54699cbc04
The TokenAwarePolicy now takes into account what keyspace the query is being run against so that replication settings can be taken into account. This means that all replicas for the queried row can be used instead of just the first replica.
1726 lines
64 KiB
Python
1726 lines
64 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 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
|
|
from itertools import groupby
|
|
|
|
from cassandra import ConsistencyLevel, AuthenticationFailed
|
|
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, Query)
|
|
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
|
|
|
|
|
|
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
|
|
|
|
|
|
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 = RoundRobinPolicy()
|
|
"""
|
|
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:`.Query` objects which do not have a :attr:`~.Query.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`.
|
|
"""
|
|
|
|
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
|
|
|
|
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,
|
|
sockopts=None,
|
|
executor_threads=2,
|
|
max_schema_agreement_wait=10):
|
|
"""
|
|
Any of the mutable Cluster attributes may be set as keyword arguments
|
|
to the constructor.
|
|
"""
|
|
|
|
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
|
|
|
|
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.sockopts = sockopts
|
|
self.max_schema_agreement_wait = max_schema_agreement_wait
|
|
|
|
# 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)
|
|
for address in contact_points:
|
|
self.add_host(address, signal=True)
|
|
|
|
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.
|
|
"""
|
|
if self.auth_provider:
|
|
kwargs['credentials'] = self.auth_provider(address)
|
|
|
|
kwargs['compression'] = self.compression
|
|
kwargs['sockopts'] = self.sockopts
|
|
|
|
return self.connection_class.factory(address, *args, **kwargs)
|
|
|
|
def _make_connection_factory(self, host, *args, **kwargs):
|
|
if self.auth_provider:
|
|
kwargs['credentials'] = self.auth_provider(host)
|
|
|
|
kwargs['compression'] = self.compression
|
|
kwargs['sockopts'] = self.sockopts
|
|
|
|
return partial(self.connection_class.factory, host.address, *args, **kwargs)
|
|
|
|
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:
|
|
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 on_up(self, host):
|
|
"""
|
|
Called when a host is marked up by its :class:`~.HealthMonitor`.
|
|
Intended for internal use only.
|
|
"""
|
|
reconnector = host.get_and_set_reconnection_handler(None)
|
|
if reconnector:
|
|
reconnector.cancel()
|
|
|
|
self._prepare_all_queries(host)
|
|
|
|
self.control_connection.on_up(host)
|
|
for session in self.sessions:
|
|
session.on_up(host)
|
|
|
|
def on_down(self, host):
|
|
"""
|
|
Called when a host is marked down by its :class:`~.HealthMonitor`.
|
|
Intended for internal use only.
|
|
"""
|
|
self.control_connection.on_down(host)
|
|
for session in self.sessions:
|
|
session.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, self.scheduler, schedule,
|
|
host.get_and_set_reconnection_handler, new_handler=None)
|
|
|
|
old_reconnector = host.get_and_set_reconnection_handler(reconnector)
|
|
if old_reconnector:
|
|
old_reconnector.cancel()
|
|
|
|
reconnector.start()
|
|
|
|
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.
|
|
"""
|
|
log.info("Now considering host %s for new connections", address)
|
|
new_host = self.metadata.add_host(address)
|
|
if new_host and signal:
|
|
self._prepare_all_queries(new_host)
|
|
self.control_connection.on_add(new_host)
|
|
for session in self.sessions: # TODO need to copy/lock?
|
|
session.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.
|
|
"""
|
|
log.info("Host %s will no longer be considered for new connections", host)
|
|
if host and self.metadata.remove_host(host):
|
|
self.control_connection.on_remove(host)
|
|
for session in self.sessions:
|
|
session.on_remove(host)
|
|
|
|
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:
|
|
pass
|
|
|
|
statements = self._prepared_statements.values()
|
|
for keyspace, ks_statements in groupby(statements, lambda s: s.keyspace):
|
|
if keyspace is not None:
|
|
connection.set_keyspace(keyspace)
|
|
|
|
# note: we could potentially prepare some of these in parallel,
|
|
# but at the same time, we don't want to put too much load on
|
|
# the server at once
|
|
for statement in ks_statements:
|
|
message = PrepareMessage(query=statement.query_string)
|
|
try:
|
|
response = connection.wait_for_response(message)
|
|
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))
|
|
except Exception:
|
|
log.exception("Error trying to prepare statement on "
|
|
"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:
|
|
self.add_host(host)
|
|
|
|
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.Query`.
|
|
|
|
`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:`~.Query.trace` attribute in the form of a :class:`.QueryTrace`
|
|
instance. This requires that `query` be a :class:`.Query` subclass
|
|
instance and not just a string. If there is an error fetching the
|
|
trace details, the :attr:`~.Query.trace` attribute will be left as
|
|
:const:`None`.
|
|
"""
|
|
if trace and not isinstance(query, Query):
|
|
raise TypeError(
|
|
"The query argument must be an instance of a subclass of "
|
|
"cassandra.query.Query 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.
|
|
"""
|
|
for host, pool in self._pools.items():
|
|
if host != excluded_host:
|
|
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" % (host,))
|
|
continue
|
|
|
|
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_host(self, host):
|
|
""" Internal """
|
|
distance = self._load_balancer.distance(host)
|
|
if distance == HostDistance.IGNORED:
|
|
return self._pools.get(host)
|
|
else:
|
|
try:
|
|
new_pool = HostConnectionPool(host, distance, self)
|
|
except AuthenticationFailed as auth_exc:
|
|
conn_exc = ConnectionException(str(auth_exc), host=host)
|
|
host.monitor.signal_connection_failure(conn_exc)
|
|
return self._pools.get(host)
|
|
except Exception as conn_exc:
|
|
host.monitor.signal_connection_failure(conn_exc)
|
|
return self._pools.get(host)
|
|
|
|
previous = self._pools.get(host)
|
|
self._pools[host] = new_pool
|
|
return previous
|
|
|
|
def on_up(self, host):
|
|
"""
|
|
Called by the parent Cluster instance when a host's :class:`HealthMonitor`
|
|
marks it up. Only intended for internal use.
|
|
"""
|
|
previous_pool = self.add_host(host)
|
|
self._load_balancer.on_up(host)
|
|
if previous_pool:
|
|
previous_pool.shutdown()
|
|
|
|
def on_down(self, host):
|
|
"""
|
|
Called by the parent Cluster instance when a host's :class:`HealthMonitor`
|
|
marks it down. Only intended for internal use.
|
|
"""
|
|
self._load_balancer.on_down(host)
|
|
pool = self._pools.pop(host, None)
|
|
if pool:
|
|
pool.shutdown()
|
|
|
|
for host in self.cluster.metadata.all_hosts():
|
|
if not host.monitor.is_up:
|
|
continue
|
|
|
|
distance = self._load_balancer.distance(host)
|
|
if distance != HostDistance.IGNORED:
|
|
pool = self._pools.get(host)
|
|
if not pool:
|
|
self.add_host(host)
|
|
else:
|
|
pool.host_distance = distance
|
|
|
|
def on_add(self, host):
|
|
""" Internal """
|
|
previous_pool = self.add_host(host)
|
|
self._load_balancer.on_add(host)
|
|
if previous_pool:
|
|
previous_pool.shutdown()
|
|
|
|
def on_remove(self, host):
|
|
""" Internal """
|
|
self._load_balancer.on_remove(host)
|
|
pool = self._pools.pop(host)
|
|
if pool:
|
|
pool.shutdown()
|
|
|
|
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 submit(self, fn, *args, **kwargs):
|
|
""" Internal """
|
|
return self.cluster.executor.submit(fn, *args, **kwargs)
|
|
|
|
|
|
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:
|
|
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
|
|
host.monitor.signal_connection_failure(exc)
|
|
log.warn("[control connection] Error connecting to %s:", host, exc_info=True)
|
|
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 to %s, "
|
|
"registering watchers and refreshing schema and topology",
|
|
host)
|
|
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)
|
|
log.debug("[control connection] Got system table results to refresh node list and token map")
|
|
|
|
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:
|
|
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:
|
|
self._cluster.scheduler.schedule(1, host.monitor.set_up)
|
|
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:
|
|
self._cluster.scheduler.schedule(1, host.monitor.set_down)
|
|
|
|
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.monitor.is_up:
|
|
versions.add(row.get("schema_version"))
|
|
|
|
if len(versions) == 1:
|
|
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 host monitor, 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:
|
|
host.monitor.signal_connection_failure(self._connection.last_error)
|
|
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):
|
|
log.debug("[control connection] Host %s is considered up" % (host,))
|
|
self._balancing_policy.on_up(host)
|
|
|
|
def on_down(self, host):
|
|
log.debug("[control connection] Host %s is considered down" % (host,))
|
|
self._balancing_policy.on_down(host)
|
|
|
|
conn = self._connection
|
|
if conn and conn.host == host.address and \
|
|
self._reconnection_handler is None:
|
|
self.reconnect()
|
|
|
|
def on_add(self, host):
|
|
log.debug("[control connection] Adding host %r and refreshing topology" % (host,))
|
|
self._balancing_policy.on_add(host)
|
|
self.refresh_node_list_and_token_map()
|
|
|
|
def on_remove(self, host):
|
|
log.debug("[control connection] Removing host %r and refreshing topology" % (host,))
|
|
self._balancing_policy.on_remove(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._final_exception = NoHostAvailable(
|
|
"Unable to complete the operation against any hosts", self._errors)
|
|
|
|
def _query(self, host):
|
|
pool = self.session._pools.get(host)
|
|
if not pool or 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(self.message, cb=self._set_result)
|
|
self._current_host = host
|
|
self._current_pool = pool
|
|
self._connection = connection
|
|
return request_id
|
|
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
|
|
|
|
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)
|
|
if session:
|
|
session.keyspace = response.results
|
|
self._set_final_result(None)
|
|
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
|
|
|
|
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._connection.send_msg,
|
|
prepare_message,
|
|
cb=self._execute_after_prepare)
|
|
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 _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 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
|
|
self._query(self._current_host)
|
|
else:
|
|
self._set_final_exception(ConnectionException(
|
|
"Got unexpected response when preparing statement "
|
|
"on host %s: %s" % (self._host, response)))
|
|
elif isinstance(response, ErrorMessage):
|
|
self._set_final_exception(response)
|
|
else:
|
|
self._set_final_exception(ConnectionException(
|
|
"Got unexpected response type when preparing "
|
|
"statement on host %s: %s" % (self._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._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):
|
|
"""
|
|
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()
|
|
if self._final_result is not _NO_RESULT_YET:
|
|
return self._final_result
|
|
elif self._final_exception:
|
|
raise self._final_exception
|
|
else:
|
|
assert False # shouldn't get here
|
|
|
|
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)
|