Source code for cassandra.connection

# 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.

from __future__ import absolute_import  # to enable import io from stdlib
from collections import defaultdict, deque
import errno
from functools import wraps, partial
from heapq import heappush, heappop
import io
import logging
import six
from six.moves import range
import socket
import struct
import sys
from threading import Thread, Event, RLock
import time

    import ssl
except ImportError:
    ssl = None  # NOQA

if 'gevent.monkey' in sys.modules:
    from gevent.queue import Queue, Empty
    from six.moves.queue import Queue, Empty  # noqa

from cassandra import ConsistencyLevel, AuthenticationFailed, OperationTimedOut, ProtocolVersion
from cassandra.marshal import int32_pack
from cassandra.protocol import (ReadyMessage, AuthenticateMessage, OptionsMessage,
                                StartupMessage, ErrorMessage, CredentialsMessage,
                                QueryMessage, ResultMessage, ProtocolHandler,
                                InvalidRequestException, SupportedMessage,
                                AuthResponseMessage, AuthChallengeMessage,
                                AuthSuccessMessage, ProtocolException,
from cassandra.util import OrderedDict

log = logging.getLogger(__name__)

# We use an ordered dictionary and specifically add lz4 before
# snappy so that lz4 will be preferred. Changing the order of this
# will change the compression preferences for the driver.
locally_supported_compressions = OrderedDict()

    import lz4
except ImportError:
    # The compress and decompress functions we need were moved from the lz4 to
    # the lz4.block namespace, so we try both here.
        from lz4 import block as lz4_block
    except ImportError:
        lz4_block = lz4

    # Cassandra writes the uncompressed message length in big endian order,
    # but the lz4 lib requires little endian order, so we wrap these
    # functions to handle that

    def lz4_compress(byts):
        # write length in big-endian instead of little-endian
        return int32_pack(len(byts)) + lz4_block.compress(byts)[4:]

    def lz4_decompress(byts):
        # flip from big-endian to little-endian
        return lz4_block.decompress(byts[3::-1] + byts[4:])

    locally_supported_compressions['lz4'] = (lz4_compress, lz4_decompress)

    import snappy
except ImportError:
    # work around apparently buggy snappy decompress
    def decompress(byts):
        if byts == '\x00':
            return ''
        return snappy.decompress(byts)
    locally_supported_compressions['snappy'] = (snappy.compress, decompress)



frame_header_v1_v2 = struct.Struct('>BbBi')
frame_header_v3 = struct.Struct('>BhBi')

class _Frame(object):
    def __init__(self, version, flags, stream, opcode, body_offset, end_pos):
        self.version = version
        self.flags = flags = stream
        self.opcode = opcode
        self.body_offset = body_offset
        self.end_pos = end_pos

    def __eq__(self, other):  # facilitates testing
        if isinstance(other, _Frame):
            return (self.version == other.version and
                    self.flags == other.flags and
           == and
                    self.opcode == other.opcode and
                    self.body_offset == other.body_offset and
                    self.end_pos == other.end_pos)
        return NotImplemented

    def __str__(self):
        return "ver({0}); flags({1:04b}); stream({2}); op({3}); offset({4}); len({5})".format(self.version, self.flags,, self.opcode, self.body_offset, self.end_pos - self.body_offset)


[docs]class ConnectionException(Exception): """ An unrecoverable error was hit when attempting to use a connection, or the connection was already closed or defunct. """ def __init__(self, message, host=None): Exception.__init__(self, message) = host
[docs]class ConnectionShutdown(ConnectionException): """ Raised when a connection has been marked as defunct or has been closed. """ pass
class ProtocolVersionUnsupported(ConnectionException): """ Server rejected startup message due to unsupported protocol version """ def __init__(self, host, startup_version): msg = "Unsupported protocol version on %s: %d" % (host, startup_version) super(ProtocolVersionUnsupported, self).__init__(msg, host) self.startup_version = startup_version
[docs]class ConnectionBusy(Exception): """ An attempt was made to send a message through a :class:`.Connection` that was already at the max number of in-flight operations. """ pass
[docs]class ProtocolError(Exception): """ Communication did not match the protocol that this driver expects. """ pass
def defunct_on_error(f): @wraps(f) def wrapper(self, *args, **kwargs): try: return f(self, *args, **kwargs) except Exception as exc: self.defunct(exc) return wrapper DEFAULT_CQL_VERSION = '3.0.0' if six.PY3: def int_from_buf_item(i): return i else: int_from_buf_item = ord class Connection(object): CALLBACK_ERR_THREAD_THRESHOLD = 100 in_buffer_size = 4096 out_buffer_size = 4096 cql_version = None no_compact = False protocol_version = ProtocolVersion.MAX_SUPPORTED keyspace = None compression = True compressor = None decompressor = None ssl_options = None last_error = None # The current number of operations that are in flight. More precisely, # the number of request IDs that are currently in use. in_flight = 0 # Max concurrent requests allowed per connection. This is set optimistically high, allowing # all request ids to be used in protocol version 3+. Normally concurrency would be controlled # at a higher level by the application or concurrent.execute_concurrent. This attribute # is for lower-level integrations that want some upper bound without reimplementing. max_in_flight = 2 ** 15 # A set of available request IDs. When using the v3 protocol or higher, # this will not initially include all request IDs in order to save memory, # but the set will grow if it is exhausted. request_ids = None # Tracks the highest used request ID in order to help with growing the # request_ids set highest_request_id = 0 is_defunct = False is_closed = False lock = None user_type_map = None msg_received = False is_unsupported_proto_version = False is_control_connection = False signaled_error = False # used for flagging at the pool level allow_beta_protocol_version = False _iobuf = None _current_frame = None _socket = None _socket_impl = socket _ssl_impl = ssl _check_hostname = False def __init__(self, host='', port=9042, authenticator=None, ssl_options=None, sockopts=None, compression=True, cql_version=None, protocol_version=ProtocolVersion.MAX_SUPPORTED, is_control_connection=False, user_type_map=None, connect_timeout=None, allow_beta_protocol_version=False, no_compact=False): = host self.port = port self.authenticator = authenticator self.ssl_options = ssl_options.copy() if ssl_options else None self.sockopts = sockopts self.compression = compression self.cql_version = cql_version self.protocol_version = protocol_version self.is_control_connection = is_control_connection self.user_type_map = user_type_map self.connect_timeout = connect_timeout self.allow_beta_protocol_version = allow_beta_protocol_version self.no_compact = no_compact self._push_watchers = defaultdict(set) self._requests = {} self._iobuf = io.BytesIO() if ssl_options: self._check_hostname = bool(self.ssl_options.pop('check_hostname', False)) if self._check_hostname: if not getattr(ssl, 'match_hostname', None): raise RuntimeError("ssl_options specify 'check_hostname', but ssl.match_hostname is not provided. " "Patch or upgrade Python to use this option.") if protocol_version >= 3: self.max_request_id = min(self.max_in_flight - 1, (2 ** 15) - 1) # Don't fill the deque with 2**15 items right away. Start with some and add # more if needed. initial_size = min(300, self.max_in_flight) self.request_ids = deque(range(initial_size)) self.highest_request_id = initial_size - 1 else: self.max_request_id = min(self.max_in_flight, (2 ** 7) - 1) self.request_ids = deque(range(self.max_request_id + 1)) self.highest_request_id = self.max_request_id self.lock = RLock() self.connected_event = Event() @classmethod def initialize_reactor(cls): """ Called once by Cluster.connect(). This should be used by implementations to set up any resources that will be shared across connections. """ pass @classmethod def handle_fork(cls): """ Called after a forking. This should cleanup any remaining reactor state from the parent process. """ pass @classmethod def create_timer(cls, timeout, callback): raise NotImplementedError() @classmethod def factory(cls, host, timeout, *args, **kwargs): """ A factory function which returns connections which have succeeded in connecting and are ready for service (or raises an exception otherwise). """ start = time.time() kwargs['connect_timeout'] = timeout conn = cls(host, *args, **kwargs) elapsed = time.time() - start conn.connected_event.wait(timeout - elapsed) if conn.last_error: if conn.is_unsupported_proto_version: raise ProtocolVersionUnsupported(host, conn.protocol_version) raise conn.last_error elif not conn.connected_event.is_set(): conn.close() raise OperationTimedOut("Timed out creating connection (%s seconds)" % timeout) else: return conn def _connect_socket(self): sockerr = None addresses = socket.getaddrinfo(, self.port, socket.AF_UNSPEC, socket.SOCK_STREAM) if not addresses: raise ConnectionException("getaddrinfo returned empty list for %s" % (,)) for (af, socktype, proto, canonname, sockaddr) in addresses: try: self._socket = self._socket_impl.socket(af, socktype, proto) if self.ssl_options: if not self._ssl_impl: raise RuntimeError("This version of Python was not compiled with SSL support") self._socket = self._ssl_impl.wrap_socket(self._socket, **self.ssl_options) self._socket.settimeout(self.connect_timeout) self._socket.connect(sockaddr) self._socket.settimeout(None) if self._check_hostname: ssl.match_hostname(self._socket.getpeercert(), sockerr = None break except socket.error as err: if self._socket: self._socket.close() self._socket = None sockerr = err if sockerr: raise socket.error(sockerr.errno, "Tried connecting to %s. Last error: %s" % ([a[4] for a in addresses], sockerr.strerror or sockerr)) if self.sockopts: for args in self.sockopts: self._socket.setsockopt(*args) def close(self): raise NotImplementedError() def defunct(self, exc): with self.lock: if self.is_defunct or self.is_closed: return self.is_defunct = True exc_info = sys.exc_info() # if we are not handling an exception, just use the passed exception, and don't try to format exc_info with the message if any(exc_info): log.debug("Defuncting connection (%s) to %s:", id(self),, exc_info=exc_info) else: log.debug("Defuncting connection (%s) to %s: %s", id(self),, exc) self.last_error = exc self.close() self.error_all_requests(exc) self.connected_event.set() return exc def error_all_requests(self, exc): with self.lock: requests = self._requests self._requests = {} if not requests: return new_exc = ConnectionShutdown(str(exc)) def try_callback(cb): try: cb(new_exc) except Exception: log.warning("Ignoring unhandled exception while erroring requests for a " "failed connection (%s) to host %s:", id(self),, exc_info=True) # run first callback from this thread to ensure pool state before leaving cb, _, _ = requests.popitem()[1] try_callback(cb) if not requests: return # additional requests are optionally errored from a separate thread # The default callback and retry logic is fairly expensive -- we don't # want to tie up the event thread when there are many requests def err_all_callbacks(): for cb, _, _ in requests.values(): try_callback(cb) if len(requests) < Connection.CALLBACK_ERR_THREAD_THRESHOLD: err_all_callbacks() else: # daemon thread here because we want to stay decoupled from the cluster TPE # TODO: would it make sense to just have a driver-global TPE? t = Thread(target=err_all_callbacks) t.daemon = True t.start() def get_request_id(self): """ This must be called while self.lock is held. """ try: return self.request_ids.popleft() except IndexError: new_request_id = self.highest_request_id + 1 # in_flight checks should guarantee this assert new_request_id <= self.max_request_id self.highest_request_id = new_request_id return self.highest_request_id def handle_pushed(self, response): log.debug("Message pushed from server: %r", response) for cb in self._push_watchers.get(response.event_type, []): try: cb(response.event_args) except Exception: log.exception("Pushed event handler errored, ignoring:") def send_msg(self, msg, request_id, cb, encoder=ProtocolHandler.encode_message, decoder=ProtocolHandler.decode_message, result_metadata=None): if self.is_defunct: raise ConnectionShutdown("Connection to %s is defunct" % elif self.is_closed: raise ConnectionShutdown("Connection to %s is closed" % # queue the decoder function with the request # this allows us to inject custom functions per request to encode, decode messages self._requests[request_id] = (cb, decoder, result_metadata) msg = encoder(msg, request_id, self.protocol_version, compressor=self.compressor, allow_beta_protocol_version=self.allow_beta_protocol_version) self.push(msg) return len(msg) def wait_for_response(self, msg, timeout=None): return self.wait_for_responses(msg, timeout=timeout)[0] def wait_for_responses(self, *msgs, **kwargs): """ Returns a list of (success, response) tuples. If success is False, response will be an Exception. Otherwise, response will be the normal query response. If fail_on_error was left as True and one of the requests failed, the corresponding Exception will be raised. """ if self.is_closed or self.is_defunct: raise ConnectionShutdown("Connection %s is already closed" % (self, )) timeout = kwargs.get('timeout') fail_on_error = kwargs.get('fail_on_error', True) waiter = ResponseWaiter(self, len(msgs), fail_on_error) # busy wait for sufficient space on the connection messages_sent = 0 while True: needed = len(msgs) - messages_sent with self.lock: available = min(needed, self.max_request_id - self.in_flight + 1) request_ids = [self.get_request_id() for _ in range(available)] self.in_flight += available for i, request_id in enumerate(request_ids): self.send_msg(msgs[messages_sent + i], request_id, partial(waiter.got_response, index=messages_sent + i)) messages_sent += available if messages_sent == len(msgs): break else: if timeout is not None: timeout -= 0.01 if timeout <= 0.0: raise OperationTimedOut() time.sleep(0.01) try: return waiter.deliver(timeout) except OperationTimedOut: raise except Exception as exc: self.defunct(exc) raise def register_watcher(self, event_type, callback, register_timeout=None): """ Register a callback for a given event type. """ self._push_watchers[event_type].add(callback) self.wait_for_response( RegisterMessage(event_list=[event_type]), timeout=register_timeout) def register_watchers(self, type_callback_dict, register_timeout=None): """ Register multiple callback/event type pairs, expressed as a dict. """ for event_type, callback in type_callback_dict.items(): self._push_watchers[event_type].add(callback) self.wait_for_response( RegisterMessage(event_list=type_callback_dict.keys()), timeout=register_timeout) def control_conn_disposed(self): self.is_control_connection = False self._push_watchers = {} @defunct_on_error def _read_frame_header(self): buf = self._iobuf.getvalue() pos = len(buf) if pos: version = int_from_buf_item(buf[0]) & PROTOCOL_VERSION_MASK if version > ProtocolVersion.MAX_SUPPORTED: raise ProtocolError("This version of the driver does not support protocol version %d" % version) frame_header = frame_header_v3 if version >= 3 else frame_header_v1_v2 # this frame header struct is everything after the version byte header_size = frame_header.size + 1 if pos >= header_size: flags, stream, op, body_len = frame_header.unpack_from(buf, 1) if body_len < 0: raise ProtocolError("Received negative body length: %r" % body_len) self._current_frame = _Frame(version, flags, stream, op, header_size, body_len + header_size) return pos def _reset_frame(self): self._iobuf = io.BytesIO(, 2) # io.SEEK_END == 2 (constant not present in 2.6) self._current_frame = None def process_io_buffer(self): while True: if not self._current_frame: pos = self._read_frame_header() else: pos = self._iobuf.tell() if not self._current_frame or pos < self._current_frame.end_pos: # we don't have a complete header yet or we # already saw a header, but we don't have a # complete message yet return else: frame = self._current_frame msg = - frame.body_offset) self.process_msg(frame, msg) self._reset_frame() @defunct_on_error def process_msg(self, header, body): self.msg_received = True stream_id = if stream_id < 0: callback = None decoder = ProtocolHandler.decode_message result_metadata = None else: try: callback, decoder, result_metadata = self._requests.pop(stream_id) # This can only happen if the stream_id was # removed due to an OperationTimedOut except KeyError: return with self.lock: self.request_ids.append(stream_id) try: response = decoder(header.version, self.user_type_map, stream_id, header.flags, header.opcode, body, self.decompressor, result_metadata) except Exception as exc: log.exception("Error decoding response from Cassandra. " "%s; buffer: %r", header, self._iobuf.getvalue()) if callback is not None: callback(exc) self.defunct(exc) return try: if stream_id >= 0: if isinstance(response, ProtocolException): if 'unsupported protocol version' in response.message: self.is_unsupported_proto_version = True else: log.error("Closing connection %s due to protocol error: %s", self, response.summary_msg()) self.defunct(response) if callback is not None: callback(response) else: self.handle_pushed(response) except Exception: log.exception("Callback handler errored, ignoring:") @defunct_on_error def _send_options_message(self): if self.cql_version is None and (not self.compression or not locally_supported_compressions): log.debug("Not sending options message for new connection(%s) to %s " "because compression is disabled and a cql version was not " "specified", id(self), self._compressor = None self.cql_version = DEFAULT_CQL_VERSION self._send_startup_message(no_compact=self.no_compact) else: log.debug("Sending initial options message for new connection (%s) to %s", id(self), self.send_msg(OptionsMessage(), self.get_request_id(), self._handle_options_response) @defunct_on_error def _handle_options_response(self, options_response): if self.is_defunct: return if not isinstance(options_response, SupportedMessage): if isinstance(options_response, ConnectionException): raise options_response else: log.error("Did not get expected SupportedMessage response; " "instead, got: %s", options_response) raise ConnectionException("Did not get expected SupportedMessage " "response; instead, got: %s" % (options_response,)) log.debug("Received options response on new connection (%s) from %s", id(self), supported_cql_versions = options_response.cql_versions remote_supported_compressions = options_response.options['COMPRESSION'] if self.cql_version: if self.cql_version not in supported_cql_versions: raise ProtocolError( "cql_version %r is not supported by remote (w/ native " "protocol). Supported versions: %r" % (self.cql_version, supported_cql_versions)) else: self.cql_version = supported_cql_versions[0] self._compressor = None compression_type = None if self.compression: overlap = (set(locally_supported_compressions.keys()) & set(remote_supported_compressions)) if len(overlap) == 0: log.debug("No available compression types supported on both ends." " locally supported: %r. remotely supported: %r", locally_supported_compressions.keys(), remote_supported_compressions) else: compression_type = None if isinstance(self.compression, six.string_types): # the user picked a specific compression type ('snappy' or 'lz4') if self.compression not in remote_supported_compressions: raise ProtocolError( "The requested compression type (%s) is not supported by the Cassandra server at %s" % (self.compression, compression_type = self.compression else: # our locally supported compressions are ordered to prefer # lz4, if available for k in locally_supported_compressions.keys(): if k in overlap: compression_type = k break # set the decompressor here, but set the compressor only after # a successful Ready message self._compressor, self.decompressor = \ locally_supported_compressions[compression_type] self._send_startup_message(compression_type, no_compact=self.no_compact) @defunct_on_error def _send_startup_message(self, compression=None, no_compact=False): log.debug("Sending StartupMessage on %s", self) opts = {} if compression: opts['COMPRESSION'] = compression if no_compact: opts['NO_COMPACT'] = 'true' sm = StartupMessage(cqlversion=self.cql_version, options=opts) self.send_msg(sm, self.get_request_id(), cb=self._handle_startup_response) log.debug("Sent StartupMessage on %s", self) @defunct_on_error def _handle_startup_response(self, startup_response, did_authenticate=False): if self.is_defunct: return if isinstance(startup_response, ReadyMessage): log.debug("Got ReadyMessage on new connection (%s) from %s", id(self), if self._compressor: self.compressor = self._compressor self.connected_event.set() elif isinstance(startup_response, AuthenticateMessage): log.debug("Got AuthenticateMessage on new connection (%s) from %s: %s", id(self),, startup_response.authenticator) if self.authenticator is None: raise AuthenticationFailed('Remote end requires authentication.') if isinstance(self.authenticator, dict): log.debug("Sending credentials-based auth response on %s", self) cm = CredentialsMessage(creds=self.authenticator) callback = partial(self._handle_startup_response, did_authenticate=True) self.send_msg(cm, self.get_request_id(), cb=callback) else: log.debug("Sending SASL-based auth response on %s", self) self.authenticator.server_authenticator_class = startup_response.authenticator initial_response = self.authenticator.initial_response() initial_response = "" if initial_response is None else initial_response self.send_msg(AuthResponseMessage(initial_response), self.get_request_id(), self._handle_auth_response) elif isinstance(startup_response, ErrorMessage): log.debug("Received ErrorMessage on new connection (%s) from %s: %s", id(self),, startup_response.summary_msg()) if did_authenticate: raise AuthenticationFailed( "Failed to authenticate to %s: %s" % (, startup_response.summary_msg())) else: raise ConnectionException( "Failed to initialize new connection to %s: %s" % (, startup_response.summary_msg())) elif isinstance(startup_response, ConnectionShutdown): log.debug("Connection to %s was closed during the startup handshake", ( raise startup_response else: msg = "Unexpected response during Connection setup: %r" log.error(msg, startup_response) raise ProtocolError(msg % (startup_response,)) @defunct_on_error def _handle_auth_response(self, auth_response): if self.is_defunct: return if isinstance(auth_response, AuthSuccessMessage): log.debug("Connection %s successfully authenticated", self) self.authenticator.on_authentication_success(auth_response.token) if self._compressor: self.compressor = self._compressor self.connected_event.set() elif isinstance(auth_response, AuthChallengeMessage): response = self.authenticator.evaluate_challenge(auth_response.challenge) msg = AuthResponseMessage("" if response is None else response) log.debug("Responding to auth challenge on %s", self) self.send_msg(msg, self.get_request_id(), self._handle_auth_response) elif isinstance(auth_response, ErrorMessage): log.debug("Received ErrorMessage on new connection (%s) from %s: %s", id(self),, auth_response.summary_msg()) raise AuthenticationFailed( "Failed to authenticate to %s: %s" % (, auth_response.summary_msg())) elif isinstance(auth_response, ConnectionShutdown): log.debug("Connection to %s was closed during the authentication process", raise auth_response else: msg = "Unexpected response during Connection authentication to %s: %r" log.error(msg,, auth_response) raise ProtocolError(msg % (, auth_response)) def set_keyspace_blocking(self, keyspace): if not keyspace or keyspace == self.keyspace: return query = QueryMessage(query='USE "%s"' % (keyspace,), consistency_level=ConsistencyLevel.ONE) try: result = self.wait_for_response(query) except InvalidRequestException as ire: # the keyspace probably doesn't exist raise ire.to_exception() except Exception as exc: conn_exc = ConnectionException( "Problem while setting keyspace: %r" % (exc,), self.defunct(conn_exc) raise conn_exc if isinstance(result, ResultMessage): self.keyspace = keyspace else: conn_exc = ConnectionException( "Problem while setting keyspace: %r" % (result,), self.defunct(conn_exc) raise conn_exc def set_keyspace_async(self, keyspace, callback): """ Use this in order to avoid deadlocking the event loop thread. When the operation completes, `callback` will be called with two arguments: this connection and an Exception if an error occurred, otherwise :const:`None`. This method will always increment :attr:`.in_flight` attribute, even if it doesn't need to make a request, just to maintain an ":attr:`.in_flight` is incremented" invariant. """ # Here we increment in_flight unconditionally, whether we need to issue # a request or not. This is bad, but allows callers -- specifically # _set_keyspace_for_all_conns -- to assume that we increment # self.in_flight during this call. This allows the passed callback to # safely call HostConnection{Pool,}.return_connection on this # Connection. # # We use a busy wait on the lock here because: # - we'll only spin if the connection is at max capacity, which is very # unlikely for a set_keyspace call # - it allows us to avoid signaling a condition every time a request completes while True: with self.lock: if self.in_flight < self.max_request_id: self.in_flight += 1 break time.sleep(0.001) if not keyspace or keyspace == self.keyspace: callback(self, None) return query = QueryMessage(query='USE "%s"' % (keyspace,), consistency_level=ConsistencyLevel.ONE) def process_result(result): if isinstance(result, ResultMessage): self.keyspace = keyspace callback(self, None) elif isinstance(result, InvalidRequestException): callback(self, result.to_exception()) else: callback(self, self.defunct(ConnectionException( "Problem while setting keyspace: %r" % (result,), # We've incremented self.in_flight above, so we "have permission" to # acquire a new request id request_id = self.get_request_id() self.send_msg(query, request_id, process_result) @property def is_idle(self): return not self.msg_received def reset_idle(self): self.msg_received = False def __str__(self): status = "" if self.is_defunct: status = " (defunct)" elif self.is_closed: status = " (closed)" return "<%s(%r) %s:%d%s>" % (self.__class__.__name__, id(self),, self.port, status) __repr__ = __str__ class ResponseWaiter(object): def __init__(self, connection, num_responses, fail_on_error): self.connection = connection self.pending = num_responses self.fail_on_error = fail_on_error self.error = None self.responses = [None] * num_responses self.event = Event() def got_response(self, response, index): with self.connection.lock: self.connection.in_flight -= 1 if isinstance(response, Exception): if hasattr(response, 'to_exception'): response = response.to_exception() if self.fail_on_error: self.error = response self.event.set() else: self.responses[index] = (False, response) else: if not self.fail_on_error: self.responses[index] = (True, response) else: self.responses[index] = response self.pending -= 1 if not self.pending: self.event.set() def deliver(self, timeout=None): """ If fail_on_error was set to False, a list of (success, response) tuples will be returned. If success is False, response will be an Exception. Otherwise, response will be the normal query response. If fail_on_error was left as True and one of the requests failed, the corresponding Exception will be raised. Otherwise, the normal response will be returned. """ self.event.wait(timeout) if self.error: raise self.error elif not self.event.is_set(): raise OperationTimedOut() else: return self.responses class HeartbeatFuture(object): def __init__(self, connection, owner): self._exception = None self._event = Event() self.connection = connection self.owner = owner log.debug("Sending options message heartbeat on idle connection (%s) %s", id(connection), with connection.lock: if connection.in_flight <= connection.max_request_id: connection.in_flight += 1 connection.send_msg(OptionsMessage(), connection.get_request_id(), self._options_callback) else: self._exception = Exception("Failed to send heartbeat because connection 'in_flight' exceeds threshold") self._event.set() def wait(self, timeout): self._event.wait(timeout) if self._event.is_set(): if self._exception: raise self._exception else: raise OperationTimedOut("Connection heartbeat timeout after %s seconds" % (timeout,), def _options_callback(self, response): if isinstance(response, SupportedMessage): log.debug("Received options response on connection (%s) from %s", id(self.connection), else: if isinstance(response, ConnectionException): self._exception = response else: self._exception = ConnectionException("Received unexpected response to OptionsMessage: %s" % (response,)) self._event.set() class ConnectionHeartbeat(Thread): def __init__(self, interval_sec, get_connection_holders, timeout): Thread.__init__(self, name="Connection heartbeat") self._interval = interval_sec self._timeout = timeout self._get_connection_holders = get_connection_holders self._shutdown_event = Event() self.daemon = True self.start() class ShutdownException(Exception): pass def run(self): self._shutdown_event.wait(self._interval) while not self._shutdown_event.is_set(): start_time = time.time() futures = [] failed_connections = [] try: for connections, owner in [(o.get_connections(), o) for o in self._get_connection_holders()]: for connection in connections: self._raise_if_stopped() if not (connection.is_defunct or connection.is_closed): if connection.is_idle: try: futures.append(HeartbeatFuture(connection, owner)) except Exception as e: log.warning("Failed sending heartbeat message on connection (%s) to %s", id(connection), failed_connections.append((connection, owner, e)) else: connection.reset_idle() else: log.debug("Cannot send heartbeat message on connection (%s) to %s", id(connection), # make sure the owner sees this defunt/closed connection owner.return_connection(connection) self._raise_if_stopped() # Wait max `self._timeout` seconds for all HeartbeatFutures to complete timeout = self._timeout start_time = time.time() for f in futures: self._raise_if_stopped() connection = f.connection try: f.wait(timeout) # TODO: move this, along with connection locks in pool, down into Connection with connection.lock: connection.in_flight -= 1 connection.reset_idle() except Exception as e: log.warning("Heartbeat failed for connection (%s) to %s", id(connection), failed_connections.append((f.connection, f.owner, e)) timeout = self._timeout - (time.time() - start_time) for connection, owner, exc in failed_connections: self._raise_if_stopped() if not connection.is_control_connection: # Only HostConnection supports shutdown_on_error owner.shutdown_on_error = True connection.defunct(exc) owner.return_connection(connection) except self.ShutdownException: pass except Exception: log.error("Failed connection heartbeat", exc_info=True) elapsed = time.time() - start_time self._shutdown_event.wait(max(self._interval - elapsed, 0.01)) def stop(self): self._shutdown_event.set() self.join() def _raise_if_stopped(self): if self._shutdown_event.is_set(): raise self.ShutdownException() class Timer(object): canceled = False def __init__(self, timeout, callback): self.end = time.time() + timeout self.callback = callback def __lt__(self, other): return self.end < other.end def cancel(self): self.canceled = True def finish(self, time_now): if self.canceled: return True if time_now >= self.end: self.callback() return True return False class TimerManager(object): def __init__(self): self._queue = [] self._new_timers = [] def add_timer(self, timer): """ called from client thread with a Timer object """ self._new_timers.append((timer.end, timer)) def service_timeouts(self): """ run callbacks on all expired timers Called from the event thread :return: next end time, or None """ queue = self._queue if self._new_timers: new_timers = self._new_timers while new_timers: heappush(queue, new_timers.pop()) if queue: now = time.time() while queue: try: timer = queue[0][1] if timer.finish(now): heappop(queue) else: return timer.end except Exception: log.exception("Exception while servicing timeout callback: ") @property def next_timeout(self): try: return self._queue[0][0] except IndexError: pass