Source code for redis.asyncio.cluster

import asyncio
import collections
import random
import socket
import warnings
from typing import (

from redis.asyncio.client import ResponseCallbackT
from redis.asyncio.connection import (
from redis.asyncio.lock import Lock
from redis.asyncio.parser import CommandsParser
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 (
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 (
from redis.typing import AnyKeyT, EncodableT, KeyT
from redis.utils import dict_merge, safe_str, str_if_bytes

TargetNodesT = TypeVar(
    "TargetNodesT", str, "ClusterNode", List["ClusterNode"], Dict[Any, "ClusterNode"]

class ClusterParser(DefaultParser):
    EXCEPTION_CLASSES = dict_merge(
            "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: :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 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: <> - `rediss://` creates a SSL wrapped TCP socket connection. See more at: <> 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, # 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[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, 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, # 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, } 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"] = self.__class__.RESPONSE_CALLBACKS.copy() self.connection_kwargs = kwargs if startup_nodes: passed_nodes = [] for node in startup_nodes: passed_nodes.append( ClusterNode(, 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 = CommandsParser() 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.close() await self.nodes_manager.close("startup_nodes") raise return self
[docs] async def close(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.close() await self.nodes_manager.close("startup_nodes")
async def __aenter__(self) -> "RedisCluster": return await self.initialize() async def __aexit__(self, exc_type: None, exc_value: None, traceback: None) -> None: await self.close() def __await__(self) -> Generator[Any, None, "RedisCluster"]: return self.initialize().__await__() _DEL_MESSAGE = "Unclosed RedisCluster client" def __del__(self) -> None: if hasattr(self, "_initialize") and not self._initialize: warnings.warn(f"{self._DEL_MESSAGE} {self!r}", ResourceWarning, source=self) try: context = {"client": self, "message": self._DEL_MESSAGE} asyncio.get_running_loop().call_exception_handler(context) except RuntimeError: ... 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( 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: """ 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: # - fix: if command 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 + 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 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 = [ 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(, None) # Hard force of reinitialize of the node/slots setup # and try again with the new setup await self.close() 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.close() 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.close() # 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(, 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 = host self.port = port = 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={}, port={self.port}, " f"name={}, server_type={self.server_type}]" ) def __eq__(self, obj: Any) -> bool: return isinstance(obj, ClusterNode) and == _DEL_MESSAGE = "Unclosed ClusterNode object" def __del__(self) -> None: for connection in self._connections: if connection.is_connected: warnings.warn( f"{self._DEL_MESSAGE} {self!r}", ResourceWarning, source=self ) try: context = {"client": self, "message": self._DEL_MESSAGE} asyncio.get_running_loop().call_exception_handler(context) except RuntimeError: ... 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 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: asyncio.create_task(old.pop(name).disconnect()) for name, node in new.items(): if name in old: if old[name] is node: continue asyncio.create_task(old[name].disconnect()) old[name] = node def _update_moved_slots(self) -> None: e = self._moved_exception redirected_node = self.get_node(, 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.port, PRIMARY, **self.connection_kwargs ) self.set_nodes(self.nodes_cache, { 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] = 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 = 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 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 else: # Validate that 2 nodes want to use the same slot cache # setup tmp_slot = tmp_slots[i][0] if != disagreements.append( f"{} vs {} 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 close(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.close() 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 not in nodes: nodes[] = (node, []) nodes[][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})"