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2bf9a6d415
Since browsers can be stingy with websockets, have the consoles all share a single websocket.
201 lines
7.1 KiB
Python
201 lines
7.1 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2016-2018 Lenovo
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# Overall, the result of this shall be:
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# - Web clients can create the same out-of-order responsiveness as socket
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# clients (but with more complexity on their end)
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# - Web clients can share single request among console sessions
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# - Web clients can get async notify of things like node add/remove, events
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# This provides an async strategy to http clients. The design is that a http
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# session may have an 'async' resource. In such a case, any requests are
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# queued and immediately the response is given accepting the queued request.
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# A request flags itself as queue-compatible through an HTTP header indicating
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# the identifier of the async thread. As responses happen to the queued
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# request, data is dispatched to the first registered poller for data on
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# the session. This way, a client may elect to provide multiple pollers
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# to mitigate general choppiness of http network pattern. It may not be
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# worth it, but it's possible.
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# Additionally support console session multiplexing, to mitigate needed
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# connection count.
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# Also, this should allow a client to register for notifications of things
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# like node add/delete or an event firing, ultimately.
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# Much like console sessions, these will be reaped if a client spends too
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# far away.
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import collections
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import confluent.exceptions as exc
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import confluent.messages as messages
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import confluent.util as util
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import eventlet
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import greenlet
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import time
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_asyncsessions = {}
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_cleanthread = None
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_consolesessions = None
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def _assign_asyncid(asyncsession):
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sessid = util.randomstring(32)
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while sessid in _asyncsessions:
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sessid = util.randomstring(32)
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_asyncsessions[sessid] = {'asyncsession': asyncsession}
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return sessid
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class AsyncTermRelation(object):
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# Need to keep an association of term object to async
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# This allows the async handler to know the context of
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# outgoing data to provide to calling code
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def __init__(self, termid, asynchdl):
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self.asynchdl = asynchdl
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self.termid = termid
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def got_data(self, data):
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self.asynchdl.add(self.termid, data)
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class AsyncSession(object):
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def __init__(self, wshandler=None):
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self.asyncid = _assign_asyncid(self)
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self.responses = collections.deque()
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self.wshandler = wshandler
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self._evt = None
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self.termrelations = []
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self.consoles = set([])
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if not wshandler:
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self.reaper = eventlet.spawn_after(15, self.destroy)
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def add(self, requestid, rsp):
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if self.wshandler:
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self.wshandler(messages.AsyncMessage((requestid, rsp)))
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if self.responses is None:
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return
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self.responses.append((requestid, rsp))
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if self._evt:
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self._evt.send()
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self._evt = None
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def set_term_relation(self, env):
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# need a term relation to keep track of what data belongs
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# to what object (since the callback does not provide context
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# for data, and here ultimately the client is responsible
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# for sorting out which is which.
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termrel = AsyncTermRelation(env['HTTP_CONFLUENTREQUESTID'], self)
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self.termrelations.append(termrel)
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return termrel
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def add_console_session(self, sessionid):
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self.consoles.add(sessionid)
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def destroy(self):
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if self._evt:
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self._evt.send()
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self._evt = None
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for console in self.consoles:
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_consolesessions[console]['session'].destroy()
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self.consoles = set([])
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self.responses = None
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del _asyncsessions[self.asyncid]
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def run_handler(self, handler, requestid):
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try:
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for rsp in handler:
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self.add(requestid, rsp)
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self.add(requestid, messages.AsyncCompletion())
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except Exception as e:
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self.add(requestid, e)
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def get_responses(self, timeout=25):
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self.reaper.cancel()
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self.reaper = eventlet.spawn_after(timeout + 15, self.destroy)
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nextexpiry = time.time() + 90
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for csess in list(self.consoles):
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try:
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_consolesessions[csess]['expiry'] = nextexpiry
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except KeyError: # session has been closed elsewhere
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self.consoles.discard(csess)
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if self._evt:
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# TODO(jjohnson2): This precludes the goal of 'double barreled'
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# access.... revisit if this could matter
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raise Exception('get_responses is not re-entrant')
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if not self.responses: # wait to accumulate some
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self._evt = eventlet.event.Event()
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with eventlet.Timeout(timeout, False):
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self._evt.wait()
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self._evt = None
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while self.responses:
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yield self.responses.popleft()
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def run_handler(hdlr, env):
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asyncsessid = env['HTTP_CONFLUENTASYNCID']
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try:
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asyncsession = _asyncsessions[asyncsessid]['asyncsession']
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requestid = env['HTTP_CONFLUENTREQUESTID']
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except KeyError:
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raise exc.InvalidArgumentException(
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'Invalid Session ID or missing request id')
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eventlet.spawn_n(asyncsession.run_handler, hdlr, requestid)
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return requestid
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def get_async(env, querydict):
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global _cleanthread
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return _asyncsessions[env['HTTP_CONFLUENTASYNCID']]['asyncsession']
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def handle_async(env, querydict, threadset, wshandler=None):
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global _cleanthread
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# This may be one of two things, a request for a new async stream
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# or a request for next data from async stream
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# httpapi otherwise handles requests an injecting them to queue
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if 'asyncid' not in querydict or not querydict['asyncid']:
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# This is a new request, create a new multiplexer
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currsess = AsyncSession(wshandler)
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if wshandler:
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yield currsess
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return
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yield messages.AsyncSession(currsess.asyncid)
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return
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if querydict['asyncid'] not in _asyncsessions:
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raise exc.InvalidArgumentException(
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'Invalid or expired async id')
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mythreadid = greenlet.getcurrent()
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threadset.add(mythreadid)
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loggedout = None
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currsess = None
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try:
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currsess = _asyncsessions[querydict['asyncid']]['asyncsession']
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for rsp in currsess.get_responses():
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yield messages.AsyncMessage(rsp)
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except greenlet.GreenletExit as ge:
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loggedout = ge
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threadset.discard(mythreadid)
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if loggedout is not None:
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currsess.destroy()
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raise exc.LoggedOut()
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def set_console_sessions(consolesessions):
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global _consolesessions
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_consolesessions = consolesessions
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