420 lines
14 KiB
Python
420 lines
14 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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from __future__ import absolute_import # to enable import io from stdlib
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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 io
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import logging
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import os
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import socket
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from threading import Event, Lock, Thread
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import weakref
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from six.moves import xrange
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from cassandra import OperationTimedOut
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from cassandra.connection import Connection, ConnectionShutdown, NONBLOCKING
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from cassandra.protocol import RegisterMessage
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from cassandra.marshal import int32_unpack
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try:
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import cassandra.io.libevwrapper as libev
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except ImportError:
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raise ImportError(
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"The C extension needed to use libev was not found. This "
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"probably means that you didn't have the required build dependencies "
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"when installing the driver. See "
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"http://datastax.github.io/python-driver/installation.html#c-extensions "
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"for instructions on installing build dependencies and building "
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"the C extension.")
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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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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 LibevLoop(object):
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def __init__(self):
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self._pid = os.getpid()
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self._loop = libev.Loop()
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self._notifier = libev.Async(self._loop)
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self._notifier.start()
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# prevent _notifier from keeping the loop from returning
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self._loop.unref()
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self._started = False
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self._shutdown = False
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self._lock = Lock()
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self._thread = None
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# set of all connections; only replaced with a new copy
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# while holding _conn_set_lock, never modified in place
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self._live_conns = set()
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# newly created connections that need their write/read watcher started
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self._new_conns = set()
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# recently closed connections that need their write/read watcher stopped
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self._closed_conns = set()
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self._conn_set_lock = Lock()
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self._preparer = libev.Prepare(self._loop, self._loop_will_run)
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# prevent _preparer from keeping the loop from returning
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self._loop.unref()
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self._preparer.start()
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atexit.register(partial(_cleanup, weakref.ref(self)))
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def notify(self):
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self._notifier.send()
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def maybe_start(self):
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should_start = False
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with self._lock:
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if not self._started:
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log.debug("Starting libev event loop")
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self._started = True
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should_start = True
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if should_start:
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self._thread = Thread(target=self._run_loop, name="event_loop")
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self._thread.daemon = True
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self._thread.start()
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self._notifier.send()
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def _run_loop(self):
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while True:
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end_condition = self._loop.start()
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# there are still active watchers, no deadlock
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with self._lock:
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if not self._shutdown and (end_condition or self._live_conns):
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log.debug("Restarting event loop")
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continue
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else:
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# all Connections have been closed, no active watchers
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log.debug("All Connections currently closed, event loop ended")
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self._started = False
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break
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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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for conn in self._live_conns | self._new_conns | self._closed_conns:
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conn.close()
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if conn._write_watcher:
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conn._write_watcher.stop()
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del conn._write_watcher
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if conn._read_watcher:
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conn._read_watcher.stop()
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del conn._read_watcher
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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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self._loop = None
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def connection_created(self, conn):
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with self._conn_set_lock:
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new_live_conns = self._live_conns.copy()
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new_live_conns.add(conn)
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self._live_conns = new_live_conns
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new_new_conns = self._new_conns.copy()
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new_new_conns.add(conn)
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self._new_conns = new_new_conns
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def connection_destroyed(self, conn):
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with self._conn_set_lock:
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new_live_conns = self._live_conns.copy()
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new_live_conns.discard(conn)
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self._live_conns = new_live_conns
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new_closed_conns = self._closed_conns.copy()
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new_closed_conns.add(conn)
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self._closed_conns = new_closed_conns
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self._notifier.send()
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def _loop_will_run(self, prepare):
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changed = False
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for conn in self._live_conns:
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if not conn.deque and conn._write_watcher_is_active:
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if conn._write_watcher:
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conn._write_watcher.stop()
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conn._write_watcher_is_active = False
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changed = True
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elif conn.deque and not conn._write_watcher_is_active:
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conn._write_watcher.start()
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conn._write_watcher_is_active = True
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changed = True
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if self._new_conns:
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with self._conn_set_lock:
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to_start = self._new_conns
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self._new_conns = set()
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for conn in to_start:
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conn._read_watcher.start()
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changed = True
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if self._closed_conns:
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with self._conn_set_lock:
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to_stop = self._closed_conns
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self._closed_conns = set()
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for conn in to_stop:
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if conn._write_watcher:
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conn._write_watcher.stop()
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# clear reference cycles from IO callback
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del conn._write_watcher
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if conn._read_watcher:
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conn._read_watcher.stop()
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# clear reference cycles from IO callback
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del conn._read_watcher
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changed = True
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if changed:
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self._notifier.send()
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class LibevConnection(Connection):
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"""
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An implementation of :class:`.Connection` that uses libev for its event loop.
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"""
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_libevloop = None
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_write_watcher_is_active = False
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_total_reqd_bytes = 0
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_read_watcher = None
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_write_watcher = None
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_socket = None
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@classmethod
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def initialize_reactor(cls):
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if not cls._libevloop:
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cls._libevloop = LibevLoop()
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else:
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if cls._libevloop._pid != os.getpid():
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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._libevloop = LibevLoop()
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@classmethod
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def handle_fork(cls):
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if cls._libevloop:
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cls._libevloop._cleanup()
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cls._libevloop = 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 new 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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self.connected_event = Event()
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self._iobuf = io.BytesIO()
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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._socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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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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self._socket = ssl.wrap_socket(self._socket, **self.ssl_options)
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self._socket.settimeout(1.0) # TODO potentially make this value configurable
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self._socket.connect((self.host, self.port))
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self._socket.setblocking(0)
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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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with self._libevloop._lock:
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self._read_watcher = libev.IO(self._socket.fileno(), libev.EV_READ, self._libevloop._loop, self.handle_read)
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self._write_watcher = libev.IO(self._socket.fileno(), libev.EV_WRITE, self._libevloop._loop, self.handle_write)
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self._send_options_message()
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self._libevloop.connection_created(self)
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# start the global event loop if needed
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self._libevloop.maybe_start()
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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._libevloop.connection_destroyed(self)
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self._socket.close()
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log.debug("Closed socket to %s", self.host)
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# don't leave in-progress operations hanging
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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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def handle_write(self, watcher, revents, errno=None):
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if revents & libev.EV_ERROR:
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if errno:
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exc = IOError(errno, os.strerror(errno))
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else:
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exc = Exception("libev reported an error")
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self.defunct(exc)
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return
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while True:
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try:
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with self._deque_lock:
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next_msg = self.deque.popleft()
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except IndexError:
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return
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try:
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sent = self._socket.send(next_msg)
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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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def handle_read(self, watcher, revents, errno=None):
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if revents & libev.EV_ERROR:
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if errno:
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exc = IOError(errno, os.strerror(errno))
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else:
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exc = Exception("libev reported an error")
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self.defunct(exc)
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return
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try:
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while True:
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buf = self._socket.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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while True:
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pos = self._iobuf.tell()
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if pos < 8 or (self._total_reqd_bytes > 0 and pos < self._total_reqd_bytes):
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# we don't have a complete header yet or we
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# already saw a header, but we don't have a
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# complete message yet
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break
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else:
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# have enough for header, read body len from header
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self._iobuf.seek(4)
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body_len = int32_unpack(self._iobuf.read(4))
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# seek to end to get length of current buffer
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self._iobuf.seek(0, os.SEEK_END)
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pos = self._iobuf.tell()
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if pos >= body_len + 8:
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# read message header and body
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self._iobuf.seek(0)
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msg = self._iobuf.read(8 + body_len)
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# leave leftover in current buffer
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leftover = self._iobuf.read()
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self._iobuf = io.BytesIO()
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self._iobuf.write(leftover)
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self._total_reqd_bytes = 0
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self.process_msg(msg, body_len)
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else:
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self._total_reqd_bytes = body_len + 8
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break
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else:
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log.debug("Connection %s closed by server", self)
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self.close()
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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 xrange(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._libevloop.notify()
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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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