Source code for

# Copyright 2014 Symantec Corporation
# Copyright DataStax, Inc.
# 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
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

# Originally derived from MagnetoDB source:

import eventlet
from import socket
from eventlet.queue import Queue
from greenlet import GreenletExit
import logging
from threading import Event
import time

from six.moves import xrange

from cassandra.connection import Connection, ConnectionShutdown, Timer, TimerManager

log = logging.getLogger(__name__)

[docs]class EventletConnection(Connection): """ An implementation of :class:`.Connection` that utilizes ``eventlet``. This implementation assumes all eventlet monkey patching is active. It is not tested with partial patching. """ _read_watcher = None _write_watcher = None _socket_impl = _ssl_impl = _timers = None _timeout_watcher = None _new_timer = None @classmethod def initialize_reactor(cls): eventlet.monkey_patch() if not cls._timers: cls._timers = TimerManager() cls._timeout_watcher = eventlet.spawn(cls.service_timeouts) cls._new_timer = Event() @classmethod def create_timer(cls, timeout, callback): timer = Timer(timeout, callback) cls._timers.add_timer(timer) cls._new_timer.set() return timer
[docs] @classmethod def service_timeouts(cls): """ cls._timeout_watcher runs in this loop forever. It is usually waiting for the next timeout on the cls._new_timer Event. When new timers are added, that event is set so that the watcher can wake up and possibly set an earlier timeout. """ timer_manager = cls._timers while True: next_end = timer_manager.service_timeouts() sleep_time = max(next_end - time.time(), 0) if next_end else 10000 cls._new_timer.wait(sleep_time) cls._new_timer.clear()
def __init__(self, *args, **kwargs): Connection.__init__(self, *args, **kwargs) self._write_queue = Queue() self._connect_socket() self._read_watcher = eventlet.spawn(lambda: self.handle_read()) self._write_watcher = eventlet.spawn(lambda: self.handle_write()) self._send_options_message() def close(self): with self.lock: if self.is_closed: return self.is_closed = True log.debug("Closing connection (%s) to %s" % (id(self), cur_gthread = eventlet.getcurrent() if self._read_watcher and self._read_watcher != cur_gthread: self._read_watcher.kill() if self._write_watcher and self._write_watcher != cur_gthread: self._write_watcher.kill() if self._socket: self._socket.close() log.debug("Closed socket to %s" % (,)) if not self.is_defunct: self.error_all_requests( ConnectionShutdown("Connection to %s was closed" % # don't leave in-progress operations hanging self.connected_event.set() def handle_close(self): log.debug("connection closed by server") self.close() def handle_write(self): while True: try: next_msg = self._write_queue.get() self._socket.sendall(next_msg) except socket.error as err: log.debug("Exception during socket send for %s: %s", self, err) self.defunct(err) return # Leave the write loop except GreenletExit: # graceful greenthread exit return def handle_read(self): while True: try: buf = self._socket.recv(self.in_buffer_size) self._iobuf.write(buf) except socket.error as err: log.debug("Exception during socket recv for %s: %s", self, err) self.defunct(err) return # leave the read loop except GreenletExit: # graceful greenthread exit return if buf and self._iobuf.tell(): self.process_io_buffer() else: log.debug("Connection %s closed by server", self) self.close() return def push(self, data): chunk_size = self.out_buffer_size for i in xrange(0, len(data), chunk_size): self._write_queue.put(data[i:i + chunk_size])