import asyncio
import collections
import random
import socket
import warnings
from typing import (
Any,
Callable,
Deque,
Dict,
Generator,
List,
Mapping,
Optional,
Tuple,
Type,
TypeVar,
Union,
)
from redis._parsers import AsyncCommandsParser, Encoder
from redis._parsers.helpers import (
_RedisCallbacks,
_RedisCallbacksRESP2,
_RedisCallbacksRESP3,
)
from redis.asyncio.client import ResponseCallbackT
from redis.asyncio.connection import Connection, DefaultParser, SSLConnection, parse_url
from redis.asyncio.lock import Lock
from redis.asyncio.retry import Retry
from redis.backoff import default_backoff
from redis.client import EMPTY_RESPONSE, NEVER_DECODE, AbstractRedis
from redis.cluster import (
PIPELINE_BLOCKED_COMMANDS,
PRIMARY,
REPLICA,
SLOT_ID,
AbstractRedisCluster,
LoadBalancer,
block_pipeline_command,
get_node_name,
parse_cluster_slots,
)
from redis.commands import READ_COMMANDS, AsyncRedisClusterCommands
from redis.crc import REDIS_CLUSTER_HASH_SLOTS, key_slot
from redis.credentials import CredentialProvider
from redis.exceptions import (
AskError,
BusyLoadingError,
ClusterCrossSlotError,
ClusterDownError,
ClusterError,
ConnectionError,
DataError,
MasterDownError,
MaxConnectionsError,
MovedError,
RedisClusterException,
ResponseError,
SlotNotCoveredError,
TimeoutError,
TryAgainError,
)
from redis.typing import AnyKeyT, EncodableT, KeyT
from redis.utils import (
deprecated_function,
dict_merge,
get_lib_version,
safe_str,
str_if_bytes,
)
TargetNodesT = TypeVar(
"TargetNodesT", str, "ClusterNode", List["ClusterNode"], Dict[Any, "ClusterNode"]
)
class ClusterParser(DefaultParser):
EXCEPTION_CLASSES = dict_merge(
DefaultParser.EXCEPTION_CLASSES,
{
"ASK": AskError,
"CLUSTERDOWN": ClusterDownError,
"CROSSSLOT": ClusterCrossSlotError,
"MASTERDOWN": MasterDownError,
"MOVED": MovedError,
"TRYAGAIN": TryAgainError,
},
)
[docs]class RedisCluster(AbstractRedis, AbstractRedisCluster, AsyncRedisClusterCommands):
"""
Create a new RedisCluster client.
Pass one of parameters:
- `host` & `port`
- `startup_nodes`
| Use ``await`` :meth:`initialize` to find cluster nodes & create connections.
| Use ``await`` :meth:`close` to disconnect connections & close client.
Many commands support the target_nodes kwarg. It can be one of the
:attr:`NODE_FLAGS`:
- :attr:`PRIMARIES`
- :attr:`REPLICAS`
- :attr:`ALL_NODES`
- :attr:`RANDOM`
- :attr:`DEFAULT_NODE`
Note: This client is not thread/process/fork safe.
:param host:
| Can be used to point to a startup node
:param port:
| Port used if **host** is provided
:param startup_nodes:
| :class:`~.ClusterNode` to used as a startup node
:param require_full_coverage:
| When set to ``False``: the client will not require a full coverage of
the slots. However, if not all slots are covered, and at least one node
has ``cluster-require-full-coverage`` set to ``yes``, the server will throw
a :class:`~.ClusterDownError` for some key-based commands.
| When set to ``True``: all slots must be covered to construct the cluster
client. If not all slots are covered, :class:`~.RedisClusterException` will be
thrown.
| See:
https://redis.io/docs/manual/scaling/#redis-cluster-configuration-parameters
:param read_from_replicas:
| Enable read from replicas in READONLY mode. You can read possibly stale data.
When set to true, read commands will be assigned between the primary and
its replications in a Round-Robin manner.
:param reinitialize_steps:
| Specifies the number of MOVED errors that need to occur before reinitializing
the whole cluster topology. If a MOVED error occurs and the cluster does not
need to be reinitialized on this current error handling, only the MOVED slot
will be patched with the redirected node.
To reinitialize the cluster on every MOVED error, set reinitialize_steps to 1.
To avoid reinitializing the cluster on moved errors, set reinitialize_steps to
0.
:param cluster_error_retry_attempts:
| Number of times to retry before raising an error when :class:`~.TimeoutError`
or :class:`~.ConnectionError` or :class:`~.ClusterDownError` are encountered
:param connection_error_retry_attempts:
| Number of times to retry before reinitializing when :class:`~.TimeoutError`
or :class:`~.ConnectionError` are encountered.
The default backoff strategy will be set if Retry object is not passed (see
default_backoff in backoff.py). To change it, pass a custom Retry object
using the "retry" keyword.
:param max_connections:
| Maximum number of connections per node. If there are no free connections & the
maximum number of connections are already created, a
:class:`~.MaxConnectionsError` is raised. This error may be retried as defined
by :attr:`connection_error_retry_attempts`
:param address_remap:
| An optional callable which, when provided with an internal network
address of a node, e.g. a `(host, port)` tuple, will return the address
where the node is reachable. This can be used to map the addresses at
which the nodes _think_ they are, to addresses at which a client may
reach them, such as when they sit behind a proxy.
| Rest of the arguments will be passed to the
:class:`~redis.asyncio.connection.Connection` instances when created
:raises RedisClusterException:
if any arguments are invalid or unknown. Eg:
- `db` != 0 or None
- `path` argument for unix socket connection
- none of the `host`/`port` & `startup_nodes` were provided
"""
[docs] @classmethod
def from_url(cls, url: str, **kwargs: Any) -> "RedisCluster":
"""
Return a Redis client object configured from the given URL.
For example::
redis://[[username]:[password]]@localhost:6379/0
rediss://[[username]:[password]]@localhost:6379/0
Three URL schemes are supported:
- `redis://` creates a TCP socket connection. See more at:
<https://www.iana.org/assignments/uri-schemes/prov/redis>
- `rediss://` creates a SSL wrapped TCP socket connection. See more at:
<https://www.iana.org/assignments/uri-schemes/prov/rediss>
The username, password, hostname, path and all querystring values are passed
through ``urllib.parse.unquote`` in order to replace any percent-encoded values
with their corresponding characters.
All querystring options are cast to their appropriate Python types. Boolean
arguments can be specified with string values "True"/"False" or "Yes"/"No".
Values that cannot be properly cast cause a ``ValueError`` to be raised. Once
parsed, the querystring arguments and keyword arguments are passed to
:class:`~redis.asyncio.connection.Connection` when created.
In the case of conflicting arguments, querystring arguments are used.
"""
kwargs.update(parse_url(url))
if kwargs.pop("connection_class", None) is SSLConnection:
kwargs["ssl"] = True
return cls(**kwargs)
__slots__ = (
"_initialize",
"_lock",
"cluster_error_retry_attempts",
"command_flags",
"commands_parser",
"connection_error_retry_attempts",
"connection_kwargs",
"encoder",
"node_flags",
"nodes_manager",
"read_from_replicas",
"reinitialize_counter",
"reinitialize_steps",
"response_callbacks",
"result_callbacks",
)
def __init__(
self,
host: Optional[str] = None,
port: Union[str, int] = 6379,
# Cluster related kwargs
startup_nodes: Optional[List["ClusterNode"]] = None,
require_full_coverage: bool = True,
read_from_replicas: bool = False,
reinitialize_steps: int = 5,
cluster_error_retry_attempts: int = 3,
connection_error_retry_attempts: int = 3,
max_connections: int = 2**31,
# Client related kwargs
db: Union[str, int] = 0,
path: Optional[str] = None,
credential_provider: Optional[CredentialProvider] = None,
username: Optional[str] = None,
password: Optional[str] = None,
client_name: Optional[str] = None,
lib_name: Optional[str] = "redis-py",
lib_version: Optional[str] = get_lib_version(),
# Encoding related kwargs
encoding: str = "utf-8",
encoding_errors: str = "strict",
decode_responses: bool = False,
# Connection related kwargs
health_check_interval: float = 0,
socket_connect_timeout: Optional[float] = None,
socket_keepalive: bool = False,
socket_keepalive_options: Optional[Mapping[int, Union[int, bytes]]] = None,
socket_timeout: Optional[float] = None,
retry: Optional["Retry"] = None,
retry_on_error: Optional[List[Type[Exception]]] = None,
# SSL related kwargs
ssl: bool = False,
ssl_ca_certs: Optional[str] = None,
ssl_ca_data: Optional[str] = None,
ssl_cert_reqs: str = "required",
ssl_certfile: Optional[str] = None,
ssl_check_hostname: bool = False,
ssl_keyfile: Optional[str] = None,
protocol: Optional[int] = 2,
address_remap: Optional[Callable[[str, int], Tuple[str, int]]] = None,
) -> None:
if db:
raise RedisClusterException(
"Argument 'db' must be 0 or None in cluster mode"
)
if path:
raise RedisClusterException(
"Unix domain socket is not supported in cluster mode"
)
if (not host or not port) and not startup_nodes:
raise RedisClusterException(
"RedisCluster requires at least one node to discover the cluster.\n"
"Please provide one of the following or use RedisCluster.from_url:\n"
' - host and port: RedisCluster(host="localhost", port=6379)\n'
" - startup_nodes: RedisCluster(startup_nodes=["
'ClusterNode("localhost", 6379), ClusterNode("localhost", 6380)])'
)
kwargs: Dict[str, Any] = {
"max_connections": max_connections,
"connection_class": Connection,
"parser_class": ClusterParser,
# Client related kwargs
"credential_provider": credential_provider,
"username": username,
"password": password,
"client_name": client_name,
"lib_name": lib_name,
"lib_version": lib_version,
# Encoding related kwargs
"encoding": encoding,
"encoding_errors": encoding_errors,
"decode_responses": decode_responses,
# Connection related kwargs
"health_check_interval": health_check_interval,
"socket_connect_timeout": socket_connect_timeout,
"socket_keepalive": socket_keepalive,
"socket_keepalive_options": socket_keepalive_options,
"socket_timeout": socket_timeout,
"retry": retry,
"protocol": protocol,
}
if ssl:
# SSL related kwargs
kwargs.update(
{
"connection_class": SSLConnection,
"ssl_ca_certs": ssl_ca_certs,
"ssl_ca_data": ssl_ca_data,
"ssl_cert_reqs": ssl_cert_reqs,
"ssl_certfile": ssl_certfile,
"ssl_check_hostname": ssl_check_hostname,
"ssl_keyfile": ssl_keyfile,
}
)
if read_from_replicas:
# Call our on_connect function to configure READONLY mode
kwargs["redis_connect_func"] = self.on_connect
self.retry = retry
if retry or retry_on_error or connection_error_retry_attempts > 0:
# Set a retry object for all cluster nodes
self.retry = retry or Retry(
default_backoff(), connection_error_retry_attempts
)
if not retry_on_error:
# Default errors for retrying
retry_on_error = [ConnectionError, TimeoutError]
self.retry.update_supported_errors(retry_on_error)
kwargs.update({"retry": self.retry})
kwargs["response_callbacks"] = _RedisCallbacks.copy()
if kwargs.get("protocol") in ["3", 3]:
kwargs["response_callbacks"].update(_RedisCallbacksRESP3)
else:
kwargs["response_callbacks"].update(_RedisCallbacksRESP2)
self.connection_kwargs = kwargs
if startup_nodes:
passed_nodes = []
for node in startup_nodes:
passed_nodes.append(
ClusterNode(node.host, node.port, **self.connection_kwargs)
)
startup_nodes = passed_nodes
else:
startup_nodes = []
if host and port:
startup_nodes.append(ClusterNode(host, port, **self.connection_kwargs))
self.nodes_manager = NodesManager(
startup_nodes,
require_full_coverage,
kwargs,
address_remap=address_remap,
)
self.encoder = Encoder(encoding, encoding_errors, decode_responses)
self.read_from_replicas = read_from_replicas
self.reinitialize_steps = reinitialize_steps
self.cluster_error_retry_attempts = cluster_error_retry_attempts
self.connection_error_retry_attempts = connection_error_retry_attempts
self.reinitialize_counter = 0
self.commands_parser = AsyncCommandsParser()
self.node_flags = self.__class__.NODE_FLAGS.copy()
self.command_flags = self.__class__.COMMAND_FLAGS.copy()
self.response_callbacks = kwargs["response_callbacks"]
self.result_callbacks = self.__class__.RESULT_CALLBACKS.copy()
self.result_callbacks[
"CLUSTER SLOTS"
] = lambda cmd, res, **kwargs: parse_cluster_slots(
list(res.values())[0], **kwargs
)
self._initialize = True
self._lock: Optional[asyncio.Lock] = None
[docs] async def initialize(self) -> "RedisCluster":
"""Get all nodes from startup nodes & creates connections if not initialized."""
if self._initialize:
if not self._lock:
self._lock = asyncio.Lock()
async with self._lock:
if self._initialize:
try:
await self.nodes_manager.initialize()
await self.commands_parser.initialize(
self.nodes_manager.default_node
)
self._initialize = False
except BaseException:
await self.nodes_manager.aclose()
await self.nodes_manager.aclose("startup_nodes")
raise
return self
[docs] async def aclose(self) -> None:
"""Close all connections & client if initialized."""
if not self._initialize:
if not self._lock:
self._lock = asyncio.Lock()
async with self._lock:
if not self._initialize:
self._initialize = True
await self.nodes_manager.aclose()
await self.nodes_manager.aclose("startup_nodes")
[docs] @deprecated_function(version="5.0.0", reason="Use aclose() instead", name="close")
async def close(self) -> None:
"""alias for aclose() for backwards compatibility"""
await self.aclose()
async def __aenter__(self) -> "RedisCluster":
return await self.initialize()
async def __aexit__(self, exc_type: None, exc_value: None, traceback: None) -> None:
await self.aclose()
def __await__(self) -> Generator[Any, None, "RedisCluster"]:
return self.initialize().__await__()
_DEL_MESSAGE = "Unclosed RedisCluster client"
def __del__(
self,
_warn: Any = warnings.warn,
_grl: Any = asyncio.get_running_loop,
) -> None:
if hasattr(self, "_initialize") and not self._initialize:
_warn(f"{self._DEL_MESSAGE} {self!r}", ResourceWarning, source=self)
try:
context = {"client": self, "message": self._DEL_MESSAGE}
_grl().call_exception_handler(context)
except RuntimeError:
pass
async def on_connect(self, connection: Connection) -> None:
await connection.on_connect()
# Sending READONLY command to server to configure connection as
# readonly. Since each cluster node may change its server type due
# to a failover, we should establish a READONLY connection
# regardless of the server type. If this is a primary connection,
# READONLY would not affect executing write commands.
await connection.send_command("READONLY")
if str_if_bytes(await connection.read_response()) != "OK":
raise ConnectionError("READONLY command failed")
[docs] def get_nodes(self) -> List["ClusterNode"]:
"""Get all nodes of the cluster."""
return list(self.nodes_manager.nodes_cache.values())
[docs] def get_primaries(self) -> List["ClusterNode"]:
"""Get the primary nodes of the cluster."""
return self.nodes_manager.get_nodes_by_server_type(PRIMARY)
[docs] def get_replicas(self) -> List["ClusterNode"]:
"""Get the replica nodes of the cluster."""
return self.nodes_manager.get_nodes_by_server_type(REPLICA)
[docs] def get_random_node(self) -> "ClusterNode":
"""Get a random node of the cluster."""
return random.choice(list(self.nodes_manager.nodes_cache.values()))
[docs] def get_default_node(self) -> "ClusterNode":
"""Get the default node of the client."""
return self.nodes_manager.default_node
[docs] def set_default_node(self, node: "ClusterNode") -> None:
"""
Set the default node of the client.
:raises DataError: if None is passed or node does not exist in cluster.
"""
if not node or not self.get_node(node_name=node.name):
raise DataError("The requested node does not exist in the cluster.")
self.nodes_manager.default_node = node
[docs] def get_node(
self,
host: Optional[str] = None,
port: Optional[int] = None,
node_name: Optional[str] = None,
) -> Optional["ClusterNode"]:
"""Get node by (host, port) or node_name."""
return self.nodes_manager.get_node(host, port, node_name)
[docs] def get_node_from_key(
self, key: str, replica: bool = False
) -> Optional["ClusterNode"]:
"""
Get the cluster node corresponding to the provided key.
:param key:
:param replica:
| Indicates if a replica should be returned
|
None will returned if no replica holds this key
:raises SlotNotCoveredError: if the key is not covered by any slot.
"""
slot = self.keyslot(key)
slot_cache = self.nodes_manager.slots_cache.get(slot)
if not slot_cache:
raise SlotNotCoveredError(f'Slot "{slot}" is not covered by the cluster.')
if replica:
if len(self.nodes_manager.slots_cache[slot]) < 2:
return None
node_idx = 1
else:
node_idx = 0
return slot_cache[node_idx]
[docs] def keyslot(self, key: EncodableT) -> int:
"""
Find the keyslot for a given key.
See: https://redis.io/docs/manual/scaling/#redis-cluster-data-sharding
"""
return key_slot(self.encoder.encode(key))
[docs] def get_encoder(self) -> Encoder:
"""Get the encoder object of the client."""
return self.encoder
[docs] def get_connection_kwargs(self) -> Dict[str, Optional[Any]]:
"""Get the kwargs passed to :class:`~redis.asyncio.connection.Connection`."""
return self.connection_kwargs
def get_retry(self) -> Optional["Retry"]:
return self.retry
def set_retry(self, retry: "Retry") -> None:
self.retry = retry
for node in self.get_nodes():
node.connection_kwargs.update({"retry": retry})
for conn in node._connections:
conn.retry = retry
[docs] def set_response_callback(self, command: str, callback: ResponseCallbackT) -> None:
"""Set a custom response callback."""
self.response_callbacks[command] = callback
async def _determine_nodes(
self, command: str, *args: Any, node_flag: Optional[str] = None
) -> List["ClusterNode"]:
# Determine which nodes should be executed the command on.
# Returns a list of target nodes.
if not node_flag:
# get the nodes group for this command if it was predefined
node_flag = self.command_flags.get(command)
if node_flag in self.node_flags:
if node_flag == self.__class__.DEFAULT_NODE:
# return the cluster's default node
return [self.nodes_manager.default_node]
if node_flag == self.__class__.PRIMARIES:
# return all primaries
return self.nodes_manager.get_nodes_by_server_type(PRIMARY)
if node_flag == self.__class__.REPLICAS:
# return all replicas
return self.nodes_manager.get_nodes_by_server_type(REPLICA)
if node_flag == self.__class__.ALL_NODES:
# return all nodes
return list(self.nodes_manager.nodes_cache.values())
if node_flag == self.__class__.RANDOM:
# return a random node
return [random.choice(list(self.nodes_manager.nodes_cache.values()))]
# get the node that holds the key's slot
return [
self.nodes_manager.get_node_from_slot(
await self._determine_slot(command, *args),
self.read_from_replicas and command in READ_COMMANDS,
)
]
async def _determine_slot(self, command: str, *args: Any) -> int:
if self.command_flags.get(command) == SLOT_ID:
# The command contains the slot ID
return int(args[0])
# Get the keys in the command
# EVAL and EVALSHA are common enough that it's wasteful to go to the
# redis server to parse the keys. Besides, there is a bug in redis<7.0
# where `self._get_command_keys()` fails anyway. So, we special case
# EVAL/EVALSHA.
# - issue: https://github.com/redis/redis/issues/9493
# - fix: https://github.com/redis/redis/pull/9733
if command.upper() in ("EVAL", "EVALSHA"):
# command syntax: EVAL "script body" num_keys ...
if len(args) < 2:
raise RedisClusterException(
f"Invalid args in command: {command, *args}"
)
keys = args[2 : 2 + int(args[1])]
# if there are 0 keys, that means the script can be run on any node
# so we can just return a random slot
if not keys:
return random.randrange(0, REDIS_CLUSTER_HASH_SLOTS)
else:
keys = await self.commands_parser.get_keys(command, *args)
if not keys:
# FCALL can call a function with 0 keys, that means the function
# can be run on any node so we can just return a random slot
if command.upper() in ("FCALL", "FCALL_RO"):
return random.randrange(0, REDIS_CLUSTER_HASH_SLOTS)
raise RedisClusterException(
"No way to dispatch this command to Redis Cluster. "
"Missing key.\nYou can execute the command by specifying "
f"target nodes.\nCommand: {args}"
)
# single key command
if len(keys) == 1:
return self.keyslot(keys[0])
# multi-key command; we need to make sure all keys are mapped to
# the same slot
slots = {self.keyslot(key) for key in keys}
if len(slots) != 1:
raise RedisClusterException(
f"{command} - all keys must map to the same key slot"
)
return slots.pop()
def _is_node_flag(self, target_nodes: Any) -> bool:
return isinstance(target_nodes, str) and target_nodes in self.node_flags
def _parse_target_nodes(self, target_nodes: Any) -> List["ClusterNode"]:
if isinstance(target_nodes, list):
nodes = target_nodes
elif isinstance(target_nodes, ClusterNode):
# Supports passing a single ClusterNode as a variable
nodes = [target_nodes]
elif isinstance(target_nodes, dict):
# Supports dictionaries of the format {node_name: node}.
# It enables to execute commands with multi nodes as follows:
# rc.cluster_save_config(rc.get_primaries())
nodes = list(target_nodes.values())
else:
raise TypeError(
"target_nodes type can be one of the following: "
"node_flag (PRIMARIES, REPLICAS, RANDOM, ALL_NODES),"
"ClusterNode, list<ClusterNode>, or dict<any, ClusterNode>. "
f"The passed type is {type(target_nodes)}"
)
return nodes
[docs] async def execute_command(self, *args: EncodableT, **kwargs: Any) -> Any:
"""
Execute a raw command on the appropriate cluster node or target_nodes.
It will retry the command as specified by :attr:`cluster_error_retry_attempts` &
then raise an exception.
:param args:
| Raw command args
:param kwargs:
- target_nodes: :attr:`NODE_FLAGS` or :class:`~.ClusterNode`
or List[:class:`~.ClusterNode`] or Dict[Any, :class:`~.ClusterNode`]
- Rest of the kwargs are passed to the Redis connection
:raises RedisClusterException: if target_nodes is not provided & the command
can't be mapped to a slot
"""
command = args[0]
target_nodes = []
target_nodes_specified = False
retry_attempts = self.cluster_error_retry_attempts
passed_targets = kwargs.pop("target_nodes", None)
if passed_targets and not self._is_node_flag(passed_targets):
target_nodes = self._parse_target_nodes(passed_targets)
target_nodes_specified = True
retry_attempts = 0
# Add one for the first execution
execute_attempts = 1 + retry_attempts
for _ in range(execute_attempts):
if self._initialize:
await self.initialize()
if (
len(target_nodes) == 1
and target_nodes[0] == self.get_default_node()
):
# Replace the default cluster node
self.replace_default_node()
try:
if not target_nodes_specified:
# Determine the nodes to execute the command on
target_nodes = await self._determine_nodes(
*args, node_flag=passed_targets
)
if not target_nodes:
raise RedisClusterException(
f"No targets were found to execute {args} command on"
)
if len(target_nodes) == 1:
# Return the processed result
ret = await self._execute_command(target_nodes[0], *args, **kwargs)
if command in self.result_callbacks:
return self.result_callbacks[command](
command, {target_nodes[0].name: ret}, **kwargs
)
return ret
else:
keys = [node.name for node in target_nodes]
values = await asyncio.gather(
*(
asyncio.create_task(
self._execute_command(node, *args, **kwargs)
)
for node in target_nodes
)
)
if command in self.result_callbacks:
return self.result_callbacks[command](
command, dict(zip(keys, values)), **kwargs
)
return dict(zip(keys, values))
except Exception as e:
if retry_attempts > 0 and type(e) in self.__class__.ERRORS_ALLOW_RETRY:
# The nodes and slots cache were should be reinitialized.
# Try again with the new cluster setup.
retry_attempts -= 1
continue
else:
# raise the exception
raise e
async def _execute_command(
self, target_node: "ClusterNode", *args: Union[KeyT, EncodableT], **kwargs: Any
) -> Any:
asking = moved = False
redirect_addr = None
ttl = self.RedisClusterRequestTTL
while ttl > 0:
ttl -= 1
try:
if asking:
target_node = self.get_node(node_name=redirect_addr)
await target_node.execute_command("ASKING")
asking = False
elif moved:
# MOVED occurred and the slots cache was updated,
# refresh the target node
slot = await self._determine_slot(*args)
target_node = self.nodes_manager.get_node_from_slot(
slot, self.read_from_replicas and args[0] in READ_COMMANDS
)
moved = False
return await target_node.execute_command(*args, **kwargs)
except (BusyLoadingError, MaxConnectionsError):
raise
except (ConnectionError, TimeoutError):
# Connection retries are being handled in the node's
# Retry object.
# Remove the failed node from the startup nodes before we try
# to reinitialize the cluster
self.nodes_manager.startup_nodes.pop(target_node.name, None)
# Hard force of reinitialize of the node/slots setup
# and try again with the new setup
await self.aclose()
raise
except ClusterDownError:
# ClusterDownError can occur during a failover and to get
# self-healed, we will try to reinitialize the cluster layout
# and retry executing the command
await self.aclose()
await asyncio.sleep(0.25)
raise
except MovedError as e:
# First, we will try to patch the slots/nodes cache with the
# redirected node output and try again. If MovedError exceeds
# 'reinitialize_steps' number of times, we will force
# reinitializing the tables, and then try again.
# 'reinitialize_steps' counter will increase faster when
# the same client object is shared between multiple threads. To
# reduce the frequency you can set this variable in the
# RedisCluster constructor.
self.reinitialize_counter += 1
if (
self.reinitialize_steps
and self.reinitialize_counter % self.reinitialize_steps == 0
):
await self.aclose()
# Reset the counter
self.reinitialize_counter = 0
else:
self.nodes_manager._moved_exception = e
moved = True
except AskError as e:
redirect_addr = get_node_name(host=e.host, port=e.port)
asking = True
except TryAgainError:
if ttl < self.RedisClusterRequestTTL / 2:
await asyncio.sleep(0.05)
raise ClusterError("TTL exhausted.")
[docs] def pipeline(
self, transaction: Optional[Any] = None, shard_hint: Optional[Any] = None
) -> "ClusterPipeline":
"""
Create & return a new :class:`~.ClusterPipeline` object.
Cluster implementation of pipeline does not support transaction or shard_hint.
:raises RedisClusterException: if transaction or shard_hint are truthy values
"""
if shard_hint:
raise RedisClusterException("shard_hint is deprecated in cluster mode")
if transaction:
raise RedisClusterException("transaction is deprecated in cluster mode")
return ClusterPipeline(self)
[docs] def lock(
self,
name: KeyT,
timeout: Optional[float] = None,
sleep: float = 0.1,
blocking: bool = True,
blocking_timeout: Optional[float] = None,
lock_class: Optional[Type[Lock]] = None,
thread_local: bool = True,
) -> Lock:
"""
Return a new Lock object using key ``name`` that mimics
the behavior of threading.Lock.
If specified, ``timeout`` indicates a maximum life for the lock.
By default, it will remain locked until release() is called.
``sleep`` indicates the amount of time to sleep per loop iteration
when the lock is in blocking mode and another client is currently
holding the lock.
``blocking`` indicates whether calling ``acquire`` should block until
the lock has been acquired or to fail immediately, causing ``acquire``
to return False and the lock not being acquired. Defaults to True.
Note this value can be overridden by passing a ``blocking``
argument to ``acquire``.
``blocking_timeout`` indicates the maximum amount of time in seconds to
spend trying to acquire the lock. A value of ``None`` indicates
continue trying forever. ``blocking_timeout`` can be specified as a
float or integer, both representing the number of seconds to wait.
``lock_class`` forces the specified lock implementation. Note that as
of redis-py 3.0, the only lock class we implement is ``Lock`` (which is
a Lua-based lock). So, it's unlikely you'll need this parameter, unless
you have created your own custom lock class.
``thread_local`` indicates whether the lock token is placed in
thread-local storage. By default, the token is placed in thread local
storage so that a thread only sees its token, not a token set by
another thread. Consider the following timeline:
time: 0, thread-1 acquires `my-lock`, with a timeout of 5 seconds.
thread-1 sets the token to "abc"
time: 1, thread-2 blocks trying to acquire `my-lock` using the
Lock instance.
time: 5, thread-1 has not yet completed. redis expires the lock
key.
time: 5, thread-2 acquired `my-lock` now that it's available.
thread-2 sets the token to "xyz"
time: 6, thread-1 finishes its work and calls release(). if the
token is *not* stored in thread local storage, then
thread-1 would see the token value as "xyz" and would be
able to successfully release the thread-2's lock.
In some use cases it's necessary to disable thread local storage. For
example, if you have code where one thread acquires a lock and passes
that lock instance to a worker thread to release later. If thread
local storage isn't disabled in this case, the worker thread won't see
the token set by the thread that acquired the lock. Our assumption
is that these cases aren't common and as such default to using
thread local storage."""
if lock_class is None:
lock_class = Lock
return lock_class(
self,
name,
timeout=timeout,
sleep=sleep,
blocking=blocking,
blocking_timeout=blocking_timeout,
thread_local=thread_local,
)
[docs]class ClusterNode:
"""
Create a new ClusterNode.
Each ClusterNode manages multiple :class:`~redis.asyncio.connection.Connection`
objects for the (host, port).
"""
__slots__ = (
"_connections",
"_free",
"connection_class",
"connection_kwargs",
"host",
"max_connections",
"name",
"port",
"response_callbacks",
"server_type",
)
def __init__(
self,
host: str,
port: Union[str, int],
server_type: Optional[str] = None,
*,
max_connections: int = 2**31,
connection_class: Type[Connection] = Connection,
**connection_kwargs: Any,
) -> None:
if host == "localhost":
host = socket.gethostbyname(host)
connection_kwargs["host"] = host
connection_kwargs["port"] = port
self.host = host
self.port = port
self.name = get_node_name(host, port)
self.server_type = server_type
self.max_connections = max_connections
self.connection_class = connection_class
self.connection_kwargs = connection_kwargs
self.response_callbacks = connection_kwargs.pop("response_callbacks", {})
self._connections: List[Connection] = []
self._free: Deque[Connection] = collections.deque(maxlen=self.max_connections)
def __repr__(self) -> str:
return (
f"[host={self.host}, port={self.port}, "
f"name={self.name}, server_type={self.server_type}]"
)
def __eq__(self, obj: Any) -> bool:
return isinstance(obj, ClusterNode) and obj.name == self.name
_DEL_MESSAGE = "Unclosed ClusterNode object"
def __del__(
self,
_warn: Any = warnings.warn,
_grl: Any = asyncio.get_running_loop,
) -> None:
for connection in self._connections:
if connection.is_connected:
_warn(f"{self._DEL_MESSAGE} {self!r}", ResourceWarning, source=self)
try:
context = {"client": self, "message": self._DEL_MESSAGE}
_grl().call_exception_handler(context)
except RuntimeError:
pass
break
async def disconnect(self) -> None:
ret = await asyncio.gather(
*(
asyncio.create_task(connection.disconnect())
for connection in self._connections
),
return_exceptions=True,
)
exc = next((res for res in ret if isinstance(res, Exception)), None)
if exc:
raise exc
def acquire_connection(self) -> Connection:
try:
return self._free.popleft()
except IndexError:
if len(self._connections) < self.max_connections:
connection = self.connection_class(**self.connection_kwargs)
self._connections.append(connection)
return connection
raise MaxConnectionsError()
async def parse_response(
self, connection: Connection, command: str, **kwargs: Any
) -> Any:
try:
if NEVER_DECODE in kwargs:
response = await connection.read_response(disable_decoding=True)
kwargs.pop(NEVER_DECODE)
else:
response = await connection.read_response()
except ResponseError:
if EMPTY_RESPONSE in kwargs:
return kwargs[EMPTY_RESPONSE]
raise
if EMPTY_RESPONSE in kwargs:
kwargs.pop(EMPTY_RESPONSE)
# Return response
if command in self.response_callbacks:
return self.response_callbacks[command](response, **kwargs)
return response
async def execute_command(self, *args: Any, **kwargs: Any) -> Any:
# Acquire connection
connection = self.acquire_connection()
# Execute command
await connection.send_packed_command(connection.pack_command(*args), False)
# Read response
try:
return await self.parse_response(connection, args[0], **kwargs)
finally:
# Release connection
self._free.append(connection)
async def execute_pipeline(self, commands: List["PipelineCommand"]) -> bool:
# Acquire connection
connection = self.acquire_connection()
# Execute command
await connection.send_packed_command(
connection.pack_commands(cmd.args for cmd in commands), False
)
# Read responses
ret = False
for cmd in commands:
try:
cmd.result = await self.parse_response(
connection, cmd.args[0], **cmd.kwargs
)
except Exception as e:
cmd.result = e
ret = True
# Release connection
self._free.append(connection)
return ret
class NodesManager:
__slots__ = (
"_moved_exception",
"connection_kwargs",
"default_node",
"nodes_cache",
"read_load_balancer",
"require_full_coverage",
"slots_cache",
"startup_nodes",
"address_remap",
)
def __init__(
self,
startup_nodes: List["ClusterNode"],
require_full_coverage: bool,
connection_kwargs: Dict[str, Any],
address_remap: Optional[Callable[[str, int], Tuple[str, int]]] = None,
) -> None:
self.startup_nodes = {node.name: node for node in startup_nodes}
self.require_full_coverage = require_full_coverage
self.connection_kwargs = connection_kwargs
self.address_remap = address_remap
self.default_node: "ClusterNode" = None
self.nodes_cache: Dict[str, "ClusterNode"] = {}
self.slots_cache: Dict[int, List["ClusterNode"]] = {}
self.read_load_balancer = LoadBalancer()
self._moved_exception: MovedError = None
def get_node(
self,
host: Optional[str] = None,
port: Optional[int] = None,
node_name: Optional[str] = None,
) -> Optional["ClusterNode"]:
if host and port:
# the user passed host and port
if host == "localhost":
host = socket.gethostbyname(host)
return self.nodes_cache.get(get_node_name(host=host, port=port))
elif node_name:
return self.nodes_cache.get(node_name)
else:
raise DataError(
"get_node requires one of the following: "
"1. node name "
"2. host and port"
)
def set_nodes(
self,
old: Dict[str, "ClusterNode"],
new: Dict[str, "ClusterNode"],
remove_old: bool = False,
) -> None:
if remove_old:
for name in list(old.keys()):
if name not in new:
task = asyncio.create_task(old.pop(name).disconnect()) # noqa
for name, node in new.items():
if name in old:
if old[name] is node:
continue
task = asyncio.create_task(old[name].disconnect()) # noqa
old[name] = node
def _update_moved_slots(self) -> None:
e = self._moved_exception
redirected_node = self.get_node(host=e.host, port=e.port)
if redirected_node:
# The node already exists
if redirected_node.server_type != PRIMARY:
# Update the node's server type
redirected_node.server_type = PRIMARY
else:
# This is a new node, we will add it to the nodes cache
redirected_node = ClusterNode(
e.host, e.port, PRIMARY, **self.connection_kwargs
)
self.set_nodes(self.nodes_cache, {redirected_node.name: redirected_node})
if redirected_node in self.slots_cache[e.slot_id]:
# The MOVED error resulted from a failover, and the new slot owner
# had previously been a replica.
old_primary = self.slots_cache[e.slot_id][0]
# Update the old primary to be a replica and add it to the end of
# the slot's node list
old_primary.server_type = REPLICA
self.slots_cache[e.slot_id].append(old_primary)
# Remove the old replica, which is now a primary, from the slot's
# node list
self.slots_cache[e.slot_id].remove(redirected_node)
# Override the old primary with the new one
self.slots_cache[e.slot_id][0] = redirected_node
if self.default_node == old_primary:
# Update the default node with the new primary
self.default_node = redirected_node
else:
# The new slot owner is a new server, or a server from a different
# shard. We need to remove all current nodes from the slot's list
# (including replications) and add just the new node.
self.slots_cache[e.slot_id] = [redirected_node]
# Reset moved_exception
self._moved_exception = None
def get_node_from_slot(
self, slot: int, read_from_replicas: bool = False
) -> "ClusterNode":
if self._moved_exception:
self._update_moved_slots()
try:
if read_from_replicas:
# get the server index in a Round-Robin manner
primary_name = self.slots_cache[slot][0].name
node_idx = self.read_load_balancer.get_server_index(
primary_name, len(self.slots_cache[slot])
)
return self.slots_cache[slot][node_idx]
return self.slots_cache[slot][0]
except (IndexError, TypeError):
raise SlotNotCoveredError(
f'Slot "{slot}" not covered by the cluster. '
f'"require_full_coverage={self.require_full_coverage}"'
)
def get_nodes_by_server_type(self, server_type: str) -> List["ClusterNode"]:
return [
node
for node in self.nodes_cache.values()
if node.server_type == server_type
]
async def initialize(self) -> None:
self.read_load_balancer.reset()
tmp_nodes_cache: Dict[str, "ClusterNode"] = {}
tmp_slots: Dict[int, List["ClusterNode"]] = {}
disagreements = []
startup_nodes_reachable = False
fully_covered = False
exception = None
for startup_node in self.startup_nodes.values():
try:
# Make sure cluster mode is enabled on this node
if not (await startup_node.execute_command("INFO")).get(
"cluster_enabled"
):
raise RedisClusterException(
"Cluster mode is not enabled on this node"
)
cluster_slots = await startup_node.execute_command("CLUSTER SLOTS")
startup_nodes_reachable = True
except Exception as e:
# Try the next startup node.
# The exception is saved and raised only if we have no more nodes.
exception = e
continue
# CLUSTER SLOTS command results in the following output:
# [[slot_section[from_slot,to_slot,master,replica1,...,replicaN]]]
# where each node contains the following list: [IP, port, node_id]
# Therefore, cluster_slots[0][2][0] will be the IP address of the
# primary node of the first slot section.
# If there's only one server in the cluster, its ``host`` is ''
# Fix it to the host in startup_nodes
if (
len(cluster_slots) == 1
and not cluster_slots[0][2][0]
and len(self.startup_nodes) == 1
):
cluster_slots[0][2][0] = startup_node.host
for slot in cluster_slots:
for i in range(2, len(slot)):
slot[i] = [str_if_bytes(val) for val in slot[i]]
primary_node = slot[2]
host = primary_node[0]
if host == "":
host = startup_node.host
port = int(primary_node[1])
host, port = self.remap_host_port(host, port)
target_node = tmp_nodes_cache.get(get_node_name(host, port))
if not target_node:
target_node = ClusterNode(
host, port, PRIMARY, **self.connection_kwargs
)
# add this node to the nodes cache
tmp_nodes_cache[target_node.name] = target_node
for i in range(int(slot[0]), int(slot[1]) + 1):
if i not in tmp_slots:
tmp_slots[i] = []
tmp_slots[i].append(target_node)
replica_nodes = [slot[j] for j in range(3, len(slot))]
for replica_node in replica_nodes:
host = replica_node[0]
port = replica_node[1]
host, port = self.remap_host_port(host, port)
target_replica_node = tmp_nodes_cache.get(
get_node_name(host, port)
)
if not target_replica_node:
target_replica_node = ClusterNode(
host, port, REPLICA, **self.connection_kwargs
)
tmp_slots[i].append(target_replica_node)
# add this node to the nodes cache
tmp_nodes_cache[
target_replica_node.name
] = target_replica_node
else:
# Validate that 2 nodes want to use the same slot cache
# setup
tmp_slot = tmp_slots[i][0]
if tmp_slot.name != target_node.name:
disagreements.append(
f"{tmp_slot.name} vs {target_node.name} on slot: {i}"
)
if len(disagreements) > 5:
raise RedisClusterException(
f"startup_nodes could not agree on a valid "
f'slots cache: {", ".join(disagreements)}'
)
# Validate if all slots are covered or if we should try next startup node
fully_covered = True
for i in range(REDIS_CLUSTER_HASH_SLOTS):
if i not in tmp_slots:
fully_covered = False
break
if fully_covered:
break
if not startup_nodes_reachable:
raise RedisClusterException(
f"Redis Cluster cannot be connected. Please provide at least "
f"one reachable node: {str(exception)}"
) from exception
# Check if the slots are not fully covered
if not fully_covered and self.require_full_coverage:
# Despite the requirement that the slots be covered, there
# isn't a full coverage
raise RedisClusterException(
f"All slots are not covered after query all startup_nodes. "
f"{len(tmp_slots)} of {REDIS_CLUSTER_HASH_SLOTS} "
f"covered..."
)
# Set the tmp variables to the real variables
self.slots_cache = tmp_slots
self.set_nodes(self.nodes_cache, tmp_nodes_cache, remove_old=True)
# Populate the startup nodes with all discovered nodes
self.set_nodes(self.startup_nodes, self.nodes_cache, remove_old=True)
# Set the default node
self.default_node = self.get_nodes_by_server_type(PRIMARY)[0]
# If initialize was called after a MovedError, clear it
self._moved_exception = None
async def aclose(self, attr: str = "nodes_cache") -> None:
self.default_node = None
await asyncio.gather(
*(
asyncio.create_task(node.disconnect())
for node in getattr(self, attr).values()
)
)
def remap_host_port(self, host: str, port: int) -> Tuple[str, int]:
"""
Remap the host and port returned from the cluster to a different
internal value. Useful if the client is not connecting directly
to the cluster.
"""
if self.address_remap:
return self.address_remap((host, port))
return host, port
[docs]class ClusterPipeline(AbstractRedis, AbstractRedisCluster, AsyncRedisClusterCommands):
"""
Create a new ClusterPipeline object.
Usage::
result = await (
rc.pipeline()
.set("A", 1)
.get("A")
.hset("K", "F", "V")
.hgetall("K")
.mset_nonatomic({"A": 2, "B": 3})
.get("A")
.get("B")
.delete("A", "B", "K")
.execute()
)
# result = [True, "1", 1, {"F": "V"}, True, True, "2", "3", 1, 1, 1]
Note: For commands `DELETE`, `EXISTS`, `TOUCH`, `UNLINK`, `mset_nonatomic`, which
are split across multiple nodes, you'll get multiple results for them in the array.
Retryable errors:
- :class:`~.ClusterDownError`
- :class:`~.ConnectionError`
- :class:`~.TimeoutError`
Redirection errors:
- :class:`~.TryAgainError`
- :class:`~.MovedError`
- :class:`~.AskError`
:param client:
| Existing :class:`~.RedisCluster` client
"""
__slots__ = ("_command_stack", "_client")
def __init__(self, client: RedisCluster) -> None:
self._client = client
self._command_stack: List["PipelineCommand"] = []
async def initialize(self) -> "ClusterPipeline":
if self._client._initialize:
await self._client.initialize()
self._command_stack = []
return self
async def __aenter__(self) -> "ClusterPipeline":
return await self.initialize()
async def __aexit__(self, exc_type: None, exc_value: None, traceback: None) -> None:
self._command_stack = []
def __await__(self) -> Generator[Any, None, "ClusterPipeline"]:
return self.initialize().__await__()
def __enter__(self) -> "ClusterPipeline":
self._command_stack = []
return self
def __exit__(self, exc_type: None, exc_value: None, traceback: None) -> None:
self._command_stack = []
def __bool__(self) -> bool:
return bool(self._command_stack)
def __len__(self) -> int:
return len(self._command_stack)
[docs] def execute_command(
self, *args: Union[KeyT, EncodableT], **kwargs: Any
) -> "ClusterPipeline":
"""
Append a raw command to the pipeline.
:param args:
| Raw command args
:param kwargs:
- target_nodes: :attr:`NODE_FLAGS` or :class:`~.ClusterNode`
or List[:class:`~.ClusterNode`] or Dict[Any, :class:`~.ClusterNode`]
- Rest of the kwargs are passed to the Redis connection
"""
self._command_stack.append(
PipelineCommand(len(self._command_stack), *args, **kwargs)
)
return self
[docs] async def execute(
self, raise_on_error: bool = True, allow_redirections: bool = True
) -> List[Any]:
"""
Execute the pipeline.
It will retry the commands as specified by :attr:`cluster_error_retry_attempts`
& then raise an exception.
:param raise_on_error:
| Raise the first error if there are any errors
:param allow_redirections:
| Whether to retry each failed command individually in case of redirection
errors
:raises RedisClusterException: if target_nodes is not provided & the command
can't be mapped to a slot
"""
if not self._command_stack:
return []
try:
for _ in range(self._client.cluster_error_retry_attempts):
if self._client._initialize:
await self._client.initialize()
try:
return await self._execute(
self._client,
self._command_stack,
raise_on_error=raise_on_error,
allow_redirections=allow_redirections,
)
except BaseException as e:
if type(e) in self.__class__.ERRORS_ALLOW_RETRY:
# Try again with the new cluster setup.
exception = e
await self._client.aclose()
await asyncio.sleep(0.25)
else:
# All other errors should be raised.
raise
# If it fails the configured number of times then raise an exception
raise exception
finally:
self._command_stack = []
async def _execute(
self,
client: "RedisCluster",
stack: List["PipelineCommand"],
raise_on_error: bool = True,
allow_redirections: bool = True,
) -> List[Any]:
todo = [
cmd for cmd in stack if not cmd.result or isinstance(cmd.result, Exception)
]
nodes = {}
for cmd in todo:
passed_targets = cmd.kwargs.pop("target_nodes", None)
if passed_targets and not client._is_node_flag(passed_targets):
target_nodes = client._parse_target_nodes(passed_targets)
else:
target_nodes = await client._determine_nodes(
*cmd.args, node_flag=passed_targets
)
if not target_nodes:
raise RedisClusterException(
f"No targets were found to execute {cmd.args} command on"
)
if len(target_nodes) > 1:
raise RedisClusterException(f"Too many targets for command {cmd.args}")
node = target_nodes[0]
if node.name not in nodes:
nodes[node.name] = (node, [])
nodes[node.name][1].append(cmd)
errors = await asyncio.gather(
*(
asyncio.create_task(node[0].execute_pipeline(node[1]))
for node in nodes.values()
)
)
if any(errors):
if allow_redirections:
# send each errored command individually
for cmd in todo:
if isinstance(cmd.result, (TryAgainError, MovedError, AskError)):
try:
cmd.result = await client.execute_command(
*cmd.args, **cmd.kwargs
)
except Exception as e:
cmd.result = e
if raise_on_error:
for cmd in todo:
result = cmd.result
if isinstance(result, Exception):
command = " ".join(map(safe_str, cmd.args))
msg = (
f"Command # {cmd.position + 1} ({command}) of pipeline "
f"caused error: {result.args}"
)
result.args = (msg,) + result.args[1:]
raise result
default_node = nodes.get(client.get_default_node().name)
if default_node is not None:
# This pipeline execution used the default node, check if we need
# to replace it.
# Note: when the error is raised we'll reset the default node in the
# caller function.
for cmd in default_node[1]:
# Check if it has a command that failed with a relevant
# exception
if type(cmd.result) in self.__class__.ERRORS_ALLOW_RETRY:
client.replace_default_node()
break
return [cmd.result for cmd in stack]
def _split_command_across_slots(
self, command: str, *keys: KeyT
) -> "ClusterPipeline":
for slot_keys in self._client._partition_keys_by_slot(keys).values():
self.execute_command(command, *slot_keys)
return self
def mset_nonatomic(
self, mapping: Mapping[AnyKeyT, EncodableT]
) -> "ClusterPipeline":
encoder = self._client.encoder
slots_pairs = {}
for pair in mapping.items():
slot = key_slot(encoder.encode(pair[0]))
slots_pairs.setdefault(slot, []).extend(pair)
for pairs in slots_pairs.values():
self.execute_command("MSET", *pairs)
return self
for command in PIPELINE_BLOCKED_COMMANDS:
command = command.replace(" ", "_").lower()
if command == "mset_nonatomic":
continue
setattr(ClusterPipeline, command, block_pipeline_command(command))
class PipelineCommand:
def __init__(self, position: int, *args: Any, **kwargs: Any) -> None:
self.args = args
self.kwargs = kwargs
self.position = position
self.result: Union[Any, Exception] = None
def __repr__(self) -> str:
return f"[{self.position}] {self.args} ({self.kwargs})"