488 lines
16 KiB
Python
488 lines
16 KiB
Python
from collections import defaultdict, deque
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import errno
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from functools import partial, wraps
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import logging
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import socket
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from threading import RLock, Event, Lock, Thread
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import traceback
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from Queue import Queue
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import pyev
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from cassandra import ConsistencyLevel
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from cassandra.marshal import (int8_unpack, int32_unpack)
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from cassandra.decoder import (OptionsMessage, ReadyMessage, AuthenticateMessage,
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StartupMessage, ErrorMessage, CredentialsMessage,
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QueryMessage, ResultMessage, decode_response)
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log = logging.getLogger(__name__)
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locally_supported_compressions = {}
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try:
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import snappy
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except ImportError:
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pass
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else:
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# work around apparently buggy snappy decompress
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def decompress(byts):
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if byts == '\x00':
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return ''
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return snappy.decompress(byts)
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locally_supported_compressions['snappy'] = (snappy.compress, decompress)
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MAX_STREAM_PER_CONNECTION = 128
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PROTOCOL_VERSION = 0x01
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PROTOCOL_VERSION_MASK = 0x7f
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HEADER_DIRECTION_FROM_CLIENT = 0x00
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HEADER_DIRECTION_TO_CLIENT = 0x80
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HEADER_DIRECTION_MASK = 0x80
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NONBLOCKING = (errno.EAGAIN, errno.EWOULDBLOCK)
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class ConnectionException(Exception):
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def __init__(self, message, host=None):
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Exception.__init__(self, message)
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self.host = host
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class ConnectionBusy(Exception):
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pass
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class ProgrammingError(Exception):
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pass
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class ProtocolError(Exception):
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pass
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_loop = pyev.default_loop(pyev.EVBACKEND_SELECT)
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_loop_notifier = _loop.async(lambda *a, **kw: None)
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_loop_notifier.start()
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# prevent _loop_notifier from keeping the loop from returning
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_loop.unref()
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_loop_started = None
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_loop_lock = Lock()
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def _run_loop():
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while True:
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end_condition = _loop.start()
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# there are still active watchers, no deadlock
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with _loop_lock:
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if end_condition:
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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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global _loop_started
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_loop_started = False
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break
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def _start_loop():
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global _loop_started
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should_start = False
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with _loop_lock:
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if not _loop_started:
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log.debug("Starting pyev event loop")
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_loop_started = True
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should_start = True
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if should_start:
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t = Thread(target=_run_loop, name="async_event_loop")
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t.daemon = True
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t.start()
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return should_start
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def defunct_on_error(f):
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@wraps(f)
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def wrapper(self, *args, **kwargs):
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try:
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return f(self, *args, **kwargs)
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except Exception, exc:
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self.defunct(exc)
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return wrapper
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class Connection(object):
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in_buffer_size = 4096
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out_buffer_size = 4096
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cql_version = None
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keyspace = None
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compression = True
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compressor = None
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decompressor = None
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last_error = None
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in_flight = 0
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is_defunct = False
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is_closed = False
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lock = None
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_buf = ""
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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 factory(cls, *args, **kwargs):
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conn = cls(*args, **kwargs)
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conn.connected_event.wait()
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if conn.last_error:
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raise conn.last_error
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else:
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return conn
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def __init__(self, host='127.0.0.1', port=9042, credentials=None, sockopts=None, compression=True, cql_version=None):
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self.host = host
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self.port = port
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self.credentials = credentials
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self.compression = compression
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self.cql_version = cql_version
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self.connected_event = Event()
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self._id_queue = Queue(MAX_STREAM_PER_CONNECTION)
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for i in range(MAX_STREAM_PER_CONNECTION):
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self._id_queue.put_nowait(i)
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self._callbacks = {}
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self._push_watchers = defaultdict(set)
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self.lock = RLock()
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self.id_lock = Lock()
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self.deque = deque()
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self._socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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self._socket.connect((host, port))
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self._socket.setblocking(0)
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if sockopts:
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for args in sockopts:
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self._socket.setsockopt(*args)
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self._read_watcher = pyev.Io(self._socket._sock, pyev.EV_READ, _loop, self.handle_read)
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self._write_watcher = pyev.Io(self._socket._sock, pyev.EV_WRITE, _loop, self.handle_write)
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with _loop_lock:
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self._read_watcher.start()
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self._write_watcher.start()
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log.debug("Sending initial options message for new Connection to %s" % (host,))
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self.send_msg(OptionsMessage(), self._handle_options_response)
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# start the global event loop if needed
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if not _start_loop():
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# if the loop was already started, notify it
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with _loop_lock:
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_loop_notifier.send()
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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 to %s" % (self.host,))
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if self._read_watcher:
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self._read_watcher.stop()
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if self._write_watcher:
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self._write_watcher.stop()
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self._socket.close()
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with _loop_lock:
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_loop_notifier.send()
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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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ConnectionException("Connection to %s was closed" % self.host))
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def __del__(self):
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self.close()
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def defunct(self, exc):
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log.debug("Defuncting connection to %s: %s %s" %
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(self.host, exc, traceback.format_exc(exc)))
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self.last_error = exc
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self.is_defunct = True
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self._error_all_callbacks(exc)
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self.connected_event.set()
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return exc
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def _error_all_callbacks(self, exc):
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for cb in self._callbacks.values():
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cb(exc)
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def handle_write(self, watcher, revents):
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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._write_watcher.stop()
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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, err:
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if (err.args[0] in NONBLOCKING):
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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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self.deque.appendleft(next_msg[sent:])
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if not self.deque:
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self._write_watcher.stop()
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def handle_read(self, watcher, revents):
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try:
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buf = self._socket.recv(self.in_buffer_size)
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except socket.error, err:
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if err.args[0] not in NONBLOCKING:
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self.defunct(err)
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return
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if buf:
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self._buf += buf
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while True:
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if len(self._buf) < 8:
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# we don't have a complete header yet
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break
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elif self._total_reqd_bytes and len(self._buf) < self._total_reqd_bytes:
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# we already saw a header, but we don't have a complete message yet
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break
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else:
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body_len = int32_unpack(self._buf[4:8])
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if len(self._buf) - 8 >= body_len:
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msg = self._buf[:8 + body_len]
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self._buf = self._buf[8 + body_len:]
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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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else:
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logging.debug("connection closed by server")
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self.close()
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@defunct_on_error
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def process_msg(self, msg, body_len):
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version, flags, stream_id, opcode = map(int8_unpack, msg[:4])
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if stream_id < 0:
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callback = None
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else:
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callback = self._callbacks.pop(stream_id)
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self._id_queue.put_nowait(stream_id)
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# check that the protocol version is supported
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given_version = version & PROTOCOL_VERSION_MASK
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if given_version != PROTOCOL_VERSION:
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raise ProtocolError("Unsupported CQL protocol version: %d" % given_version)
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# check that the header direction is correct
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if version & HEADER_DIRECTION_MASK != HEADER_DIRECTION_TO_CLIENT:
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raise ProtocolError(
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"Header direction in response is incorrect; opcode %04x, stream id %r"
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% (opcode, stream_id))
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if body_len > 0:
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body = msg[8:]
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elif body_len == 0:
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body = ""
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else:
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raise ProtocolError("Got negative body length: %r" % body_len)
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response = decode_response(stream_id, flags, opcode, body, self.decompressor)
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try:
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if stream_id < 0:
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self.handle_pushed(response)
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elif callback is not None:
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callback(response)
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except:
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log.exception("Callback handler errored, ignoring:")
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def handle_pushed(self, response):
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for cb in self._push_watchers[response.type]:
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try:
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cb(response)
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except:
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log.exception("Pushed event handler errored, ignoring:")
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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.lock:
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self.deque.extend(chunks)
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if not self._write_watcher.active:
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with _loop_lock:
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self._write_watcher.start()
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_loop_notifier.send()
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def send_msg(self, msg, cb):
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if self.is_defunct:
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raise ConnectionException("Connection to %s is defunct" % self.host)
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elif self.is_closed:
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raise ConnectionException("Connection to %s is closed" % self.host)
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try:
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request_id = self._id_queue.get_nowait()
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except Queue.EMPTY:
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raise ConnectionBusy(
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"Connection to %s is at the max number of requests" % self.host)
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self._callbacks[request_id] = cb
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self.push(msg.to_string(request_id, compression=self.compressor))
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return request_id
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def wait_for_response(self, msg):
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return self.wait_for_responses(msg)[0]
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def wait_for_responses(self, *msgs):
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waiter = ResponseWaiter(len(msgs))
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for i, msg in enumerate(msgs):
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self.send_msg(msg, partial(waiter.got_response, index=i))
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return waiter.deliver()
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def register_watcher(self, event_type, callback):
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self._push_watchers[event_type].add(callback)
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def register_watchers(self, type_callback_dict):
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for event_type, callback in type_callback_dict.items():
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self.register_watcher(event_type, callback)
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@defunct_on_error
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def _handle_options_response(self, options_response):
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if self.is_defunct:
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return
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log.debug("Received options response on new Connection from %s" % self.host)
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self.supported_cql_versions = options_response.cql_versions
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self.remote_supported_compressions = options_response.options['COMPRESSION']
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if self.cql_version:
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if self.cql_version not in self.supported_cql_versions:
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raise ProtocolError(
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"cql_version %r is not supported by remote (w/ native "
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"protocol). Supported versions: %r"
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% (self.cql_version, self.supported_cql_versions))
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else:
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self.cql_version = self.supported_cql_versions[0]
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opts = {}
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self._compressor = None
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if self.compression:
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overlap = (set(locally_supported_compressions.keys()) &
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set(self.remote_supported_compressions))
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if len(overlap) == 0:
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log.debug("No available compression types supported on both ends."
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" locally supported: %r. remotely supported: %r"
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% (locally_supported_compressions.keys(),
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self.remote_supported_compressions))
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else:
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compression_type = iter(overlap).next() # choose any
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opts['COMPRESSION'] = compression_type
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# set the decompressor here, but set the compressor only after
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# a successful Ready message
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self._compressor, self.decompressor = \
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locally_supported_compressions[compression_type]
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sm = StartupMessage(cqlversion=self.cql_version, options=opts)
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self.send_msg(sm, cb=self._handle_startup_response)
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@defunct_on_error
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def _handle_startup_response(self, startup_response):
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if self.is_defunct:
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return
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if isinstance(startup_response, ReadyMessage):
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log.debug("Got ReadyMessage on new Connection from %s" % self.host)
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if self._compressor:
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self.compressor = self._compressor
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self.connected_event.set()
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elif isinstance(startup_response, AuthenticateMessage):
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log.debug("Got AuthenticateMessage on new Connection from %s" % self.host)
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if self.credentials is None:
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raise ProgrammingError('Remote end requires authentication.')
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self.authenticator = startup_response.authenticator
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cm = CredentialsMessage(creds=self.credentials)
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self.send_msg(cm, cb=self._handle_startup_response)
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elif isinstance(startup_response, ErrorMessage):
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log.debug("Received ErrorMessage on new Connection from %s: %s"
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% (self.host, startup_response.summary_msg()))
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raise ConnectionException(
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"Failed to initialize new connection to %s: %s"
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% (self.host, startup_response.summary_msg()))
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else:
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msg = "Unexpected response during Connection setup: %r" % (startup_response,)
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log.error(msg)
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raise ProtocolError(msg)
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def set_keyspace(self, keyspace):
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if not keyspace or keyspace == self.keyspace:
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return
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with self.lock:
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query = 'USE "%s"' % (keyspace,)
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try:
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result = self.wait_for_response(
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QueryMessage(query=query, consistency_level=ConsistencyLevel.ONE))
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if isinstance(result, ResultMessage):
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self.keyspace = keyspace
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else:
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raise self.defunct(ConnectionException(
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"Problem while setting keyspace: %r" % (result,), self.host))
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except Exception, exc:
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raise self.defunct(ConnectionException(
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"Problem while setting keyspace: %r" % (exc,), self.host))
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class ResponseWaiter(object):
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def __init__(self, num_responses):
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self.pending = num_responses
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self.error = None
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self.responses = [None] * num_responses
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self.event = Event()
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def got_response(self, response, index):
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if isinstance(response, Exception):
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self.error = response
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self.event.set()
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else:
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self.responses[index] = response
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self.pending -= 1
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if not self.pending:
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self.event.set()
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def deliver(self):
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self.event.wait()
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if self.error:
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raise self.error
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else:
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return self.responses
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