/usr/lib/python2.7/dist-packages/oslo_messaging/_drivers/amqp1_driver/eventloop.py is in python-oslo.messaging 5.10.0-2.
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#
# 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.
"""
A thread that performs all messaging I/O and protocol event handling.
This module provides a background thread that handles messaging operations
scheduled via the Controller, and performs blocking socket I/O and timer
processing. This thread is designed to be as simple as possible - all the
protocol specific intelligence is provided by the Controller and executed on
the background thread via callables.
"""
import errno
import heapq
import logging
import math
from monotonic import monotonic as now # noqa
import os
import select
import socket
import threading
import uuid
import pyngus
from six import moves
from oslo_messaging._i18n import _LE, _LI, _LW
LOG = logging.getLogger(__name__)
def compute_timeout(offset):
# minimize the timer granularity to one second so we don't have to track
# too many timers
return math.ceil(now() + offset)
class _SocketConnection(object):
"""Associates a pyngus Connection with a python network socket,
and handles all connection-related I/O and timer events.
"""
def __init__(self, name, container, properties, handler):
self.name = name
self.socket = None
self._properties = properties
# The handler is a pyngus ConnectionEventHandler, which is invoked by
# pyngus on connection-related events (active, closed, error, etc).
# Currently it is the Controller object.
self._handler = handler
self._container = container
self.connection = None
def fileno(self):
"""Allows use of a _SocketConnection in a select() call.
"""
return self.socket.fileno()
def read(self):
"""Called when socket is read-ready."""
while True:
try:
rc = pyngus.read_socket_input(self.connection, self.socket)
self.connection.process(now())
return rc
except (socket.timeout, socket.error) as e:
# pyngus handles EAGAIN/EWOULDBLOCK and EINTER
self.connection.close_input()
self.connection.close_output()
self._handler.socket_error(str(e))
return pyngus.Connection.EOS
def write(self):
"""Called when socket is write-ready."""
while True:
try:
rc = pyngus.write_socket_output(self.connection, self.socket)
self.connection.process(now())
return rc
except (socket.timeout, socket.error) as e:
# pyngus handles EAGAIN/EWOULDBLOCK and EINTER
self.connection.close_output()
self.connection.close_input()
self._handler.socket_error(str(e))
return pyngus.Connection.EOS
def connect(self, host):
"""Connect to host and start the AMQP protocol."""
addr = socket.getaddrinfo(host.hostname, host.port,
socket.AF_INET, socket.SOCK_STREAM)
if not addr:
key = "%s:%i" % (host.hostname, host.port)
error = "Invalid peer address '%s'" % key
LOG.error(_LE("Invalid peer address '%s'"), key)
self._handler.socket_error(error)
return
my_socket = socket.socket(addr[0][0], addr[0][1], addr[0][2])
my_socket.setblocking(0) # 0=non-blocking
my_socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
try:
my_socket.connect(addr[0][4])
except socket.error as e:
if e.errno != errno.EINPROGRESS:
error = "Socket connect failure '%s'" % str(e)
LOG.error(_LE("Socket connect failure '%s'"), str(e))
self._handler.socket_error(error)
return
self.socket = my_socket
props = self._properties.copy()
if pyngus.VERSION >= (2, 0, 0):
# configure client authentication
#
props['x-server'] = False
if host.username:
props['x-username'] = host.username
props['x-password'] = host.password or ""
c = self._container.create_connection(self.name, self._handler, props)
c.user_context = self
self.connection = c
if pyngus.VERSION < (2, 0, 0):
# older versions of pyngus requires manual SASL configuration:
# determine the proper SASL mechanism: PLAIN if a username/password
# is present, else ANONYMOUS
pn_sasl = self.connection.pn_sasl
if host.username:
password = host.password if host.password else ""
pn_sasl.plain(host.username, password)
else:
pn_sasl.mechanisms("ANONYMOUS")
pn_sasl.client()
self.connection.open()
def reset(self, name=None):
"""Clean up the current state, expect 'connect()' to be recalled
later.
"""
# note well: since destroy() is called on the connection, do not invoke
# this method from a pyngus callback!
if self.connection:
self.connection.destroy()
self.connection = None
self.close()
if name:
self.name = name
def close(self):
if self.socket:
self.socket.close()
self.socket = None
class Scheduler(object):
"""Schedule callables to be run in the future.
"""
class Event(object):
# simply hold a reference to a callback that can be set to None if the
# alarm is canceled
def __init__(self, callback):
self.callback = callback
def cancel(self):
# quicker than rebalancing the tree
self.callback = None
def __init__(self):
self._callbacks = {}
self._deadlines = []
def alarm(self, request, deadline):
"""Request a callable be executed at a specific time
"""
try:
callbacks = self._callbacks[deadline]
except KeyError:
callbacks = list()
self._callbacks[deadline] = callbacks
heapq.heappush(self._deadlines, deadline)
entry = Scheduler.Event(request)
callbacks.append(entry)
return entry
def defer(self, request, delay):
"""Request a callable be executed after delay seconds
"""
return self.alarm(request, compute_timeout(delay))
@property
def _next_deadline(self):
"""The timestamp of the next expiring event or None
"""
return self._deadlines[0] if self._deadlines else None
def _get_delay(self, max_delay=None):
"""Get the delay in milliseconds until the next callable needs to be
run, or 'max_delay' if no outstanding callables or the delay to the
next callable is > 'max_delay'.
"""
due = self._deadlines[0] if self._deadlines else None
if due is None:
return max_delay
_now = now()
if due <= _now:
return 0
else:
return min(due - _now, max_delay) if max_delay else due - _now
def _process(self):
"""Invoke all expired callables."""
if self._deadlines:
_now = now()
try:
while self._deadlines[0] <= _now:
deadline = heapq.heappop(self._deadlines)
callbacks = self._callbacks[deadline]
del self._callbacks[deadline]
for cb in callbacks:
cb.callback and cb.callback()
except IndexError:
pass
class Requests(object):
"""A queue of callables to execute from the eventloop thread's main
loop.
"""
def __init__(self):
self._requests = moves.queue.Queue(maxsize=10)
self._wakeup_pipe = os.pipe()
def wakeup(self, request=None):
"""Enqueue a callable to be executed by the eventloop, and force the
eventloop thread to wake up from select().
"""
if request:
self._requests.put(request)
os.write(self._wakeup_pipe[1], b'!')
def fileno(self):
"""Allows this request queue to be used by select()."""
return self._wakeup_pipe[0]
def read(self):
"""Invoked by the eventloop thread, execute each queued callable."""
os.read(self._wakeup_pipe[0], 512)
# first pop of all current tasks
requests = []
while not self._requests.empty():
requests.append(self._requests.get())
# then process them, this allows callables to re-register themselves to
# be run on the next iteration of the I/O loop
for r in requests:
r()
class Thread(threading.Thread):
"""Manages socket I/O and executes callables queued up by external
threads.
"""
def __init__(self, container_name, node, command, pid):
super(Thread, self).__init__()
# callables from other threads:
self._requests = Requests()
# delayed callables (only used on this thread for now):
self._scheduler = Scheduler()
# Configure a container
if container_name is None:
container_name = ("openstack.org/om/container/%s/%s/%s/%s" %
(node, command, pid, uuid.uuid4().hex))
self._container = pyngus.Container(container_name)
self.name = "Thread for Proton container: %s" % self._container.name
self._shutdown = False
self.daemon = True
self.start()
def wakeup(self, request=None):
"""Wake up the eventloop thread, Optionally providing a callable to run
when the eventloop wakes up. Thread safe.
"""
self._requests.wakeup(request)
def shutdown(self):
"""Shutdown the eventloop thread. Thread safe.
"""
LOG.debug("eventloop shutdown requested")
self._shutdown = True
self.wakeup()
def destroy(self):
# release the container. This can only be called after the eventloop
# thread exited
self._container.destroy()
self._container = None
# the following methods are not thread safe - they must be run from the
# eventloop thread
def defer(self, request, delay):
"""Invoke request after delay seconds."""
return self._scheduler.defer(request, delay)
def alarm(self, request, deadline):
"""Invoke request at a particular time"""
return self._scheduler.alarm(request, deadline)
def connect(self, host, handler, properties):
"""Get a _SocketConnection to a peer represented by url."""
key = "openstack.org/om/connection/%s:%s/" % (host.hostname, host.port)
# return pre-existing
conn = self._container.get_connection(key)
if conn:
return conn.user_context
# create a new connection - this will be stored in the
# container, using the specified name as the lookup key, or if
# no name was provided, the host:port combination
sc = _SocketConnection(key, self._container,
properties, handler=handler)
sc.connect(host)
return sc
def run(self):
"""Run the proton event/timer loop."""
LOG.debug("Starting Proton thread, container=%s",
self._container.name)
while not self._shutdown:
readers, writers, timers = self._container.need_processing()
readfds = [c.user_context for c in readers]
# additionally, always check for readability of pipe we
# are using to wakeup processing thread by other threads
readfds.append(self._requests)
writefds = [c.user_context for c in writers]
# force select to return in time to service the next expiring timer
d1 = self._scheduler._next_deadline
d2 = timers[0].deadline if timers else None
deadline = min(d1, d2) if d1 and d2 else d1 if not d2 else d2
if deadline:
_now = now()
timeout = 0 if deadline <= _now else (deadline - _now)
else:
timeout = None
# and now we wait...
try:
results = select.select(readfds, writefds, [], timeout)
except select.error as serror:
if serror[0] == errno.EINTR:
LOG.warning(_LW("ignoring interrupt from select(): %s"),
str(serror))
continue
raise # assuming fatal...
readable, writable, ignore = results
for r in readable:
r.read()
if timers:
_now = now()
for t in timers:
if t.deadline > _now:
break
t.process(_now)
for w in writable:
w.write()
self._scheduler._process() # run any deferred requests
LOG.info(_LI("eventloop thread exiting, container=%s"),
self._container.name)
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