests>=2.27.1",
     "sockjs_tornado>=1.0.7",
-    "tornado>=4.3,<5.0",
+    "tornado>=6,<6.3",
     "typing_extensions>=4.12.2",
 ]
 license = {file = "LICENSE"}