Source code for redis.client

import copy
import re
import threading
import time
import warnings
from itertools import chain
from typing import Any, Callable, Dict, List, Optional, Type, Union

from redis._cache import (
from redis._parsers.encoders import Encoder
from redis._parsers.helpers import (
from redis.commands import (
from redis.connection import ConnectionPool, SSLConnection, UnixDomainSocketConnection
from redis.credentials import CredentialProvider
from redis.exceptions import (
from redis.lock import Lock
from redis.retry import Retry
from redis.utils import (


# some responses (ie. dump) are binary, and just meant to never be decoded

class CaseInsensitiveDict(dict):
    "Case insensitive dict implementation. Assumes string keys only."

    def __init__(self, data: Dict[str, str]) -> None:
        for k, v in data.items():
            self[k.upper()] = v

    def __contains__(self, k):
        return super().__contains__(k.upper())

    def __delitem__(self, k):

    def __getitem__(self, k):
        return super().__getitem__(k.upper())

    def get(self, k, default=None):
        return super().get(k.upper(), default)

    def __setitem__(self, k, v):
        super().__setitem__(k.upper(), v)

    def update(self, data):
        data = CaseInsensitiveDict(data)

class AbstractRedis:

[docs]class Redis(RedisModuleCommands, CoreCommands, SentinelCommands): """ Implementation of the Redis protocol. This abstract class provides a Python interface to all Redis commands and an implementation of the Redis protocol. Pipelines derive from this, implementing how the commands are sent and received to the Redis server. Based on configuration, an instance will either use a ConnectionPool, or Connection object to talk to redis. It is not safe to pass PubSub or Pipeline objects between threads. """
[docs] @classmethod def from_url(cls, url: str, **kwargs) -> "Redis": """ 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: <> - `rediss://` creates a SSL wrapped TCP socket connection. See more at: <> - ``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. """ single_connection_client = kwargs.pop("single_connection_client", False) connection_pool = ConnectionPool.from_url(url, **kwargs) client = cls( connection_pool=connection_pool, single_connection_client=single_connection_client, ) client.auto_close_connection_pool = True return client
[docs] @classmethod def from_pool( cls: Type["Redis"], connection_pool: ConnectionPool, ) -> "Redis": """ Return a Redis client from the given connection pool. The Redis client will take ownership of the connection pool and close it when the Redis client is closed. """ client = cls( connection_pool=connection_pool, ) client.auto_close_connection_pool = True return client
def __init__( self, host="localhost", port=6379, db=0, password=None, socket_timeout=None, socket_connect_timeout=None, socket_keepalive=None, socket_keepalive_options=None, connection_pool=None, unix_socket_path=None, encoding="utf-8", encoding_errors="strict", charset=None, errors=None, decode_responses=False, retry_on_timeout=False, retry_on_error=None, ssl=False, ssl_keyfile=None, ssl_certfile=None, ssl_cert_reqs="required", ssl_ca_certs=None, ssl_ca_path=None, ssl_ca_data=None, ssl_check_hostname=False, ssl_password=None, ssl_validate_ocsp=False, ssl_validate_ocsp_stapled=False, ssl_ocsp_context=None, ssl_ocsp_expected_cert=None, max_connections=None, single_connection_client=False, health_check_interval=0, client_name=None, lib_name="redis-py", lib_version=get_lib_version(), username=None, retry=None, redis_connect_func=None, credential_provider: Optional[CredentialProvider] = None, protocol: Optional[int] = 2, cache_enabled: bool = False, client_cache: Optional[AbstractCache] = None, cache_max_size: int = 10000, cache_ttl: int = 0, cache_policy: str = DEFAULT_EVICTION_POLICY, cache_blacklist: List[str] = DEFAULT_BLACKLIST, cache_whitelist: List[str] = DEFAULT_WHITELIST, ) -> None: """ Initialize a new Redis client. To specify a retry policy for specific errors, first set `retry_on_error` to a list of the error/s to retry on, then set `retry` to a valid `Retry` object. To retry on TimeoutError, `retry_on_timeout` can also be set to `True`. Args: single_connection_client: if `True`, connection pool is not used. In that case `Redis` instance use is not thread safe. """ if not connection_pool: if charset is not None: warnings.warn( DeprecationWarning( '"charset" is deprecated. Use "encoding" instead' ) ) encoding = charset if errors is not None: warnings.warn( DeprecationWarning( '"errors" is deprecated. Use "encoding_errors" instead' ) ) encoding_errors = errors if not retry_on_error: retry_on_error = [] if retry_on_timeout is True: retry_on_error.append(TimeoutError) kwargs = { "db": db, "username": username, "password": password, "socket_timeout": socket_timeout, "encoding": encoding, "encoding_errors": encoding_errors, "decode_responses": decode_responses, "retry_on_error": retry_on_error, "retry": copy.deepcopy(retry), "max_connections": max_connections, "health_check_interval": health_check_interval, "client_name": client_name, "lib_name": lib_name, "lib_version": lib_version, "redis_connect_func": redis_connect_func, "credential_provider": credential_provider, "protocol": protocol, "cache_enabled": cache_enabled, "client_cache": client_cache, "cache_max_size": cache_max_size, "cache_ttl": cache_ttl, "cache_policy": cache_policy, "cache_blacklist": cache_blacklist, "cache_whitelist": cache_whitelist, } # based on input, setup appropriate connection args if unix_socket_path is not None: kwargs.update( { "path": unix_socket_path, "connection_class": UnixDomainSocketConnection, } ) else: # TCP specific options kwargs.update( { "host": host, "port": port, "socket_connect_timeout": socket_connect_timeout, "socket_keepalive": socket_keepalive, "socket_keepalive_options": socket_keepalive_options, } ) if ssl: kwargs.update( { "connection_class": SSLConnection, "ssl_keyfile": ssl_keyfile, "ssl_certfile": ssl_certfile, "ssl_cert_reqs": ssl_cert_reqs, "ssl_ca_certs": ssl_ca_certs, "ssl_ca_data": ssl_ca_data, "ssl_check_hostname": ssl_check_hostname, "ssl_password": ssl_password, "ssl_ca_path": ssl_ca_path, "ssl_validate_ocsp_stapled": ssl_validate_ocsp_stapled, "ssl_validate_ocsp": ssl_validate_ocsp, "ssl_ocsp_context": ssl_ocsp_context, "ssl_ocsp_expected_cert": ssl_ocsp_expected_cert, } ) connection_pool = ConnectionPool(**kwargs) self.auto_close_connection_pool = True else: self.auto_close_connection_pool = False self.connection_pool = connection_pool self.connection = None if single_connection_client: self.connection = self.connection_pool.get_connection("_") self.response_callbacks = CaseInsensitiveDict(_RedisCallbacks) if self.connection_pool.connection_kwargs.get("protocol") in ["3", 3]: self.response_callbacks.update(_RedisCallbacksRESP3) else: self.response_callbacks.update(_RedisCallbacksRESP2) def __repr__(self) -> str: return ( f"<{type(self).__module__}.{type(self).__name__}" f"({repr(self.connection_pool)})>" )
[docs] def get_encoder(self) -> "Encoder": """Get the connection pool's encoder""" return self.connection_pool.get_encoder()
[docs] def get_connection_kwargs(self) -> Dict: """Get the connection's key-word arguments""" return self.connection_pool.connection_kwargs
def get_retry(self) -> Optional["Retry"]: return self.get_connection_kwargs().get("retry") def set_retry(self, retry: "Retry") -> None: self.get_connection_kwargs().update({"retry": retry}) self.connection_pool.set_retry(retry)
[docs] def set_response_callback(self, command: str, callback: Callable) -> None: """Set a custom Response Callback""" self.response_callbacks[command] = callback
[docs] def load_external_module(self, funcname, func) -> None: """ 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. ex: Assume that one has a custom redis module named foomod that creates command named 'foo.dothing' and 'foo.anotherthing' in redis. To load function functions into this namespace: from redis import Redis from foomodule import F r = Redis() r.load_external_module("foo", F)'your', 'arguments') For a concrete example see the reimport of the redisjson module in tests/ """ setattr(self, funcname, func)
[docs] def pipeline(self, transaction=True, shard_hint=None) -> "Pipeline": """ Return a new pipeline object that can queue multiple commands for later execution. ``transaction`` indicates whether all commands should be executed atomically. Apart from making a group of operations atomic, pipelines are useful for reducing the back-and-forth overhead between the client and server. """ return Pipeline( self.connection_pool, self.response_callbacks, transaction, shard_hint )
[docs] def transaction( self, func: Callable[["Pipeline"], None], *watches, **kwargs ) -> None: """ Convenience method for executing the callable `func` as a transaction while watching all keys specified in `watches`. The 'func' callable should expect a single argument which is a Pipeline object. """ shard_hint = kwargs.pop("shard_hint", None) value_from_callable = kwargs.pop("value_from_callable", False) watch_delay = kwargs.pop("watch_delay", None) with self.pipeline(True, shard_hint) as pipe: while True: try: if watches:*watches) func_value = func(pipe) exec_value = pipe.execute() return func_value if value_from_callable else exec_value except WatchError: if watch_delay is not None and watch_delay > 0: time.sleep(watch_delay) continue
[docs] def lock( self, name: str, timeout: Optional[float] = None, sleep: float = 0.1, blocking: bool = True, blocking_timeout: Optional[float] = None, lock_class: Union[None, Any] = None, thread_local: bool = 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, )
[docs] def pubsub(self, **kwargs): """ Return a Publish/Subscribe object. With this object, you can subscribe to channels and listen for messages that get published to them. """ return PubSub(self.connection_pool, **kwargs)
def monitor(self): return Monitor(self.connection_pool) def client(self): return self.__class__( connection_pool=self.connection_pool, single_connection_client=True ) def __enter__(self): return self def __exit__(self, exc_type, exc_value, traceback): self.close() def __del__(self): self.close() def close(self): # In case a connection property does not yet exist # (due to a crash earlier in the Redis() constructor), return # immediately as there is nothing to clean-up. if not hasattr(self, "connection"): return conn = self.connection if conn: self.connection = None self.connection_pool.release(conn) if self.auto_close_connection_pool: self.connection_pool.disconnect() def _send_command_parse_response(self, conn, command_name, *args, **options): """ Send a command and parse the response """ conn.send_command(*args) return self.parse_response(conn, command_name, **options) def _disconnect_raise(self, conn, error): """ Close the connection and raise an exception if retry_on_error is not set or the error is not one of the specified error types """ conn.disconnect() if ( conn.retry_on_error is None or isinstance(error, tuple(conn.retry_on_error)) is False ): raise error # COMMAND EXECUTION AND PROTOCOL PARSING
[docs] def execute_command(self, *args, **options): """Execute a command and return a parsed response""" command_name = args[0] keys = options.pop("keys", None) pool = self.connection_pool conn = self.connection or pool.get_connection(command_name, **options) response_from_cache = conn._get_from_local_cache(args) if response_from_cache is not None: return response_from_cache else: try: response = conn.retry.call_with_retry( lambda: self._send_command_parse_response( conn, command_name, *args, **options ), lambda error: self._disconnect_raise(conn, error), ) conn._add_to_local_cache(args, response, keys) return response finally: if not self.connection: pool.release(conn)
[docs] def parse_response(self, connection, command_name, **options): """Parses a response from the Redis server""" try: if NEVER_DECODE in options: response = connection.read_response(disable_decoding=True) options.pop(NEVER_DECODE) else: response = connection.read_response() except ResponseError: if EMPTY_RESPONSE in options: return options[EMPTY_RESPONSE] raise if EMPTY_RESPONSE in options: options.pop(EMPTY_RESPONSE) if command_name in self.response_callbacks: return self.response_callbacks[command_name](response, **options) return response
def flush_cache(self): try: if self.connection: self.connection.client_cache.flush() else: self.connection_pool.flush_cache() except AttributeError: pass def delete_command_from_cache(self, command): try: if self.connection: self.connection.client_cache.delete_command(command) else: self.connection_pool.delete_command_from_cache(command) except AttributeError: pass def invalidate_key_from_cache(self, key): try: if self.connection: self.connection.client_cache.invalidate_key(key) else: self.connection_pool.invalidate_key_from_cache(key) except AttributeError: pass
StrictRedis = Redis class Monitor: """ 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. """ monitor_re = re.compile(r"\[(\d+) (.*?)\] (.*)") command_re = re.compile(r'"(.*?)(?<!\\)"') def __init__(self, connection_pool): self.connection_pool = connection_pool self.connection = self.connection_pool.get_connection("MONITOR") def __enter__(self): self.connection.send_command("MONITOR") # check that monitor returns 'OK', but don't return it to user response = self.connection.read_response() if not bool_ok(response): raise RedisError(f"MONITOR failed: {response}") return self def __exit__(self, *args): self.connection.disconnect() self.connection_pool.release(self.connection) def next_command(self): """Parse the response from a monitor command""" response = self.connection.read_response() if isinstance(response, bytes): response = self.connection.encoder.decode(response, force=True) command_time, command_data = response.split(" ", 1) m = self.monitor_re.match(command_data) db_id, client_info, command = m.groups() command = " ".join(self.command_re.findall(command)) # Redis escapes double quotes because each piece of the command # string is surrounded by double quotes. We don't have that # requirement so remove the escaping and leave the quote. command = command.replace('\\"', '"') if client_info == "lua": client_address = "lua" client_port = "" client_type = "lua" elif client_info.startswith("unix"): client_address = "unix" client_port = client_info[5:] client_type = "unix" else: # use rsplit as ipv6 addresses contain colons client_address, client_port = client_info.rsplit(":", 1) client_type = "tcp" return { "time": float(command_time), "db": int(db_id), "client_address": client_address, "client_port": client_port, "client_type": client_type, "command": command, } def listen(self): """Listen for commands coming to the server.""" while True: yield self.next_command() class PubSub: """ PubSub provides publish, subscribe and listen support to Redis channels. After subscribing to one or more channels, the listen() method will block until a message arrives on one of the subscribed channels. That message will be returned and it's safe to start listening again. """ PUBLISH_MESSAGE_TYPES = ("message", "pmessage", "smessage") UNSUBSCRIBE_MESSAGE_TYPES = ("unsubscribe", "punsubscribe", "sunsubscribe") HEALTH_CHECK_MESSAGE = "redis-py-health-check" def __init__( self, connection_pool, shard_hint=None, ignore_subscribe_messages: bool = False, encoder: Optional["Encoder"] = None, push_handler_func: Union[None, Callable[[str], None]] = None, ): self.connection_pool = connection_pool self.shard_hint = shard_hint self.ignore_subscribe_messages = ignore_subscribe_messages self.connection = None self.subscribed_event = threading.Event() # we need to know the encoding options for this connection in order # to lookup channel and pattern names for callback handlers. self.encoder = encoder self.push_handler_func = push_handler_func if self.encoder is None: self.encoder = self.connection_pool.get_encoder() self.health_check_response_b = self.encoder.encode(self.HEALTH_CHECK_MESSAGE) if self.encoder.decode_responses: self.health_check_response = ["pong", self.HEALTH_CHECK_MESSAGE] else: self.health_check_response = [b"pong", self.health_check_response_b] if self.push_handler_func is None: _set_info_logger() self.reset() def __enter__(self) -> "PubSub": return self def __exit__(self, exc_type, exc_value, traceback) -> None: self.reset() def __del__(self) -> None: try: # if this object went out of scope prior to shutting down # subscriptions, close the connection manually before # returning it to the connection pool self.reset() except Exception: pass def reset(self) -> None: if self.connection: self.connection.disconnect() self.connection.deregister_connect_callback(self.on_connect) self.connection_pool.release(self.connection) self.connection = None self.health_check_response_counter = 0 self.channels = {} self.pending_unsubscribe_channels = set() self.shard_channels = {} self.pending_unsubscribe_shard_channels = set() self.patterns = {} self.pending_unsubscribe_patterns = set() self.subscribed_event.clear() def close(self) -> None: self.reset() def on_connect(self, connection) -> None: "Re-subscribe to any channels and patterns previously subscribed to" # NOTE: for python3, we can't pass bytestrings as keyword arguments # so we need to decode channel/pattern names back to unicode strings # before passing them to [p]subscribe. self.pending_unsubscribe_channels.clear() self.pending_unsubscribe_patterns.clear() self.pending_unsubscribe_shard_channels.clear() if self.channels: channels = { self.encoder.decode(k, force=True): v for k, v in self.channels.items() } self.subscribe(**channels) if self.patterns: patterns = { self.encoder.decode(k, force=True): v for k, v in self.patterns.items() } self.psubscribe(**patterns) if self.shard_channels: shard_channels = { self.encoder.decode(k, force=True): v for k, v in self.shard_channels.items() } self.ssubscribe(**shard_channels) @property def subscribed(self) -> bool: """Indicates if there are subscriptions to any channels or patterns""" return self.subscribed_event.is_set() def execute_command(self, *args): """Execute a publish/subscribe command""" # 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: 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_pubsub_push_handler(self.push_handler_func) connection = self.connection kwargs = {"check_health": not self.subscribed} if not self.subscribed: self.clean_health_check_responses() self._execute(connection, connection.send_command, *args, **kwargs) def clean_health_check_responses(self) -> None: """ If any health check responses are present, clean them """ ttl = 10 conn = self.connection while self.health_check_response_counter > 0 and ttl > 0: if self._execute(conn, conn.can_read, timeout=conn.socket_timeout): response = self._execute(conn, conn.read_response) if self.is_health_check_response(response): self.health_check_response_counter -= 1 else: raise PubSubError( "A non health check response was cleaned by " "execute_command: {0}".format(response) ) ttl -= 1 def _disconnect_raise_connect(self, conn, error) -> None: """ Close the connection and raise an exception if retry_on_timeout is not set or the error is not a TimeoutError. Otherwise, try to reconnect """ conn.disconnect() if not (conn.retry_on_timeout and isinstance(error, TimeoutError)): raise error conn.connect() def _execute(self, conn, command, *args, **kwargs): """ Connect manually upon disconnection. If the Redis server is down, this will fail and raise a ConnectionError as desired. After reconnection, the ``on_connect`` callback should have been called by the # connection to resubscribe us to any channels and patterns we were previously listening to """ return conn.retry.call_with_retry( lambda: command(*args, **kwargs), lambda error: self._disconnect_raise_connect(conn, error), ) def parse_response(self, block=True, timeout=0): """Parse the response from a publish/subscribe command""" conn = self.connection if conn is None: raise RuntimeError( "pubsub connection not set: " "did you forget to call subscribe() or psubscribe()?" ) self.check_health() def try_read(): if not block: if not conn.can_read(timeout=timeout): return None else: conn.connect() return conn.read_response(disconnect_on_error=False, push_request=True) response = self._execute(conn, try_read) if self.is_health_check_response(response): # ignore the health check message as user might not expect it self.health_check_response_counter -= 1 return None return response def is_health_check_response(self, response) -> bool: """ Check if the response is a health check response. If there are no subscriptions redis responds to PING command with a bulk response, instead of a multi-bulk with "pong" and the response. """ return response in [ self.health_check_response, # If there was a subscription self.health_check_response_b, # If there wasn't ] def check_health(self) -> None: conn = self.connection if conn is None: raise RuntimeError( "pubsub connection not set: " "did you forget to call subscribe() or psubscribe()?" ) if conn.health_check_interval and time.time() > conn.next_health_check: conn.send_command("PING", self.HEALTH_CHECK_MESSAGE, check_health=False) self.health_check_response_counter += 1 def _normalize_keys(self, data) -> Dict: """ normalize channel/pattern names to be either bytes or strings based on whether responses are automatically decoded. this saves us from coercing the value for each message coming in. """ encode = self.encoder.encode decode = self.encoder.decode return {decode(encode(k)): v for k, v in data.items()} def psubscribe(self, *args, **kwargs): """ Subscribe to channel patterns. Patterns supplied as keyword arguments expect a pattern name as the key and a callable as the value. A pattern's callable will be invoked automatically when a message is received on that pattern rather than producing a message via ``listen()``. """ if args: args = list_or_args(args[0], args[1:]) new_patterns = dict.fromkeys(args) new_patterns.update(kwargs) ret_val = self.execute_command("PSUBSCRIBE", *new_patterns.keys()) # update the patterns dict AFTER we send the command. we don't want to # subscribe twice to these patterns, once for the command and again # for the reconnection. new_patterns = self._normalize_keys(new_patterns) self.patterns.update(new_patterns) if not self.subscribed: # Set the subscribed_event flag to True self.subscribed_event.set() # Clear the health check counter self.health_check_response_counter = 0 self.pending_unsubscribe_patterns.difference_update(new_patterns) return ret_val def punsubscribe(self, *args): """ Unsubscribe from the supplied patterns. If empty, unsubscribe from all patterns. """ if args: args = list_or_args(args[0], args[1:]) patterns = self._normalize_keys(dict.fromkeys(args)) else: patterns = self.patterns self.pending_unsubscribe_patterns.update(patterns) return self.execute_command("PUNSUBSCRIBE", *args) def subscribe(self, *args, **kwargs): """ Subscribe to channels. Channels supplied as keyword arguments expect a channel name as the key and a callable as the value. A channel's callable will be invoked automatically when a message is received on that channel rather than producing a message via ``listen()`` or ``get_message()``. """ if args: args = list_or_args(args[0], args[1:]) new_channels = dict.fromkeys(args) new_channels.update(kwargs) ret_val = self.execute_command("SUBSCRIBE", *new_channels.keys()) # update the channels dict AFTER we send the command. we don't want to # subscribe twice to these channels, once for the command and again # for the reconnection. new_channels = self._normalize_keys(new_channels) self.channels.update(new_channels) if not self.subscribed: # Set the subscribed_event flag to True self.subscribed_event.set() # Clear the health check counter self.health_check_response_counter = 0 self.pending_unsubscribe_channels.difference_update(new_channels) return ret_val def unsubscribe(self, *args): """ Unsubscribe from the supplied channels. If empty, unsubscribe from all channels """ if args: args = list_or_args(args[0], args[1:]) channels = self._normalize_keys(dict.fromkeys(args)) else: channels = self.channels self.pending_unsubscribe_channels.update(channels) return self.execute_command("UNSUBSCRIBE", *args) def ssubscribe(self, *args, target_node=None, **kwargs): """ Subscribes the client to the specified shard channels. Channels supplied as keyword arguments expect a channel name as the key and a callable as the value. A channel's callable will be invoked automatically when a message is received on that channel rather than producing a message via ``listen()`` or ``get_sharded_message()``. """ if args: args = list_or_args(args[0], args[1:]) new_s_channels = dict.fromkeys(args) new_s_channels.update(kwargs) ret_val = self.execute_command("SSUBSCRIBE", *new_s_channels.keys()) # update the s_channels dict AFTER we send the command. we don't want to # subscribe twice to these channels, once for the command and again # for the reconnection. new_s_channels = self._normalize_keys(new_s_channels) self.shard_channels.update(new_s_channels) if not self.subscribed: # Set the subscribed_event flag to True self.subscribed_event.set() # Clear the health check counter self.health_check_response_counter = 0 self.pending_unsubscribe_shard_channels.difference_update(new_s_channels) return ret_val def sunsubscribe(self, *args, target_node=None): """ Unsubscribe from the supplied shard_channels. If empty, unsubscribe from all shard_channels """ if args: args = list_or_args(args[0], args[1:]) s_channels = self._normalize_keys(dict.fromkeys(args)) else: s_channels = self.shard_channels self.pending_unsubscribe_shard_channels.update(s_channels) return self.execute_command("SUNSUBSCRIBE", *args) def listen(self): "Listen for messages on channels this client has been subscribed to" while self.subscribed: response = self.handle_message(self.parse_response(block=True)) if response is not None: yield response def get_message( self, ignore_subscribe_messages: bool = False, timeout: float = 0.0 ): """ Get the next message if one is available, otherwise None. If timeout is specified, the system will wait for `timeout` seconds before returning. Timeout should be specified as a floating point number, or None, to wait indefinitely. """ if not self.subscribed: # Wait for subscription start_time = time.time() if self.subscribed_event.wait(timeout) is True: # The connection was subscribed during the timeout time frame. # The timeout should be adjusted based on the time spent # waiting for the subscription time_spent = time.time() - start_time timeout = max(0.0, timeout - time_spent) else: # The connection isn't subscribed to any channels or patterns, # so no messages are available return None response = self.parse_response(block=(timeout is None), timeout=timeout) if response: return self.handle_message(response, ignore_subscribe_messages) return None get_sharded_message = get_message def ping(self, message: Union[str, None] = None) -> bool: """ Ping the Redis server """ args = ["PING", message] if message is not None else ["PING"] return self.execute_command(*args) def handle_message(self, response, ignore_subscribe_messages=False): """ Parses a pub/sub message. If the channel or pattern was subscribed to with a message handler, the handler is invoked instead of a parsed message being returned. """ if response is None: return None if isinstance(response, bytes): response = [b"pong", response] if response != b"PONG" else [b"pong", b""] message_type = str_if_bytes(response[0]) if message_type == "pmessage": message = { "type": message_type, "pattern": response[1], "channel": response[2], "data": response[3], } elif message_type == "pong": message = { "type": message_type, "pattern": None, "channel": None, "data": response[1], } else: message = { "type": message_type, "pattern": None, "channel": response[1], "data": response[2], } # if this is an unsubscribe message, remove it from memory if message_type in self.UNSUBSCRIBE_MESSAGE_TYPES: if message_type == "punsubscribe": pattern = response[1] if pattern in self.pending_unsubscribe_patterns: self.pending_unsubscribe_patterns.remove(pattern) self.patterns.pop(pattern, None) elif message_type == "sunsubscribe": s_channel = response[1] if s_channel in self.pending_unsubscribe_shard_channels: self.pending_unsubscribe_shard_channels.remove(s_channel) self.shard_channels.pop(s_channel, None) else: channel = response[1] if channel in self.pending_unsubscribe_channels: self.pending_unsubscribe_channels.remove(channel) self.channels.pop(channel, None) 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 message_type in self.PUBLISH_MESSAGE_TYPES: # if there's a message handler, invoke it if message_type == "pmessage": handler = self.patterns.get(message["pattern"], None) elif message_type == "smessage": handler = self.shard_channels.get(message["channel"], None) else: handler = self.channels.get(message["channel"], None) if handler: handler(message) return None elif message_type != "pong": # this is a subscribe/unsubscribe message. ignore if we don't # want them if ignore_subscribe_messages or self.ignore_subscribe_messages: return None return message def run_in_thread( self, sleep_time: float = 0.0, daemon: bool = False, exception_handler: Optional[Callable] = None, ) -> "PubSubWorkerThread": for channel, handler in self.channels.items(): if handler is None: raise PubSubError(f"Channel: '{channel}' has no handler registered") for pattern, handler in self.patterns.items(): if handler is None: raise PubSubError(f"Pattern: '{pattern}' has no handler registered") for s_channel, handler in self.shard_channels.items(): if handler is None: raise PubSubError( f"Shard Channel: '{s_channel}' has no handler registered" ) thread = PubSubWorkerThread( self, sleep_time, daemon=daemon, exception_handler=exception_handler ) thread.start() return thread class PubSubWorkerThread(threading.Thread): def __init__( self, pubsub, sleep_time: float, daemon: bool = False, exception_handler: Union[ Callable[[Exception, "PubSub", "PubSubWorkerThread"], None], None ] = None, ): super().__init__() self.daemon = daemon self.pubsub = pubsub self.sleep_time = sleep_time self.exception_handler = exception_handler self._running = threading.Event() def run(self) -> None: if self._running.is_set(): return self._running.set() pubsub = self.pubsub sleep_time = self.sleep_time while self._running.is_set(): try: pubsub.get_message(ignore_subscribe_messages=True, timeout=sleep_time) except BaseException as e: if self.exception_handler is None: raise self.exception_handler(e, pubsub, self) pubsub.close() def stop(self) -> None: # trip the flag so the run loop exits. the run loop will # close the pubsub connection, which disconnects the socket # and returns the connection to the pool. self._running.clear() class Pipeline(Redis): """ Pipelines provide a way to transmit multiple commands to the Redis server in one transmission. This is convenient for batch processing, such as saving all the values in a list to Redis. All commands executed within a pipeline are wrapped with MULTI and EXEC calls. This guarantees all commands executed in the pipeline will be executed atomically. Any command raising an exception does *not* halt the execution of subsequent commands in the pipeline. Instead, the exception is caught and its instance is placed into the response list returned by execute(). Code iterating over the response list should be able to deal with an instance of an exception as a potential value. In general, these will be ResponseError exceptions, such as those raised when issuing a command on a key of a different datatype. """ UNWATCH_COMMANDS = {"DISCARD", "EXEC", "UNWATCH"} def __init__(self, connection_pool, response_callbacks, transaction, shard_hint): self.connection_pool = connection_pool self.connection = None self.response_callbacks = response_callbacks self.transaction = transaction self.shard_hint = shard_hint self.watching = False self.reset() def __enter__(self) -> "Pipeline": return self def __exit__(self, exc_type, exc_value, traceback): self.reset() def __del__(self): try: self.reset() except Exception: pass def __len__(self) -> int: return len(self.command_stack) def __bool__(self) -> bool: """Pipeline instances should always evaluate to True""" return True def reset(self) -> None: self.command_stack = [] self.scripts = set() # 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 # 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 close(self) -> None: """Close the pipeline""" self.reset() def multi(self) -> None: """ Start a transactional block of the pipeline after WATCH commands are issued. End the transactional block with `execute`. """ if self.explicit_transaction: raise RedisError("Cannot issue nested calls to MULTI") if self.command_stack: raise RedisError( "Commands without an initial WATCH have already been issued" ) self.explicit_transaction = True def execute_command(self, *args, **kwargs): kwargs.pop("keys", None) # the keys are used only for client side caching if (self.watching or args[0] == "WATCH") and not self.explicit_transaction: return self.immediate_execute_command(*args, **kwargs) return self.pipeline_execute_command(*args, **kwargs) def _disconnect_reset_raise(self, conn, error) -> None: """ Close the connection, reset watching state and raise an exception if we were watching, retry_on_timeout is not set, or the error is not a TimeoutError """ conn.disconnect() # if we were already watching a variable, the watch is no longer # valid since this connection has died. raise a WatchError, which # indicates the user should retry this transaction. if self.watching: self.reset() raise WatchError( "A ConnectionError occurred on while watching one or more keys" ) # if retry_on_timeout is not set, or the error is not # a TimeoutError, raise it if not (conn.retry_on_timeout and isinstance(error, TimeoutError)): self.reset() raise def immediate_execute_command(self, *args, **options): """ Execute a command immediately, but don't auto-retry on a ConnectionError if we're already WATCHing a variable. Used when issuing WATCH or subsequent commands retrieving their values but before MULTI is called. """ command_name = args[0] conn = self.connection # if this is the first call, we need a connection if not conn: conn = self.connection_pool.get_connection(command_name, self.shard_hint) self.connection = conn return conn.retry.call_with_retry( lambda: self._send_command_parse_response( conn, command_name, *args, **options ), lambda error: self._disconnect_reset_raise(conn, error), ) def pipeline_execute_command(self, *args, **options) -> "Pipeline": """ Stage a command to be executed when execute() is next called Returns the current Pipeline object back so commands can be chained together, such as: pipe = pipe.set('foo', 'bar').incr('baz').decr('bang') At some other point, you can then run: pipe.execute(), which will execute all commands queued in the pipe. """ self.command_stack.append((args, options)) return self def _execute_transaction(self, connection, commands, raise_on_error) -> List: cmds = chain([(("MULTI",), {})], commands, [(("EXEC",), {})]) all_cmds = connection.pack_commands( [args for args, options in cmds if EMPTY_RESPONSE not in options] ) connection.send_packed_command(all_cmds) errors = [] # parse off the response for MULTI # NOTE: we need to handle ResponseErrors here and continue # so that we read all the additional command messages from # the socket try: self.parse_response(connection, "_") except ResponseError as e: errors.append((0, e)) # and all the other commands for i, command in enumerate(commands): if EMPTY_RESPONSE in command[1]: errors.append((i, command[1][EMPTY_RESPONSE])) else: try: self.parse_response(connection, "_") except ResponseError as e: self.annotate_exception(e, i + 1, command[0]) errors.append((i, e)) # parse the EXEC. try: response = self.parse_response(connection, "_") except ExecAbortError: if errors: raise errors[0][1] raise # EXEC clears any watched keys self.watching = False if response is None: raise WatchError("Watched variable changed.") # put any parse errors into the response for i, e in errors: response.insert(i, e) if len(response) != len(commands): self.connection.disconnect() raise ResponseError( "Wrong number of response items from pipeline execution" ) # find any errors in the response and raise if necessary if raise_on_error: self.raise_first_error(commands, response) # We have to run response callbacks manually data = [] for r, cmd in zip(response, commands): if not isinstance(r, Exception): args, options = cmd command_name = args[0] if command_name in self.response_callbacks: r = self.response_callbacks[command_name](r, **options) data.append(r) return data def _execute_pipeline(self, connection, commands, raise_on_error): # build up all commands into a single request to increase network perf all_cmds = connection.pack_commands([args for args, _ in commands]) connection.send_packed_command(all_cmds) response = [] for args, options in commands: try: response.append(self.parse_response(connection, args[0], **options)) except ResponseError as e: response.append(e) if raise_on_error: self.raise_first_error(commands, response) return response def raise_first_error(self, commands, response): for i, r in enumerate(response): if isinstance(r, ResponseError): self.annotate_exception(r, i + 1, commands[i][0]) raise r def annotate_exception(self, exception, number, command): 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 parse_response(self, connection, command_name, **options): result = Redis.parse_response(self, connection, command_name, **options) if command_name in self.UNWATCH_COMMANDS: self.watching = False elif command_name == "WATCH": self.watching = True return result def load_scripts(self): # make sure all scripts that are about to be run on this pipeline exist scripts = list(self.scripts) immediate = self.immediate_execute_command shas = [s.sha for s in scripts] # we can't use the normal script_* methods because they would just # get buffered in the pipeline. exists = immediate("SCRIPT EXISTS", *shas) if not all(exists): for s, exist in zip(scripts, exists): if not exist: s.sha = immediate("SCRIPT LOAD", s.script) def _disconnect_raise_reset(self, conn: Redis, error: Exception) -> None: """ Close the connection, raise an exception if we were watching, and raise an exception if TimeoutError is not part of retry_on_error, or the error is not a TimeoutError """ conn.disconnect() # if we were watching a variable, the watch is no longer valid # since this connection has died. raise a WatchError, which # indicates the user should retry this transaction. if self.watching: raise WatchError( "A ConnectionError occurred on while watching one or more keys" ) # if TimeoutError is not part of retry_on_error, or the error # is not a TimeoutError, raise it if not ( TimeoutError in conn.retry_on_error and isinstance(error, TimeoutError) ): self.reset() raise error def execute(self, raise_on_error=True): """Execute all the commands in the current pipeline""" stack = self.command_stack if not stack and not self.watching: return [] if self.scripts: self.load_scripts() if self.transaction or self.explicit_transaction: execute = self._execute_transaction else: execute = self._execute_pipeline conn = self.connection if not conn: conn = self.connection_pool.get_connection("MULTI", self.shard_hint) # assign to self.connection so reset() releases the connection # back to the pool after we're done self.connection = conn try: return conn.retry.call_with_retry( lambda: execute(conn, stack, raise_on_error), lambda error: self._disconnect_raise_reset(conn, error), ) finally: self.reset() def discard(self): """ Flushes all previously queued commands See: """ self.execute_command("DISCARD") def watch(self, *names): """Watches the values at keys ``names``""" if self.explicit_transaction: raise RedisError("Cannot issue a WATCH after a MULTI") return self.execute_command("WATCH", *names) def unwatch(self) -> bool: """Unwatches all previously specified keys""" return self.watching and self.execute_command("UNWATCH") or True