From 65923c94ef32de72320f031d954b335eb74d540c Mon Sep 17 00:00:00 2001
From: JackDandy <jackdandy@users.noreply.github.com>
Date: Sat, 28 Apr 2018 15:57:04 +0100
Subject: [PATCH] =?UTF-8?q?Update=20Tornado=20Web=20Server=205.0.1=20(35a5?=
 =?UTF-8?q?38f)=20=E2=86=92=205.0.1=20(2b2a220a).?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 CHANGES.md               |  1 +
 lib/tornado/ioloop.py    | 18 +++++++++++++++++-
 lib/tornado/web.py       |  1 +
 lib/tornado/websocket.py | 18 +++++-------------
 4 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index 5f4ac222..faf1a9d2 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,6 @@
 ### 0.17.0 (2018-xx-xx xx:xx:xx UTC)
 
+* Update Tornado Web Server 5.0.1 (35a538f) to 5.0.1 (2b2a220a)
 
 
 [develop changelog]
diff --git a/lib/tornado/ioloop.py b/lib/tornado/ioloop.py
index 48700139..123f2ba5 100644
--- a/lib/tornado/ioloop.py
+++ b/lib/tornado/ioloop.py
@@ -47,6 +47,7 @@ import threading
 import time
 import traceback
 import math
+import random
 
 from tornado.concurrent import Future, is_future, chain_future, future_set_exc_info, future_add_done_callback  # noqa: E501
 from tornado.log import app_log, gen_log
@@ -1161,6 +1162,14 @@ class PeriodicCallback(object):
     Note that the timeout is given in milliseconds, while most other
     time-related functions in Tornado use seconds.
 
+    If ``jitter`` is specified, each callback time will be randomly selected
+    within a window of ``jitter * callback_time`` milliseconds.
+    Jitter can be used to reduce alignment of events with similar periods.
+    A jitter of 0.1 means allowing a 10% variation in callback time.
+    The window is centered on ``callback_time`` so the total number of calls
+    within a given interval should not be significantly affected by adding
+    jitter.
+
     If the callback runs for longer than ``callback_time`` milliseconds,
     subsequent invocations will be skipped to get back on schedule.
 
@@ -1168,12 +1177,16 @@ class PeriodicCallback(object):
 
     .. versionchanged:: 5.0
        The ``io_loop`` argument (deprecated since version 4.1) has been removed.
+
+    .. versionchanged:: 5.1
+       The ``jitter`` argument is added.
     """
-    def __init__(self, callback, callback_time):
+    def __init__(self, callback, callback_time, jitter=0):
         self.callback = callback
         if callback_time <= 0:
             raise ValueError("Periodic callback must have a positive callback_time")
         self.callback_time = callback_time
+        self.jitter = jitter
         self._running = False
         self._timeout = None
 
@@ -1218,6 +1231,9 @@ class PeriodicCallback(object):
 
     def _update_next(self, current_time):
         callback_time_sec = self.callback_time / 1000.0
+        if self.jitter:
+            # apply jitter fraction
+            callback_time_sec *= 1 + (self.jitter * (random.random() - 0.5))
         if self._next_timeout <= current_time:
             # The period should be measured from the start of one call
             # to the start of the next. If one call takes too long,
diff --git a/lib/tornado/web.py b/lib/tornado/web.py
index 8a9a8053..4f427729 100644
--- a/lib/tornado/web.py
+++ b/lib/tornado/web.py
@@ -2825,6 +2825,7 @@ class FallbackHandler(RequestHandler):
     def prepare(self):
         self.fallback(self.request)
         self._finished = True
+        self.on_finish()
 
 
 class OutputTransform(object):
diff --git a/lib/tornado/websocket.py b/lib/tornado/websocket.py
index 91c5f1ff..738a9ccb 100644
--- a/lib/tornado/websocket.py
+++ b/lib/tornado/websocket.py
@@ -19,7 +19,6 @@ the protocol (known as "draft 76") and are not compatible with this module.
 from __future__ import absolute_import, division, print_function
 
 import base64
-import collections
 import hashlib
 import os
 import struct
@@ -34,6 +33,7 @@ from tornado.ioloop import IOLoop, PeriodicCallback
 from tornado.iostream import StreamClosedError
 from tornado.log import gen_log, app_log
 from tornado import simple_httpclient
+from tornado.queues import Queue
 from tornado.tcpclient import TCPClient
 from tornado.util import _websocket_mask, PY3
 
@@ -1096,8 +1096,7 @@ class WebSocketClientConnection(simple_httpclient._HTTPConnection):
         self.compression_options = compression_options
         self.connect_future = Future()
         self.protocol = None
-        self.read_future = None
-        self.read_queue = collections.deque()
+        self.read_queue = Queue(1)
         self.key = base64.b64encode(os.urandom(16))
         self._on_message_callback = on_message_callback
         self.close_code = self.close_reason = None
@@ -1207,12 +1206,8 @@ class WebSocketClientConnection(simple_httpclient._HTTPConnection):
         is given it will be called with the future when it is
         ready.
         """
-        assert self.read_future is None
-        future = Future()
-        if self.read_queue:
-            future_set_result_unless_cancelled(future, self.read_queue.popleft())
-        else:
-            self.read_future = future
+
+        future = self.read_queue.get()
         if callback is not None:
             self.io_loop.add_future(future, callback)
         return future
@@ -1220,11 +1215,8 @@ class WebSocketClientConnection(simple_httpclient._HTTPConnection):
     def on_message(self, message):
         if self._on_message_callback:
             self._on_message_callback(message)
-        elif self.read_future is not None:
-            future_set_result_unless_cancelled(self.read_future, message)
-            self.read_future = None
         else:
-            self.read_queue.append(message)
+            return self.read_queue.put(message)
 
     def ping(self, data=b''):
         """Send ping frame to the remote end.