import random
import socket
import sys
import threading
import time
from collections import OrderedDict
from typing import Any, Callable, Dict, List, Optional, Tuple, Union
from redis._parsers import CommandsParser, Encoder
from redis._parsers.helpers import parse_scan
from redis.backoff import default_backoff
from redis.client import CaseInsensitiveDict, PubSub, Redis
from redis.commands import READ_COMMANDS, RedisClusterCommands
from redis.commands.helpers import list_or_args
from redis.connection import ConnectionPool, DefaultParser, parse_url
from redis.crc import REDIS_CLUSTER_HASH_SLOTS, key_slot
from redis.exceptions import (
AskError,
AuthenticationError,
ClusterCrossSlotError,
ClusterDownError,
ClusterError,
ConnectionError,
DataError,
MasterDownError,
MovedError,
RedisClusterException,
RedisError,
ResponseError,
SlotNotCoveredError,
TimeoutError,
TryAgainError,
)
from redis.lock import Lock
from redis.retry import Retry
from redis.utils import (
HIREDIS_AVAILABLE,
dict_merge,
list_keys_to_dict,
merge_result,
safe_str,
str_if_bytes,
)
def get_node_name(host: str, port: Union[str, int]) -> str:
return f"{host}:{port}"
def get_connection(redis_node, *args, **options):
return redis_node.connection or redis_node.connection_pool.get_connection(
args[0], **options
)
def parse_scan_result(command, res, **options):
cursors = {}
ret = []
for node_name, response in res.items():
cursor, r = parse_scan(response, **options)
cursors[node_name] = cursor
ret += r
return cursors, ret
def parse_pubsub_numsub(command, res, **options):
numsub_d = OrderedDict()
for numsub_tups in res.values():
for channel, numsubbed in numsub_tups:
try:
numsub_d[channel] += numsubbed
except KeyError:
numsub_d[channel] = numsubbed
ret_numsub = [(channel, numsub) for channel, numsub in numsub_d.items()]
return ret_numsub
def parse_cluster_slots(
resp: Any, **options: Any
) -> Dict[Tuple[int, int], Dict[str, Any]]:
current_host = options.get("current_host", "")
def fix_server(*args: Any) -> Tuple[str, Any]:
return str_if_bytes(args[0]) or current_host, args[1]
slots = {}
for slot in resp:
start, end, primary = slot[:3]
replicas = slot[3:]
slots[start, end] = {
"primary": fix_server(*primary),
"replicas": [fix_server(*replica) for replica in replicas],
}
return slots
def parse_cluster_shards(resp, **options):
"""
Parse CLUSTER SHARDS response.
"""
if isinstance(resp[0], dict):
return resp
shards = []
for x in resp:
shard = {"slots": [], "nodes": []}
for i in range(0, len(x[1]), 2):
shard["slots"].append((x[1][i], (x[1][i + 1])))
nodes = x[3]
for node in nodes:
dict_node = {}
for i in range(0, len(node), 2):
dict_node[node[i]] = node[i + 1]
shard["nodes"].append(dict_node)
shards.append(shard)
return shards
def parse_cluster_myshardid(resp, **options):
"""
Parse CLUSTER MYSHARDID response.
"""
return resp.decode("utf-8")
PRIMARY = "primary"
REPLICA = "replica"
SLOT_ID = "slot-id"
REDIS_ALLOWED_KEYS = (
"charset",
"connection_class",
"connection_pool",
"connection_pool_class",
"client_name",
"credential_provider",
"db",
"decode_responses",
"encoding",
"encoding_errors",
"errors",
"host",
"lib_name",
"lib_version",
"max_connections",
"nodes_flag",
"redis_connect_func",
"password",
"port",
"queue_class",
"retry",
"retry_on_timeout",
"protocol",
"socket_connect_timeout",
"socket_keepalive",
"socket_keepalive_options",
"socket_timeout",
"ssl",
"ssl_ca_certs",
"ssl_ca_data",
"ssl_certfile",
"ssl_cert_reqs",
"ssl_keyfile",
"ssl_password",
"unix_socket_path",
"username",
)
KWARGS_DISABLED_KEYS = ("host", "port")
def cleanup_kwargs(**kwargs):
"""
Remove unsupported or disabled keys from kwargs
"""
connection_kwargs = {
k: v
for k, v in kwargs.items()
if k in REDIS_ALLOWED_KEYS and k not in KWARGS_DISABLED_KEYS
}
return connection_kwargs
class ClusterParser(DefaultParser):
EXCEPTION_CLASSES = dict_merge(
DefaultParser.EXCEPTION_CLASSES,
{
"ASK": AskError,
"TRYAGAIN": TryAgainError,
"MOVED": MovedError,
"CLUSTERDOWN": ClusterDownError,
"CROSSSLOT": ClusterCrossSlotError,
"MASTERDOWN": MasterDownError,
},
)
class AbstractRedisCluster:
RedisClusterRequestTTL = 16
PRIMARIES = "primaries"
REPLICAS = "replicas"
ALL_NODES = "all"
RANDOM = "random"
DEFAULT_NODE = "default-node"
NODE_FLAGS = {PRIMARIES, REPLICAS, ALL_NODES, RANDOM, DEFAULT_NODE}
COMMAND_FLAGS = dict_merge(
list_keys_to_dict(
[
"ACL CAT",
"ACL DELUSER",
"ACL DRYRUN",
"ACL GENPASS",
"ACL GETUSER",
"ACL HELP",
"ACL LIST",
"ACL LOG",
"ACL LOAD",
"ACL SAVE",
"ACL SETUSER",
"ACL USERS",
"ACL WHOAMI",
"AUTH",
"CLIENT LIST",
"CLIENT SETINFO",
"CLIENT SETNAME",
"CLIENT GETNAME",
"CONFIG SET",
"CONFIG REWRITE",
"CONFIG RESETSTAT",
"TIME",
"PUBSUB CHANNELS",
"PUBSUB NUMPAT",
"PUBSUB NUMSUB",
"PUBSUB SHARDCHANNELS",
"PUBSUB SHARDNUMSUB",
"PING",
"INFO",
"SHUTDOWN",
"KEYS",
"DBSIZE",
"BGSAVE",
"SLOWLOG GET",
"SLOWLOG LEN",
"SLOWLOG RESET",
"WAIT",
"WAITAOF",
"SAVE",
"MEMORY PURGE",
"MEMORY MALLOC-STATS",
"MEMORY STATS",
"LASTSAVE",
"CLIENT TRACKINGINFO",
"CLIENT PAUSE",
"CLIENT UNPAUSE",
"CLIENT UNBLOCK",
"CLIENT ID",
"CLIENT REPLY",
"CLIENT GETREDIR",
"CLIENT INFO",
"CLIENT KILL",
"READONLY",
"CLUSTER INFO",
"CLUSTER MEET",
"CLUSTER MYSHARDID",
"CLUSTER NODES",
"CLUSTER REPLICAS",
"CLUSTER RESET",
"CLUSTER SET-CONFIG-EPOCH",
"CLUSTER SLOTS",
"CLUSTER SHARDS",
"CLUSTER COUNT-FAILURE-REPORTS",
"CLUSTER KEYSLOT",
"COMMAND",
"COMMAND COUNT",
"COMMAND LIST",
"COMMAND GETKEYS",
"CONFIG GET",
"DEBUG",
"RANDOMKEY",
"READONLY",
"READWRITE",
"TIME",
"TFUNCTION LOAD",
"TFUNCTION DELETE",
"TFUNCTION LIST",
"TFCALL",
"TFCALLASYNC",
"GRAPH.CONFIG",
"LATENCY HISTORY",
"LATENCY LATEST",
"LATENCY RESET",
"MODULE LIST",
"MODULE LOAD",
"MODULE UNLOAD",
"MODULE LOADEX",
],
DEFAULT_NODE,
),
list_keys_to_dict(
[
"FLUSHALL",
"FLUSHDB",
"FUNCTION DELETE",
"FUNCTION FLUSH",
"FUNCTION LIST",
"FUNCTION LOAD",
"FUNCTION RESTORE",
"REDISGEARS_2.REFRESHCLUSTER",
"SCAN",
"SCRIPT EXISTS",
"SCRIPT FLUSH",
"SCRIPT LOAD",
],
PRIMARIES,
),
list_keys_to_dict(["FUNCTION DUMP"], RANDOM),
list_keys_to_dict(
[
"CLUSTER COUNTKEYSINSLOT",
"CLUSTER DELSLOTS",
"CLUSTER DELSLOTSRANGE",
"CLUSTER GETKEYSINSLOT",
"CLUSTER SETSLOT",
],
SLOT_ID,
),
)
SEARCH_COMMANDS = (
[
"FT.CREATE",
"FT.SEARCH",
"FT.AGGREGATE",
"FT.EXPLAIN",
"FT.EXPLAINCLI",
"FT,PROFILE",
"FT.ALTER",
"FT.DROPINDEX",
"FT.ALIASADD",
"FT.ALIASUPDATE",
"FT.ALIASDEL",
"FT.TAGVALS",
"FT.SUGADD",
"FT.SUGGET",
"FT.SUGDEL",
"FT.SUGLEN",
"FT.SYNUPDATE",
"FT.SYNDUMP",
"FT.SPELLCHECK",
"FT.DICTADD",
"FT.DICTDEL",
"FT.DICTDUMP",
"FT.INFO",
"FT._LIST",
"FT.CONFIG",
"FT.ADD",
"FT.DEL",
"FT.DROP",
"FT.GET",
"FT.MGET",
"FT.SYNADD",
],
)
CLUSTER_COMMANDS_RESPONSE_CALLBACKS = {
"CLUSTER SLOTS": parse_cluster_slots,
"CLUSTER SHARDS": parse_cluster_shards,
"CLUSTER MYSHARDID": parse_cluster_myshardid,
}
RESULT_CALLBACKS = dict_merge(
list_keys_to_dict(["PUBSUB NUMSUB", "PUBSUB SHARDNUMSUB"], parse_pubsub_numsub),
list_keys_to_dict(
["PUBSUB NUMPAT"], lambda command, res: sum(list(res.values()))
),
list_keys_to_dict(
["KEYS", "PUBSUB CHANNELS", "PUBSUB SHARDCHANNELS"], merge_result
),
list_keys_to_dict(
[
"PING",
"CONFIG SET",
"CONFIG REWRITE",
"CONFIG RESETSTAT",
"CLIENT SETNAME",
"BGSAVE",
"SLOWLOG RESET",
"SAVE",
"MEMORY PURGE",
"CLIENT PAUSE",
"CLIENT UNPAUSE",
],
lambda command, res: all(res.values()) if isinstance(res, dict) else res,
),
list_keys_to_dict(
["DBSIZE", "WAIT"],
lambda command, res: sum(res.values()) if isinstance(res, dict) else res,
),
list_keys_to_dict(
["CLIENT UNBLOCK"], lambda command, res: 1 if sum(res.values()) > 0 else 0
),
list_keys_to_dict(["SCAN"], parse_scan_result),
list_keys_to_dict(
["SCRIPT LOAD"], lambda command, res: list(res.values()).pop()
),
list_keys_to_dict(
["SCRIPT EXISTS"], lambda command, res: [all(k) for k in zip(*res.values())]
),
list_keys_to_dict(["SCRIPT FLUSH"], lambda command, res: all(res.values())),
)
ERRORS_ALLOW_RETRY = (ConnectionError, TimeoutError, ClusterDownError)
def replace_default_node(self, target_node: "ClusterNode" = None) -> None:
"""Replace the default cluster node.
A random cluster node will be chosen if target_node isn't passed, and primaries
will be prioritized. The default node will not be changed if there are no other
nodes in the cluster.
Args:
target_node (ClusterNode, optional): Target node to replace the default
node. Defaults to None.
"""
if target_node:
self.nodes_manager.default_node = target_node
else:
curr_node = self.get_default_node()
primaries = [node for node in self.get_primaries() if node != curr_node]
if primaries:
# Choose a primary if the cluster contains different primaries
self.nodes_manager.default_node = random.choice(primaries)
else:
# Otherwise, hoose a primary if the cluster contains different primaries
replicas = [node for node in self.get_replicas() if node != curr_node]
if replicas:
self.nodes_manager.default_node = random.choice(replicas)
class RedisCluster(AbstractRedisCluster, RedisClusterCommands):
@classmethod
def from_url(cls, url, **kwargs):
"""
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@]/path/to/socket.sock?db=0[&password=password]
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 the ``ConnectionPool``'s
class initializer. In the case of conflicting arguments, querystring
arguments always win.
"""
return cls(url=url, **kwargs)
def __init__(
self,
host: Optional[str] = None,
port: int = 6379,
startup_nodes: Optional[List["ClusterNode"]] = None,
cluster_error_retry_attempts: int = 3,
retry: Optional["Retry"] = None,
require_full_coverage: bool = False,
reinitialize_steps: int = 5,
read_from_replicas: bool = False,
dynamic_startup_nodes: bool = True,
url: Optional[str] = None,
address_remap: Optional[Callable[[Tuple[str, int]], Tuple[str, int]]] = None,
**kwargs,
):
"""
Initialize a new RedisCluster client.
:param startup_nodes:
List of nodes from which initial bootstrapping can be done
:param host:
Can be used to point to a startup node
:param port:
Can be used to point to a startup node
:param require_full_coverage:
When set to False (default value): 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 ClusterDownError for some key-based
commands. See -
https://redis.io/topics/cluster-tutorial#redis-cluster-configuration-parameters
When set to True: all slots must be covered to construct the
cluster client. If not all slots are covered, RedisClusterException
will be thrown.
: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 dynamic_startup_nodes:
Set the RedisCluster's startup nodes to all of the discovered nodes.
If true (default value), the cluster's discovered nodes will be used to
determine the cluster nodes-slots mapping in the next topology refresh.
It will remove the initial passed startup nodes if their endpoints aren't
listed in the CLUSTER SLOTS output.
If you use dynamic DNS endpoints for startup nodes but CLUSTER SLOTS lists
specific IP addresses, it is best to set it to false.
: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 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 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.
:**kwargs:
Extra arguments that will be sent into Redis instance when created
(See Official redis-py doc for supported kwargs
[https://github.com/andymccurdy/redis-py/blob/master/redis/client.py])
Some kwargs are not supported and will raise a
RedisClusterException:
- db (Redis do not support database SELECT in cluster mode)
"""
if startup_nodes is None:
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
from_url = False
if url is not None:
from_url = True
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)
startup_nodes.append(ClusterNode(host, port))
elif host is not None and port is not None:
startup_nodes.append(ClusterNode(host, port))
elif len(startup_nodes) == 0:
# 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
# If the user passed on_connect function we'll save it and run it
# inside the RedisCluster.on_connect() function
self.user_on_connect_func = kwargs.pop("redis_connect_func", None)
kwargs.update({"redis_connect_func": self.on_connect})
kwargs = cleanup_kwargs(**kwargs)
if retry:
self.retry = retry
kwargs.update({"retry": self.retry})
else:
kwargs.update({"retry": Retry(default_backoff(), 0)})
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.command_flags = self.__class__.COMMAND_FLAGS.copy()
self.node_flags = self.__class__.NODE_FLAGS.copy()
self.read_from_replicas = read_from_replicas
self.reinitialize_counter = 0
self.reinitialize_steps = reinitialize_steps
self.nodes_manager = NodesManager(
startup_nodes=startup_nodes,
from_url=from_url,
require_full_coverage=require_full_coverage,
dynamic_startup_nodes=dynamic_startup_nodes,
address_remap=address_remap,
**kwargs,
)
self.cluster_response_callbacks = CaseInsensitiveDict(
self.__class__.CLUSTER_COMMANDS_RESPONSE_CALLBACKS
)
self.result_callbacks = CaseInsensitiveDict(self.__class__.RESULT_CALLBACKS)
self.commands_parser = CommandsParser(self)
self._lock = threading.Lock()
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self.close()
def __del__(self):
self.close()
def disconnect_connection_pools(self):
for node in self.get_nodes():
if node.redis_connection:
try:
node.redis_connection.connection_pool.disconnect()
except OSError:
# Client was already disconnected. do nothing
pass
def on_connect(self, connection):
"""
Initialize the connection, authenticate and select a database and send
READONLY if it is set during object initialization.
"""
connection.set_parser(ClusterParser)
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.
connection.send_command("READONLY")
if str_if_bytes(connection.read_response()) != "OK":
raise ConnectionError("READONLY command failed")
if self.user_on_connect_func is not None:
self.user_on_connect_func(connection)
def get_redis_connection(self, node):
if not node.redis_connection:
with self._lock:
if not node.redis_connection:
self.nodes_manager.create_redis_connections([node])
return node.redis_connection
def get_node(self, host=None, port=None, node_name=None):
return self.nodes_manager.get_node(host, port, node_name)
def get_primaries(self):
return self.nodes_manager.get_nodes_by_server_type(PRIMARY)
def get_replicas(self):
return self.nodes_manager.get_nodes_by_server_type(REPLICA)
def get_random_node(self):
return random.choice(list(self.nodes_manager.nodes_cache.values()))
def get_nodes(self):
return list(self.nodes_manager.nodes_cache.values())
def get_node_from_key(self, key, replica=False):
"""
Get the node that holds the key's slot.
If replica set to True but the slot doesn't have any replicas, None is
returned.
"""
slot = self.keyslot(key)
slot_cache = self.nodes_manager.slots_cache.get(slot)
if slot_cache is None or len(slot_cache) == 0:
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 get_default_node(self):
"""
Get the cluster's default node
"""
return self.nodes_manager.default_node
def set_default_node(self, node):
"""
Set the default node of the cluster.
:param node: 'ClusterNode'
:return True if the default node was set, else False
"""
if node is None or self.get_node(node_name=node.name) is None:
return False
self.nodes_manager.default_node = node
return True
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.redis_connection.set_retry(retry)
def monitor(self, target_node=None):
"""
Returns a Monitor object for the specified target node.
The default cluster node will be selected if no target node was
specified.
Monitor is useful for handling the MONITOR command to the redis server.
next_command() method returns one command from monitor
listen() method yields commands from monitor.
"""
if target_node is None:
target_node = self.get_default_node()
if target_node.redis_connection is None:
raise RedisClusterException(
f"Cluster Node {target_node.name} has no redis_connection"
)
return target_node.redis_connection.monitor()
def pubsub(self, node=None, host=None, port=None, **kwargs):
"""
Allows passing a ClusterNode, or host&port, to get a pubsub instance
connected to the specified node
"""
return ClusterPubSub(self, node=node, host=host, port=port, **kwargs)
def pipeline(self, transaction=None, shard_hint=None):
"""
Cluster impl:
Pipelines do not work in cluster mode the same way they
do in normal mode. Create a clone of this object so
that simulating pipelines will work correctly. Each
command will be called directly when used and
when calling execute() will only return the result stack.
"""
if shard_hint:
raise RedisClusterException("shard_hint is deprecated in cluster mode")
if transaction:
raise RedisClusterException("transaction is deprecated in cluster mode")
return ClusterPipeline(
nodes_manager=self.nodes_manager,
commands_parser=self.commands_parser,
startup_nodes=self.nodes_manager.startup_nodes,
result_callbacks=self.result_callbacks,
cluster_response_callbacks=self.cluster_response_callbacks,
cluster_error_retry_attempts=self.cluster_error_retry_attempts,
read_from_replicas=self.read_from_replicas,
reinitialize_steps=self.reinitialize_steps,
lock=self._lock,
)
def lock(
self,
name,
timeout=None,
sleep=0.1,
blocking=True,
blocking_timeout=None,
lock_class=None,
thread_local=True,
):
"""
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,
)
def set_response_callback(self, command, callback):
"""Set a custom Response Callback"""
self.cluster_response_callbacks[command] = callback
def _determine_nodes(self, *args, **kwargs) -> List["ClusterNode"]:
# Determine which nodes should be executed the command on.
# Returns a list of target nodes.
command = args[0].upper()
if len(args) >= 2 and f"{args[0]} {args[1]}".upper() in self.command_flags:
command = f"{args[0]} {args[1]}".upper()
nodes_flag = kwargs.pop("nodes_flag", None)
if nodes_flag is not None:
# nodes flag passed by the user
command_flag = nodes_flag
else:
# get the nodes group for this command if it was predefined
command_flag = self.command_flags.get(command)
if command_flag == self.__class__.RANDOM:
# return a random node
return [self.get_random_node()]
elif command_flag == self.__class__.PRIMARIES:
# return all primaries
return self.get_primaries()
elif command_flag == self.__class__.REPLICAS:
# return all replicas
return self.get_replicas()
elif command_flag == self.__class__.ALL_NODES:
# return all nodes
return self.get_nodes()
elif command_flag == self.__class__.DEFAULT_NODE:
# return the cluster's default node
return [self.nodes_manager.default_node]
elif command in self.__class__.SEARCH_COMMANDS[0]:
return [self.nodes_manager.default_node]
else:
# get the node that holds the key's slot
slot = self.determine_slot(*args)
node = self.nodes_manager.get_node_from_slot(
slot, self.read_from_replicas and command in READ_COMMANDS
)
return [node]
def _should_reinitialized(self):
# 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.
if self.reinitialize_steps == 0:
return False
else:
return self.reinitialize_counter % self.reinitialize_steps == 0
def keyslot(self, key):
"""
Calculate keyslot for a given key.
See Keys distribution model in https://redis.io/topics/cluster-spec
"""
k = self.encoder.encode(key)
return key_slot(k)
def _get_command_keys(self, *args):
"""
Get the keys in the command. If the command has no keys in in, None is
returned.
NOTE: Due to a bug in redis<7.0, this function does not work properly
for EVAL or EVALSHA when the `numkeys` arg is 0.
- issue: https://github.com/redis/redis/issues/9493
- fix: https://github.com/redis/redis/pull/9733
So, don't use this function with EVAL or EVALSHA.
"""
redis_conn = self.get_default_node().redis_connection
return self.commands_parser.get_keys(redis_conn, *args)
def determine_slot(self, *args):
"""
Figure out what slot to use based on args.
Raises a RedisClusterException if there's a missing key and we can't
determine what slots to map the command to; or, if the keys don't
all map to the same key slot.
"""
command = args[0]
if self.command_flags.get(command) == SLOT_ID:
# The command contains the slot ID
return args[1]
# 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.
if command.upper() in ("EVAL", "EVALSHA"):
# command syntax: EVAL "script body" num_keys ...
if len(args) <= 2:
raise RedisClusterException(f"Invalid args in command: {args}")
num_actual_keys = int(args[2])
eval_keys = args[3 : 3 + num_actual_keys]
# if there are 0 keys, that means the script can be run on any node
# so we can just return a random slot
if len(eval_keys) == 0:
return random.randrange(0, REDIS_CLUSTER_HASH_SLOTS)
keys = eval_keys
else:
keys = self._get_command_keys(*args)
if keys is None or len(keys) == 0:
# 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 get_encoder(self):
"""
Get the connections' encoder
"""
return self.encoder
def get_connection_kwargs(self):
"""
Get the connections' key-word arguments
"""
return self.nodes_manager.connection_kwargs
def _is_nodes_flag(self, target_nodes):
return isinstance(target_nodes, str) and target_nodes in self.node_flags
def _parse_target_nodes(self, target_nodes):
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 = 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
def execute_command(self, *args, **kwargs):
"""
Wrapper for ERRORS_ALLOW_RETRY error handling.
It will try the number of times specified by the config option
"self.cluster_error_retry_attempts" which defaults to 3 unless manually
configured.
If it reaches the number of times, the command will raise the exception
Key argument :target_nodes: can be passed with the following types:
nodes_flag: PRIMARIES, REPLICAS, ALL_NODES, RANDOM
ClusterNode
list<ClusterNode>
dict<Any, ClusterNode>
"""
target_nodes_specified = False
is_default_node = False
target_nodes = None
passed_targets = kwargs.pop("target_nodes", None)
if passed_targets is not None and not self._is_nodes_flag(passed_targets):
target_nodes = self._parse_target_nodes(passed_targets)
target_nodes_specified = True
# If an error that allows retrying was thrown, the nodes and slots
# cache were reinitialized. We will retry executing the command with
# the updated cluster setup only when the target nodes can be
# determined again with the new cache tables. Therefore, when target
# nodes were passed to this function, we cannot retry the command
# execution since the nodes may not be valid anymore after the tables
# were reinitialized. So in case of passed target nodes,
# retry_attempts will be set to 0.
retry_attempts = (
0 if target_nodes_specified else self.cluster_error_retry_attempts
)
# Add one for the first execution
execute_attempts = 1 + retry_attempts
for _ in range(execute_attempts):
try:
res = {}
if not target_nodes_specified:
# Determine the nodes to execute the command on
target_nodes = self._determine_nodes(
*args, **kwargs, nodes_flag=passed_targets
)
if not target_nodes:
raise RedisClusterException(
f"No targets were found to execute {args} command on"
)
if (
len(target_nodes) == 1
and target_nodes[0] == self.get_default_node()
):
is_default_node = True
for node in target_nodes:
res[node.name] = self._execute_command(node, *args, **kwargs)
# Return the processed result
return self._process_result(args[0], res, **kwargs)
except Exception as e:
if retry_attempts > 0 and type(e) in self.__class__.ERRORS_ALLOW_RETRY:
if is_default_node:
# Replace the default cluster node
self.replace_default_node()
# The nodes and slots cache were reinitialized.
# Try again with the new cluster setup.
retry_attempts -= 1
continue
else:
# raise the exception
raise e
def _execute_command(self, target_node, *args, **kwargs):
"""
Send a command to a node in the cluster
"""
command = args[0]
redis_node = None
connection = None
redirect_addr = None
asking = False
moved = False
ttl = int(self.RedisClusterRequestTTL)
while ttl > 0:
ttl -= 1
try:
if asking:
target_node = self.get_node(node_name=redirect_addr)
elif moved:
# MOVED occurred and the slots cache was updated,
# refresh the target node
slot = self.determine_slot(*args)
target_node = self.nodes_manager.get_node_from_slot(
slot, self.read_from_replicas and command in READ_COMMANDS
)
moved = False
redis_node = self.get_redis_connection(target_node)
connection = get_connection(redis_node, *args, **kwargs)
if asking:
connection.send_command("ASKING")
redis_node.parse_response(connection, "ASKING", **kwargs)
asking = False
connection.send_command(*args)
response = redis_node.parse_response(connection, command, **kwargs)
if command in self.cluster_response_callbacks:
response = self.cluster_response_callbacks[command](
response, **kwargs
)
return response
except AuthenticationError:
raise
except (ConnectionError, TimeoutError) as e:
# Connection retries are being handled in the node's
# Retry object.
# ConnectionError can also be raised if we couldn't get a
# connection from the pool before timing out, so check that
# this is an actual connection before attempting to disconnect.
if connection is not None:
connection.disconnect()
# 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)
# Reset the cluster node's connection
target_node.redis_connection = None
self.nodes_manager.initialize()
raise e
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._should_reinitialized():
self.nodes_manager.initialize()
# Reset the counter
self.reinitialize_counter = 0
else:
self.nodes_manager.update_moved_exception(e)
moved = True
except TryAgainError:
if ttl < self.RedisClusterRequestTTL / 2:
time.sleep(0.05)
except AskError as e:
redirect_addr = get_node_name(host=e.host, port=e.port)
asking = True
except ClusterDownError as e:
# ClusterDownError can occur during a failover and to get
# self-healed, we will try to reinitialize the cluster layout
# and retry executing the command
time.sleep(0.25)
self.nodes_manager.initialize()
raise e
except ResponseError:
raise
except Exception as e:
if connection:
connection.disconnect()
raise e
finally:
if connection is not None:
redis_node.connection_pool.release(connection)
raise ClusterError("TTL exhausted.")
def close(self):
try:
with self._lock:
if self.nodes_manager:
self.nodes_manager.close()
except AttributeError:
# RedisCluster's __init__ can fail before nodes_manager is set
pass
def _process_result(self, command, res, **kwargs):
"""
Process the result of the executed command.
The function would return a dict or a single value.
:type command: str
:type res: dict
`res` should be in the following format:
Dict<node_name, command_result>
"""
if command in self.result_callbacks:
return self.result_callbacks[command](command, res, **kwargs)
elif len(res) == 1:
# When we execute the command on a single node, we can
# remove the dictionary and return a single response
return list(res.values())[0]
else:
return res
def load_external_module(self, funcname, func):
"""
This function can be used to add externally defined redis modules,
and their namespaces to the redis client.
``funcname`` - A string containing the name of the function to create
``func`` - The function, being added to this class.
"""
setattr(self, funcname, func)
class ClusterNode:
def __init__(self, host, port, server_type=None, redis_connection=None):
if host == "localhost":
host = socket.gethostbyname(host)
self.host = host
self.port = port
self.name = get_node_name(host, port)
self.server_type = server_type
self.redis_connection = redis_connection
def __repr__(self):
return (
f"[host={self.host},"
f"port={self.port},"
f"name={self.name},"
f"server_type={self.server_type},"
f"redis_connection={self.redis_connection}]"
)
def __eq__(self, obj):
return isinstance(obj, ClusterNode) and obj.name == self.name
def __del__(self):
if self.redis_connection is not None:
self.redis_connection.close()
class LoadBalancer:
"""
Round-Robin Load Balancing
"""
def __init__(self, start_index: int = 0) -> None:
self.primary_to_idx = {}
self.start_index = start_index
def get_server_index(self, primary: str, list_size: int) -> int:
server_index = self.primary_to_idx.setdefault(primary, self.start_index)
# Update the index
self.primary_to_idx[primary] = (server_index + 1) % list_size
return server_index
def reset(self) -> None:
self.primary_to_idx.clear()
class NodesManager:
def __init__(
self,
startup_nodes,
from_url=False,
require_full_coverage=False,
lock=None,
dynamic_startup_nodes=True,
connection_pool_class=ConnectionPool,
address_remap: Optional[Callable[[Tuple[str, int]], Tuple[str, int]]] = None,
**kwargs,
):
self.nodes_cache = {}
self.slots_cache = {}
self.startup_nodes = {}
self.default_node = None
self.populate_startup_nodes(startup_nodes)
self.from_url = from_url
self._require_full_coverage = require_full_coverage
self._dynamic_startup_nodes = dynamic_startup_nodes
self.connection_pool_class = connection_pool_class
self.address_remap = address_remap
self._moved_exception = None
self.connection_kwargs = kwargs
self.read_load_balancer = LoadBalancer()
if lock is None:
lock = threading.Lock()
self._lock = lock
self.initialize()
def get_node(self, host=None, port=None, node_name=None):
"""
Get the requested node from the cluster's nodes.
nodes.
:return: ClusterNode if the node exists, else None
"""
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:
return None
def update_moved_exception(self, exception):
self._moved_exception = exception
def _update_moved_slots(self):
"""
Update the slot's node with the redirected one
"""
e = self._moved_exception
redirected_node = self.get_node(host=e.host, port=e.port)
if redirected_node is not None:
# The node already exists
if redirected_node.server_type is not 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.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, read_from_replicas=False, server_type=None):
"""
Gets a node that servers this hash slot
"""
if self._moved_exception:
with self._lock:
if self._moved_exception:
self._update_moved_slots()
if self.slots_cache.get(slot) is None or len(self.slots_cache[slot]) == 0:
raise SlotNotCoveredError(
f'Slot "{slot}" not covered by the cluster. '
f'"require_full_coverage={self._require_full_coverage}"'
)
if read_from_replicas is True:
# 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])
)
elif (
server_type is None
or server_type == PRIMARY
or len(self.slots_cache[slot]) == 1
):
# return a primary
node_idx = 0
else:
# return a replica
# randomly choose one of the replicas
node_idx = random.randint(1, len(self.slots_cache[slot]) - 1)
return self.slots_cache[slot][node_idx]
def get_nodes_by_server_type(self, server_type):
"""
Get all nodes with the specified server type
:param server_type: 'primary' or 'replica'
:return: list of ClusterNode
"""
return [
node
for node in self.nodes_cache.values()
if node.server_type == server_type
]
def populate_startup_nodes(self, nodes):
"""
Populate all startup nodes and filters out any duplicates
"""
for n in nodes:
self.startup_nodes[n.name] = n
def check_slots_coverage(self, slots_cache):
# Validate if all slots are covered or if we should try next
# startup node
for i in range(0, REDIS_CLUSTER_HASH_SLOTS):
if i not in slots_cache:
return False
return True
def create_redis_connections(self, nodes):
"""
This function will create a redis connection to all nodes in :nodes:
"""
for node in nodes:
if node.redis_connection is None:
node.redis_connection = self.create_redis_node(
host=node.host, port=node.port, **self.connection_kwargs
)
def create_redis_node(self, host, port, **kwargs):
if self.from_url:
# Create a redis node with a costumed connection pool
kwargs.update({"host": host})
kwargs.update({"port": port})
r = Redis(connection_pool=self.connection_pool_class(**kwargs))
else:
r = Redis(host=host, port=port, **kwargs)
return r
def _get_or_create_cluster_node(self, host, port, role, tmp_nodes_cache):
node_name = get_node_name(host, port)
# check if we already have this node in the tmp_nodes_cache
target_node = tmp_nodes_cache.get(node_name)
if target_node is None:
# before creating a new cluster node, check if the cluster node already
# exists in the current nodes cache and has a valid connection so we can
# reuse it
target_node = self.nodes_cache.get(node_name)
if target_node is None or target_node.redis_connection is None:
# create new cluster node for this cluster
target_node = ClusterNode(host, port, role)
if target_node.server_type != role:
target_node.server_type = role
return target_node
def initialize(self):
"""
Initializes the nodes cache, slots cache and redis connections.
:startup_nodes:
Responsible for discovering other nodes in the cluster
"""
self.reset()
tmp_nodes_cache = {}
tmp_slots = {}
disagreements = []
startup_nodes_reachable = False
fully_covered = False
kwargs = self.connection_kwargs
exception = None
for startup_node in self.startup_nodes.values():
try:
if startup_node.redis_connection:
r = startup_node.redis_connection
else:
# Create a new Redis connection
r = self.create_redis_node(
startup_node.host, startup_node.port, **kwargs
)
self.startup_nodes[startup_node.name].redis_connection = r
# Make sure cluster mode is enabled on this node
try:
cluster_slots = str_if_bytes(r.execute_command("CLUSTER SLOTS"))
except ResponseError:
raise RedisClusterException(
"Cluster mode is not enabled on this node"
)
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 len(cluster_slots[0][2][0]) == 0
and len(self.startup_nodes) == 1
):
cluster_slots[0][2][0] = startup_node.host
for slot in cluster_slots:
primary_node = slot[2]
host = str_if_bytes(primary_node[0])
if host == "":
host = startup_node.host
port = int(primary_node[1])
host, port = self.remap_host_port(host, port)
target_node = self._get_or_create_cluster_node(
host, port, PRIMARY, tmp_nodes_cache
)
# 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 = str_if_bytes(replica_node[0])
port = replica_node[1]
host, port = self.remap_host_port(host, port)
target_replica_node = self._get_or_create_cluster_node(
host, port, REPLICA, tmp_nodes_cache
)
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)}'
)
fully_covered = self.check_slots_coverage(tmp_slots)
if fully_covered:
# Don't need to continue to the next startup node if all
# slots are 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
# Create Redis connections to all nodes
self.create_redis_connections(list(tmp_nodes_cache.values()))
# 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.nodes_cache = tmp_nodes_cache
self.slots_cache = tmp_slots
# Set the default node
self.default_node = self.get_nodes_by_server_type(PRIMARY)[0]
if self._dynamic_startup_nodes:
# Populate the startup nodes with all discovered nodes
self.startup_nodes = tmp_nodes_cache
# If initialize was called after a MovedError, clear it
self._moved_exception = None
def close(self):
self.default_node = None
for node in self.nodes_cache.values():
if node.redis_connection:
node.redis_connection.close()
def reset(self):
try:
self.read_load_balancer.reset()
except TypeError:
# The read_load_balancer is None, do nothing
pass
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
class ClusterPubSub(PubSub):
"""
Wrapper for PubSub class.
IMPORTANT: before using ClusterPubSub, read about the known limitations
with pubsub in Cluster mode and learn how to workaround them:
https://redis-py-cluster.readthedocs.io/en/stable/pubsub.html
"""
def __init__(
self,
redis_cluster,
node=None,
host=None,
port=None,
push_handler_func=None,
**kwargs,
):
"""
When a pubsub instance is created without specifying a node, a single
node will be transparently chosen for the pubsub connection on the
first command execution. The node will be determined by:
1. Hashing the channel name in the request to find its keyslot
2. Selecting a node that handles the keyslot: If read_from_replicas is
set to true, a replica can be selected.
:type redis_cluster: RedisCluster
:type node: ClusterNode
:type host: str
:type port: int
"""
self.node = None
self.set_pubsub_node(redis_cluster, node, host, port)
connection_pool = (
None
if self.node is None
else redis_cluster.get_redis_connection(self.node).connection_pool
)
self.cluster = redis_cluster
self.node_pubsub_mapping = {}
self._pubsubs_generator = self._pubsubs_generator()
super().__init__(
connection_pool=connection_pool,
encoder=redis_cluster.encoder,
push_handler_func=push_handler_func,
**kwargs,
)
def set_pubsub_node(self, cluster, node=None, host=None, port=None):
"""
The pubsub node will be set according to the passed node, host and port
When none of the node, host, or port are specified - the node is set
to None and will be determined by the keyslot of the channel in the
first command to be executed.
RedisClusterException will be thrown if the passed node does not exist
in the cluster.
If host is passed without port, or vice versa, a DataError will be
thrown.
:type cluster: RedisCluster
:type node: ClusterNode
:type host: str
:type port: int
"""
if node is not None:
# node is passed by the user
self._raise_on_invalid_node(cluster, node, node.host, node.port)
pubsub_node = node
elif host is not None and port is not None:
# host and port passed by the user
node = cluster.get_node(host=host, port=port)
self._raise_on_invalid_node(cluster, node, host, port)
pubsub_node = node
elif any([host, port]) is True:
# only 'host' or 'port' passed
raise DataError("Passing a host requires passing a port, and vice versa")
else:
# nothing passed by the user. set node to None
pubsub_node = None
self.node = pubsub_node
def get_pubsub_node(self):
"""
Get the node that is being used as the pubsub connection
"""
return self.node
def _raise_on_invalid_node(self, redis_cluster, node, host, port):
"""
Raise a RedisClusterException if the node is None or doesn't exist in
the cluster.
"""
if node is None or redis_cluster.get_node(node_name=node.name) is None:
raise RedisClusterException(
f"Node {host}:{port} doesn't exist in the cluster"
)
def execute_command(self, *args):
"""
Execute a subscribe/unsubscribe command.
Taken code from redis-py and tweak to make it work within a cluster.
"""
# NOTE: don't parse the response in this function -- it could pull a
# legitimate message off the stack if the connection is already
# subscribed to one or more channels
if self.connection is None:
if self.connection_pool is None:
if len(args) > 1:
# Hash the first channel and get one of the nodes holding
# this slot
channel = args[1]
slot = self.cluster.keyslot(channel)
node = self.cluster.nodes_manager.get_node_from_slot(
slot, self.cluster.read_from_replicas
)
else:
# Get a random node
node = self.cluster.get_random_node()
self.node = node
redis_connection = self.cluster.get_redis_connection(node)
self.connection_pool = redis_connection.connection_pool
self.connection = self.connection_pool.get_connection(
"pubsub", self.shard_hint
)
# register a callback that re-subscribes to any channels we
# were listening to when we were disconnected
self.connection.register_connect_callback(self.on_connect)
if self.push_handler_func is not None and not HIREDIS_AVAILABLE:
self.connection._parser.set_push_handler(self.push_handler_func)
connection = self.connection
self._execute(connection, connection.send_command, *args)
def _get_node_pubsub(self, node):
try:
return self.node_pubsub_mapping[node.name]
except KeyError:
pubsub = node.redis_connection.pubsub(
push_handler_func=self.push_handler_func
)
self.node_pubsub_mapping[node.name] = pubsub
return pubsub
def _sharded_message_generator(self):
for _ in range(len(self.node_pubsub_mapping)):
pubsub = next(self._pubsubs_generator)
message = pubsub.get_message()
if message is not None:
return message
return None
def _pubsubs_generator(self):
while True:
for pubsub in self.node_pubsub_mapping.values():
yield pubsub
def get_sharded_message(
self, ignore_subscribe_messages=False, timeout=0.0, target_node=None
):
if target_node:
message = self.node_pubsub_mapping[target_node.name].get_message(
ignore_subscribe_messages=ignore_subscribe_messages, timeout=timeout
)
else:
message = self._sharded_message_generator()
if message is None:
return None
elif str_if_bytes(message["type"]) == "sunsubscribe":
if message["channel"] in self.pending_unsubscribe_shard_channels:
self.pending_unsubscribe_shard_channels.remove(message["channel"])
self.shard_channels.pop(message["channel"], None)
node = self.cluster.get_node_from_key(message["channel"])
if self.node_pubsub_mapping[node.name].subscribed is False:
self.node_pubsub_mapping.pop(node.name)
if not self.channels and not self.patterns and not self.shard_channels:
# There are no subscriptions anymore, set subscribed_event flag
# to false
self.subscribed_event.clear()
if self.ignore_subscribe_messages or ignore_subscribe_messages:
return None
return message
def ssubscribe(self, *args, **kwargs):
if args:
args = list_or_args(args[0], args[1:])
s_channels = dict.fromkeys(args)
s_channels.update(kwargs)
for s_channel, handler in s_channels.items():
node = self.cluster.get_node_from_key(s_channel)
pubsub = self._get_node_pubsub(node)
if handler:
pubsub.ssubscribe(**{s_channel: handler})
else:
pubsub.ssubscribe(s_channel)
self.shard_channels.update(pubsub.shard_channels)
self.pending_unsubscribe_shard_channels.difference_update(
self._normalize_keys({s_channel: None})
)
if pubsub.subscribed and not self.subscribed:
self.subscribed_event.set()
self.health_check_response_counter = 0
def sunsubscribe(self, *args):
if args:
args = list_or_args(args[0], args[1:])
else:
args = self.shard_channels
for s_channel in args:
node = self.cluster.get_node_from_key(s_channel)
p = self._get_node_pubsub(node)
p.sunsubscribe(s_channel)
self.pending_unsubscribe_shard_channels.update(
p.pending_unsubscribe_shard_channels
)
def get_redis_connection(self):
"""
Get the Redis connection of the pubsub connected node.
"""
if self.node is not None:
return self.node.redis_connection
def disconnect(self):
"""
Disconnect the pubsub connection.
"""
if self.connection:
self.connection.disconnect()
for pubsub in self.node_pubsub_mapping.values():
pubsub.connection.disconnect()
class ClusterPipeline(RedisCluster):
"""
Support for Redis pipeline
in cluster mode
"""
ERRORS_ALLOW_RETRY = (
ConnectionError,
TimeoutError,
MovedError,
AskError,
TryAgainError,
)
def __init__(
self,
nodes_manager: "NodesManager",
commands_parser: "CommandsParser",
result_callbacks: Optional[Dict[str, Callable]] = None,
cluster_response_callbacks: Optional[Dict[str, Callable]] = None,
startup_nodes: Optional[List["ClusterNode"]] = None,
read_from_replicas: bool = False,
cluster_error_retry_attempts: int = 3,
reinitialize_steps: int = 5,
lock=None,
**kwargs,
):
""" """
self.command_stack = []
self.nodes_manager = nodes_manager
self.commands_parser = commands_parser
self.refresh_table_asap = False
self.result_callbacks = (
result_callbacks or self.__class__.RESULT_CALLBACKS.copy()
)
self.startup_nodes = startup_nodes if startup_nodes else []
self.read_from_replicas = read_from_replicas
self.command_flags = self.__class__.COMMAND_FLAGS.copy()
self.cluster_response_callbacks = cluster_response_callbacks
self.cluster_error_retry_attempts = cluster_error_retry_attempts
self.reinitialize_counter = 0
self.reinitialize_steps = reinitialize_steps
self.encoder = Encoder(
kwargs.get("encoding", "utf-8"),
kwargs.get("encoding_errors", "strict"),
kwargs.get("decode_responses", False),
)
if lock is None:
lock = threading.Lock()
self._lock = lock
def __repr__(self):
""" """
return f"{type(self).__name__}"
def __enter__(self):
""" """
return self
def __exit__(self, exc_type, exc_value, traceback):
""" """
self.reset()
def __del__(self):
try:
self.reset()
except Exception:
pass
def __len__(self):
""" """
return len(self.command_stack)
def __bool__(self):
"Pipeline instances should always evaluate to True on Python 3+"
return True
def execute_command(self, *args, **kwargs):
"""
Wrapper function for pipeline_execute_command
"""
return self.pipeline_execute_command(*args, **kwargs)
def pipeline_execute_command(self, *args, **options):
"""
Appends the executed command to the pipeline's command stack
"""
self.command_stack.append(
PipelineCommand(args, options, len(self.command_stack))
)
return self
def raise_first_error(self, stack):
"""
Raise the first exception on the stack
"""
for c in stack:
r = c.result
if isinstance(r, Exception):
self.annotate_exception(r, c.position + 1, c.args)
raise r
def annotate_exception(self, exception, number, command):
"""
Provides extra context to the exception prior to it being handled
"""
cmd = " ".join(map(safe_str, command))
msg = (
f"Command # {number} ({cmd}) of pipeline "
f"caused error: {exception.args[0]}"
)
exception.args = (msg,) + exception.args[1:]
def execute(self, raise_on_error=True):
"""
Execute all the commands in the current pipeline
"""
stack = self.command_stack
try:
return self.send_cluster_commands(stack, raise_on_error)
finally:
self.reset()
def reset(self):
"""
Reset back to empty pipeline.
"""
self.command_stack = []
self.scripts = set()
# TODO: Implement
# make sure to reset the connection state in the event that we were
# watching something
# if self.watching and self.connection:
# try:
# # call this manually since our unwatch or
# # immediate_execute_command methods can call reset()
# self.connection.send_command('UNWATCH')
# self.connection.read_response()
# except ConnectionError:
# # disconnect will also remove any previous WATCHes
# self.connection.disconnect()
# clean up the other instance attributes
self.watching = False
self.explicit_transaction = False
# TODO: Implement
# we can safely return the connection to the pool here since we're
# sure we're no longer WATCHing anything
# if self.connection:
# self.connection_pool.release(self.connection)
# self.connection = None
def send_cluster_commands(
self, stack, raise_on_error=True, allow_redirections=True
):
"""
Wrapper for CLUSTERDOWN error handling.
If the cluster reports it is down it is assumed that:
- connection_pool was disconnected
- connection_pool was reseted
- refereh_table_asap set to True
It will try the number of times specified by
the config option "self.cluster_error_retry_attempts"
which defaults to 3 unless manually configured.
If it reaches the number of times, the command will
raises ClusterDownException.
"""
if not stack:
return []
retry_attempts = self.cluster_error_retry_attempts
while True:
try:
return self._send_cluster_commands(
stack,
raise_on_error=raise_on_error,
allow_redirections=allow_redirections,
)
except (ClusterDownError, ConnectionError) as e:
if retry_attempts > 0:
# Try again with the new cluster setup. All other errors
# should be raised.
retry_attempts -= 1
pass
else:
raise e
def _send_cluster_commands(
self, stack, raise_on_error=True, allow_redirections=True
):
"""
Send a bunch of cluster commands to the redis cluster.
`allow_redirections` If the pipeline should follow
`ASK` & `MOVED` responses automatically. If set
to false it will raise RedisClusterException.
"""
# the first time sending the commands we send all of
# the commands that were queued up.
# if we have to run through it again, we only retry
# the commands that failed.
attempt = sorted(stack, key=lambda x: x.position)
is_default_node = False
# build a list of node objects based on node names we need to
nodes = {}
# as we move through each command that still needs to be processed,
# we figure out the slot number that command maps to, then from
# the slot determine the node.
for c in attempt:
while True:
# refer to our internal node -> slot table that
# tells us where a given command should route to.
# (it might be possible we have a cached node that no longer
# exists in the cluster, which is why we do this in a loop)
passed_targets = c.options.pop("target_nodes", None)
if passed_targets and not self._is_nodes_flag(passed_targets):
target_nodes = self._parse_target_nodes(passed_targets)
else:
target_nodes = self._determine_nodes(
*c.args, node_flag=passed_targets
)
if not target_nodes:
raise RedisClusterException(
f"No targets were found to execute {c.args} command on"
)
if len(target_nodes) > 1:
raise RedisClusterException(
f"Too many targets for command {c.args}"
)
node = target_nodes[0]
if node == self.get_default_node():
is_default_node = True
# now that we know the name of the node
# ( it's just a string in the form of host:port )
# we can build a list of commands for each node.
node_name = node.name
if node_name not in nodes:
redis_node = self.get_redis_connection(node)
try:
connection = get_connection(redis_node, c.args)
except ConnectionError:
for n in nodes.values():
n.connection_pool.release(n.connection)
# Connection retries are being handled in the node's
# Retry object. Reinitialize the node -> slot table.
self.nodes_manager.initialize()
if is_default_node:
self.replace_default_node()
raise
nodes[node_name] = NodeCommands(
redis_node.parse_response,
redis_node.connection_pool,
connection,
)
nodes[node_name].append(c)
break
# send the commands in sequence.
# we write to all the open sockets for each node first,
# before reading anything
# this allows us to flush all the requests out across the
# network essentially in parallel
# so that we can read them all in parallel as they come back.
# we dont' multiplex on the sockets as they come available,
# but that shouldn't make too much difference.
node_commands = nodes.values()
try:
node_commands = nodes.values()
for n in node_commands:
n.write()
for n in node_commands:
n.read()
finally:
# release all of the redis connections we allocated earlier
# back into the connection pool.
# we used to do this step as part of a try/finally block,
# but it is really dangerous to
# release connections back into the pool if for some
# reason the socket has data still left in it
# from a previous operation. The write and
# read operations already have try/catch around them for
# all known types of errors including connection
# and socket level errors.
# So if we hit an exception, something really bad
# happened and putting any oF
# these connections back into the pool is a very bad idea.
# the socket might have unread buffer still sitting in it,
# and then the next time we read from it we pass the
# buffered result back from a previous command and
# every single request after to that connection will always get
# a mismatched result.
for n in nodes.values():
n.connection_pool.release(n.connection)
# if the response isn't an exception it is a
# valid response from the node
# we're all done with that command, YAY!
# if we have more commands to attempt, we've run into problems.
# collect all the commands we are allowed to retry.
# (MOVED, ASK, or connection errors or timeout errors)
attempt = sorted(
(
c
for c in attempt
if isinstance(c.result, ClusterPipeline.ERRORS_ALLOW_RETRY)
),
key=lambda x: x.position,
)
if attempt and allow_redirections:
# RETRY MAGIC HAPPENS HERE!
# send these remaining commands one at a time using `execute_command`
# in the main client. This keeps our retry logic
# in one place mostly,
# and allows us to be more confident in correctness of behavior.
# at this point any speed gains from pipelining have been lost
# anyway, so we might as well make the best
# attempt to get the correct behavior.
#
# The client command will handle retries for each
# individual command sequentially as we pass each
# one into `execute_command`. Any exceptions
# that bubble out should only appear once all
# retries have been exhausted.
#
# If a lot of commands have failed, we'll be setting the
# flag to rebuild the slots table from scratch.
# So MOVED errors should correct themselves fairly quickly.
self.reinitialize_counter += 1
if self._should_reinitialized():
self.nodes_manager.initialize()
if is_default_node:
self.replace_default_node()
for c in attempt:
try:
# send each command individually like we
# do in the main client.
c.result = super().execute_command(*c.args, **c.options)
except RedisError as e:
c.result = e
# turn the response back into a simple flat array that corresponds
# to the sequence of commands issued in the stack in pipeline.execute()
response = []
for c in sorted(stack, key=lambda x: x.position):
if c.args[0] in self.cluster_response_callbacks:
c.result = self.cluster_response_callbacks[c.args[0]](
c.result, **c.options
)
response.append(c.result)
if raise_on_error:
self.raise_first_error(stack)
return response
def _fail_on_redirect(self, allow_redirections):
""" """
if not allow_redirections:
raise RedisClusterException(
"ASK & MOVED redirection not allowed in this pipeline"
)
def exists(self, *keys):
return self.execute_command("EXISTS", *keys)
def eval(self):
""" """
raise RedisClusterException("method eval() is not implemented")
def multi(self):
""" """
raise RedisClusterException("method multi() is not implemented")
def immediate_execute_command(self, *args, **options):
""" """
raise RedisClusterException(
"method immediate_execute_command() is not implemented"
)
def _execute_transaction(self, *args, **kwargs):
""" """
raise RedisClusterException("method _execute_transaction() is not implemented")
def load_scripts(self):
""" """
raise RedisClusterException("method load_scripts() is not implemented")
def watch(self, *names):
""" """
raise RedisClusterException("method watch() is not implemented")
def unwatch(self):
""" """
raise RedisClusterException("method unwatch() is not implemented")
def script_load_for_pipeline(self, *args, **kwargs):
""" """
raise RedisClusterException(
"method script_load_for_pipeline() is not implemented"
)
def delete(self, *names):
"""
"Delete a key specified by ``names``"
"""
if len(names) != 1:
raise RedisClusterException(
"deleting multiple keys is not implemented in pipeline command"
)
return self.execute_command("DEL", names[0])
def unlink(self, *names):
"""
"Unlink a key specified by ``names``"
"""
if len(names) != 1:
raise RedisClusterException(
"unlinking multiple keys is not implemented in pipeline command"
)
return self.execute_command("UNLINK", names[0])
def block_pipeline_command(name: str) -> Callable[..., Any]:
"""
Prints error because some pipelined commands should
be blocked when running in cluster-mode
"""
def inner(*args, **kwargs):
raise RedisClusterException(
f"ERROR: Calling pipelined function {name} is blocked "
f"when running redis in cluster mode..."
)
return inner
# Blocked pipeline commands
PIPELINE_BLOCKED_COMMANDS = (
"BGREWRITEAOF",
"BGSAVE",
"BITOP",
"BRPOPLPUSH",
"CLIENT GETNAME",
"CLIENT KILL",
"CLIENT LIST",
"CLIENT SETNAME",
"CLIENT",
"CONFIG GET",
"CONFIG RESETSTAT",
"CONFIG REWRITE",
"CONFIG SET",
"CONFIG",
"DBSIZE",
"ECHO",
"EVALSHA",
"FLUSHALL",
"FLUSHDB",
"INFO",
"KEYS",
"LASTSAVE",
"MGET",
"MGET NONATOMIC",
"MOVE",
"MSET",
"MSET NONATOMIC",
"MSETNX",
"PFCOUNT",
"PFMERGE",
"PING",
"PUBLISH",
"RANDOMKEY",
"READONLY",
"READWRITE",
"RENAME",
"RENAMENX",
"RPOPLPUSH",
"SAVE",
"SCAN",
"SCRIPT EXISTS",
"SCRIPT FLUSH",
"SCRIPT KILL",
"SCRIPT LOAD",
"SCRIPT",
"SDIFF",
"SDIFFSTORE",
"SENTINEL GET MASTER ADDR BY NAME",
"SENTINEL MASTER",
"SENTINEL MASTERS",
"SENTINEL MONITOR",
"SENTINEL REMOVE",
"SENTINEL SENTINELS",
"SENTINEL SET",
"SENTINEL SLAVES",
"SENTINEL",
"SHUTDOWN",
"SINTER",
"SINTERSTORE",
"SLAVEOF",
"SLOWLOG GET",
"SLOWLOG LEN",
"SLOWLOG RESET",
"SLOWLOG",
"SMOVE",
"SORT",
"SUNION",
"SUNIONSTORE",
"TIME",
)
for command in PIPELINE_BLOCKED_COMMANDS:
command = command.replace(" ", "_").lower()
setattr(ClusterPipeline, command, block_pipeline_command(command))
class PipelineCommand:
""" """
def __init__(self, args, options=None, position=None):
self.args = args
if options is None:
options = {}
self.options = options
self.position = position
self.result = None
self.node = None
self.asking = False
class NodeCommands:
""" """
def __init__(self, parse_response, connection_pool, connection):
""" """
self.parse_response = parse_response
self.connection_pool = connection_pool
self.connection = connection
self.commands = []
def append(self, c):
""" """
self.commands.append(c)
def write(self):
"""
Code borrowed from Redis so it can be fixed
"""
connection = self.connection
commands = self.commands
# We are going to clobber the commands with the write, so go ahead
# and ensure that nothing is sitting there from a previous run.
for c in commands:
c.result = None
# build up all commands into a single request to increase network perf
# send all the commands and catch connection and timeout errors.
try:
connection.send_packed_command(
connection.pack_commands([c.args for c in commands])
)
except (ConnectionError, TimeoutError) as e:
for c in commands:
c.result = e
def read(self):
""" """
connection = self.connection
for c in self.commands:
# if there is a result on this command,
# it means we ran into an exception
# like a connection error. Trying to parse
# a response on a connection that
# is no longer open will result in a
# connection error raised by redis-py.
# but redis-py doesn't check in parse_response
# that the sock object is
# still set and if you try to
# read from a closed connection, it will
# result in an AttributeError because
# it will do a readline() call on None.
# This can have all kinds of nasty side-effects.
# Treating this case as a connection error
# is fine because it will dump
# the connection object back into the
# pool and on the next write, it will
# explicitly open the connection and all will be well.
if c.result is None:
try:
c.result = self.parse_response(connection, c.args[0], **c.options)
except (ConnectionError, TimeoutError) as e:
for c in self.commands:
c.result = e
return
except RedisError:
c.result = sys.exc_info()[1]