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cluster.py
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import asyncio import collections import random import socket import warnings from typing import ( Any, Deque, Dict, Generator, List, Mapping, Optional, Type, TypeVar, Union, ) from redis.asyncio.client import ResponseCallbackT from redis.asyncio.connection import Connection, DefaultParser, Encoder, parse_url from redis.asyncio.parser import CommandsParser 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.exceptions import ( AskError, BusyLoadingError, ClusterCrossSlotError, ClusterDownError, ClusterError, ConnectionError, DataError, MasterDownError, MovedError, RedisClusterException, ResponseError, SlotNotCoveredError, TimeoutError, TryAgainError, ) 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"] ) CONNECTION_ALLOWED_KEYS = ( "client_name", "db", "decode_responses", "encoder_class", "encoding", "encoding_errors", "health_check_interval", "parser_class", "password", "redis_connect_func", "retry", "retry_on_timeout", "socket_connect_timeout", "socket_keepalive", "socket_keepalive_options", "socket_read_size", "socket_timeout", "socket_type", "username", ) def cleanup_kwargs(**kwargs: Any) -> Dict[str, Any]: """Remove unsupported or disabled keys from kwargs.""" return {k: v for k, v in kwargs.items() if k in CONNECTION_ALLOWED_KEYS} class ClusterParser(DefaultParser): EXCEPTION_CLASSES = dict_merge( DefaultParser.EXCEPTION_CLASSES, { "ASK": AskError, "TRYAGAIN": TryAgainError, "MOVED": MovedError, "CLUSTERDOWN": ClusterDownError, "CROSSSLOT": ClusterCrossSlotError, "MASTERDOWN": MasterDownError, }, ) class RedisCluster(AbstractRedis, AbstractRedisCluster, AsyncRedisClusterCommands): """ Create a new RedisCluster client. Pass one of parameters: - `url` - `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 cluster_error_retry_attempts: | Retry command execution attempts when encountering :class:`~.ClusterDownError` or :class:`~.ConnectionError` :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 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 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 url: | See :meth:`.from_url` :param kwargs: | Extra arguments that will be passed to the :class:`~redis.asyncio.connection.Connection` instances when created :raises RedisClusterException: if any arguments are invalid. Eg: - db kwarg - db != 0 in url - unix socket connection - none of host & url & startup_nodes were provided """ @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 unix://[[username]:[password]]@/path/to/socket.sock?db=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> - ``unix://``: creates a Unix Domain Socket connection. 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. There are several ways to specify a database number. The first value found will be used: 1. A ``db`` querystring option, e.g. redis://localhost?db=0 2. If using the redis:// or rediss:// schemes, the path argument of the url, e.g. redis://localhost/0 3. A ``db`` keyword argument to this function. If none of these options are specified, the default db=0 is used. 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 always win. """ return cls(url=url, **kwargs) __slots__ = ( "_initialize", "_lock", "cluster_error_retry_attempts", "command_flags", "commands_parser", "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: int = 6379, startup_nodes: Optional[List["ClusterNode"]] = None, require_full_coverage: bool = False, read_from_replicas: bool = False, cluster_error_retry_attempts: int = 3, reinitialize_steps: int = 10, url: Optional[str] = None, **kwargs: Any, ) -> None: if not startup_nodes: startup_nodes = [] if "db" in kwargs: # Argument 'db' is not possible to use in cluster mode raise RedisClusterException( "Argument 'db' is not possible to use in cluster mode" ) # Get the startup node(s) if url: url_options = parse_url(url) if "path" in url_options: raise RedisClusterException( "RedisCluster does not currently support Unix Domain " "Socket connections" ) if "db" in url_options and url_options["db"] != 0: # Argument 'db' is not possible to use in cluster mode raise RedisClusterException( "A ``db`` querystring option can only be 0 in cluster mode" ) kwargs.update(url_options) host = kwargs.get("host") port = kwargs.get("port", port) elif (not host or not port) and not startup_nodes: # No startup node was provided raise RedisClusterException( "RedisCluster requires at least one node to discover the " "cluster. Please provide one of the followings:\n" "1. host and port, for example:\n" " RedisCluster(host='localhost', port=6379)\n" "2. list of startup nodes, for example:\n" " RedisCluster(startup_nodes=[ClusterNode('localhost', 6379)," " ClusterNode('localhost', 6378)])" ) # Update the connection arguments # Whenever a new connection is established, RedisCluster's on_connect # method should be run kwargs["redis_connect_func"] = self.on_connect self.connection_kwargs = kwargs = cleanup_kwargs(**kwargs) self.response_callbacks = kwargs[ "response_callbacks" ] = self.__class__.RESPONSE_CALLBACKS.copy() if host and port: startup_nodes.append(ClusterNode(host, port, **self.connection_kwargs)) self.nodes_manager = NodesManager( startup_nodes=startup_nodes, require_full_coverage=require_full_coverage, **self.connection_kwargs, ) self.encoder = Encoder( kwargs.get("encoding", "utf-8"), kwargs.get("encoding_errors", "strict"), kwargs.get("decode_responses", False), ) self.cluster_error_retry_attempts = cluster_error_retry_attempts self.read_from_replicas = read_from_replicas self.reinitialize_steps = reinitialize_steps 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.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 = asyncio.Lock() async def initialize(self) -> "RedisCluster": """Get all nodes from startup nodes & creates connections if not initialized.""" if self._initialize: 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 async def close(self) -> None: """Close all connections & client if initialized.""" if not self._initialize: 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} # TODO: Change to get_running_loop() when dropping support for py3.6 asyncio.get_event_loop().call_exception_handler(context) except RuntimeError: ... async def on_connect(self, connection: Connection) -> None: connection.set_parser(ClusterParser) await connection.on_connect() if self.read_from_replicas: # 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_without_lock()) != "OK": raise ConnectionError("READONLY command failed") def get_nodes(self) -> List["ClusterNode"]: """Get all nodes of the cluster.""" return list(self.nodes_manager.nodes_cache.values()) def get_primaries(self) -> List["ClusterNode"]: """Get the primary nodes of the cluster.""" return self.nodes_manager.get_nodes_by_server_type(PRIMARY) def get_replicas(self) -> List["ClusterNode"]: """Get the replica nodes of the cluster.""" return self.nodes_manager.get_nodes_by_server_type(REPLICA) def get_random_node(self) -> "ClusterNode": """Get a random node of the cluster.""" return random.choice(list(self.nodes_manager.nodes_cache.values())) def get_default_node(self) -> "ClusterNode": """Get the default node of the client.""" return self.nodes_manager.default_node 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 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) 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 and len(self.nodes_manager.slots_cache[slot]) < 2: return None elif replica: node_idx = 1 else: # primary node_idx = 0 return slot_cache[node_idx] 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)) def get_encoder(self) -> Encoder: """Get the encoder object of the client.""" return self.encoder def get_connection_kwargs(self) -> Dict[str, Optional[Any]]: """Get the kwargs passed to :class:`~redis.asyncio.connection.Connection`.""" return self.connection_kwargs 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"]: 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 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 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 = 1 for _ in range(retry_attempts): if self._initialize: await self.initialize() 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.ensure_future( 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 BaseException as e: if type(e) in self.__class__.ERRORS_ALLOW_RETRY: # The nodes and slots cache were reinitialized. # Try again with the new cluster setup. exception = e else: # All other errors should be raised. raise e # If it fails the configured number of times then raise exception back # to caller of this method raise exception async def _execute_command( self, target_node: "ClusterNode", *args: Union[KeyT, EncodableT], **kwargs: Any ) -> Any: asking = moved = False redirect_addr = None ttl = self.RedisClusterRequestTTL connection_error_retry_counter = 0 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: raise except (ConnectionError, TimeoutError): # Give the node 0.25 seconds to get back up and retry again # with same node and configuration. After 5 attempts then try # to reinitialize the cluster and see if the nodes # configuration has changed or not connection_error_retry_counter += 1 if connection_error_retry_counter < 5: await asyncio.sleep(0.25) else: # Hard force of reinitialize of the node/slots setup # and try again with the new setup await self.close() 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 TryAgainError: if ttl < self.RedisClusterRequestTTL / 2: await asyncio.sleep(0.05) except AskError as e: redirect_addr = get_node_name(host=e.host, port=e.port) asking = True 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 asyncio.sleep(0.25) await self.close() raise raise ClusterError("TTL exhausted.") 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) class ClusterNode: """ Create a new ClusterNode. Each ClusterNode manages multiple :class:`~redis.asyncio.connection.Connection` objects for the (host, port). """ __slots__ = ( "_command_stack", "_connections", "_free", "connection_class", "connection_kwargs", "host", "max_connections", "name", "port", "response_callbacks", "server_type", ) def __init__( self, host: str, port: 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", RedisCluster.RESPONSE_CALLBACKS ) self._connections: List[Connection] = [] self._free: Deque[Connection] = collections.deque(maxlen=self.max_connections) self._command_stack: List["PipelineCommand"] = [] 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) -> 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} # TODO: Change to get_running_loop() when dropping support for py3.6 asyncio.get_event_loop().call_exception_handler(context) except RuntimeError: ... break async def disconnect(self) -> None: ret = await asyncio.gather( *( asyncio.ensure_future(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: if self._free: for _ in range(len(self._free)): connection = self._free.popleft() if connection.is_connected: return connection self._free.append(connection) return self._free.popleft() if len(self._connections) < self.max_connections: connection = self.connection_class(**self.connection_kwargs) self._connections.append(connection) return connection raise ConnectionError("Too many connections") async def parse_response( self, connection: Connection, command: str, **kwargs: Any ) -> Any: try: if NEVER_DECODE in kwargs: response = await connection.read_response_without_lock( disable_decoding=True ) else: response = await connection.read_response_without_lock() except ResponseError: if EMPTY_RESPONSE in kwargs: return kwargs[EMPTY_RESPONSE] raise # 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) -> bool: # Acquire connection connection = self.acquire_connection() # Execute command await connection.send_packed_command( connection.pack_commands(cmd.args for cmd in self._command_stack), False ) # Read responses ret = False for cmd in self._command_stack: 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", ) def __init__( self, startup_nodes: List["ClusterNode"], require_full_coverage: bool = False, **kwargs: Any, ) -> None: self.startup_nodes = {node.name: node for node in startup_nodes} self.require_full_coverage = require_full_coverage self.connection_kwargs = kwargs 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.ensure_future(old.pop(name).disconnect()) for name, node in new.items(): if name in old: if old[name] is node: continue asyncio.ensure_future(old[name].disconnect()) 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 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 (ConnectionError, TimeoutError): continue except ResponseError as e: # Isn't a cluster connection, so it won't parse these # exceptions automatically message = e.__str__() if "CLUSTERDOWN" in message or "MASTERDOWN" in message: continue else: raise RedisClusterException( 'ERROR sending "cluster slots" command to redis ' f"server: {startup_node}. error: {message}" ) except Exception as e: message = e.__str__() raise RedisClusterException( 'ERROR sending "cluster slots" command to redis ' f"server {startup_node.name}. error: {message}" ) # 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]) 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] 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( "Redis Cluster cannot be connected. Please provide at least " "one reachable node. " ) # 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.ensure_future(node.disconnect()) for node in getattr(self, attr).values() ) ) 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) 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 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 e # 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 node._command_stack = [] node._command_stack.append(cmd) errors = await asyncio.gather( *(asyncio.ensure_future(node.execute_pipeline()) 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 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})"