46d1cc1316
The query was being resubmitted on the event loop thread, which could cause a deadlock if there were not any connections available for use.
2074 lines
77 KiB
Python
2074 lines
77 KiB
Python
"""
|
|
This module houses the main classes you will interact with,
|
|
:class:`.Cluster` and :class:`.Session`.
|
|
"""
|
|
|
|
from concurrent.futures import ThreadPoolExecutor
|
|
import logging
|
|
import sys
|
|
import time
|
|
from threading import Lock, RLock, Thread, Event
|
|
import Queue
|
|
import weakref
|
|
try:
|
|
from weakref import WeakSet
|
|
except ImportError:
|
|
from cassandra.util import WeakSet # NOQA
|
|
|
|
from functools import partial, wraps
|
|
from itertools import groupby
|
|
|
|
from cassandra import ConsistencyLevel, AuthenticationFailed, OperationTimedOut
|
|
from cassandra.connection import ConnectionException, ConnectionShutdown
|
|
from cassandra.decoder import (QueryMessage, ResultMessage,
|
|
ErrorMessage, ReadTimeoutErrorMessage,
|
|
WriteTimeoutErrorMessage,
|
|
UnavailableErrorMessage,
|
|
OverloadedErrorMessage,
|
|
PrepareMessage, ExecuteMessage,
|
|
PreparedQueryNotFound,
|
|
IsBootstrappingErrorMessage, named_tuple_factory,
|
|
dict_factory)
|
|
from cassandra.metadata import Metadata
|
|
from cassandra.metrics import Metrics
|
|
from cassandra.policies import (RoundRobinPolicy, SimpleConvictionPolicy,
|
|
ExponentialReconnectionPolicy, HostDistance,
|
|
RetryPolicy)
|
|
from cassandra.query import (SimpleStatement, PreparedStatement, BoundStatement,
|
|
bind_params, QueryTrace, Statement)
|
|
from cassandra.pool import (_ReconnectionHandler, _HostReconnectionHandler,
|
|
HostConnectionPool)
|
|
|
|
# libev is all around faster, so we want to try and default to using that when we can
|
|
try:
|
|
from cassandra.io.libevreactor import LibevConnection as DefaultConnection
|
|
except ImportError:
|
|
from cassandra.io.asyncorereactor import AsyncoreConnection as DefaultConnection # NOQA
|
|
|
|
# Forces load of utf8 encoding module to avoid deadlock that occurs
|
|
# if code that is being imported tries to import the module in a seperate
|
|
# thread.
|
|
# See http://bugs.python.org/issue10923
|
|
"".encode('utf8')
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
|
|
DEFAULT_MIN_REQUESTS = 5
|
|
DEFAULT_MAX_REQUESTS = 100
|
|
|
|
DEFAULT_MIN_CONNECTIONS_PER_LOCAL_HOST = 2
|
|
DEFAULT_MAX_CONNECTIONS_PER_LOCAL_HOST = 8
|
|
|
|
DEFAULT_MIN_CONNECTIONS_PER_REMOTE_HOST = 1
|
|
DEFAULT_MAX_CONNECTIONS_PER_REMOTE_HOST = 2
|
|
|
|
|
|
class NoHostAvailable(Exception):
|
|
"""
|
|
Raised when an operation is attempted but all connections are
|
|
busy, defunct, closed, or resulted in errors when used.
|
|
"""
|
|
|
|
errors = None
|
|
"""
|
|
A map of the form ``{ip: exception}`` which details the particular
|
|
Exception that was caught for each host the operation was attempted
|
|
against.
|
|
"""
|
|
|
|
def __init__(self, message, errors):
|
|
Exception.__init__(self, message, errors)
|
|
self.errors = errors
|
|
|
|
|
|
def _future_completed(future):
|
|
""" Helper for run_in_executor() """
|
|
exc = future.exception()
|
|
if exc:
|
|
log.debug("Failed to run task on executor", exc_info=exc)
|
|
|
|
|
|
def run_in_executor(f):
|
|
"""
|
|
A decorator to run the given method in the ThreadPoolExecutor.
|
|
"""
|
|
|
|
@wraps(f)
|
|
def new_f(self, *args, **kwargs):
|
|
|
|
try:
|
|
future = self.executor.submit(f, self, *args, **kwargs)
|
|
future.add_done_callback(_future_completed)
|
|
except Exception:
|
|
log.exception("Failed to submit task to executor")
|
|
|
|
return new_f
|
|
|
|
|
|
class Cluster(object):
|
|
"""
|
|
The main class to use when interacting with a Cassandra cluster.
|
|
Typically, one instance of this class will be created for each
|
|
separate Cassandra cluster that your application interacts with.
|
|
|
|
Example usage::
|
|
|
|
>>> from cassandra.cluster import Cluster
|
|
>>> cluster = Cluster(['192.168.1.1', '192.168.1.2'])
|
|
>>> session = cluster.connect()
|
|
>>> session.execute("CREATE KEYSPACE ...")
|
|
>>> ...
|
|
>>> cluster.shutdown()
|
|
|
|
"""
|
|
|
|
port = 9042
|
|
"""
|
|
The server-side port to open connections to. Defaults to 9042.
|
|
"""
|
|
|
|
compression = True
|
|
"""
|
|
Whether or not compression should be enabled when possible. Defaults to
|
|
:const:`True` and attempts to use snappy compression.
|
|
"""
|
|
|
|
auth_provider = None
|
|
"""
|
|
An optional function that accepts one argument, the IP address of a node,
|
|
and returns a dict of credentials for that node.
|
|
"""
|
|
|
|
load_balancing_policy = None
|
|
"""
|
|
An instance of :class:`.policies.LoadBalancingPolicy` or
|
|
one of its subclasses. Defaults to :class:`~.RoundRobinPolicy`.
|
|
"""
|
|
|
|
reconnection_policy = ExponentialReconnectionPolicy(1.0, 600.0)
|
|
"""
|
|
An instance of :class:`.policies.ReconnectionPolicy`. Defaults to an instance
|
|
of :class:`.ExponentialReconnectionPolicy` with a base delay of one second and
|
|
a max delay of ten minutes.
|
|
"""
|
|
|
|
default_retry_policy = RetryPolicy()
|
|
"""
|
|
A default :class:`.policies.RetryPolicy` instance to use for all
|
|
:class:`.Statement` objects which do not have a :attr:`~.Statement.retry_policy`
|
|
explicitly set.
|
|
"""
|
|
|
|
conviction_policy_factory = SimpleConvictionPolicy
|
|
"""
|
|
A factory function which creates instances of
|
|
:class:`.policies.ConvictionPolicy`. Defaults to
|
|
:class:`.policies.SimpleConvictionPolicy`.
|
|
"""
|
|
|
|
metrics_enabled = False
|
|
"""
|
|
Whether or not metric collection is enabled.
|
|
"""
|
|
|
|
metrics = None
|
|
"""
|
|
An instance of :class:`.metrics.Metrics` if :attr:`.metrics_enabled` is
|
|
:const:`True`, else :const:`None`.
|
|
"""
|
|
|
|
ssl_options = None
|
|
"""
|
|
A optional dict which will be used as kwargs for ``ssl.wrap_socket()``
|
|
when new sockets are created. This should be used when client encryption
|
|
is enabled in Cassandra.
|
|
|
|
By default, a ``ca_certs`` value should be supplied (the value should be
|
|
a string pointing to the location of the CA certs file), and you probably
|
|
want to specify ``ssl_version`` as ``ssl.PROTOCOL_TLSv1`` to match
|
|
Cassandra's default protocol.
|
|
"""
|
|
|
|
sockopts = None
|
|
"""
|
|
An optional list of tuples which will be used as arguments to
|
|
``socket.setsockopt()`` for all created sockets.
|
|
"""
|
|
|
|
max_schema_agreement_wait = 10
|
|
"""
|
|
The maximum duration (in seconds) that the driver will wait for schema
|
|
agreement across the cluster. Defaults to ten seconds.
|
|
"""
|
|
|
|
metadata = None
|
|
"""
|
|
An instance of :class:`cassandra.metadata.Metadata`.
|
|
"""
|
|
|
|
connection_class = DefaultConnection
|
|
"""
|
|
This determines what event loop system will be used for managing
|
|
I/O with Cassandra. These are the current options:
|
|
|
|
* :class:`cassandra.io.asyncorereactor.AsyncoreConnection`
|
|
* :class:`cassandra.io.libevreactor.LibevConnection`
|
|
|
|
By default, ``AsyncoreConnection`` will be used, which uses
|
|
the ``asyncore`` module in the Python standard library. The
|
|
performance is slightly worse than with ``libev``, but it is
|
|
supported on a wider range of systems.
|
|
|
|
If ``libev`` is installed, ``LibevConnection`` will be used instead.
|
|
"""
|
|
|
|
sessions = None
|
|
control_connection = None
|
|
scheduler = None
|
|
executor = None
|
|
_is_shutdown = False
|
|
_is_setup = False
|
|
_prepared_statements = None
|
|
|
|
_listeners = None
|
|
_listener_lock = None
|
|
|
|
def __init__(self,
|
|
contact_points=("127.0.0.1",),
|
|
port=9042,
|
|
compression=True,
|
|
auth_provider=None,
|
|
load_balancing_policy=None,
|
|
reconnection_policy=None,
|
|
default_retry_policy=None,
|
|
conviction_policy_factory=None,
|
|
metrics_enabled=False,
|
|
connection_class=None,
|
|
ssl_options=None,
|
|
sockopts=None,
|
|
cql_version=None,
|
|
executor_threads=2,
|
|
max_schema_agreement_wait=10):
|
|
"""
|
|
Any of the mutable Cluster attributes may be set as keyword arguments
|
|
to the constructor.
|
|
"""
|
|
if 'gevent.monkey' in sys.modules:
|
|
raise Exception(
|
|
"gevent monkey-patching detected. This driver does not currently "
|
|
"support gevent, and monkey patching will break the driver "
|
|
"completely. You can track progress towards adding gevent "
|
|
"support here: https://datastax-oss.atlassian.net/browse/PYTHON-7.")
|
|
|
|
self.contact_points = contact_points
|
|
self.port = port
|
|
self.compression = compression
|
|
|
|
if auth_provider is not None:
|
|
if not callable(auth_provider):
|
|
raise ValueError("auth_provider must be callable")
|
|
self.auth_provider = auth_provider
|
|
|
|
if load_balancing_policy is not None:
|
|
self.load_balancing_policy = load_balancing_policy
|
|
else:
|
|
self.load_balancing_policy = RoundRobinPolicy()
|
|
|
|
if reconnection_policy is not None:
|
|
self.reconnection_policy = reconnection_policy
|
|
|
|
if default_retry_policy is not None:
|
|
self.default_retry_policy = default_retry_policy
|
|
|
|
if conviction_policy_factory is not None:
|
|
if not callable(conviction_policy_factory):
|
|
raise ValueError("conviction_policy_factory must be callable")
|
|
self.conviction_policy_factory = conviction_policy_factory
|
|
|
|
if connection_class is not None:
|
|
self.connection_class = connection_class
|
|
|
|
self.metrics_enabled = metrics_enabled
|
|
self.ssl_options = ssl_options
|
|
self.sockopts = sockopts
|
|
self.cql_version = cql_version
|
|
self.max_schema_agreement_wait = max_schema_agreement_wait
|
|
|
|
self._listeners = set()
|
|
self._listener_lock = Lock()
|
|
|
|
# let Session objects be GC'ed (and shutdown) when the user no longer
|
|
# holds a reference. Normally the cycle detector would handle this,
|
|
# but implementing __del__ prevents that.
|
|
self.sessions = WeakSet()
|
|
self.metadata = Metadata(self)
|
|
self.control_connection = None
|
|
self._prepared_statements = {}
|
|
|
|
self._min_requests_per_connection = {
|
|
HostDistance.LOCAL: DEFAULT_MIN_REQUESTS,
|
|
HostDistance.REMOTE: DEFAULT_MIN_REQUESTS
|
|
}
|
|
|
|
self._max_requests_per_connection = {
|
|
HostDistance.LOCAL: DEFAULT_MAX_REQUESTS,
|
|
HostDistance.REMOTE: DEFAULT_MAX_REQUESTS
|
|
}
|
|
|
|
self._core_connections_per_host = {
|
|
HostDistance.LOCAL: DEFAULT_MIN_CONNECTIONS_PER_LOCAL_HOST,
|
|
HostDistance.REMOTE: DEFAULT_MIN_CONNECTIONS_PER_REMOTE_HOST
|
|
}
|
|
|
|
self._max_connections_per_host = {
|
|
HostDistance.LOCAL: DEFAULT_MAX_CONNECTIONS_PER_LOCAL_HOST,
|
|
HostDistance.REMOTE: DEFAULT_MAX_CONNECTIONS_PER_REMOTE_HOST
|
|
}
|
|
|
|
self.executor = ThreadPoolExecutor(max_workers=executor_threads)
|
|
self.scheduler = _Scheduler(self.executor)
|
|
|
|
self._lock = RLock()
|
|
|
|
if self.metrics_enabled:
|
|
self.metrics = Metrics(weakref.proxy(self))
|
|
|
|
self.control_connection = ControlConnection(self)
|
|
|
|
def get_min_requests_per_connection(self, host_distance):
|
|
return self._min_requests_per_connection[host_distance]
|
|
|
|
def set_min_requests_per_connection(self, host_distance, min_requests):
|
|
self._min_requests_per_connection[host_distance] = min_requests
|
|
|
|
def get_max_requests_per_connection(self, host_distance):
|
|
return self._max_requests_per_connection[host_distance]
|
|
|
|
def set_max_requests_per_connection(self, host_distance, max_requests):
|
|
self._max_requests_per_connection[host_distance] = max_requests
|
|
|
|
def get_core_connections_per_host(self, host_distance):
|
|
return self._core_connections_per_host[host_distance]
|
|
|
|
def set_core_connections_per_host(self, host_distance, core_connections):
|
|
old = self._core_connections_per_host[host_distance]
|
|
self._core_connections_per_host[host_distance] = core_connections
|
|
if old < core_connections:
|
|
self.ensure_core_connections()
|
|
|
|
def get_max_connections_per_host(self, host_distance):
|
|
return self._max_connections_per_host[host_distance]
|
|
|
|
def set_max_connections_per_host(self, host_distance, max_connections):
|
|
self._max_connections_per_host[host_distance] = max_connections
|
|
|
|
def connection_factory(self, address, *args, **kwargs):
|
|
"""
|
|
Called to create a new connection with proper configuration.
|
|
Intended for internal use only.
|
|
"""
|
|
kwargs = self._make_connection_kwargs(address, kwargs)
|
|
return self.connection_class.factory(address, *args, **kwargs)
|
|
|
|
def _make_connection_factory(self, host, *args, **kwargs):
|
|
kwargs = self._make_connection_kwargs(host.address, kwargs)
|
|
return partial(self.connection_class.factory, host.address, *args, **kwargs)
|
|
|
|
def _make_connection_kwargs(self, address, kwargs_dict):
|
|
if self.auth_provider:
|
|
kwargs_dict['credentials'] = self.auth_provider(address)
|
|
|
|
kwargs_dict['port'] = self.port
|
|
kwargs_dict['compression'] = self.compression
|
|
kwargs_dict['sockopts'] = self.sockopts
|
|
kwargs_dict['ssl_options'] = self.ssl_options
|
|
kwargs_dict['cql_version'] = self.cql_version
|
|
|
|
return kwargs_dict
|
|
|
|
def connect(self, keyspace=None):
|
|
"""
|
|
Creates and returns a new :class:`~.Session` object. If `keyspace`
|
|
is specified, that keyspace will be the default keyspace for
|
|
operations on the ``Session``.
|
|
"""
|
|
with self._lock:
|
|
if self._is_shutdown:
|
|
raise Exception("Cluster is already shut down")
|
|
|
|
if not self._is_setup:
|
|
for address in self.contact_points:
|
|
host = self.add_host(address, signal=False)
|
|
if host:
|
|
host.set_up()
|
|
for listener in self.listeners:
|
|
listener.on_add(host)
|
|
|
|
self.load_balancing_policy.populate(
|
|
weakref.proxy(self), self.metadata.all_hosts())
|
|
self._is_setup = True
|
|
|
|
if self.control_connection:
|
|
try:
|
|
self.control_connection.connect()
|
|
log.debug("Control connection created")
|
|
except Exception:
|
|
log.exception("Control connection failed to connect, "
|
|
"shutting down Cluster:")
|
|
self.shutdown()
|
|
raise
|
|
|
|
session = self._new_session()
|
|
if keyspace:
|
|
session.set_keyspace(keyspace)
|
|
return session
|
|
|
|
def shutdown(self):
|
|
"""
|
|
Closes all sessions and connection associated with this Cluster.
|
|
Once shutdown, a Cluster should not be used for any purpose.
|
|
"""
|
|
with self._lock:
|
|
if self._is_shutdown:
|
|
raise Exception("The Cluster was already shutdown")
|
|
else:
|
|
self._is_shutdown = True
|
|
|
|
if self.scheduler:
|
|
self.scheduler.shutdown()
|
|
|
|
if self.control_connection:
|
|
self.control_connection.shutdown()
|
|
|
|
if self.sessions:
|
|
for session in self.sessions:
|
|
session.shutdown()
|
|
|
|
if self.executor:
|
|
self.executor.shutdown()
|
|
|
|
def __del__(self):
|
|
# we don't use shutdown() because we want to avoid shutting down
|
|
# Sessions while they are still being used (in case there are no
|
|
# longer any references to this Cluster object, but there are
|
|
# still references to the Session object)
|
|
if not self._is_shutdown:
|
|
if self.scheduler:
|
|
self.scheduler.shutdown()
|
|
if self.control_connection:
|
|
self.control_connection.shutdown()
|
|
if self.executor:
|
|
self.executor.shutdown(wait=False)
|
|
|
|
def _new_session(self):
|
|
session = Session(self, self.metadata.all_hosts())
|
|
self.sessions.add(session)
|
|
return session
|
|
|
|
def _cleanup_failed_on_up_handling(self, host):
|
|
self.load_balancing_policy.on_down(host)
|
|
self.control_connection.on_down(host)
|
|
for session in self.sessions:
|
|
session.remove_pool(host)
|
|
|
|
def _on_up_future_completed(self, host, futures, results, lock, finished_future):
|
|
with lock:
|
|
futures.discard(finished_future)
|
|
|
|
try:
|
|
results.append(finished_future.result())
|
|
except Exception as exc:
|
|
results.append(exc)
|
|
|
|
if futures:
|
|
return
|
|
|
|
try:
|
|
# all futures have completed at this point
|
|
for exc in [f for f in results if isinstance(f, Exception)]:
|
|
log.error("Unexpected failure while marking node %s up:", host, exc_info=exc)
|
|
self._cleanup_failed_on_up_handling(host)
|
|
return
|
|
|
|
if not all(results):
|
|
log.debug("Connection pool could not be created, not marking node %s up", host)
|
|
self._cleanup_failed_on_up_handling(host)
|
|
return
|
|
|
|
# mark the host as up and notify all listeners
|
|
host.set_up()
|
|
for listener in self.listeners:
|
|
listener.on_up(host)
|
|
finally:
|
|
host._handle_node_up_condition.acquire()
|
|
if host._currently_handling_node_up:
|
|
host._currently_handling_node_up = False
|
|
host._handle_node_up_condition.notify()
|
|
host._handle_node_up_condition.release()
|
|
|
|
# see if there are any pools to add or remove now that the host is marked up
|
|
for session in self.sessions:
|
|
session.update_created_pools()
|
|
|
|
def on_up(self, host):
|
|
"""
|
|
Intended for internal use only.
|
|
"""
|
|
if self._is_shutdown:
|
|
return
|
|
|
|
host._handle_node_up_condition.acquire()
|
|
while host._currently_handling_node_up:
|
|
host._handle_node_up_condition.wait()
|
|
host.handling_up_down = True
|
|
host._handle_node_up_condition.release()
|
|
|
|
if host.is_up:
|
|
return
|
|
|
|
futures = set()
|
|
try:
|
|
log.info("Host %s has been marked up", host)
|
|
|
|
reconnector = host.get_and_set_reconnection_handler(None)
|
|
if reconnector:
|
|
log.debug("Now that host %s is up, cancelling the reconnection handler", host)
|
|
reconnector.cancel()
|
|
|
|
self._prepare_all_queries(host)
|
|
|
|
for session in self.sessions:
|
|
session.remove_pool(host)
|
|
|
|
self.load_balancing_policy.on_up(host)
|
|
self.control_connection.on_up(host)
|
|
|
|
futures_lock = Lock()
|
|
futures_results = []
|
|
callback = partial(self._on_up_future_completed, host, futures, futures_results, futures_lock)
|
|
for session in self.sessions:
|
|
future = session.add_or_renew_pool(host, is_host_addition=False)
|
|
future.add_done_callback(callback)
|
|
futures.add(future)
|
|
except Exception:
|
|
# this shouldn't happen, but just in case, reset the condition
|
|
for future in futures:
|
|
future.cancel()
|
|
host._handle_node_up_condition.acquire()
|
|
host._currently_handling_node_up = False
|
|
host._handle_node_up_condition.notify()
|
|
host._handle_node_up_condition.release()
|
|
raise
|
|
|
|
# for testing purposes
|
|
return futures
|
|
|
|
@run_in_executor
|
|
def on_down(self, host, is_host_addition):
|
|
"""
|
|
Intended for internal use only.
|
|
"""
|
|
if self._is_shutdown:
|
|
return
|
|
|
|
with host.lock:
|
|
if (not host.is_up) or host.is_currently_reconnecting():
|
|
return
|
|
|
|
host.set_down()
|
|
|
|
log.warn("Host %s has been marked down", host)
|
|
|
|
self.load_balancing_policy.on_down(host)
|
|
self.control_connection.on_down(host)
|
|
for session in self.sessions:
|
|
session.on_down(host)
|
|
|
|
for listener in self.listeners:
|
|
listener.on_down(host)
|
|
|
|
schedule = self.reconnection_policy.new_schedule()
|
|
|
|
# in order to not hold references to this Cluster open and prevent
|
|
# proper shutdown when the program ends, we'll just make a closure
|
|
# of the current Cluster attributes to create new Connections with
|
|
conn_factory = self._make_connection_factory(host)
|
|
|
|
reconnector = _HostReconnectionHandler(
|
|
host, conn_factory, is_host_addition, self.on_add, self.on_up,
|
|
self.scheduler, schedule, host.get_and_set_reconnection_handler,
|
|
new_handler=None)
|
|
|
|
old_reconnector = host.get_and_set_reconnection_handler(reconnector)
|
|
if old_reconnector:
|
|
log.debug("Old host reconnector found for %s, cancelling", host)
|
|
old_reconnector.cancel()
|
|
|
|
log.debug("Staring reconnector for host %s", host)
|
|
reconnector.start()
|
|
|
|
def on_add(self, host):
|
|
if self._is_shutdown:
|
|
return
|
|
|
|
log.debug("Adding new host %s", host)
|
|
self._prepare_all_queries(host)
|
|
|
|
self.load_balancing_policy.on_add(host)
|
|
self.control_connection.on_add(host)
|
|
|
|
futures_lock = Lock()
|
|
futures_results = []
|
|
futures = set()
|
|
|
|
def future_completed(future):
|
|
with futures_lock:
|
|
futures.discard(future)
|
|
|
|
try:
|
|
futures_results.append(future.result())
|
|
except Exception as exc:
|
|
futures_results.append(exc)
|
|
|
|
if futures:
|
|
return
|
|
|
|
# all futures have completed at this point
|
|
for exc in [f for f in futures_results if isinstance(f, Exception)]:
|
|
log.error("Unexpected failure while adding node %s, will not mark up:", host, exc_info=exc)
|
|
return
|
|
|
|
if not all(futures_results):
|
|
log.debug("Connection pool could not be created, not marking node %s up:", host)
|
|
return
|
|
|
|
# mark the host as up and notify all listeners
|
|
host.set_up()
|
|
for listener in self.listeners:
|
|
listener.on_add(host)
|
|
|
|
# see if there are any pools to add or remove now that the host is marked up
|
|
for session in self.sessions:
|
|
session.update_created_pools()
|
|
|
|
for session in self.sessions:
|
|
future = session.add_or_renew_host(host, is_host_addition=True)
|
|
future.add_done_callback(future_completed)
|
|
|
|
def on_remove(self, host):
|
|
if self._is_shutdown:
|
|
return
|
|
|
|
log.debug("Removing host %s", host)
|
|
host.set_down()
|
|
self.load_balancing_policy.on_remove(host)
|
|
for session in self.sessions:
|
|
session.on_remove()
|
|
for listener in self.listeners:
|
|
listener.on_remove()
|
|
|
|
def signal_connection_failure(self, host, connection_exc, is_host_addition):
|
|
is_down = host.signal_connection_failure(connection_exc)
|
|
if is_down:
|
|
self.on_down(host, is_host_addition)
|
|
return is_down
|
|
|
|
def add_host(self, address, signal):
|
|
"""
|
|
Called when adding initial contact points and when the control
|
|
connection subsequently discovers a new node. Intended for internal
|
|
use only.
|
|
"""
|
|
new_host = self.metadata.add_host(address)
|
|
if new_host and signal:
|
|
log.info("New Cassandra host %s added", address)
|
|
self.on_add(new_host)
|
|
|
|
return new_host
|
|
|
|
def remove_host(self, host):
|
|
"""
|
|
Called when the control connection observes that a node has left the
|
|
ring. Intended for internal use only.
|
|
"""
|
|
if host and self.metadata.remove_host(host):
|
|
log.info("Cassandra host %s removed", host)
|
|
self.on_remove(host)
|
|
|
|
def register_listener(self, listener):
|
|
"""
|
|
Adds a :class:`cassandra.policies.HostStateListener` subclass instance to
|
|
the list of listeners to be notified when a host is added, removed,
|
|
marked up, or marked down.
|
|
"""
|
|
with self._listener_lock:
|
|
self._listeners.add(listener)
|
|
|
|
def unregister_listener(self, listener):
|
|
""" Removes a registered listener. """
|
|
with self._listener_lock:
|
|
self._listeners.remove(listener)
|
|
|
|
@property
|
|
def listeners(self):
|
|
with self._listener_lock:
|
|
return self._listeners.copy()
|
|
|
|
def ensure_core_connections(self):
|
|
"""
|
|
If any host has fewer than the configured number of core connections
|
|
open, attempt to open connections until that number is met.
|
|
"""
|
|
for session in self.sessions:
|
|
for pool in session._pools.values():
|
|
pool.ensure_core_connections()
|
|
|
|
def submit_schema_refresh(self, keyspace=None, table=None):
|
|
"""
|
|
Schedule a refresh of the internal representation of the current
|
|
schema for this cluster. If `keyspace` is specified, only that
|
|
keyspace will be refreshed, and likewise for `table`.
|
|
"""
|
|
return self.executor.submit(
|
|
self.control_connection.refresh_schema, keyspace, table)
|
|
|
|
def _prepare_all_queries(self, host):
|
|
if not self._prepared_statements:
|
|
return
|
|
|
|
log.debug("Preparing all known prepared statements against host %s", host)
|
|
try:
|
|
connection = self.connection_factory(host.address)
|
|
try:
|
|
self.control_connection.wait_for_schema_agreement(connection)
|
|
except Exception:
|
|
log.debug("Error waiting for schema agreement before preparing statements against host %s", host, exc_info=True)
|
|
# TODO: potentially error out the connection?
|
|
|
|
statements = self._prepared_statements.values()
|
|
for keyspace, ks_statements in groupby(statements, lambda s: s.keyspace):
|
|
if keyspace is not None:
|
|
connection.set_keyspace_blocking(keyspace)
|
|
|
|
# prepare 10 statements at a time
|
|
ks_statements = list(ks_statements)
|
|
chunks = []
|
|
for i in xrange(0, len(ks_statements), 10):
|
|
chunks.append(ks_statements[i:i + 10])
|
|
|
|
for ks_chunk in chunks:
|
|
messages = [PrepareMessage(query=s.query_string) for s in ks_chunk]
|
|
# TODO: make this timeout configurable somehow?
|
|
responses = connection.wait_for_responses(*messages, timeout=2.0)
|
|
for response in responses:
|
|
if (not isinstance(response, ResultMessage) or
|
|
response.kind != ResultMessage.KIND_PREPARED):
|
|
log.debug("Got unexpected response when preparing "
|
|
"statement on host %s: %r", host, response)
|
|
|
|
connection.close()
|
|
log.debug("Done preparing all known prepared statements against host %s", host)
|
|
except Exception:
|
|
# log and ignore
|
|
log.exception("Error trying to prepare all statements on host %s", host)
|
|
|
|
def prepare_on_all_sessions(self, query_id, prepared_statement, excluded_host):
|
|
self._prepared_statements[query_id] = prepared_statement
|
|
for session in self.sessions:
|
|
session.prepare_on_all_hosts(prepared_statement.query_string, excluded_host)
|
|
|
|
|
|
class Session(object):
|
|
"""
|
|
A collection of connection pools for each host in the cluster.
|
|
Instances of this class should not be created directly, only
|
|
using :meth:`.Cluster.connect()`.
|
|
|
|
Queries and statements can be executed through ``Session`` instances
|
|
using the :meth:`~.Session.execute()` and :meth:`~.Session.execute_async()`
|
|
method.
|
|
|
|
Example usage::
|
|
|
|
>>> session = cluster.connect()
|
|
>>> session.set_keyspace("mykeyspace")
|
|
>>> session.execute("SELECT * FROM mycf")
|
|
|
|
"""
|
|
|
|
cluster = None
|
|
hosts = None
|
|
keyspace = None
|
|
is_shutdown = False
|
|
|
|
row_factory = staticmethod(named_tuple_factory)
|
|
"""
|
|
The format to return row results in. By default, each
|
|
returned row will be a named tuple. You can alternatively
|
|
use any of the following:
|
|
|
|
- :func:`cassandra.decoder.tuple_factory`
|
|
- :func:`cassandra.decoder.named_tuple_factory`
|
|
- :func:`cassandra.decoder.dict_factory`
|
|
- :func:`cassandra.decoder.ordered_dict_factory`
|
|
|
|
"""
|
|
|
|
_lock = None
|
|
_pools = None
|
|
_load_balancer = None
|
|
_metrics = None
|
|
|
|
def __init__(self, cluster, hosts):
|
|
self.cluster = cluster
|
|
self.hosts = hosts
|
|
|
|
self._lock = RLock()
|
|
self._pools = {}
|
|
self._load_balancer = cluster.load_balancing_policy
|
|
self._metrics = cluster.metrics
|
|
|
|
for host in hosts:
|
|
future = self.add_or_renew_pool(host, is_host_addition=False)
|
|
future.result()
|
|
|
|
def execute(self, query, parameters=None, trace=False):
|
|
"""
|
|
Execute the given query and synchronously wait for the response.
|
|
|
|
If an error is encountered while executing the query, an Exception
|
|
will be raised.
|
|
|
|
`query` may be a query string or an instance of :class:`cassandra.query.Statement`.
|
|
|
|
`parameters` may be a sequence or dict of parameters to bind. If a
|
|
sequence is used, ``%s`` should be used the placeholder for each
|
|
argument. If a dict is used, ``%(name)s`` style placeholders must
|
|
be used.
|
|
|
|
If `trace` is set to :const:`True`, an attempt will be made to
|
|
fetch the trace details and attach them to the `query`'s
|
|
:attr:`~.Statement.trace` attribute in the form of a :class:`.QueryTrace`
|
|
instance. This requires that `query` be a :class:`.Statement` subclass
|
|
instance and not just a string. If there is an error fetching the
|
|
trace details, the :attr:`~.Statement.trace` attribute will be left as
|
|
:const:`None`.
|
|
"""
|
|
if trace and not isinstance(query, Statement):
|
|
raise TypeError(
|
|
"The query argument must be an instance of a subclass of "
|
|
"cassandra.query.Statement when trace=True")
|
|
|
|
future = self.execute_async(query, parameters, trace)
|
|
try:
|
|
result = future.result()
|
|
finally:
|
|
if trace:
|
|
try:
|
|
query.trace = future.get_query_trace()
|
|
except Exception:
|
|
log.exception("Unable to fetch query trace:")
|
|
|
|
return result
|
|
|
|
def execute_async(self, query, parameters=None, trace=False):
|
|
"""
|
|
Execute the given query and return a :class:`~.ResponseFuture` object
|
|
which callbacks may be attached to for asynchronous response
|
|
delivery. You may also call :meth:`~.ResponseFuture.result()`
|
|
on the ``ResponseFuture`` to syncronously block for results at
|
|
any time.
|
|
|
|
If `trace` is set to :const:`True`, you may call
|
|
:meth:`.ResponseFuture.get_query_trace()` after the request
|
|
completes to retrieve a :class:`.QueryTrace` instance.
|
|
|
|
Example usage::
|
|
|
|
>>> session = cluster.connect()
|
|
>>> future = session.execute_async("SELECT * FROM mycf")
|
|
|
|
>>> def log_results(results):
|
|
... for row in results:
|
|
... log.info("Results: %s", row)
|
|
|
|
>>> def log_error(exc):
|
|
>>> log.error("Operation failed: %s", exc)
|
|
|
|
>>> future.add_callbacks(log_results, log_error)
|
|
|
|
Async execution with blocking wait for results::
|
|
|
|
>>> future = session.execute_async("SELECT * FROM mycf")
|
|
>>> # do other stuff...
|
|
|
|
>>> try:
|
|
... results = future.result()
|
|
... except Exception:
|
|
... log.exception("Operation failed:")
|
|
|
|
"""
|
|
if isinstance(query, basestring):
|
|
query = SimpleStatement(query)
|
|
elif isinstance(query, PreparedStatement):
|
|
query = query.bind(parameters)
|
|
|
|
if isinstance(query, BoundStatement):
|
|
message = ExecuteMessage(
|
|
query_id=query.prepared_statement.query_id,
|
|
query_params=query.values,
|
|
consistency_level=query.consistency_level)
|
|
else:
|
|
query_string = query.query_string
|
|
if parameters:
|
|
query_string = bind_params(query.query_string, parameters)
|
|
message = QueryMessage(query=query_string, consistency_level=query.consistency_level)
|
|
|
|
if trace:
|
|
message.tracing = True
|
|
|
|
future = ResponseFuture(self, message, query, metrics=self._metrics)
|
|
future.send_request()
|
|
return future
|
|
|
|
def prepare(self, query):
|
|
"""
|
|
Prepares a query string, returing a :class:`~cassandra.query.PreparedStatement`
|
|
instance which can be used as follows::
|
|
|
|
>>> session = cluster.connect("mykeyspace")
|
|
>>> query = "INSERT INTO users (id, name, age) VALUES (?, ?, ?)"
|
|
>>> prepared = session.prepare(query)
|
|
>>> session.execute(prepared.bind((user.id, user.name, user.age)))
|
|
|
|
"""
|
|
message = PrepareMessage(query=query)
|
|
future = ResponseFuture(self, message, query=None)
|
|
try:
|
|
future.send_request()
|
|
query_id, column_metadata = future.result()
|
|
except Exception:
|
|
log.exception("Error preparing query:")
|
|
raise
|
|
|
|
prepared_statement = PreparedStatement.from_message(
|
|
query_id, column_metadata, self.cluster.metadata, query, self.keyspace)
|
|
|
|
host = future._current_host
|
|
try:
|
|
self.cluster.prepare_on_all_sessions(query_id, prepared_statement, host)
|
|
except Exception:
|
|
log.exception("Error preparing query on all hosts:")
|
|
|
|
return prepared_statement
|
|
|
|
def prepare_on_all_hosts(self, query, excluded_host):
|
|
"""
|
|
Prepare the given query on all hosts, excluding ``excluded_host``.
|
|
Intended for internal use only.
|
|
"""
|
|
futures = []
|
|
for host in self._pools:
|
|
if host != excluded_host and host.is_up:
|
|
future = ResponseFuture(self, PrepareMessage(query=query), None)
|
|
|
|
# we don't care about errors preparing against specific hosts,
|
|
# since we can always prepare them as needed when the prepared
|
|
# statement is used. Just log errors and continue on.
|
|
try:
|
|
request_id = future._query(host)
|
|
except Exception:
|
|
log.exception("Error preparing query for host %s:", host)
|
|
continue
|
|
|
|
if request_id is None:
|
|
# the error has already been logged by ResponsFuture
|
|
log.debug("Failed to prepare query for host %s: %r",
|
|
host, future._errors.get(host))
|
|
continue
|
|
|
|
futures.append((host, future))
|
|
|
|
for host, future in futures:
|
|
try:
|
|
future.result()
|
|
except Exception:
|
|
log.exception("Error preparing query for host %s:", host)
|
|
|
|
def shutdown(self):
|
|
"""
|
|
Close all connections. ``Session`` instances should not be used
|
|
for any purpose after being shutdown.
|
|
"""
|
|
with self._lock:
|
|
if self.is_shutdown:
|
|
return
|
|
else:
|
|
self.is_shutdown = True
|
|
|
|
for pool in self._pools.values():
|
|
pool.shutdown()
|
|
|
|
def __del__(self):
|
|
try:
|
|
self.shutdown()
|
|
del self.cluster
|
|
except TypeError:
|
|
pass
|
|
|
|
def add_or_renew_pool(self, host, is_host_addition):
|
|
"""
|
|
For internal use only.
|
|
"""
|
|
distance = self._load_balancer.distance(host)
|
|
if distance == HostDistance.IGNORED:
|
|
return None
|
|
|
|
def run_add_or_renew_pool():
|
|
try:
|
|
new_pool = HostConnectionPool(host, distance, self)
|
|
except AuthenticationFailed as auth_exc:
|
|
conn_exc = ConnectionException(str(auth_exc), host=host)
|
|
self.cluster.signal_connection_failure(host, conn_exc, is_host_addition)
|
|
return False
|
|
except Exception as conn_exc:
|
|
log.debug("Signaling connection failure during Session.add_host: %s", conn_exc)
|
|
self.cluster.signal_connection_failure(host, conn_exc, is_host_addition)
|
|
return False
|
|
|
|
previous = self._pools.get(host)
|
|
self._pools[host] = new_pool
|
|
log.debug("Added pool for host %s to session", host)
|
|
if previous:
|
|
previous.shutdown()
|
|
|
|
return True
|
|
|
|
return self.submit(run_add_or_renew_pool)
|
|
|
|
def remove_pool(self, host):
|
|
log.debug("Removing connection pool for %r", host)
|
|
pool = self._pools.pop(host, None)
|
|
if pool:
|
|
return self.submit(pool.shutdown)
|
|
else:
|
|
return None
|
|
|
|
def update_created_pools(self):
|
|
"""
|
|
When the set of live nodes change, the loadbalancer will change its
|
|
mind on host distances. It might change it on the node that came/left
|
|
but also on other nodes (for instance, if a node dies, another
|
|
previously ignored node may be now considered).
|
|
|
|
This method ensures that all hosts for which a pool should exist
|
|
have one, and hosts that shouldn't don't.
|
|
|
|
For internal use only.
|
|
"""
|
|
for host in self.cluster.metadata.all_hosts():
|
|
distance = self._load_balancer.distance(host)
|
|
pool = self._pools.get(host)
|
|
|
|
if not pool or pool.is_shutdown:
|
|
if distance != HostDistance.IGNORED and host.is_up:
|
|
self.add_or_renew_pool(host, False)
|
|
elif distance != pool.host_distance:
|
|
# the distance has changed
|
|
if distance == HostDistance.IGNORED:
|
|
self.remove_pool(host)
|
|
else:
|
|
pool.host_distance = distance
|
|
|
|
def on_down(self, host):
|
|
"""
|
|
Called by the parent Cluster instance when a node is marked down.
|
|
Only intended for internal use.
|
|
"""
|
|
future = self.remove_pool(host)
|
|
if future:
|
|
future.add_done_callback(lambda f: self.update_created_pools())
|
|
|
|
def on_remove(self, host):
|
|
""" Internal """
|
|
self.on_down(host)
|
|
|
|
def set_keyspace(self, keyspace):
|
|
"""
|
|
Set the default keyspace for all queries made through this Session.
|
|
This operation blocks until complete.
|
|
"""
|
|
self.execute('USE "%s"' % (keyspace,))
|
|
|
|
def _set_keyspace_for_all_pools(self, keyspace, callback):
|
|
"""
|
|
Asynchronously sets the keyspace on all pools. When all
|
|
pools have set all of their connections, `callback` will be
|
|
called with a dictionary of all errors that occurred, keyed
|
|
by the `Host` that they occurred against.
|
|
"""
|
|
self.keyspace = keyspace
|
|
|
|
remaining_callbacks = set(self._pools.values())
|
|
errors = {}
|
|
|
|
def pool_finished_setting_keyspace(pool, host_errors):
|
|
remaining_callbacks.remove(pool)
|
|
if host_errors:
|
|
errors[pool.host] = host_errors
|
|
|
|
if not remaining_callbacks:
|
|
callback(host_errors)
|
|
|
|
for pool in self._pools.values():
|
|
pool._set_keyspace_for_all_conns(keyspace, pool_finished_setting_keyspace)
|
|
|
|
def submit(self, fn, *args, **kwargs):
|
|
""" Internal """
|
|
return self.cluster.executor.submit(fn, *args, **kwargs)
|
|
|
|
def get_pool_state(self):
|
|
return dict((host, pool.get_state()) for host, pool in self._pools.items())
|
|
|
|
|
|
class _ControlReconnectionHandler(_ReconnectionHandler):
|
|
"""
|
|
Internal
|
|
"""
|
|
|
|
def __init__(self, control_connection, *args, **kwargs):
|
|
_ReconnectionHandler.__init__(self, *args, **kwargs)
|
|
self.control_connection = weakref.proxy(control_connection)
|
|
|
|
def try_reconnect(self):
|
|
# we'll either get back a new Connection or a NoHostAvailable
|
|
return self.control_connection._reconnect_internal()
|
|
|
|
def on_reconnection(self, connection):
|
|
self.control_connection._set_new_connection(connection)
|
|
|
|
def on_exception(self, exc, next_delay):
|
|
# TODO only overridden to add logging, so add logging
|
|
if isinstance(exc, AuthenticationFailed):
|
|
return False
|
|
else:
|
|
log.debug("Error trying to reconnect control connection: %r", exc)
|
|
return True
|
|
|
|
|
|
class ControlConnection(object):
|
|
"""
|
|
Internal
|
|
"""
|
|
|
|
_SELECT_KEYSPACES = "SELECT * FROM system.schema_keyspaces"
|
|
_SELECT_COLUMN_FAMILIES = "SELECT * FROM system.schema_columnfamilies"
|
|
_SELECT_COLUMNS = "SELECT * FROM system.schema_columns"
|
|
|
|
_SELECT_PEERS = "SELECT peer, data_center, rack, tokens, rpc_address FROM system.peers"
|
|
_SELECT_LOCAL = "SELECT cluster_name, data_center, rack, tokens, partitioner FROM system.local WHERE key='local'"
|
|
|
|
_SELECT_SCHEMA_PEERS = "SELECT rpc_address, schema_version FROM system.peers"
|
|
_SELECT_SCHEMA_LOCAL = "SELECT schema_version FROM system.local WHERE key='local'"
|
|
|
|
# for testing purposes
|
|
_time = time
|
|
|
|
def __init__(self, cluster):
|
|
# use a weak reference to allow the Cluster instance to be GC'ed (and
|
|
# shutdown) since implementing __del__ disables the cycle detector
|
|
self._cluster = weakref.proxy(cluster)
|
|
self._balancing_policy = cluster.load_balancing_policy
|
|
self._balancing_policy.populate(cluster, [])
|
|
self._reconnection_policy = cluster.reconnection_policy
|
|
self._connection = None
|
|
|
|
self._lock = RLock()
|
|
self._schema_agreement_lock = Lock()
|
|
|
|
self._reconnection_handler = None
|
|
self._reconnection_lock = RLock()
|
|
|
|
self._is_shutdown = False
|
|
|
|
def connect(self):
|
|
if self._is_shutdown:
|
|
return
|
|
|
|
self._set_new_connection(self._reconnect_internal())
|
|
|
|
def _set_new_connection(self, conn):
|
|
"""
|
|
Replace existing connection (if there is one) and close it.
|
|
"""
|
|
with self._lock:
|
|
old = self._connection
|
|
self._connection = conn
|
|
|
|
if old:
|
|
log.debug("[control connection] Closing old connection %r, replacing with %r", old, conn)
|
|
old.close()
|
|
|
|
def _reconnect_internal(self):
|
|
"""
|
|
Tries to connect to each host in the query plan until one succeeds
|
|
or every attempt fails. If successful, a new Connection will be
|
|
returned. Otherwise, :exc:`NoHostAvailable` will be raised
|
|
with an "errors" arg that is a dict mapping host addresses
|
|
to the exception that was raised when an attempt was made to open
|
|
a connection to that host.
|
|
"""
|
|
errors = {}
|
|
for host in self._balancing_policy.make_query_plan():
|
|
try:
|
|
return self._try_connect(host)
|
|
except ConnectionException as exc:
|
|
errors[host.address] = exc
|
|
log.warn("[control connection] Error connecting to %s:", host, exc_info=True)
|
|
self._cluster.signal_connection_failure(host, exc, is_host_addition=False)
|
|
except Exception as exc:
|
|
errors[host.address] = exc
|
|
log.warn("[control connection] Error connecting to %s:", host, exc_info=True)
|
|
|
|
raise NoHostAvailable("Unable to connect to any servers", errors)
|
|
|
|
def _try_connect(self, host):
|
|
"""
|
|
Creates a new Connection, registers for pushed events, and refreshes
|
|
node/token and schema metadata.
|
|
"""
|
|
log.debug("[control connection] Opening new connection to %s", host)
|
|
connection = self._cluster.connection_factory(host.address)
|
|
|
|
log.debug("[control connection] Established new connection %r, "
|
|
"registering watchers and refreshing schema and topology",
|
|
connection)
|
|
try:
|
|
connection.register_watchers({
|
|
"TOPOLOGY_CHANGE": self._handle_topology_change,
|
|
"STATUS_CHANGE": self._handle_status_change,
|
|
"SCHEMA_CHANGE": self._handle_schema_change
|
|
})
|
|
|
|
self._refresh_node_list_and_token_map(connection)
|
|
self._refresh_schema(connection)
|
|
except Exception:
|
|
connection.close()
|
|
raise
|
|
|
|
return connection
|
|
|
|
def reconnect(self):
|
|
if self._is_shutdown:
|
|
return
|
|
|
|
self._cluster.executor.submit(self._reconnect)
|
|
|
|
def _reconnect(self):
|
|
log.debug("[control connection] Attempting to reconnect")
|
|
try:
|
|
self._set_new_connection(self._reconnect_internal())
|
|
except NoHostAvailable:
|
|
# make a retry schedule (which includes backoff)
|
|
schedule = self._reconnection_policy.new_schedule()
|
|
|
|
with self._reconnection_lock:
|
|
|
|
# cancel existing reconnection attempts
|
|
if self._reconnection_handler:
|
|
self._reconnection_handler.cancel()
|
|
|
|
# when a connection is successfully made, _set_new_connection
|
|
# will be called with the new connection and then our
|
|
# _reconnection_handler will be cleared out
|
|
self._reconnection_handler = _ControlReconnectionHandler(
|
|
self, self._cluster.scheduler, schedule,
|
|
self._get_and_set_reconnection_handler,
|
|
new_handler=None)
|
|
self._reconnection_handler.start()
|
|
except Exception:
|
|
log.debug("[control connection] error reconnecting", exc_info=True)
|
|
raise
|
|
|
|
def _get_and_set_reconnection_handler(self, new_handler):
|
|
"""
|
|
Called by the _ControlReconnectionHandler when a new connection
|
|
is successfully created. Clears out the _reconnection_handler on
|
|
this ControlConnection.
|
|
"""
|
|
with self._reconnection_lock:
|
|
old = self._reconnection_handler
|
|
self._reconnection_handler = new_handler
|
|
return old
|
|
|
|
def shutdown(self):
|
|
with self._lock:
|
|
if self._is_shutdown:
|
|
return
|
|
else:
|
|
self._is_shutdown = True
|
|
|
|
# stop trying to reconnect (if we are)
|
|
if self._reconnection_handler:
|
|
self._reconnection_handler.cancel()
|
|
|
|
if self._connection:
|
|
self._connection.close()
|
|
|
|
def refresh_schema(self, keyspace=None, table=None):
|
|
try:
|
|
if self._connection:
|
|
self._refresh_schema(self._connection, keyspace, table)
|
|
except Exception:
|
|
log.debug("[control connection] Error refreshing schema", exc_info=True)
|
|
self._signal_error()
|
|
|
|
def _refresh_schema(self, connection, keyspace=None, table=None):
|
|
self.wait_for_schema_agreement(connection)
|
|
|
|
where_clause = ""
|
|
if keyspace:
|
|
where_clause = " WHERE keyspace_name = '%s'" % (keyspace,)
|
|
if table:
|
|
where_clause += " AND columnfamily_name = '%s'" % (table,)
|
|
|
|
cl = ConsistencyLevel.ONE
|
|
if table:
|
|
ks_query = None
|
|
else:
|
|
ks_query = QueryMessage(query=self._SELECT_KEYSPACES + where_clause, consistency_level=cl)
|
|
cf_query = QueryMessage(query=self._SELECT_COLUMN_FAMILIES + where_clause, consistency_level=cl)
|
|
col_query = QueryMessage(query=self._SELECT_COLUMNS + where_clause, consistency_level=cl)
|
|
|
|
if ks_query:
|
|
ks_result, cf_result, col_result = connection.wait_for_responses(ks_query, cf_query, col_query)
|
|
ks_result = dict_factory(*ks_result.results)
|
|
cf_result = dict_factory(*cf_result.results)
|
|
col_result = dict_factory(*col_result.results)
|
|
else:
|
|
ks_result = None
|
|
cf_result, col_result = connection.wait_for_responses(cf_query, col_query)
|
|
cf_result = dict_factory(*cf_result.results)
|
|
col_result = dict_factory(*col_result.results)
|
|
|
|
self._cluster.metadata.rebuild_schema(keyspace, table, ks_result, cf_result, col_result)
|
|
|
|
def refresh_node_list_and_token_map(self):
|
|
try:
|
|
if self._connection:
|
|
self._refresh_node_list_and_token_map(self._connection)
|
|
except Exception:
|
|
log.debug("[control connection] Error refreshing node list and token map", exc_info=True)
|
|
self._signal_error()
|
|
|
|
def _refresh_node_list_and_token_map(self, connection):
|
|
log.debug("[control connection] Refreshing node list and token map")
|
|
cl = ConsistencyLevel.ONE
|
|
peers_query = QueryMessage(query=self._SELECT_PEERS, consistency_level=cl)
|
|
local_query = QueryMessage(query=self._SELECT_LOCAL, consistency_level=cl)
|
|
peers_result, local_result = connection.wait_for_responses(peers_query, local_query)
|
|
peers_result = dict_factory(*peers_result.results)
|
|
|
|
partitioner = None
|
|
token_map = {}
|
|
|
|
if local_result.results:
|
|
local_rows = dict_factory(*(local_result.results))
|
|
local_row = local_rows[0]
|
|
cluster_name = local_row["cluster_name"]
|
|
self._cluster.metadata.cluster_name = cluster_name
|
|
|
|
host = self._cluster.metadata.get_host(connection.host)
|
|
if host:
|
|
host.set_location_info(local_row["data_center"], local_row["rack"])
|
|
|
|
partitioner = local_row.get("partitioner")
|
|
tokens = local_row.get("tokens")
|
|
if partitioner and tokens:
|
|
token_map[host] = tokens
|
|
|
|
found_hosts = set()
|
|
for row in peers_result:
|
|
addr = row.get("rpc_address")
|
|
|
|
# TODO handle ipv6 equivalent
|
|
if not addr or addr == "0.0.0.0":
|
|
addr = row.get("peer")
|
|
|
|
found_hosts.add(addr)
|
|
|
|
host = self._cluster.metadata.get_host(addr)
|
|
if host is None:
|
|
log.debug("[control connection] Found new host to connect to: %s", addr)
|
|
host = self._cluster.add_host(addr, signal=True)
|
|
host.set_location_info(row.get("data_center"), row.get("rack"))
|
|
|
|
tokens = row.get("tokens")
|
|
if partitioner and tokens:
|
|
token_map[host] = tokens
|
|
|
|
for old_host in self._cluster.metadata.all_hosts():
|
|
if old_host.address != connection.host and \
|
|
old_host.address not in found_hosts:
|
|
log.debug("[control connection] Found host that has been removed: %r", old_host)
|
|
self._cluster.remove_host(old_host)
|
|
|
|
if partitioner:
|
|
self._cluster.metadata.rebuild_token_map(partitioner, token_map)
|
|
|
|
def _handle_topology_change(self, event):
|
|
change_type = event["change_type"]
|
|
addr, port = event["address"]
|
|
if change_type == "NEW_NODE":
|
|
self._cluster.scheduler.schedule(1, self._cluster.add_host, addr, signal=True)
|
|
elif change_type == "REMOVED_NODE":
|
|
host = self._cluster.metadata.get_host(addr)
|
|
self._cluster.scheduler.schedule(0, self._cluster.remove_host, host)
|
|
elif change_type == "MOVED_NODE":
|
|
self._cluster.scheduler.schedule(1, self.refresh_node_list_and_token_map)
|
|
|
|
def _handle_status_change(self, event):
|
|
change_type = event["change_type"]
|
|
addr, port = event["address"]
|
|
host = self._cluster.metadata.get_host(addr)
|
|
if change_type == "UP":
|
|
if host is None:
|
|
# this is the first time we've seen the node
|
|
self._cluster.scheduler.schedule(1, self._cluster.add_host, addr, signal=True)
|
|
else:
|
|
# this will be run by the scheduler
|
|
self._cluster.scheduler.schedule(1, self._cluster.on_up, host)
|
|
elif change_type == "DOWN":
|
|
# Note that there is a slight risk we can receive the event late and thus
|
|
# mark the host down even though we already had reconnected successfully.
|
|
# But it is unlikely, and don't have too much consequence since we'll try reconnecting
|
|
# right away, so we favor the detection to make the Host.is_up more accurate.
|
|
if host is not None:
|
|
# this will be run by the scheduler
|
|
self._cluster.on_down(host, is_host_addition=False)
|
|
|
|
def _handle_schema_change(self, event):
|
|
keyspace = event['keyspace'] or None
|
|
table = event['table'] or None
|
|
if event['change_type'] in ("CREATED", "DROPPED"):
|
|
keyspace = keyspace if table else None
|
|
self._cluster.executor.submit(self.refresh_schema, keyspace)
|
|
elif event['change_type'] == "UPDATED":
|
|
self._cluster.executor.submit(self.refresh_schema, keyspace, table)
|
|
|
|
def wait_for_schema_agreement(self, connection=None):
|
|
# Each schema change typically generates two schema refreshes, one
|
|
# from the response type and one from the pushed notification. Holding
|
|
# a lock is just a simple way to cut down on the number of schema queries
|
|
# we'll make.
|
|
with self._schema_agreement_lock:
|
|
log.debug("[control connection] Waiting for schema agreement")
|
|
if not connection:
|
|
connection = self._connection
|
|
|
|
start = self._time.time()
|
|
elapsed = 0
|
|
cl = ConsistencyLevel.ONE
|
|
while elapsed < self._cluster.max_schema_agreement_wait:
|
|
peers_query = QueryMessage(query=self._SELECT_SCHEMA_PEERS, consistency_level=cl)
|
|
local_query = QueryMessage(query=self._SELECT_SCHEMA_LOCAL, consistency_level=cl)
|
|
peers_result, local_result = connection.wait_for_responses(peers_query, local_query)
|
|
peers_result = dict_factory(*peers_result.results)
|
|
|
|
versions = set()
|
|
if local_result.results:
|
|
local_row = dict_factory(*local_result.results)[0]
|
|
if local_row.get("schema_version"):
|
|
versions.add(local_row.get("schema_version"))
|
|
|
|
for row in peers_result:
|
|
if not row.get("rpc_address") or not row.get("schema_version"):
|
|
continue
|
|
|
|
rpc = row.get("rpc_address")
|
|
if rpc == "0.0.0.0": # TODO ipv6 check
|
|
rpc = row.get("peer")
|
|
|
|
peer = self._cluster.metadata.get_host(rpc)
|
|
if peer and peer.is_up:
|
|
versions.add(row.get("schema_version"))
|
|
|
|
if len(versions) == 1:
|
|
log.debug("[control connection] Schemas match")
|
|
return True
|
|
|
|
log.debug("[control connection] Schemas mismatched, trying again")
|
|
self._time.sleep(0.2)
|
|
elapsed = self._time.time() - start
|
|
|
|
return False
|
|
|
|
def _signal_error(self):
|
|
# try just signaling the cluster, as this will trigger a reconnect
|
|
# as part of marking the host down
|
|
if self._connection and self._connection.is_defunct:
|
|
host = self._cluster.metadata.get_host(self._connection.host)
|
|
# host may be None if it's already been removed, but that indicates
|
|
# that errors have already been reported, so we're fine
|
|
if host:
|
|
self._cluster.signal_connection_failure(
|
|
host, self._connection.last_error, is_host_addition=False)
|
|
return
|
|
|
|
# if the connection is not defunct or the host already left, reconnect
|
|
# manually
|
|
self.reconnect()
|
|
|
|
@property
|
|
def is_open(self):
|
|
conn = self._connection
|
|
return bool(conn and conn.is_open)
|
|
|
|
def on_up(self, host):
|
|
pass
|
|
|
|
def on_down(self, host):
|
|
|
|
conn = self._connection
|
|
if conn and conn.host == host.address and \
|
|
self._reconnection_handler is None:
|
|
log.debug("[control connection] Control connection host (%s) is "
|
|
"considered down, starting reconnection", host)
|
|
# this will result in a task being submitted to the executor to reconnect
|
|
self.reconnect()
|
|
|
|
def on_add(self, host):
|
|
self.refresh_node_list_and_token_map()
|
|
|
|
def on_remove(self, host):
|
|
self.refresh_node_list_and_token_map()
|
|
|
|
|
|
class _Scheduler(object):
|
|
|
|
_scheduled = None
|
|
_executor = None
|
|
is_shutdown = False
|
|
|
|
def __init__(self, executor):
|
|
self._scheduled = Queue.PriorityQueue()
|
|
self._executor = executor
|
|
|
|
t = Thread(target=self.run, name="Task Scheduler")
|
|
t.daemon = True
|
|
t.start()
|
|
|
|
def shutdown(self):
|
|
try:
|
|
log.debug("Shutting down Cluster Scheduler")
|
|
except AttributeError:
|
|
# this can happen on interpreter shutdown
|
|
pass
|
|
self.is_shutdown = True
|
|
|
|
def schedule(self, delay, fn, *args, **kwargs):
|
|
if not self.is_shutdown:
|
|
run_at = time.time() + delay
|
|
self._scheduled.put_nowait((run_at, (fn, args, kwargs)))
|
|
else:
|
|
log.debug("Ignoring scheduled function after shutdown: %r", fn)
|
|
|
|
def run(self):
|
|
while True:
|
|
if self.is_shutdown:
|
|
return
|
|
|
|
try:
|
|
while True:
|
|
run_at, task = self._scheduled.get(block=True, timeout=None)
|
|
if self.is_shutdown:
|
|
log.debug("Not executing scheduled task due to Scheduler shutdown")
|
|
return
|
|
if run_at <= time.time():
|
|
fn, args, kwargs = task
|
|
self._executor.submit(fn, *args, **kwargs)
|
|
else:
|
|
self._scheduled.put_nowait((run_at, task))
|
|
break
|
|
except Queue.Empty:
|
|
pass
|
|
|
|
time.sleep(0.1)
|
|
|
|
|
|
def refresh_schema_and_set_result(keyspace, table, control_conn, response_future):
|
|
try:
|
|
control_conn.refresh_schema(keyspace, table)
|
|
except Exception:
|
|
log.exception("Exception refreshing schema in response to schema change:")
|
|
finally:
|
|
response_future._set_final_result(None)
|
|
|
|
|
|
_NO_RESULT_YET = object()
|
|
|
|
|
|
class ResponseFuture(object):
|
|
"""
|
|
An asynchronous response delivery mechanism that is returned from calls
|
|
to :meth:`.Session.execute_async()`.
|
|
|
|
There are two ways for results to be delivered:
|
|
- Synchronously, by calling :meth:`.result()`
|
|
- Asynchronously, by attaching callback and errback functions via
|
|
:meth:`.add_callback()`, :meth:`.add_errback()`, and
|
|
:meth:`.add_callbacks()`.
|
|
"""
|
|
session = None
|
|
row_factory = None
|
|
message = None
|
|
query = None
|
|
|
|
_req_id = None
|
|
_final_result = _NO_RESULT_YET
|
|
_final_exception = None
|
|
_query_trace = None
|
|
_callback = None
|
|
_errback = None
|
|
_current_host = None
|
|
_current_pool = None
|
|
_connection = None
|
|
_query_retries = 0
|
|
_start_time = None
|
|
_metrics = None
|
|
|
|
def __init__(self, session, message, query, metrics=None):
|
|
self.session = session
|
|
self.row_factory = session.row_factory
|
|
self.message = message
|
|
self.query = query
|
|
self._metrics = metrics
|
|
if metrics is not None:
|
|
self._start_time = time.time()
|
|
|
|
# convert the list/generator/etc to an iterator so that subsequent
|
|
# calls to send_request (which retries may do) will resume where
|
|
# they last left off
|
|
self.query_plan = iter(session._load_balancer.make_query_plan(
|
|
session.keyspace, query))
|
|
|
|
self._event = Event()
|
|
self._errors = {}
|
|
|
|
def __del__(self):
|
|
try:
|
|
del self.session
|
|
except AttributeError:
|
|
pass
|
|
|
|
def send_request(self):
|
|
""" Internal """
|
|
# query_plan is an iterator, so this will resume where we last left
|
|
# off if send_request() is called multiple times
|
|
for host in self.query_plan:
|
|
req_id = self._query(host)
|
|
if req_id is not None:
|
|
self._req_id = req_id
|
|
return
|
|
|
|
self._set_final_exception(NoHostAvailable(
|
|
"Unable to complete the operation against any hosts", self._errors))
|
|
|
|
def _query(self, host, message=None, cb=None):
|
|
if message is None:
|
|
message = self.message
|
|
|
|
if cb is None:
|
|
cb = self._set_result
|
|
|
|
pool = self.session._pools.get(host)
|
|
if not pool:
|
|
self._errors[host] = ConnectionException("Host has been marked down or removed")
|
|
return None
|
|
elif pool.is_shutdown:
|
|
self._errors[host] = ConnectionException("Pool is shutdown")
|
|
return None
|
|
|
|
connection = None
|
|
try:
|
|
# TODO get connectTimeout from cluster settings
|
|
connection = pool.borrow_connection(timeout=2.0)
|
|
request_id = connection.send_msg(message, cb=cb)
|
|
except Exception as exc:
|
|
log.debug("Error querying host %s", host, exc_info=True)
|
|
self._errors[host] = exc
|
|
if connection:
|
|
pool.return_connection(connection)
|
|
return None
|
|
|
|
self._current_host = host
|
|
self._current_pool = pool
|
|
self._connection = connection
|
|
return request_id
|
|
|
|
def _reprepare(self, prepare_message):
|
|
cb = partial(self.session.submit, self._execute_after_prepare)
|
|
request_id = self._query(self._current_host, prepare_message, cb=cb)
|
|
if request_id is None:
|
|
# try to submit the original prepared statement on some other host
|
|
self.send_request()
|
|
|
|
def _set_result(self, response):
|
|
try:
|
|
if self._current_pool and self._connection:
|
|
self._current_pool.return_connection(self._connection)
|
|
|
|
trace_id = getattr(response, 'trace_id', None)
|
|
if trace_id:
|
|
self._query_trace = QueryTrace(trace_id, self.session)
|
|
|
|
if isinstance(response, ResultMessage):
|
|
if response.kind == ResultMessage.KIND_SET_KEYSPACE:
|
|
session = getattr(self, 'session', None)
|
|
# since we're running on the event loop thread, we need to
|
|
# use a non-blocking method for setting the keyspace on
|
|
# all connections in this session, otherwise the event
|
|
# loop thread will deadlock waiting for keyspaces to be
|
|
# set. This uses a callback chain which ends with
|
|
# self._set_keyspace_completed() being called in the
|
|
# event loop thread.
|
|
if session:
|
|
session._set_keyspace_for_all_pools(
|
|
response.results, self._set_keyspace_completed)
|
|
elif response.kind == ResultMessage.KIND_SCHEMA_CHANGE:
|
|
# refresh the schema before responding, but do it in another
|
|
# thread instead of the event loop thread
|
|
self.session.submit(
|
|
refresh_schema_and_set_result,
|
|
response.results['keyspace'],
|
|
response.results['table'],
|
|
self.session.cluster.control_connection,
|
|
self)
|
|
else:
|
|
results = getattr(response, 'results', None)
|
|
if results is not None and response.kind == ResultMessage.KIND_ROWS:
|
|
results = self.row_factory(*results)
|
|
self._set_final_result(results)
|
|
elif isinstance(response, ErrorMessage):
|
|
retry_policy = None
|
|
if self.query:
|
|
retry_policy = self.query.retry_policy
|
|
if not retry_policy:
|
|
retry_policy = self.session.cluster.default_retry_policy
|
|
|
|
if isinstance(response, ReadTimeoutErrorMessage):
|
|
if self._metrics is not None:
|
|
self._metrics.on_read_timeout()
|
|
retry = retry_policy.on_read_timeout(
|
|
self.query, retry_num=self._query_retries, **response.info)
|
|
elif isinstance(response, WriteTimeoutErrorMessage):
|
|
if self._metrics is not None:
|
|
self._metrics.on_write_timeout()
|
|
retry = retry_policy.on_write_timeout(
|
|
self.query, retry_num=self._query_retries, **response.info)
|
|
elif isinstance(response, UnavailableErrorMessage):
|
|
if self._metrics is not None:
|
|
self._metrics.on_unavailable()
|
|
retry = retry_policy.on_unavailable(
|
|
self.query, retry_num=self._query_retries, **response.info)
|
|
elif isinstance(response, OverloadedErrorMessage):
|
|
if self._metrics is not None:
|
|
self._metrics.on_other_error()
|
|
# need to retry against a different host here
|
|
log.warn("Host %s is overloaded, retrying against a different "
|
|
"host", self._current_host)
|
|
self._retry(reuse_connection=False, consistency_level=None)
|
|
return
|
|
elif isinstance(response, IsBootstrappingErrorMessage):
|
|
if self._metrics is not None:
|
|
self._metrics.on_other_error()
|
|
# need to retry against a different host here
|
|
self._retry(reuse_connection=False, consistency_level=None)
|
|
return
|
|
elif isinstance(response, PreparedQueryNotFound):
|
|
query_id = response.info
|
|
try:
|
|
prepared_statement = self.session.cluster._prepared_statements[query_id]
|
|
except KeyError:
|
|
log.error("Tried to execute unknown prepared statement %s", query_id.encode('hex'))
|
|
self._set_final_exception(response)
|
|
return
|
|
|
|
current_keyspace = self._connection.keyspace
|
|
prepared_keyspace = prepared_statement.keyspace
|
|
if current_keyspace != prepared_keyspace:
|
|
self._set_final_exception(
|
|
ValueError("The Session's current keyspace (%s) does "
|
|
"not match the keyspace the statement was "
|
|
"prepared with (%s)" %
|
|
(current_keyspace, prepared_keyspace)))
|
|
return
|
|
|
|
log.debug("Re-preparing unrecognized prepared statement against host %s: %s",
|
|
self._current_host, prepared_statement.query_string)
|
|
prepare_message = PrepareMessage(query=prepared_statement.query_string)
|
|
# since this might block, run on the executor to avoid hanging
|
|
# the event loop thread
|
|
self.session.submit(self._reprepare, prepare_message)
|
|
return
|
|
else:
|
|
if hasattr(response, 'to_exception'):
|
|
self._set_final_exception(response.to_exception())
|
|
else:
|
|
self._set_final_exception(response)
|
|
return
|
|
|
|
retry_type, consistency = retry
|
|
if retry_type is RetryPolicy.RETRY:
|
|
self._query_retries += 1
|
|
self._retry(reuse_connection=True, consistency_level=consistency)
|
|
elif retry_type is RetryPolicy.RETHROW:
|
|
self._set_final_exception(response.to_exception())
|
|
else: # IGNORE
|
|
if self._metrics is not None:
|
|
self._metrics.on_ignore()
|
|
self._set_final_result(None)
|
|
elif isinstance(response, ConnectionException):
|
|
if self._metrics is not None:
|
|
self._metrics.on_connection_error()
|
|
if not isinstance(response, ConnectionShutdown):
|
|
self._connection.defunct(response)
|
|
self._retry(reuse_connection=False, consistency_level=None)
|
|
elif isinstance(response, Exception):
|
|
if hasattr(response, 'to_exception'):
|
|
self._set_final_exception(response.to_exception())
|
|
else:
|
|
self._set_final_exception(response)
|
|
else:
|
|
# we got some other kind of response message
|
|
msg = "Got unexpected message: %r" % (response,)
|
|
exc = ConnectionException(msg, self._current_host)
|
|
self._connection.defunct(exc)
|
|
self._set_final_exception(exc)
|
|
except Exception as exc:
|
|
# almost certainly caused by a bug, but we need to set something here
|
|
log.exception("Unexpected exception while handling result in ResponseFuture:")
|
|
self._set_final_exception(exc)
|
|
|
|
def _set_keyspace_completed(self, errors):
|
|
if not errors:
|
|
self._set_final_result(None)
|
|
else:
|
|
self._set_final_exception(ConnectionException(
|
|
"Failed to set keyspace on all hosts: %s" % (errors,)))
|
|
|
|
def _execute_after_prepare(self, response):
|
|
"""
|
|
Handle the response to our attempt to prepare a statement.
|
|
If it succeeded, run the original query again against the same host.
|
|
"""
|
|
if self._current_pool and self._connection:
|
|
self._current_pool.return_connection(self._connection)
|
|
|
|
if self._final_exception:
|
|
return
|
|
|
|
if isinstance(response, ResultMessage):
|
|
if response.kind == ResultMessage.KIND_PREPARED:
|
|
# use self._query to re-use the same host and
|
|
# at the same time properly borrow the connection
|
|
request_id = self._query(self._current_host)
|
|
if request_id is None:
|
|
# this host errored out, move on to the next
|
|
self.send_request()
|
|
else:
|
|
self._set_final_exception(ConnectionException(
|
|
"Got unexpected response when preparing statement "
|
|
"on host %s: %s" % (self._current_host, response)))
|
|
elif isinstance(response, ErrorMessage):
|
|
self._set_final_exception(response)
|
|
elif isinstance(response, ConnectionException):
|
|
log.debug("Connection error when preparing statement on host %s: %s",
|
|
self._current_host, response)
|
|
# try again on a different host, preparing again if necessary
|
|
self._errors[self._current_host] = response
|
|
self.send_request()
|
|
else:
|
|
self._set_final_exception(ConnectionException(
|
|
"Got unexpected response type when preparing "
|
|
"statement on host %s: %s" % (self._current_host, response)))
|
|
|
|
def _set_final_result(self, response):
|
|
if self._metrics is not None:
|
|
self._metrics.request_timer.addValue(time.time() - self._start_time)
|
|
if hasattr(self, 'session'):
|
|
try:
|
|
del self.session # clear reference cycles
|
|
except AttributeError:
|
|
pass
|
|
self._final_result = response
|
|
self._event.set()
|
|
if self._callback:
|
|
fn, args, kwargs = self._callback
|
|
fn(response, *args, **kwargs)
|
|
|
|
def _set_final_exception(self, response):
|
|
if self._metrics is not None:
|
|
self._metrics.request_timer.addValue(time.time() - self._start_time)
|
|
try:
|
|
del self.session # clear reference cycles
|
|
except AttributeError:
|
|
pass
|
|
self._final_exception = response
|
|
self._event.set()
|
|
if self._errback:
|
|
fn, args, kwargs = self._errback
|
|
fn(response, *args, **kwargs)
|
|
|
|
def _retry(self, reuse_connection, consistency_level):
|
|
if self._final_exception:
|
|
# the connection probably broke while we were waiting
|
|
# to retry the operation
|
|
return
|
|
|
|
if self._metrics is not None:
|
|
self._metrics.on_retry()
|
|
if consistency_level is not None:
|
|
self.message.consistency_level = consistency_level
|
|
|
|
# don't retry on the event loop thread
|
|
self.session.submit(self._retry_task, reuse_connection)
|
|
|
|
def _retry_task(self, reuse_connection):
|
|
if self._final_exception:
|
|
# the connection probably broke while we were waiting
|
|
# to retry the operation
|
|
return
|
|
|
|
if reuse_connection and self._query(self._current_host):
|
|
return
|
|
|
|
# otherwise, move onto another host
|
|
self.send_request()
|
|
|
|
def result(self, timeout=None):
|
|
"""
|
|
Return the final result or raise an Exception if errors were
|
|
encountered. If the final result or error has not been set
|
|
yet, this method will block until that time.
|
|
|
|
Example usage::
|
|
|
|
>>> future = session.execute_async("SELECT * FROM mycf")
|
|
>>> # do other stuff...
|
|
|
|
>>> try:
|
|
... rows = future.result()
|
|
... for row in rows:
|
|
... ... # process results
|
|
... except Exception:
|
|
... log.exception("Operation failed:")
|
|
|
|
"""
|
|
if self._final_result is not _NO_RESULT_YET:
|
|
return self._final_result
|
|
elif self._final_exception:
|
|
raise self._final_exception
|
|
else:
|
|
self._event.wait(timeout=timeout)
|
|
if self._final_result is not _NO_RESULT_YET:
|
|
return self._final_result
|
|
elif self._final_exception:
|
|
raise self._final_exception
|
|
else:
|
|
raise OperationTimedOut()
|
|
|
|
def get_query_trace(self):
|
|
"""
|
|
Returns the :class:`~.query.QueryTrace` instance representing a trace
|
|
of the last attempt for this operation, or :const:`None` if tracing was
|
|
not enabled for this query. Note that this may raise an exception if
|
|
there are problems retrieving the trace details from Cassandra.
|
|
"""
|
|
if not self._query_trace:
|
|
return None
|
|
|
|
self._query_trace.populate()
|
|
return self._query_trace
|
|
|
|
def add_callback(self, fn, *args, **kwargs):
|
|
"""
|
|
Attaches a callback function to be called when the final results arrive.
|
|
|
|
By default, `fn` will be called with the results as the first and only
|
|
argument. If `*args` or `**kwargs` are supplied, they will be passed
|
|
through as additional positional or keyword arguments to `fn`.
|
|
|
|
If an error is hit while executing the operation, a callback attached
|
|
here will not be called. Use :meth:`.add_errback()` or :meth:`add_callbacks()`
|
|
if you wish to handle that case.
|
|
|
|
If the final result has already been seen when this method is called,
|
|
the callback will be called immediately (before this method returns).
|
|
|
|
Usage example::
|
|
|
|
>>> session = cluster.connect("mykeyspace")
|
|
|
|
>>> def handle_results(rows, start_time, should_log=False):
|
|
... if should_log:
|
|
... log.info("Total time: %f", time.time() - start_time)
|
|
... ...
|
|
|
|
>>> future = session.execute_async("SELECT * FROM users")
|
|
>>> future.add_callback(handle_results, time.time(), should_log=True)
|
|
|
|
"""
|
|
if self._final_result is not _NO_RESULT_YET:
|
|
fn(self._final_result, *args, **kwargs)
|
|
else:
|
|
self._callback = (fn, args, kwargs)
|
|
return self
|
|
|
|
def add_errback(self, fn, *args, **kwargs):
|
|
"""
|
|
Like :meth:`.add_callback()`, but handles error cases.
|
|
An Exception instance will be passed as the first positional argument
|
|
to `fn`.
|
|
"""
|
|
if self._final_exception:
|
|
fn(self._final_exception, *args, **kwargs)
|
|
else:
|
|
self._errback = (fn, args, kwargs)
|
|
return self
|
|
|
|
def add_callbacks(self, callback, errback,
|
|
callback_args=(), callback_kwargs=None,
|
|
errback_args=(), errback_kwargs=None):
|
|
"""
|
|
A convenient combination of :meth:`.add_callback()` and
|
|
:meth:`.add_errback()`.
|
|
|
|
Example usage::
|
|
|
|
>>> session = cluster.connect()
|
|
>>> query = "SELECT * FROM mycf"
|
|
>>> future = session.execute_async(query)
|
|
|
|
>>> def log_results(results, level='debug'):
|
|
... for row in results:
|
|
... log.log(level, "Result: %s", row)
|
|
|
|
>>> def log_error(exc, query):
|
|
... log.error("Query '%s' failed: %s", query, exc)
|
|
|
|
>>> future.add_callbacks(
|
|
... callback=log_results, callback_kwargs={'level': 'info'},
|
|
... errback=log_error, errback_args=(query,))
|
|
|
|
"""
|
|
self.add_callback(callback, *callback_args, **(callback_kwargs or {}))
|
|
self.add_errback(errback, *errback_args, **(errback_kwargs or {}))
|
|
|
|
def __str__(self):
|
|
query = self.query.query_string
|
|
return "<ResponseFuture: query='%s' request_id=%s result=%s exception=%s host=%s>" \
|
|
% (query, self._req_id, self._final_result, self._final_exception, self._current_host)
|
|
__repr__ = __str__
|