[CalendarServer-changes] [12760] CalendarServer/trunk/calendarserver/webadmin/test/eventsource.py
source_changes at macosforge.org
source_changes at macosforge.org
Wed Feb 26 18:34:09 PST 2014
Revision: 12760
http://trac.calendarserver.org//changeset/12760
Author: wsanchez at apple.com
Date: 2014-02-26 18:34:09 -0800 (Wed, 26 Feb 2014)
Log Message:
-----------
New module for EventSource code.
Added Paths:
-----------
CalendarServer/trunk/calendarserver/webadmin/test/eventsource.py
Added: CalendarServer/trunk/calendarserver/webadmin/test/eventsource.py
===================================================================
--- CalendarServer/trunk/calendarserver/webadmin/test/eventsource.py (rev 0)
+++ CalendarServer/trunk/calendarserver/webadmin/test/eventsource.py 2014-02-27 02:34:09 UTC (rev 12760)
@@ -0,0 +1,224 @@
+# -*- test-case-name: calendarserver.webadmin.test.test_principals -*-
+##
+# Copyright (c) 2014 Apple Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+##
+
+from __future__ import print_function
+
+"""
+Calendar Server principal management web UI.
+"""
+
+__all__ = [
+ "textAsEvent",
+ "EventSourceResource",
+]
+
+from collections import deque
+
+from zope.interface import implementer, Interface
+
+from twisted.internet.defer import succeed
+
+from txweb2.stream import IByteStream, fallbackSplit
+from txweb2.resource import Resource
+from txweb2.http_headers import MimeType
+from txweb2.http import Response
+
+
+def textAsEvent(text, eventID=None, eventClass=None):
+ """
+ Format some text as an HTML5 EventSource event. Since the EventSource data
+ format is text-oriented, this function expects L{unicode}, not L{bytes};
+ binary data should be encoded as text if it is to be used in an EventSource
+ stream.
+
+ @param text: The text (ie. the message) to send in the event.
+ @type text: L{unicode}
+
+ @param eventID: An unique identifier for the event.
+ @type eventID: L{unicode}
+
+ @param eventClass: A class name (ie. a categorization) for the event.
+ @type eventClass: L{unicode}
+
+ @return: An HTML5 EventSource event as text.
+ @rtype: L{unicode}
+ """
+ event = []
+
+ if eventID is not None:
+ event.append(u"id: {0}".format(eventID))
+
+ if eventClass is not None:
+ event.append(u"event: {0}".format(eventClass))
+
+ event.extend(
+ u"data: {0}".format(l) for l in text.split("\n")
+ )
+
+ return u"\n".join(event) + u"\n\n"
+
+
+
+class IEventDecoder(Interface):
+ """
+ An object that can be used to extract data from an application-specific
+ event object for encoding into an EventSource data stream.
+ """
+
+ def idForEvent(event):
+ """
+ @return: An unique identifier for the given event.
+ @rtype: L{unicode}
+ """
+
+ def classForEvent(event):
+ """
+ @return: A class name (ie. a categorization) for the event.
+ @rtype: L{unicode}
+ """
+
+ def textForEvent(event):
+ """
+ @return: The text (ie. the message) to send in the event.
+ @rtype: L{unicode}
+ """
+
+
+
+class EventSourceResource(Resource):
+ """
+ Resource that vends HTML5 EventSource events.
+
+ Events are stored in a ring buffer and streamed to clients.
+ """
+
+ addSlash = False
+
+
+ def __init__(self, eventDecoder, bufferSize=400):
+ """
+ @param eventDecoder: An object that can be used to extract data from
+ an event for encoding into an EventSource data stream.
+ @type eventDecoder: L{IEventDecoder}
+
+ @param bufferSize: The maximum number of events to keep in the ring
+ buffer.
+ @type bufferSize: L{int}
+ """
+ Resource.__init__(self)
+
+ self._events = deque(maxlen=bufferSize)
+
+
+ def render(self, request):
+ lastID = request.headers.getRawHeaders(u"last-event-id")
+
+ response = Response()
+ response.stream = EventStream(self._eventDecoder, self._events, lastID)
+ response.headers.setHeader(
+ b"content-type", MimeType.fromString(b"text/event-stream")
+ )
+ return response
+
+
+
+ at implementer(IByteStream)
+class EventStream(object):
+ """
+ L{IByteStream} that streams out HTML5 EventSource events.
+ """
+
+ length = None
+
+
+ def __init__(self, eventDecoder, events, lastID):
+ """
+ @param eventDecoder: An object that can be used to extract data from
+ an event for encoding into an EventSource data stream.
+ @type eventDecoder: L{IEventDecoder}
+
+ @param events: Application-specific event objects.
+ @type events: sequence of L{object}
+
+ @param lastID: The identifier for the last event that was vended from
+ C{events}. Vending will resume starting from the following event.
+ @type lastID: L{int}
+ """
+ object.__init__(self)
+
+ self._eventDecoder = eventDecoder
+ self._events = events
+ self._lastID = lastID
+ self._closed = False
+
+
+ def addEvent(self, event):
+ self._events.append(event)
+
+
+ def read(self):
+ if self._closed:
+ return None
+
+ lastID = self._lastID
+ eventID = None
+
+ idForEvent = self.eventDecoder.idForEvent
+ classForEvent = self.eventDecoder.classForEvent
+ textForEvent = self.eventDecoder.textForEvent
+
+ for event in self._events:
+ eventID = idForEvent(event)
+
+ # If lastID is not None, skip messages up to and including the one
+ # referenced by lastID.
+ if lastID is not None:
+ if eventID == lastID:
+ eventID = None
+ lastID = None
+
+ continue
+
+ eventClass = classForEvent(event)
+ eventText = textForEvent(event)
+
+ return succeed(
+ textAsEvent(eventText, eventID, eventClass).encode("utf-8")
+ )
+
+
+ if eventID is not None:
+ # We just scanned all the messages, and none are the last one the
+ # client saw.
+ self._lastID = None
+
+ return succeed("")
+
+ return succeed(None)
+
+ # from twisted.internet.task import deferLater
+ # from twisted.internet import reactor
+
+ # return deferLater(reactor, 1.0, self.read)
+
+
+ def split(self, point):
+ return fallbackSplit(self, point)
+
+
+ def close(self):
+ self._closed = True
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