339 lines
10 KiB
Python
339 lines
10 KiB
Python
# Copyright 2013-2014 DataStax, Inc.
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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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import atexit
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from collections import deque
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from functools import partial
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import logging
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import os
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import socket
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import sys
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from threading import Event, Lock, Thread
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import weakref
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from six.moves import range
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from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, EINVAL, EISCONN, errorcode
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try:
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from weakref import WeakSet
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except ImportError:
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from cassandra.util import WeakSet # noqa
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import asyncore
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try:
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import ssl
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except ImportError:
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ssl = None # NOQA
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from cassandra import OperationTimedOut
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from cassandra.connection import (Connection, ConnectionShutdown,
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ConnectionException, NONBLOCKING)
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from cassandra.protocol import RegisterMessage
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log = logging.getLogger(__name__)
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def _cleanup(loop_weakref):
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try:
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loop = loop_weakref()
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except ReferenceError:
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return
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loop._cleanup()
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class AsyncoreLoop(object):
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def __init__(self):
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self._pid = os.getpid()
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self._loop_lock = Lock()
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self._started = False
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self._shutdown = False
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self._conns_lock = Lock()
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self._conns = WeakSet()
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self._thread = None
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atexit.register(partial(_cleanup, weakref.ref(self)))
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def maybe_start(self):
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should_start = False
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did_acquire = False
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try:
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did_acquire = self._loop_lock.acquire(False)
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if did_acquire and not self._started:
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self._started = True
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should_start = True
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finally:
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if did_acquire:
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self._loop_lock.release()
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if should_start:
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self._thread = Thread(target=self._run_loop, name="cassandra_driver_event_loop")
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self._thread.daemon = True
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self._thread.start()
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def _run_loop(self):
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log.debug("Starting asyncore event loop")
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with self._loop_lock:
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while True:
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try:
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asyncore.loop(timeout=0.001, use_poll=True, count=1000)
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except Exception:
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log.debug("Asyncore event loop stopped unexepectedly", exc_info=True)
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break
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if self._shutdown:
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break
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with self._conns_lock:
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if len(self._conns) == 0:
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break
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self._started = False
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log.debug("Asyncore event loop ended")
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def _cleanup(self):
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self._shutdown = True
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if not self._thread:
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return
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log.debug("Waiting for event loop thread to join...")
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self._thread.join(timeout=1.0)
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if self._thread.is_alive():
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log.warning(
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"Event loop thread could not be joined, so shutdown may not be clean. "
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"Please call Cluster.shutdown() to avoid this.")
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log.debug("Event loop thread was joined")
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def connection_created(self, connection):
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with self._conns_lock:
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self._conns.add(connection)
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def connection_destroyed(self, connection):
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with self._conns_lock:
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self._conns.discard(connection)
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class AsyncoreConnection(Connection, asyncore.dispatcher):
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"""
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An implementation of :class:`.Connection` that uses the ``asyncore``
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module in the Python standard library for its event loop.
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"""
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_loop = None
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_total_reqd_bytes = 0
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_writable = False
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_readable = False
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@classmethod
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def initialize_reactor(cls):
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if not cls._loop:
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cls._loop = AsyncoreLoop()
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else:
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current_pid = os.getpid()
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if cls._loop._pid != current_pid:
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log.debug("Detected fork, clearing and reinitializing reactor state")
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cls.handle_fork()
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cls._loop = AsyncoreLoop()
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@classmethod
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def handle_fork(cls):
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if cls._loop:
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cls._loop._cleanup()
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cls._loop = None
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@classmethod
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def factory(cls, *args, **kwargs):
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timeout = kwargs.pop('timeout', 5.0)
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conn = cls(*args, **kwargs)
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conn.connected_event.wait(timeout)
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if conn.last_error:
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raise conn.last_error
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elif not conn.connected_event.is_set():
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conn.close()
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raise OperationTimedOut("Timed out creating connection")
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else:
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return conn
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def __init__(self, *args, **kwargs):
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Connection.__init__(self, *args, **kwargs)
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asyncore.dispatcher.__init__(self)
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self.connected_event = Event()
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self._callbacks = {}
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self.deque = deque()
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self.deque_lock = Lock()
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self._loop.connection_created(self)
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self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
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self.connect((self.host, self.port))
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self.add_channel()
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if self.sockopts:
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for args in self.sockopts:
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self.socket.setsockopt(*args)
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self._writable = True
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self._readable = True
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# start the event loop if needed
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self._loop.maybe_start()
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def set_socket(self, sock):
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# Overrides the same method in asyncore. We deliberately
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# do not call add_channel() in this method so that we can call
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# it later, after connect() has completed.
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self.socket = sock
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self._fileno = sock.fileno()
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def create_socket(self, family, type):
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# copied from asyncore, but with the line to set the socket in
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# non-blocking mode removed (we will do that after connecting)
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self.family_and_type = family, type
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sock = socket.socket(family, type)
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if self.ssl_options:
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if not ssl:
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raise Exception("This version of Python was not compiled with SSL support")
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sock = ssl.wrap_socket(sock, **self.ssl_options)
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self.set_socket(sock)
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def connect(self, address):
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# this is copied directly from asyncore.py, except that
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# a timeout is set before connecting
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self.connected = False
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self.connecting = True
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self.socket.settimeout(1.0)
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err = self.socket.connect_ex(address)
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if err in (EINPROGRESS, EALREADY, EWOULDBLOCK) \
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or err == EINVAL and os.name in ('nt', 'ce'):
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raise ConnectionException("Timed out connecting to %s" % (address[0]))
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if err in (0, EISCONN):
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self.addr = address
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self.socket.setblocking(0)
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self.handle_connect_event()
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else:
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raise socket.error(err, errorcode[err])
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def close(self):
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with self.lock:
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if self.is_closed:
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return
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self.is_closed = True
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log.debug("Closing connection (%s) to %s", id(self), self.host)
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self._writable = False
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self._readable = False
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asyncore.dispatcher.close(self)
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log.debug("Closed socket to %s", self.host)
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self._loop.connection_destroyed(self)
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if not self.is_defunct:
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self.error_all_callbacks(
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ConnectionShutdown("Connection to %s was closed" % self.host))
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# don't leave in-progress operations hanging
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self.connected_event.set()
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def handle_connect(self):
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self._send_options_message()
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def handle_error(self):
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self.defunct(sys.exc_info()[1])
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def handle_close(self):
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log.debug("Connection %s closed by server", self)
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self.close()
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def handle_write(self):
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while True:
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with self.deque_lock:
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try:
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next_msg = self.deque.popleft()
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except IndexError:
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self._writable = False
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return
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try:
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sent = self.send(next_msg)
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self._readable = True
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except socket.error as err:
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if (err.args[0] in NONBLOCKING):
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with self.deque_lock:
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self.deque.appendleft(next_msg)
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else:
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self.defunct(err)
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return
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else:
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if sent < len(next_msg):
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with self.deque_lock:
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self.deque.appendleft(next_msg[sent:])
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if sent == 0:
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return
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def handle_read(self):
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try:
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while True:
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buf = self.recv(self.in_buffer_size)
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self._iobuf.write(buf)
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if len(buf) < self.in_buffer_size:
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break
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except socket.error as err:
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if ssl and isinstance(err, ssl.SSLError):
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if err.args[0] not in (ssl.SSL_ERROR_WANT_READ, ssl.SSL_ERROR_WANT_WRITE):
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self.defunct(err)
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return
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elif err.args[0] not in NONBLOCKING:
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self.defunct(err)
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return
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if self._iobuf.tell():
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self.process_io_buffer()
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if not self._callbacks and not self.is_control_connection:
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self._readable = False
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def push(self, data):
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sabs = self.out_buffer_size
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if len(data) > sabs:
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chunks = []
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for i in range(0, len(data), sabs):
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chunks.append(data[i:i + sabs])
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else:
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chunks = [data]
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with self.deque_lock:
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self.deque.extend(chunks)
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self._writable = True
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def writable(self):
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return self._writable
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def readable(self):
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return self._readable or (self.is_control_connection and not (self.is_defunct or self.is_closed))
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def register_watcher(self, event_type, callback, register_timeout=None):
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self._push_watchers[event_type].add(callback)
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self.wait_for_response(
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RegisterMessage(event_list=[event_type]), timeout=register_timeout)
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def register_watchers(self, type_callback_dict, register_timeout=None):
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for event_type, callback in type_callback_dict.items():
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self._push_watchers[event_type].add(callback)
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self.wait_for_response(
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RegisterMessage(event_list=type_callback_dict.keys()), timeout=register_timeout)
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