import copy import os import socket import sys import threading import time import weakref from abc import ABC, abstractmethod from itertools import chain from queue import Empty, Full, LifoQueue from typing import ( Any, Callable, Dict, Iterable, List, Literal, Optional, Type, TypeVar, Union, ) from urllib.parse import parse_qs, unquote, urlparse from redis.cache import ( CacheEntry, CacheEntryStatus, CacheFactory, CacheFactoryInterface, CacheInterface, CacheKey, ) from ._parsers import Encoder, _HiredisParser, _RESP2Parser, _RESP3Parser from .auth.token import TokenInterface from .backoff import NoBackoff from .credentials import CredentialProvider, UsernamePasswordCredentialProvider from .event import AfterConnectionReleasedEvent, EventDispatcher from .exceptions import ( AuthenticationError, AuthenticationWrongNumberOfArgsError, ChildDeadlockedError, ConnectionError, DataError, MaxConnectionsError, RedisError, ResponseError, TimeoutError, ) from .maint_notifications import ( MaintenanceState, MaintNotificationsConfig, MaintNotificationsConnectionHandler, MaintNotificationsPoolHandler, ) from .retry import Retry from .utils import ( CRYPTOGRAPHY_AVAILABLE, HIREDIS_AVAILABLE, SSL_AVAILABLE, compare_versions, deprecated_args, ensure_string, format_error_message, get_lib_version, str_if_bytes, ) if SSL_AVAILABLE: import ssl from ssl import VerifyFlags else: ssl = None VerifyFlags = None if HIREDIS_AVAILABLE: import hiredis SYM_STAR = b"*" SYM_DOLLAR = b"$" SYM_CRLF = b"\r\n" SYM_EMPTY = b"" DEFAULT_RESP_VERSION = 2 SENTINEL = object() DefaultParser: Type[Union[_RESP2Parser, _RESP3Parser, _HiredisParser]] if HIREDIS_AVAILABLE: DefaultParser = _HiredisParser else: DefaultParser = _RESP2Parser class HiredisRespSerializer: def pack(self, *args: List): """Pack a series of arguments into the Redis protocol""" output = [] if isinstance(args[0], str): args = tuple(args[0].encode().split()) + args[1:] elif b" " in args[0]: args = tuple(args[0].split()) + args[1:] try: output.append(hiredis.pack_command(args)) except TypeError: _, value, traceback = sys.exc_info() raise DataError(value).with_traceback(traceback) return output class PythonRespSerializer: def __init__(self, buffer_cutoff, encode) -> None: self._buffer_cutoff = buffer_cutoff self.encode = encode def pack(self, *args): """Pack a series of arguments into the Redis protocol""" output = [] # the client might have included 1 or more literal arguments in # the command name, e.g., 'CONFIG GET'. The Redis server expects these # arguments to be sent separately, so split the first argument # manually. These arguments should be bytestrings so that they are # not encoded. if isinstance(args[0], str): args = tuple(args[0].encode().split()) + args[1:] elif b" " in args[0]: args = tuple(args[0].split()) + args[1:] buff = SYM_EMPTY.join((SYM_STAR, str(len(args)).encode(), SYM_CRLF)) buffer_cutoff = self._buffer_cutoff for arg in map(self.encode, args): # to avoid large string mallocs, chunk the command into the # output list if we're sending large values or memoryviews arg_length = len(arg) if ( len(buff) > buffer_cutoff or arg_length > buffer_cutoff or isinstance(arg, memoryview) ): buff = SYM_EMPTY.join( (buff, SYM_DOLLAR, str(arg_length).encode(), SYM_CRLF) ) output.append(buff) output.append(arg) buff = SYM_CRLF else: buff = SYM_EMPTY.join( ( buff, SYM_DOLLAR, str(arg_length).encode(), SYM_CRLF, arg, SYM_CRLF, ) ) output.append(buff) return output class ConnectionInterface: @abstractmethod def repr_pieces(self): pass @abstractmethod def register_connect_callback(self, callback): pass @abstractmethod def deregister_connect_callback(self, callback): pass @abstractmethod def set_parser(self, parser_class): pass @abstractmethod def get_protocol(self): pass @abstractmethod def connect(self): pass @abstractmethod def on_connect(self): pass @abstractmethod def disconnect(self, *args): pass @abstractmethod def check_health(self): pass @abstractmethod def send_packed_command(self, command, check_health=True): pass @abstractmethod def send_command(self, *args, **kwargs): pass @abstractmethod def can_read(self, timeout=0): pass @abstractmethod def read_response( self, disable_decoding=False, *, disconnect_on_error=True, push_request=False, ): pass @abstractmethod def pack_command(self, *args): pass @abstractmethod def pack_commands(self, commands): pass @property @abstractmethod def handshake_metadata(self) -> Union[Dict[bytes, bytes], Dict[str, str]]: pass @abstractmethod def set_re_auth_token(self, token: TokenInterface): pass @abstractmethod def re_auth(self): pass @abstractmethod def mark_for_reconnect(self): """ Mark the connection to be reconnected on the next command. This is useful when a connection is moved to a different node. """ pass @abstractmethod def should_reconnect(self): """ Returns True if the connection should be reconnected. """ pass @abstractmethod def reset_should_reconnect(self): """ Reset the internal flag to False. """ pass class MaintNotificationsAbstractConnection: """ Abstract class for handling maintenance notifications logic. This class is expected to be used as base class together with ConnectionInterface. This class is intended to be used with multiple inheritance! All logic related to maintenance notifications is encapsulated in this class. """ def __init__( self, maint_notifications_config: Optional[MaintNotificationsConfig], maint_notifications_pool_handler: Optional[ MaintNotificationsPoolHandler ] = None, maintenance_state: "MaintenanceState" = MaintenanceState.NONE, maintenance_notification_hash: Optional[int] = None, orig_host_address: Optional[str] = None, orig_socket_timeout: Optional[float] = None, orig_socket_connect_timeout: Optional[float] = None, parser: Optional[Union[_HiredisParser, _RESP3Parser]] = None, ): """ Initialize the maintenance notifications for the connection. Args: maint_notifications_config (MaintNotificationsConfig): The configuration for maintenance notifications. maint_notifications_pool_handler (Optional[MaintNotificationsPoolHandler]): The pool handler for maintenance notifications. maintenance_state (MaintenanceState): The current maintenance state of the connection. maintenance_notification_hash (Optional[int]): The current maintenance notification hash of the connection. orig_host_address (Optional[str]): The original host address of the connection. orig_socket_timeout (Optional[float]): The original socket timeout of the connection. orig_socket_connect_timeout (Optional[float]): The original socket connect timeout of the connection. parser (Optional[Union[_HiredisParser, _RESP3Parser]]): The parser to use for maintenance notifications. If not provided, the parser from the connection is used. This is useful when the parser is created after this object. """ self.maint_notifications_config = maint_notifications_config self.maintenance_state = maintenance_state self.maintenance_notification_hash = maintenance_notification_hash self._configure_maintenance_notifications( maint_notifications_pool_handler, orig_host_address, orig_socket_timeout, orig_socket_connect_timeout, parser, ) @abstractmethod def _get_parser(self) -> Union[_HiredisParser, _RESP3Parser]: pass @abstractmethod def _get_socket(self) -> Optional[socket.socket]: pass @abstractmethod def get_protocol(self) -> Union[int, str]: """ Returns: The RESP protocol version, or ``None`` if the protocol is not specified, in which case the server default will be used. """ pass @property @abstractmethod def host(self) -> str: pass @host.setter @abstractmethod def host(self, value: str): pass @property @abstractmethod def socket_timeout(self) -> Optional[Union[float, int]]: pass @socket_timeout.setter @abstractmethod def socket_timeout(self, value: Optional[Union[float, int]]): pass @property @abstractmethod def socket_connect_timeout(self) -> Optional[Union[float, int]]: pass @socket_connect_timeout.setter @abstractmethod def socket_connect_timeout(self, value: Optional[Union[float, int]]): pass @abstractmethod def send_command(self, *args, **kwargs): pass @abstractmethod def read_response( self, disable_decoding=False, *, disconnect_on_error=True, push_request=False, ): pass @abstractmethod def disconnect(self, *args): pass def _configure_maintenance_notifications( self, maint_notifications_pool_handler: Optional[ MaintNotificationsPoolHandler ] = None, orig_host_address=None, orig_socket_timeout=None, orig_socket_connect_timeout=None, parser: Optional[Union[_HiredisParser, _RESP3Parser]] = None, ): """ Enable maintenance notifications by setting up handlers and storing original connection parameters. Should be used ONLY with parsers that support push notifications. """ if ( not self.maint_notifications_config or not self.maint_notifications_config.enabled ): self._maint_notifications_pool_handler = None self._maint_notifications_connection_handler = None return if not parser: raise RedisError( "To configure maintenance notifications, a parser must be provided!" ) if not isinstance(parser, _HiredisParser) and not isinstance( parser, _RESP3Parser ): raise RedisError( "Maintenance notifications are only supported with hiredis and RESP3 parsers!" ) if maint_notifications_pool_handler: # Extract a reference to a new pool handler that copies all properties # of the original one and has a different connection reference # This is needed because when we attach the handler to the parser # we need to make sure that the handler has a reference to the # connection that the parser is attached to. self._maint_notifications_pool_handler = ( maint_notifications_pool_handler.get_handler_for_connection() ) self._maint_notifications_pool_handler.set_connection(self) else: self._maint_notifications_pool_handler = None self._maint_notifications_connection_handler = ( MaintNotificationsConnectionHandler(self, self.maint_notifications_config) ) # Set up pool handler if available if self._maint_notifications_pool_handler: parser.set_node_moving_push_handler( self._maint_notifications_pool_handler.handle_notification ) # Set up connection handler parser.set_maintenance_push_handler( self._maint_notifications_connection_handler.handle_notification ) # Store original connection parameters self.orig_host_address = orig_host_address if orig_host_address else self.host self.orig_socket_timeout = ( orig_socket_timeout if orig_socket_timeout else self.socket_timeout ) self.orig_socket_connect_timeout = ( orig_socket_connect_timeout if orig_socket_connect_timeout else self.socket_connect_timeout ) def set_maint_notifications_pool_handler_for_connection( self, maint_notifications_pool_handler: MaintNotificationsPoolHandler ): # Deep copy the pool handler to avoid sharing the same pool handler # between multiple connections, because otherwise each connection will override # the connection reference and the pool handler will only hold a reference # to the last connection that was set. maint_notifications_pool_handler_copy = ( maint_notifications_pool_handler.get_handler_for_connection() ) maint_notifications_pool_handler_copy.set_connection(self) self._get_parser().set_node_moving_push_handler( maint_notifications_pool_handler_copy.handle_notification ) self._maint_notifications_pool_handler = maint_notifications_pool_handler_copy # Update maintenance notification connection handler if it doesn't exist if not self._maint_notifications_connection_handler: self._maint_notifications_connection_handler = ( MaintNotificationsConnectionHandler( self, maint_notifications_pool_handler.config ) ) self._get_parser().set_maintenance_push_handler( self._maint_notifications_connection_handler.handle_notification ) else: self._maint_notifications_connection_handler.config = ( maint_notifications_pool_handler.config ) def activate_maint_notifications_handling_if_enabled(self, check_health=True): # Send maintenance notifications handshake if RESP3 is active # and maintenance notifications are enabled # and we have a host to determine the endpoint type from # When the maint_notifications_config enabled mode is "auto", # we just log a warning if the handshake fails # When the mode is enabled=True, we raise an exception in case of failure if ( self.get_protocol() not in [2, "2"] and self.maint_notifications_config and self.maint_notifications_config.enabled and self._maint_notifications_connection_handler and hasattr(self, "host") ): self._enable_maintenance_notifications( maint_notifications_config=self.maint_notifications_config, check_health=check_health, ) def _enable_maintenance_notifications( self, maint_notifications_config: MaintNotificationsConfig, check_health=True ): try: host = getattr(self, "host", None) if host is None: raise ValueError( "Cannot enable maintenance notifications for connection" " object that doesn't have a host attribute." ) else: endpoint_type = maint_notifications_config.get_endpoint_type(host, self) self.send_command( "CLIENT", "MAINT_NOTIFICATIONS", "ON", "moving-endpoint-type", endpoint_type.value, check_health=check_health, ) response = self.read_response() if not response or str_if_bytes(response) != "OK": raise ResponseError( "The server doesn't support maintenance notifications" ) except Exception as e: if ( isinstance(e, ResponseError) and maint_notifications_config.enabled == "auto" ): # Log warning but don't fail the connection import logging logger = logging.getLogger(__name__) logger.warning(f"Failed to enable maintenance notifications: {e}") else: raise def get_resolved_ip(self) -> Optional[str]: """ Extract the resolved IP address from an established connection or resolve it from the host. First tries to get the actual IP from the socket (most accurate), then falls back to DNS resolution if needed. Args: connection: The connection object to extract the IP from Returns: str: The resolved IP address, or None if it cannot be determined """ # Method 1: Try to get the actual IP from the established socket connection # This is most accurate as it shows the exact IP being used try: conn_socket = self._get_socket() if conn_socket is not None: peer_addr = conn_socket.getpeername() if peer_addr and len(peer_addr) >= 1: # For TCP sockets, peer_addr is typically (host, port) tuple # Return just the host part return peer_addr[0] except (AttributeError, OSError): # Socket might not be connected or getpeername() might fail pass # Method 2: Fallback to DNS resolution of the host # This is less accurate but works when socket is not available try: host = getattr(self, "host", "localhost") port = getattr(self, "port", 6379) if host: # Use getaddrinfo to resolve the hostname to IP # This mimics what the connection would do during _connect() addr_info = socket.getaddrinfo( host, port, socket.AF_UNSPEC, socket.SOCK_STREAM ) if addr_info: # Return the IP from the first result # addr_info[0] is (family, socktype, proto, canonname, sockaddr) # sockaddr[0] is the IP address return str(addr_info[0][4][0]) except (AttributeError, OSError, socket.gaierror): # DNS resolution might fail pass return None @property def maintenance_state(self) -> MaintenanceState: return self._maintenance_state @maintenance_state.setter def maintenance_state(self, state: "MaintenanceState"): self._maintenance_state = state def getpeername(self): """ Returns the peer name of the connection. """ conn_socket = self._get_socket() if conn_socket: return conn_socket.getpeername()[0] return None def update_current_socket_timeout(self, relaxed_timeout: Optional[float] = None): conn_socket = self._get_socket() if conn_socket: timeout = relaxed_timeout if relaxed_timeout != -1 else self.socket_timeout conn_socket.settimeout(timeout) self.update_parser_timeout(timeout) def update_parser_timeout(self, timeout: Optional[float] = None): parser = self._get_parser() if parser and parser._buffer: if isinstance(parser, _RESP3Parser) and timeout: parser._buffer.socket_timeout = timeout elif isinstance(parser, _HiredisParser): parser._socket_timeout = timeout def set_tmp_settings( self, tmp_host_address: Optional[Union[str, object]] = SENTINEL, tmp_relaxed_timeout: Optional[float] = None, ): """ The value of SENTINEL is used to indicate that the property should not be updated. """ if tmp_host_address and tmp_host_address != SENTINEL: self.host = str(tmp_host_address) if tmp_relaxed_timeout != -1: self.socket_timeout = tmp_relaxed_timeout self.socket_connect_timeout = tmp_relaxed_timeout def reset_tmp_settings( self, reset_host_address: bool = False, reset_relaxed_timeout: bool = False, ): if reset_host_address: self.host = self.orig_host_address if reset_relaxed_timeout: self.socket_timeout = self.orig_socket_timeout self.socket_connect_timeout = self.orig_socket_connect_timeout class AbstractConnection(MaintNotificationsAbstractConnection, ConnectionInterface): "Manages communication to and from a Redis server" def __init__( self, db: int = 0, password: Optional[str] = None, socket_timeout: Optional[float] = None, socket_connect_timeout: Optional[float] = None, retry_on_timeout: bool = False, retry_on_error: Union[Iterable[Type[Exception]], object] = SENTINEL, encoding: str = "utf-8", encoding_errors: str = "strict", decode_responses: bool = False, parser_class=DefaultParser, socket_read_size: int = 65536, health_check_interval: int = 0, client_name: Optional[str] = None, lib_name: Optional[str] = "redis-py", lib_version: Optional[str] = get_lib_version(), username: Optional[str] = None, retry: Union[Any, None] = None, redis_connect_func: Optional[Callable[[], None]] = None, credential_provider: Optional[CredentialProvider] = None, protocol: Optional[int] = 2, command_packer: Optional[Callable[[], None]] = None, event_dispatcher: Optional[EventDispatcher] = None, maint_notifications_config: Optional[MaintNotificationsConfig] = None, maint_notifications_pool_handler: Optional[ MaintNotificationsPoolHandler ] = None, maintenance_state: "MaintenanceState" = MaintenanceState.NONE, maintenance_notification_hash: Optional[int] = None, orig_host_address: Optional[str] = None, orig_socket_timeout: Optional[float] = None, orig_socket_connect_timeout: Optional[float] = None, ): """ Initialize a new Connection. 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`. """ if (username or password) and credential_provider is not None: raise DataError( "'username' and 'password' cannot be passed along with 'credential_" "provider'. Please provide only one of the following arguments: \n" "1. 'password' and (optional) 'username'\n" "2. 'credential_provider'" ) if event_dispatcher is None: self._event_dispatcher = EventDispatcher() else: self._event_dispatcher = event_dispatcher self.pid = os.getpid() self.db = db self.client_name = client_name self.lib_name = lib_name self.lib_version = lib_version self.credential_provider = credential_provider self.password = password self.username = username self._socket_timeout = socket_timeout if socket_connect_timeout is None: socket_connect_timeout = socket_timeout self._socket_connect_timeout = socket_connect_timeout self.retry_on_timeout = retry_on_timeout if retry_on_error is SENTINEL: retry_on_errors_list = [] else: retry_on_errors_list = list(retry_on_error) if retry_on_timeout: # Add TimeoutError to the errors list to retry on retry_on_errors_list.append(TimeoutError) self.retry_on_error = retry_on_errors_list if retry or self.retry_on_error: if retry is None: self.retry = Retry(NoBackoff(), 1) else: # deep-copy the Retry object as it is mutable self.retry = copy.deepcopy(retry) if self.retry_on_error: # Update the retry's supported errors with the specified errors self.retry.update_supported_errors(self.retry_on_error) else: self.retry = Retry(NoBackoff(), 0) self.health_check_interval = health_check_interval self.next_health_check = 0 self.redis_connect_func = redis_connect_func self.encoder = Encoder(encoding, encoding_errors, decode_responses) self.handshake_metadata = None self._sock = None self._socket_read_size = socket_read_size self._connect_callbacks = [] self._buffer_cutoff = 6000 self._re_auth_token: Optional[TokenInterface] = None try: p = int(protocol) except TypeError: p = DEFAULT_RESP_VERSION except ValueError: raise ConnectionError("protocol must be an integer") finally: if p < 2 or p > 3: raise ConnectionError("protocol must be either 2 or 3") # p = DEFAULT_RESP_VERSION self.protocol = p if self.protocol == 3 and parser_class == _RESP2Parser: # If the protocol is 3 but the parser is RESP2, change it to RESP3 # This is needed because the parser might be set before the protocol # or might be provided as a kwarg to the constructor # We need to react on discrepancy only for RESP2 and RESP3 # as hiredis supports both parser_class = _RESP3Parser self.set_parser(parser_class) self._command_packer = self._construct_command_packer(command_packer) self._should_reconnect = False # Set up maintenance notifications MaintNotificationsAbstractConnection.__init__( self, maint_notifications_config, maint_notifications_pool_handler, maintenance_state, maintenance_notification_hash, orig_host_address, orig_socket_timeout, orig_socket_connect_timeout, self._parser, ) def __repr__(self): repr_args = ",".join([f"{k}={v}" for k, v in self.repr_pieces()]) return f"<{self.__class__.__module__}.{self.__class__.__name__}({repr_args})>" @abstractmethod def repr_pieces(self): pass def __del__(self): try: self.disconnect() except Exception: pass def _construct_command_packer(self, packer): if packer is not None: return packer elif HIREDIS_AVAILABLE: return HiredisRespSerializer() else: return PythonRespSerializer(self._buffer_cutoff, self.encoder.encode) def register_connect_callback(self, callback): """ Register a callback to be called when the connection is established either initially or reconnected. This allows listeners to issue commands that are ephemeral to the connection, for example pub/sub subscription or key tracking. The callback must be a _method_ and will be kept as a weak reference. """ wm = weakref.WeakMethod(callback) if wm not in self._connect_callbacks: self._connect_callbacks.append(wm) def deregister_connect_callback(self, callback): """ De-register a previously registered callback. It will no-longer receive notifications on connection events. Calling this is not required when the listener goes away, since the callbacks are kept as weak methods. """ try: self._connect_callbacks.remove(weakref.WeakMethod(callback)) except ValueError: pass def set_parser(self, parser_class): """ Creates a new instance of parser_class with socket size: _socket_read_size and assigns it to the parser for the connection :param parser_class: The required parser class """ self._parser = parser_class(socket_read_size=self._socket_read_size) def _get_parser(self) -> Union[_HiredisParser, _RESP3Parser, _RESP2Parser]: return self._parser def connect(self): "Connects to the Redis server if not already connected" self.connect_check_health(check_health=True) def connect_check_health( self, check_health: bool = True, retry_socket_connect: bool = True ): if self._sock: return try: if retry_socket_connect: sock = self.retry.call_with_retry( lambda: self._connect(), lambda error: self.disconnect(error) ) else: sock = self._connect() except socket.timeout: raise TimeoutError("Timeout connecting to server") except OSError as e: raise ConnectionError(self._error_message(e)) self._sock = sock try: if self.redis_connect_func is None: # Use the default on_connect function self.on_connect_check_health(check_health=check_health) else: # Use the passed function redis_connect_func self.redis_connect_func(self) except RedisError: # clean up after any error in on_connect self.disconnect() raise # run any user callbacks. right now the only internal callback # is for pubsub channel/pattern resubscription # first, remove any dead weakrefs self._connect_callbacks = [ref for ref in self._connect_callbacks if ref()] for ref in self._connect_callbacks: callback = ref() if callback: callback(self) @abstractmethod def _connect(self): pass @abstractmethod def _host_error(self): pass def _error_message(self, exception): return format_error_message(self._host_error(), exception) def on_connect(self): self.on_connect_check_health(check_health=True) def on_connect_check_health(self, check_health: bool = True): "Initialize the connection, authenticate and select a database" self._parser.on_connect(self) parser = self._parser auth_args = None # if credential provider or username and/or password are set, authenticate if self.credential_provider or (self.username or self.password): cred_provider = ( self.credential_provider or UsernamePasswordCredentialProvider(self.username, self.password) ) auth_args = cred_provider.get_credentials() # if resp version is specified and we have auth args, # we need to send them via HELLO if auth_args and self.protocol not in [2, "2"]: if isinstance(self._parser, _RESP2Parser): self.set_parser(_RESP3Parser) # update cluster exception classes self._parser.EXCEPTION_CLASSES = parser.EXCEPTION_CLASSES self._parser.on_connect(self) if len(auth_args) == 1: auth_args = ["default", auth_args[0]] # avoid checking health here -- PING will fail if we try # to check the health prior to the AUTH self.send_command( "HELLO", self.protocol, "AUTH", *auth_args, check_health=False ) self.handshake_metadata = self.read_response() # if response.get(b"proto") != self.protocol and response.get( # "proto" # ) != self.protocol: # raise ConnectionError("Invalid RESP version") elif auth_args: # avoid checking health here -- PING will fail if we try # to check the health prior to the AUTH self.send_command("AUTH", *auth_args, check_health=False) try: auth_response = self.read_response() except AuthenticationWrongNumberOfArgsError: # a username and password were specified but the Redis # server seems to be < 6.0.0 which expects a single password # arg. retry auth with just the password. # https://github.com/andymccurdy/redis-py/issues/1274 self.send_command("AUTH", auth_args[-1], check_health=False) auth_response = self.read_response() if str_if_bytes(auth_response) != "OK": raise AuthenticationError("Invalid Username or Password") # if resp version is specified, switch to it elif self.protocol not in [2, "2"]: if isinstance(self._parser, _RESP2Parser): self.set_parser(_RESP3Parser) # update cluster exception classes self._parser.EXCEPTION_CLASSES = parser.EXCEPTION_CLASSES self._parser.on_connect(self) self.send_command("HELLO", self.protocol, check_health=check_health) self.handshake_metadata = self.read_response() if ( self.handshake_metadata.get(b"proto") != self.protocol and self.handshake_metadata.get("proto") != self.protocol ): raise ConnectionError("Invalid RESP version") # Activate maintenance notifications for this connection # if enabled in the configuration # This is a no-op if maintenance notifications are not enabled self.activate_maint_notifications_handling_if_enabled(check_health=check_health) # if a client_name is given, set it if self.client_name: self.send_command( "CLIENT", "SETNAME", self.client_name, check_health=check_health, ) if str_if_bytes(self.read_response()) != "OK": raise ConnectionError("Error setting client name") try: # set the library name and version if self.lib_name: self.send_command( "CLIENT", "SETINFO", "LIB-NAME", self.lib_name, check_health=check_health, ) self.read_response() except ResponseError: pass try: if self.lib_version: self.send_command( "CLIENT", "SETINFO", "LIB-VER", self.lib_version, check_health=check_health, ) self.read_response() except ResponseError: pass # if a database is specified, switch to it if self.db: self.send_command("SELECT", self.db, check_health=check_health) if str_if_bytes(self.read_response()) != "OK": raise ConnectionError("Invalid Database") def disconnect(self, *args): "Disconnects from the Redis server" self._parser.on_disconnect() conn_sock = self._sock self._sock = None # reset the reconnect flag self.reset_should_reconnect() if conn_sock is None: return if os.getpid() == self.pid: try: conn_sock.shutdown(socket.SHUT_RDWR) except (OSError, TypeError): pass try: conn_sock.close() except OSError: pass def mark_for_reconnect(self): self._should_reconnect = True def should_reconnect(self): return self._should_reconnect def reset_should_reconnect(self): self._should_reconnect = False def _send_ping(self): """Send PING, expect PONG in return""" self.send_command("PING", check_health=False) if str_if_bytes(self.read_response()) != "PONG": raise ConnectionError("Bad response from PING health check") def _ping_failed(self, error): """Function to call when PING fails""" self.disconnect() def check_health(self): """Check the health of the connection with a PING/PONG""" if self.health_check_interval and time.monotonic() > self.next_health_check: self.retry.call_with_retry(self._send_ping, self._ping_failed) def send_packed_command(self, command, check_health=True): """Send an already packed command to the Redis server""" if not self._sock: self.connect_check_health(check_health=False) # guard against health check recursion if check_health: self.check_health() try: if isinstance(command, str): command = [command] for item in command: self._sock.sendall(item) except socket.timeout: self.disconnect() raise TimeoutError("Timeout writing to socket") except OSError as e: self.disconnect() if len(e.args) == 1: errno, errmsg = "UNKNOWN", e.args[0] else: errno = e.args[0] errmsg = e.args[1] raise ConnectionError(f"Error {errno} while writing to socket. {errmsg}.") except BaseException: # BaseExceptions can be raised when a socket send operation is not # finished, e.g. due to a timeout. Ideally, a caller could then re-try # to send un-sent data. However, the send_packed_command() API # does not support it so there is no point in keeping the connection open. self.disconnect() raise def send_command(self, *args, **kwargs): """Pack and send a command to the Redis server""" self.send_packed_command( self._command_packer.pack(*args), check_health=kwargs.get("check_health", True), ) def can_read(self, timeout=0): """Poll the socket to see if there's data that can be read.""" sock = self._sock if not sock: self.connect() host_error = self._host_error() try: return self._parser.can_read(timeout) except OSError as e: self.disconnect() raise ConnectionError(f"Error while reading from {host_error}: {e.args}") def read_response( self, disable_decoding=False, *, disconnect_on_error=True, push_request=False, ): """Read the response from a previously sent command""" host_error = self._host_error() try: if self.protocol in ["3", 3]: response = self._parser.read_response( disable_decoding=disable_decoding, push_request=push_request ) else: response = self._parser.read_response(disable_decoding=disable_decoding) except socket.timeout: if disconnect_on_error: self.disconnect() raise TimeoutError(f"Timeout reading from {host_error}") except OSError as e: if disconnect_on_error: self.disconnect() raise ConnectionError(f"Error while reading from {host_error} : {e.args}") except BaseException: # Also by default close in case of BaseException. A lot of code # relies on this behaviour when doing Command/Response pairs. # See #1128. if disconnect_on_error: self.disconnect() raise if self.health_check_interval: self.next_health_check = time.monotonic() + self.health_check_interval if isinstance(response, ResponseError): try: raise response finally: del response # avoid creating ref cycles return response def pack_command(self, *args): """Pack a series of arguments into the Redis protocol""" return self._command_packer.pack(*args) def pack_commands(self, commands): """Pack multiple commands into the Redis protocol""" output = [] pieces = [] buffer_length = 0 buffer_cutoff = self._buffer_cutoff for cmd in commands: for chunk in self._command_packer.pack(*cmd): chunklen = len(chunk) if ( buffer_length > buffer_cutoff or chunklen > buffer_cutoff or isinstance(chunk, memoryview) ): if pieces: output.append(SYM_EMPTY.join(pieces)) buffer_length = 0 pieces = [] if chunklen > buffer_cutoff or isinstance(chunk, memoryview): output.append(chunk) else: pieces.append(chunk) buffer_length += chunklen if pieces: output.append(SYM_EMPTY.join(pieces)) return output def get_protocol(self) -> Union[int, str]: return self.protocol @property def handshake_metadata(self) -> Union[Dict[bytes, bytes], Dict[str, str]]: return self._handshake_metadata @handshake_metadata.setter def handshake_metadata(self, value: Union[Dict[bytes, bytes], Dict[str, str]]): self._handshake_metadata = value def set_re_auth_token(self, token: TokenInterface): self._re_auth_token = token def re_auth(self): if self._re_auth_token is not None: self.send_command( "AUTH", self._re_auth_token.try_get("oid"), self._re_auth_token.get_value(), ) self.read_response() self._re_auth_token = None def _get_socket(self) -> Optional[socket.socket]: return self._sock @property def socket_timeout(self) -> Optional[Union[float, int]]: return self._socket_timeout @socket_timeout.setter def socket_timeout(self, value: Optional[Union[float, int]]): self._socket_timeout = value @property def socket_connect_timeout(self) -> Optional[Union[float, int]]: return self._socket_connect_timeout @socket_connect_timeout.setter def socket_connect_timeout(self, value: Optional[Union[float, int]]): self._socket_connect_timeout = value class Connection(AbstractConnection): "Manages TCP communication to and from a Redis server" def __init__( self, host="localhost", port=6379, socket_keepalive=False, socket_keepalive_options=None, socket_type=0, **kwargs, ): self._host = host self.port = int(port) self.socket_keepalive = socket_keepalive self.socket_keepalive_options = socket_keepalive_options or {} self.socket_type = socket_type super().__init__(**kwargs) def repr_pieces(self): pieces = [("host", self.host), ("port", self.port), ("db", self.db)] if self.client_name: pieces.append(("client_name", self.client_name)) return pieces def _connect(self): "Create a TCP socket connection" # we want to mimic what socket.create_connection does to support # ipv4/ipv6, but we want to set options prior to calling # socket.connect() err = None for res in socket.getaddrinfo( self.host, self.port, self.socket_type, socket.SOCK_STREAM ): family, socktype, proto, canonname, socket_address = res sock = None try: sock = socket.socket(family, socktype, proto) # TCP_NODELAY sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) # TCP_KEEPALIVE if self.socket_keepalive: sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1) for k, v in self.socket_keepalive_options.items(): sock.setsockopt(socket.IPPROTO_TCP, k, v) # set the socket_connect_timeout before we connect sock.settimeout(self.socket_connect_timeout) # connect sock.connect(socket_address) # set the socket_timeout now that we're connected sock.settimeout(self.socket_timeout) return sock except OSError as _: err = _ if sock is not None: try: sock.shutdown(socket.SHUT_RDWR) # ensure a clean close except OSError: pass sock.close() if err is not None: raise err raise OSError("socket.getaddrinfo returned an empty list") def _host_error(self): return f"{self.host}:{self.port}" @property def host(self) -> str: return self._host @host.setter def host(self, value: str): self._host = value class CacheProxyConnection(MaintNotificationsAbstractConnection, ConnectionInterface): DUMMY_CACHE_VALUE = b"foo" MIN_ALLOWED_VERSION = "7.4.0" DEFAULT_SERVER_NAME = "redis" def __init__( self, conn: ConnectionInterface, cache: CacheInterface, pool_lock: threading.RLock, ): self.pid = os.getpid() self._conn = conn self.retry = self._conn.retry self.host = self._conn.host self.port = self._conn.port self.credential_provider = conn.credential_provider self._pool_lock = pool_lock self._cache = cache self._cache_lock = threading.RLock() self._current_command_cache_key = None self._current_options = None self.register_connect_callback(self._enable_tracking_callback) if isinstance(self._conn, MaintNotificationsAbstractConnection): MaintNotificationsAbstractConnection.__init__( self, self._conn.maint_notifications_config, self._conn._maint_notifications_pool_handler, self._conn.maintenance_state, self._conn.maintenance_notification_hash, self._conn.host, self._conn.socket_timeout, self._conn.socket_connect_timeout, self._conn._get_parser(), ) def repr_pieces(self): return self._conn.repr_pieces() def register_connect_callback(self, callback): self._conn.register_connect_callback(callback) def deregister_connect_callback(self, callback): self._conn.deregister_connect_callback(callback) def set_parser(self, parser_class): self._conn.set_parser(parser_class) def set_maint_notifications_pool_handler_for_connection( self, maint_notifications_pool_handler ): if isinstance(self._conn, MaintNotificationsAbstractConnection): self._conn.set_maint_notifications_pool_handler_for_connection( maint_notifications_pool_handler ) def get_protocol(self): return self._conn.get_protocol() def connect(self): self._conn.connect() server_name = self._conn.handshake_metadata.get(b"server", None) if server_name is None: server_name = self._conn.handshake_metadata.get("server", None) server_ver = self._conn.handshake_metadata.get(b"version", None) if server_ver is None: server_ver = self._conn.handshake_metadata.get("version", None) if server_ver is None or server_ver is None: raise ConnectionError("Cannot retrieve information about server version") server_ver = ensure_string(server_ver) server_name = ensure_string(server_name) if ( server_name != self.DEFAULT_SERVER_NAME or compare_versions(server_ver, self.MIN_ALLOWED_VERSION) == 1 ): raise ConnectionError( "To maximize compatibility with all Redis products, client-side caching is supported by Redis 7.4 or later" # noqa: E501 ) def on_connect(self): self._conn.on_connect() def disconnect(self, *args): with self._cache_lock: self._cache.flush() self._conn.disconnect(*args) def check_health(self): self._conn.check_health() def send_packed_command(self, command, check_health=True): # TODO: Investigate if it's possible to unpack command # or extract keys from packed command self._conn.send_packed_command(command) def send_command(self, *args, **kwargs): self._process_pending_invalidations() with self._cache_lock: # Command is write command or not allowed # to be cached. if not self._cache.is_cachable(CacheKey(command=args[0], redis_keys=())): self._current_command_cache_key = None self._conn.send_command(*args, **kwargs) return if kwargs.get("keys") is None: raise ValueError("Cannot create cache key.") # Creates cache key. self._current_command_cache_key = CacheKey( command=args[0], redis_keys=tuple(kwargs.get("keys")) ) with self._cache_lock: # We have to trigger invalidation processing in case if # it was cached by another connection to avoid # queueing invalidations in stale connections. if self._cache.get(self._current_command_cache_key): entry = self._cache.get(self._current_command_cache_key) if entry.connection_ref != self._conn: with self._pool_lock: while entry.connection_ref.can_read(): entry.connection_ref.read_response(push_request=True) return # Set temporary entry value to prevent # race condition from another connection. self._cache.set( CacheEntry( cache_key=self._current_command_cache_key, cache_value=self.DUMMY_CACHE_VALUE, status=CacheEntryStatus.IN_PROGRESS, connection_ref=self._conn, ) ) # Send command over socket only if it's allowed # read-only command that not yet cached. self._conn.send_command(*args, **kwargs) def can_read(self, timeout=0): return self._conn.can_read(timeout) def read_response( self, disable_decoding=False, *, disconnect_on_error=True, push_request=False ): with self._cache_lock: # Check if command response exists in a cache and it's not in progress. if ( self._current_command_cache_key is not None and self._cache.get(self._current_command_cache_key) is not None and self._cache.get(self._current_command_cache_key).status != CacheEntryStatus.IN_PROGRESS ): res = copy.deepcopy( self._cache.get(self._current_command_cache_key).cache_value ) self._current_command_cache_key = None return res response = self._conn.read_response( disable_decoding=disable_decoding, disconnect_on_error=disconnect_on_error, push_request=push_request, ) with self._cache_lock: # Prevent not-allowed command from caching. if self._current_command_cache_key is None: return response # If response is None prevent from caching. if response is None: self._cache.delete_by_cache_keys([self._current_command_cache_key]) return response cache_entry = self._cache.get(self._current_command_cache_key) # Cache only responses that still valid # and wasn't invalidated by another connection in meantime. if cache_entry is not None: cache_entry.status = CacheEntryStatus.VALID cache_entry.cache_value = response self._cache.set(cache_entry) self._current_command_cache_key = None return response def pack_command(self, *args): return self._conn.pack_command(*args) def pack_commands(self, commands): return self._conn.pack_commands(commands) @property def handshake_metadata(self) -> Union[Dict[bytes, bytes], Dict[str, str]]: return self._conn.handshake_metadata def set_re_auth_token(self, token: TokenInterface): self._conn.set_re_auth_token(token) def re_auth(self): self._conn.re_auth() def mark_for_reconnect(self): self._conn.mark_for_reconnect() def should_reconnect(self): return self._conn.should_reconnect() def reset_should_reconnect(self): self._conn.reset_should_reconnect() @property def host(self) -> str: return self._conn.host @host.setter def host(self, value: str): self._conn.host = value @property def socket_timeout(self) -> Optional[Union[float, int]]: return self._conn.socket_timeout @socket_timeout.setter def socket_timeout(self, value: Optional[Union[float, int]]): self._conn.socket_timeout = value @property def socket_connect_timeout(self) -> Optional[Union[float, int]]: return self._conn.socket_connect_timeout @socket_connect_timeout.setter def socket_connect_timeout(self, value: Optional[Union[float, int]]): self._conn.socket_connect_timeout = value def _get_socket(self) -> Optional[socket.socket]: if isinstance(self._conn, MaintNotificationsAbstractConnection): return self._conn._get_socket() else: raise NotImplementedError( "Maintenance notifications are not supported by this connection type" ) def _get_maint_notifications_connection_instance( self, connection ) -> MaintNotificationsAbstractConnection: """ Validate that connection instance supports maintenance notifications. With this helper method we ensure that we are working with the correct connection type. After twe validate that connection instance supports maintenance notifications we can safely return the connection instance as MaintNotificationsAbstractConnection. """ if not isinstance(connection, MaintNotificationsAbstractConnection): raise NotImplementedError( "Maintenance notifications are not supported by this connection type" ) else: return connection @property def maintenance_state(self) -> MaintenanceState: con = self._get_maint_notifications_connection_instance(self._conn) return con.maintenance_state @maintenance_state.setter def maintenance_state(self, state: MaintenanceState): con = self._get_maint_notifications_connection_instance(self._conn) con.maintenance_state = state def getpeername(self): con = self._get_maint_notifications_connection_instance(self._conn) return con.getpeername() def get_resolved_ip(self): con = self._get_maint_notifications_connection_instance(self._conn) return con.get_resolved_ip() def update_current_socket_timeout(self, relaxed_timeout: Optional[float] = None): con = self._get_maint_notifications_connection_instance(self._conn) con.update_current_socket_timeout(relaxed_timeout) def set_tmp_settings( self, tmp_host_address: Optional[str] = None, tmp_relaxed_timeout: Optional[float] = None, ): con = self._get_maint_notifications_connection_instance(self._conn) con.set_tmp_settings(tmp_host_address, tmp_relaxed_timeout) def reset_tmp_settings( self, reset_host_address: bool = False, reset_relaxed_timeout: bool = False, ): con = self._get_maint_notifications_connection_instance(self._conn) con.reset_tmp_settings(reset_host_address, reset_relaxed_timeout) def _connect(self): self._conn._connect() def _host_error(self): self._conn._host_error() def _enable_tracking_callback(self, conn: ConnectionInterface) -> None: conn.send_command("CLIENT", "TRACKING", "ON") conn.read_response() conn._parser.set_invalidation_push_handler(self._on_invalidation_callback) def _process_pending_invalidations(self): while self.can_read(): self._conn.read_response(push_request=True) def _on_invalidation_callback(self, data: List[Union[str, Optional[List[bytes]]]]): with self._cache_lock: # Flush cache when DB flushed on server-side if data[1] is None: self._cache.flush() else: self._cache.delete_by_redis_keys(data[1]) class SSLConnection(Connection): """Manages SSL connections to and from the Redis server(s). This class extends the Connection class, adding SSL functionality, and making use of ssl.SSLContext (https://docs.python.org/3/library/ssl.html#ssl.SSLContext) """ # noqa def __init__( self, ssl_keyfile=None, ssl_certfile=None, ssl_cert_reqs="required", ssl_include_verify_flags: Optional[List["VerifyFlags"]] = None, ssl_exclude_verify_flags: Optional[List["VerifyFlags"]] = None, ssl_ca_certs=None, ssl_ca_data=None, ssl_check_hostname=True, ssl_ca_path=None, ssl_password=None, ssl_validate_ocsp=False, ssl_validate_ocsp_stapled=False, ssl_ocsp_context=None, ssl_ocsp_expected_cert=None, ssl_min_version=None, ssl_ciphers=None, **kwargs, ): """Constructor Args: ssl_keyfile: Path to an ssl private key. Defaults to None. ssl_certfile: Path to an ssl certificate. Defaults to None. ssl_cert_reqs: The string value for the SSLContext.verify_mode (none, optional, required), or an ssl.VerifyMode. Defaults to "required". ssl_include_verify_flags: A list of flags to be included in the SSLContext.verify_flags. Defaults to None. ssl_exclude_verify_flags: A list of flags to be excluded from the SSLContext.verify_flags. Defaults to None. ssl_ca_certs: The path to a file of concatenated CA certificates in PEM format. Defaults to None. ssl_ca_data: Either an ASCII string of one or more PEM-encoded certificates or a bytes-like object of DER-encoded certificates. ssl_check_hostname: If set, match the hostname during the SSL handshake. Defaults to True. ssl_ca_path: The path to a directory containing several CA certificates in PEM format. Defaults to None. ssl_password: Password for unlocking an encrypted private key. Defaults to None. ssl_validate_ocsp: If set, perform a full ocsp validation (i.e not a stapled verification) ssl_validate_ocsp_stapled: If set, perform a validation on a stapled ocsp response ssl_ocsp_context: A fully initialized OpenSSL.SSL.Context object to be used in verifying the ssl_ocsp_expected_cert ssl_ocsp_expected_cert: A PEM armoured string containing the expected certificate to be returned from the ocsp verification service. ssl_min_version: The lowest supported SSL version. It affects the supported SSL versions of the SSLContext. None leaves the default provided by ssl module. ssl_ciphers: A string listing the ciphers that are allowed to be used. Defaults to None, which means that the default ciphers are used. See https://docs.python.org/3/library/ssl.html#ssl.SSLContext.set_ciphers for more information. Raises: RedisError """ # noqa if not SSL_AVAILABLE: raise RedisError("Python wasn't built with SSL support") self.keyfile = ssl_keyfile self.certfile = ssl_certfile if ssl_cert_reqs is None: ssl_cert_reqs = ssl.CERT_NONE elif isinstance(ssl_cert_reqs, str): CERT_REQS = { # noqa: N806 "none": ssl.CERT_NONE, "optional": ssl.CERT_OPTIONAL, "required": ssl.CERT_REQUIRED, } if ssl_cert_reqs not in CERT_REQS: raise RedisError( f"Invalid SSL Certificate Requirements Flag: {ssl_cert_reqs}" ) ssl_cert_reqs = CERT_REQS[ssl_cert_reqs] self.cert_reqs = ssl_cert_reqs self.ssl_include_verify_flags = ssl_include_verify_flags self.ssl_exclude_verify_flags = ssl_exclude_verify_flags self.ca_certs = ssl_ca_certs self.ca_data = ssl_ca_data self.ca_path = ssl_ca_path self.check_hostname = ( ssl_check_hostname if self.cert_reqs != ssl.CERT_NONE else False ) self.certificate_password = ssl_password self.ssl_validate_ocsp = ssl_validate_ocsp self.ssl_validate_ocsp_stapled = ssl_validate_ocsp_stapled self.ssl_ocsp_context = ssl_ocsp_context self.ssl_ocsp_expected_cert = ssl_ocsp_expected_cert self.ssl_min_version = ssl_min_version self.ssl_ciphers = ssl_ciphers super().__init__(**kwargs) def _connect(self): """ Wrap the socket with SSL support, handling potential errors. """ sock = super()._connect() try: return self._wrap_socket_with_ssl(sock) except (OSError, RedisError): sock.close() raise def _wrap_socket_with_ssl(self, sock): """ Wraps the socket with SSL support. Args: sock: The plain socket to wrap with SSL. Returns: An SSL wrapped socket. """ context = ssl.create_default_context() context.check_hostname = self.check_hostname context.verify_mode = self.cert_reqs if self.ssl_include_verify_flags: for flag in self.ssl_include_verify_flags: context.verify_flags |= flag if self.ssl_exclude_verify_flags: for flag in self.ssl_exclude_verify_flags: context.verify_flags &= ~flag if self.certfile or self.keyfile: context.load_cert_chain( certfile=self.certfile, keyfile=self.keyfile, password=self.certificate_password, ) if ( self.ca_certs is not None or self.ca_path is not None or self.ca_data is not None ): context.load_verify_locations( cafile=self.ca_certs, capath=self.ca_path, cadata=self.ca_data ) if self.ssl_min_version is not None: context.minimum_version = self.ssl_min_version if self.ssl_ciphers: context.set_ciphers(self.ssl_ciphers) if self.ssl_validate_ocsp is True and CRYPTOGRAPHY_AVAILABLE is False: raise RedisError("cryptography is not installed.") if self.ssl_validate_ocsp_stapled and self.ssl_validate_ocsp: raise RedisError( "Either an OCSP staple or pure OCSP connection must be validated " "- not both." ) sslsock = context.wrap_socket(sock, server_hostname=self.host) # validation for the stapled case if self.ssl_validate_ocsp_stapled: import OpenSSL from .ocsp import ocsp_staple_verifier # if a context is provided use it - otherwise, a basic context if self.ssl_ocsp_context is None: staple_ctx = OpenSSL.SSL.Context(OpenSSL.SSL.SSLv23_METHOD) staple_ctx.use_certificate_file(self.certfile) staple_ctx.use_privatekey_file(self.keyfile) else: staple_ctx = self.ssl_ocsp_context staple_ctx.set_ocsp_client_callback( ocsp_staple_verifier, self.ssl_ocsp_expected_cert ) # need another socket con = OpenSSL.SSL.Connection(staple_ctx, socket.socket()) con.request_ocsp() con.connect((self.host, self.port)) con.do_handshake() con.shutdown() return sslsock # pure ocsp validation if self.ssl_validate_ocsp is True and CRYPTOGRAPHY_AVAILABLE: from .ocsp import OCSPVerifier o = OCSPVerifier(sslsock, self.host, self.port, self.ca_certs) if o.is_valid(): return sslsock else: raise ConnectionError("ocsp validation error") return sslsock class UnixDomainSocketConnection(AbstractConnection): "Manages UDS communication to and from a Redis server" def __init__(self, path="", socket_timeout=None, **kwargs): super().__init__(**kwargs) self.path = path self.socket_timeout = socket_timeout def repr_pieces(self): pieces = [("path", self.path), ("db", self.db)] if self.client_name: pieces.append(("client_name", self.client_name)) return pieces def _connect(self): "Create a Unix domain socket connection" sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) sock.settimeout(self.socket_connect_timeout) try: sock.connect(self.path) except OSError: # Prevent ResourceWarnings for unclosed sockets. try: sock.shutdown(socket.SHUT_RDWR) # ensure a clean close except OSError: pass sock.close() raise sock.settimeout(self.socket_timeout) return sock def _host_error(self): return self.path FALSE_STRINGS = ("0", "F", "FALSE", "N", "NO") def to_bool(value): if value is None or value == "": return None if isinstance(value, str) and value.upper() in FALSE_STRINGS: return False return bool(value) def parse_ssl_verify_flags(value): # flags are passed in as a string representation of a list, # e.g. VERIFY_X509_STRICT, VERIFY_X509_PARTIAL_CHAIN verify_flags_str = value.replace("[", "").replace("]", "") verify_flags = [] for flag in verify_flags_str.split(","): flag = flag.strip() if not hasattr(VerifyFlags, flag): raise ValueError(f"Invalid ssl verify flag: {flag}") verify_flags.append(getattr(VerifyFlags, flag)) return verify_flags URL_QUERY_ARGUMENT_PARSERS = { "db": int, "socket_timeout": float, "socket_connect_timeout": float, "socket_keepalive": to_bool, "retry_on_timeout": to_bool, "retry_on_error": list, "max_connections": int, "health_check_interval": int, "ssl_check_hostname": to_bool, "ssl_include_verify_flags": parse_ssl_verify_flags, "ssl_exclude_verify_flags": parse_ssl_verify_flags, "timeout": float, } def parse_url(url): if not ( url.startswith("redis://") or url.startswith("rediss://") or url.startswith("unix://") ): raise ValueError( "Redis URL must specify one of the following " "schemes (redis://, rediss://, unix://)" ) url = urlparse(url) kwargs = {} for name, value in parse_qs(url.query).items(): if value and len(value) > 0: value = unquote(value[0]) parser = URL_QUERY_ARGUMENT_PARSERS.get(name) if parser: try: kwargs[name] = parser(value) except (TypeError, ValueError): raise ValueError(f"Invalid value for '{name}' in connection URL.") else: kwargs[name] = value if url.username: kwargs["username"] = unquote(url.username) if url.password: kwargs["password"] = unquote(url.password) # We only support redis://, rediss:// and unix:// schemes. if url.scheme == "unix": if url.path: kwargs["path"] = unquote(url.path) kwargs["connection_class"] = UnixDomainSocketConnection else: # implied: url.scheme in ("redis", "rediss"): if url.hostname: kwargs["host"] = unquote(url.hostname) if url.port: kwargs["port"] = int(url.port) # If there's a path argument, use it as the db argument if a # querystring value wasn't specified if url.path and "db" not in kwargs: try: kwargs["db"] = int(unquote(url.path).replace("/", "")) except (AttributeError, ValueError): pass if url.scheme == "rediss": kwargs["connection_class"] = SSLConnection return kwargs _CP = TypeVar("_CP", bound="ConnectionPool") class ConnectionPoolInterface(ABC): @abstractmethod def get_protocol(self): pass @abstractmethod def reset(self): pass @abstractmethod @deprecated_args( args_to_warn=["*"], reason="Use get_connection() without args instead", version="5.3.0", ) def get_connection( self, command_name: Optional[str], *keys, **options ) -> ConnectionInterface: pass @abstractmethod def get_encoder(self): pass @abstractmethod def release(self, connection: ConnectionInterface): pass @abstractmethod def disconnect(self, inuse_connections: bool = True): pass @abstractmethod def close(self): pass @abstractmethod def set_retry(self, retry: Retry): pass @abstractmethod def re_auth_callback(self, token: TokenInterface): pass class MaintNotificationsAbstractConnectionPool: """ Abstract class for handling maintenance notifications logic. This class is mixed into the ConnectionPool classes. This class is not intended to be used directly! All logic related to maintenance notifications and connection pool handling is encapsulated in this class. """ def __init__( self, maint_notifications_config: Optional[MaintNotificationsConfig] = None, **kwargs, ): # Initialize maintenance notifications is_protocol_supported = kwargs.get("protocol") in [3, "3"] if maint_notifications_config is None and is_protocol_supported: maint_notifications_config = MaintNotificationsConfig() if maint_notifications_config and maint_notifications_config.enabled: if not is_protocol_supported: raise RedisError( "Maintenance notifications handlers on connection are only supported with RESP version 3" ) self._maint_notifications_pool_handler = MaintNotificationsPoolHandler( self, maint_notifications_config ) self._update_connection_kwargs_for_maint_notifications( self._maint_notifications_pool_handler ) else: self._maint_notifications_pool_handler = None @property @abstractmethod def connection_kwargs(self) -> Dict[str, Any]: pass @connection_kwargs.setter @abstractmethod def connection_kwargs(self, value: Dict[str, Any]): pass @abstractmethod def _get_pool_lock(self) -> threading.RLock: pass @abstractmethod def _get_free_connections(self) -> Iterable["MaintNotificationsAbstractConnection"]: pass @abstractmethod def _get_in_use_connections( self, ) -> Iterable["MaintNotificationsAbstractConnection"]: pass def maint_notifications_enabled(self): """ Returns: True if the maintenance notifications are enabled, False otherwise. The maintenance notifications config is stored in the pool handler. If the pool handler is not set, the maintenance notifications are not enabled. """ maint_notifications_config = ( self._maint_notifications_pool_handler.config if self._maint_notifications_pool_handler else None ) return maint_notifications_config and maint_notifications_config.enabled def update_maint_notifications_config( self, maint_notifications_config: MaintNotificationsConfig ): """ Updates the maintenance notifications configuration. This method should be called only if the pool was created without enabling the maintenance notifications and in a later point in time maintenance notifications are requested to be enabled. """ if ( self.maint_notifications_enabled() and not maint_notifications_config.enabled ): raise ValueError( "Cannot disable maintenance notifications after enabling them" ) # first update pool settings if not self._maint_notifications_pool_handler: self._maint_notifications_pool_handler = MaintNotificationsPoolHandler( self, maint_notifications_config ) else: self._maint_notifications_pool_handler.config = maint_notifications_config # then update connection kwargs and existing connections self._update_connection_kwargs_for_maint_notifications( self._maint_notifications_pool_handler ) self._update_maint_notifications_configs_for_connections( self._maint_notifications_pool_handler ) def _update_connection_kwargs_for_maint_notifications( self, maint_notifications_pool_handler: MaintNotificationsPoolHandler ): """ Update the connection kwargs for all future connections. """ if not self.maint_notifications_enabled(): return self.connection_kwargs.update( { "maint_notifications_pool_handler": maint_notifications_pool_handler, "maint_notifications_config": maint_notifications_pool_handler.config, } ) # Store original connection parameters for maintenance notifications. if self.connection_kwargs.get("orig_host_address", None) is None: # If orig_host_address is None it means we haven't # configured the original values yet self.connection_kwargs.update( { "orig_host_address": self.connection_kwargs.get("host"), "orig_socket_timeout": self.connection_kwargs.get( "socket_timeout", None ), "orig_socket_connect_timeout": self.connection_kwargs.get( "socket_connect_timeout", None ), } ) def _update_maint_notifications_configs_for_connections( self, maint_notifications_pool_handler: MaintNotificationsPoolHandler ): """Update the maintenance notifications config for all connections in the pool.""" with self._get_pool_lock(): for conn in self._get_free_connections(): conn.set_maint_notifications_pool_handler_for_connection( maint_notifications_pool_handler ) conn.maint_notifications_config = ( maint_notifications_pool_handler.config ) conn.disconnect() for conn in self._get_in_use_connections(): conn.set_maint_notifications_pool_handler_for_connection( maint_notifications_pool_handler ) conn.maint_notifications_config = ( maint_notifications_pool_handler.config ) conn.mark_for_reconnect() def _should_update_connection( self, conn: "MaintNotificationsAbstractConnection", matching_pattern: Literal[ "connected_address", "configured_address", "notification_hash" ] = "connected_address", matching_address: Optional[str] = None, matching_notification_hash: Optional[int] = None, ) -> bool: """ Check if the connection should be updated based on the matching criteria. """ if matching_pattern == "connected_address": if matching_address and conn.getpeername() != matching_address: return False elif matching_pattern == "configured_address": if matching_address and conn.host != matching_address: return False elif matching_pattern == "notification_hash": if ( matching_notification_hash and conn.maintenance_notification_hash != matching_notification_hash ): return False return True def update_connection_settings( self, conn: "MaintNotificationsAbstractConnection", state: Optional["MaintenanceState"] = None, maintenance_notification_hash: Optional[int] = None, host_address: Optional[str] = None, relaxed_timeout: Optional[float] = None, update_notification_hash: bool = False, reset_host_address: bool = False, reset_relaxed_timeout: bool = False, ): """ Update the settings for a single connection. """ if state: conn.maintenance_state = state if update_notification_hash: # update the notification hash only if requested conn.maintenance_notification_hash = maintenance_notification_hash if host_address is not None: conn.set_tmp_settings(tmp_host_address=host_address) if relaxed_timeout is not None: conn.set_tmp_settings(tmp_relaxed_timeout=relaxed_timeout) if reset_relaxed_timeout or reset_host_address: conn.reset_tmp_settings( reset_host_address=reset_host_address, reset_relaxed_timeout=reset_relaxed_timeout, ) conn.update_current_socket_timeout(relaxed_timeout) def update_connections_settings( self, state: Optional["MaintenanceState"] = None, maintenance_notification_hash: Optional[int] = None, host_address: Optional[str] = None, relaxed_timeout: Optional[float] = None, matching_address: Optional[str] = None, matching_notification_hash: Optional[int] = None, matching_pattern: Literal[ "connected_address", "configured_address", "notification_hash" ] = "connected_address", update_notification_hash: bool = False, reset_host_address: bool = False, reset_relaxed_timeout: bool = False, include_free_connections: bool = True, ): """ Update the settings for all matching connections in the pool. This method does not create new connections. This method does not affect the connection kwargs. :param state: The maintenance state to set for the connection. :param maintenance_notification_hash: The hash of the maintenance notification to set for the connection. :param host_address: The host address to set for the connection. :param relaxed_timeout: The relaxed timeout to set for the connection. :param matching_address: The address to match for the connection. :param matching_notification_hash: The notification hash to match for the connection. :param matching_pattern: The pattern to match for the connection. :param update_notification_hash: Whether to update the notification hash for the connection. :param reset_host_address: Whether to reset the host address to the original address. :param reset_relaxed_timeout: Whether to reset the relaxed timeout to the original timeout. :param include_free_connections: Whether to include free/available connections. """ with self._get_pool_lock(): for conn in self._get_in_use_connections(): if self._should_update_connection( conn, matching_pattern, matching_address, matching_notification_hash, ): self.update_connection_settings( conn, state=state, maintenance_notification_hash=maintenance_notification_hash, host_address=host_address, relaxed_timeout=relaxed_timeout, update_notification_hash=update_notification_hash, reset_host_address=reset_host_address, reset_relaxed_timeout=reset_relaxed_timeout, ) if include_free_connections: for conn in self._get_free_connections(): if self._should_update_connection( conn, matching_pattern, matching_address, matching_notification_hash, ): self.update_connection_settings( conn, state=state, maintenance_notification_hash=maintenance_notification_hash, host_address=host_address, relaxed_timeout=relaxed_timeout, update_notification_hash=update_notification_hash, reset_host_address=reset_host_address, reset_relaxed_timeout=reset_relaxed_timeout, ) def update_connection_kwargs( self, **kwargs, ): """ Update the connection kwargs for all future connections. This method updates the connection kwargs for all future connections created by the pool. Existing connections are not affected. """ self.connection_kwargs.update(kwargs) def update_active_connections_for_reconnect( self, moving_address_src: Optional[str] = None, ): """ Mark all active connections for reconnect. This is used when a cluster node is migrated to a different address. :param moving_address_src: The address of the node that is being moved. """ with self._get_pool_lock(): for conn in self._get_in_use_connections(): if self._should_update_connection( conn, "connected_address", moving_address_src ): conn.mark_for_reconnect() def disconnect_free_connections( self, moving_address_src: Optional[str] = None, ): """ Disconnect all free/available connections. This is used when a cluster node is migrated to a different address. :param moving_address_src: The address of the node that is being moved. """ with self._get_pool_lock(): for conn in self._get_free_connections(): if self._should_update_connection( conn, "connected_address", moving_address_src ): conn.disconnect() class ConnectionPool(MaintNotificationsAbstractConnectionPool, ConnectionPoolInterface): """ Create a connection pool. ``If max_connections`` is set, then this object raises :py:class:`~redis.exceptions.ConnectionError` when the pool's limit is reached. By default, TCP connections are created unless ``connection_class`` is specified. Use class:`.UnixDomainSocketConnection` for unix sockets. :py:class:`~redis.SSLConnection` can be used for SSL enabled connections. If ``maint_notifications_config`` is provided, the connection pool will support maintenance notifications. Maintenance notifications are supported only with RESP3. If the ``maint_notifications_config`` is not provided but the ``protocol`` is 3, the maintenance notifications will be enabled by default. Any additional keyword arguments are passed to the constructor of ``connection_class``. """ @classmethod def from_url(cls: Type[_CP], url: str, **kwargs) -> _CP: """ Return a connection pool 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. """ url_options = parse_url(url) if "connection_class" in kwargs: url_options["connection_class"] = kwargs["connection_class"] kwargs.update(url_options) return cls(**kwargs) def __init__( self, connection_class=Connection, max_connections: Optional[int] = None, cache_factory: Optional[CacheFactoryInterface] = None, maint_notifications_config: Optional[MaintNotificationsConfig] = None, **connection_kwargs, ): max_connections = max_connections or 2**31 if not isinstance(max_connections, int) or max_connections < 0: raise ValueError('"max_connections" must be a positive integer') self.connection_class = connection_class self._connection_kwargs = connection_kwargs self.max_connections = max_connections self.cache = None self._cache_factory = cache_factory if connection_kwargs.get("cache_config") or connection_kwargs.get("cache"): if self._connection_kwargs.get("protocol") not in [3, "3"]: raise RedisError("Client caching is only supported with RESP version 3") cache = self._connection_kwargs.get("cache") if cache is not None: if not isinstance(cache, CacheInterface): raise ValueError("Cache must implement CacheInterface") self.cache = cache else: if self._cache_factory is not None: self.cache = self._cache_factory.get_cache() else: self.cache = CacheFactory( self._connection_kwargs.get("cache_config") ).get_cache() connection_kwargs.pop("cache", None) connection_kwargs.pop("cache_config", None) self._event_dispatcher = self._connection_kwargs.get("event_dispatcher", None) if self._event_dispatcher is None: self._event_dispatcher = EventDispatcher() # a lock to protect the critical section in _checkpid(). # this lock is acquired when the process id changes, such as # after a fork. during this time, multiple threads in the child # process could attempt to acquire this lock. the first thread # to acquire the lock will reset the data structures and lock # object of this pool. subsequent threads acquiring this lock # will notice the first thread already did the work and simply # release the lock. self._fork_lock = threading.RLock() self._lock = threading.RLock() MaintNotificationsAbstractConnectionPool.__init__( self, maint_notifications_config=maint_notifications_config, **connection_kwargs, ) self.reset() def __repr__(self) -> str: conn_kwargs = ",".join([f"{k}={v}" for k, v in self.connection_kwargs.items()]) return ( f"<{self.__class__.__module__}.{self.__class__.__name__}" f"(<{self.connection_class.__module__}.{self.connection_class.__name__}" f"({conn_kwargs})>)>" ) @property def connection_kwargs(self) -> Dict[str, Any]: return self._connection_kwargs @connection_kwargs.setter def connection_kwargs(self, value: Dict[str, Any]): self._connection_kwargs = value def get_protocol(self): """ Returns: The RESP protocol version, or ``None`` if the protocol is not specified, in which case the server default will be used. """ return self.connection_kwargs.get("protocol", None) def reset(self) -> None: self._created_connections = 0 self._available_connections = [] self._in_use_connections = set() # this must be the last operation in this method. while reset() is # called when holding _fork_lock, other threads in this process # can call _checkpid() which compares self.pid and os.getpid() without # holding any lock (for performance reasons). keeping this assignment # as the last operation ensures that those other threads will also # notice a pid difference and block waiting for the first thread to # release _fork_lock. when each of these threads eventually acquire # _fork_lock, they will notice that another thread already called # reset() and they will immediately release _fork_lock and continue on. self.pid = os.getpid() def _checkpid(self) -> None: # _checkpid() attempts to keep ConnectionPool fork-safe on modern # systems. this is called by all ConnectionPool methods that # manipulate the pool's state such as get_connection() and release(). # # _checkpid() determines whether the process has forked by comparing # the current process id to the process id saved on the ConnectionPool # instance. if these values are the same, _checkpid() simply returns. # # when the process ids differ, _checkpid() assumes that the process # has forked and that we're now running in the child process. the child # process cannot use the parent's file descriptors (e.g., sockets). # therefore, when _checkpid() sees the process id change, it calls # reset() in order to reinitialize the child's ConnectionPool. this # will cause the child to make all new connection objects. # # _checkpid() is protected by self._fork_lock to ensure that multiple # threads in the child process do not call reset() multiple times. # # there is an extremely small chance this could fail in the following # scenario: # 1. process A calls _checkpid() for the first time and acquires # self._fork_lock. # 2. while holding self._fork_lock, process A forks (the fork() # could happen in a different thread owned by process A) # 3. process B (the forked child process) inherits the # ConnectionPool's state from the parent. that state includes # a locked _fork_lock. process B will not be notified when # process A releases the _fork_lock and will thus never be # able to acquire the _fork_lock. # # to mitigate this possible deadlock, _checkpid() will only wait 5 # seconds to acquire _fork_lock. if _fork_lock cannot be acquired in # that time it is assumed that the child is deadlocked and a # redis.ChildDeadlockedError error is raised. if self.pid != os.getpid(): acquired = self._fork_lock.acquire(timeout=5) if not acquired: raise ChildDeadlockedError # reset() the instance for the new process if another thread # hasn't already done so try: if self.pid != os.getpid(): self.reset() finally: self._fork_lock.release() @deprecated_args( args_to_warn=["*"], reason="Use get_connection() without args instead", version="5.3.0", ) def get_connection(self, command_name=None, *keys, **options) -> "Connection": "Get a connection from the pool" self._checkpid() with self._lock: try: connection = self._available_connections.pop() except IndexError: connection = self.make_connection() self._in_use_connections.add(connection) try: # ensure this connection is connected to Redis connection.connect() # connections that the pool provides should be ready to send # a command. if not, the connection was either returned to the # pool before all data has been read or the socket has been # closed. either way, reconnect and verify everything is good. try: if ( connection.can_read() and self.cache is None and not self.maint_notifications_enabled() ): raise ConnectionError("Connection has data") except (ConnectionError, TimeoutError, OSError): connection.disconnect() connection.connect() if connection.can_read(): raise ConnectionError("Connection not ready") except BaseException: # release the connection back to the pool so that we don't # leak it self.release(connection) raise return connection def get_encoder(self) -> Encoder: "Return an encoder based on encoding settings" kwargs = self.connection_kwargs return Encoder( encoding=kwargs.get("encoding", "utf-8"), encoding_errors=kwargs.get("encoding_errors", "strict"), decode_responses=kwargs.get("decode_responses", False), ) def make_connection(self) -> "ConnectionInterface": "Create a new connection" if self._created_connections >= self.max_connections: raise MaxConnectionsError("Too many connections") self._created_connections += 1 kwargs = dict(self.connection_kwargs) if self.cache is not None: return CacheProxyConnection( self.connection_class(**kwargs), self.cache, self._lock ) return self.connection_class(**kwargs) def release(self, connection: "Connection") -> None: "Releases the connection back to the pool" self._checkpid() with self._lock: try: self._in_use_connections.remove(connection) except KeyError: # Gracefully fail when a connection is returned to this pool # that the pool doesn't actually own return if self.owns_connection(connection): if connection.should_reconnect(): connection.disconnect() self._available_connections.append(connection) self._event_dispatcher.dispatch( AfterConnectionReleasedEvent(connection) ) else: # Pool doesn't own this connection, do not add it back # to the pool. # The created connections count should not be changed, # because the connection was not created by the pool. connection.disconnect() return def owns_connection(self, connection: "Connection") -> int: return connection.pid == self.pid def disconnect(self, inuse_connections: bool = True) -> None: """ Disconnects connections in the pool If ``inuse_connections`` is True, disconnect connections that are currently in use, potentially by other threads. Otherwise only disconnect connections that are idle in the pool. """ self._checkpid() with self._lock: if inuse_connections: connections = chain( self._available_connections, self._in_use_connections ) else: connections = self._available_connections for connection in connections: connection.disconnect() def close(self) -> None: """Close the pool, disconnecting all connections""" self.disconnect() def set_retry(self, retry: Retry) -> None: self.connection_kwargs.update({"retry": retry}) for conn in self._available_connections: conn.retry = retry for conn in self._in_use_connections: conn.retry = retry def re_auth_callback(self, token: TokenInterface): with self._lock: for conn in self._available_connections: conn.retry.call_with_retry( lambda: conn.send_command( "AUTH", token.try_get("oid"), token.get_value() ), lambda error: self._mock(error), ) conn.retry.call_with_retry( lambda: conn.read_response(), lambda error: self._mock(error) ) for conn in self._in_use_connections: conn.set_re_auth_token(token) def _get_pool_lock(self): return self._lock def _get_free_connections(self): with self._lock: return self._available_connections def _get_in_use_connections(self): with self._lock: return self._in_use_connections async def _mock(self, error: RedisError): """ Dummy functions, needs to be passed as error callback to retry object. :param error: :return: """ pass class BlockingConnectionPool(ConnectionPool): """ Thread-safe blocking connection pool:: >>> from redis.client import Redis >>> client = Redis(connection_pool=BlockingConnectionPool()) It performs the same function as the default :py:class:`~redis.ConnectionPool` implementation, in that, it maintains a pool of reusable connections that can be shared by multiple redis clients (safely across threads if required). The difference is that, in the event that a client tries to get a connection from the pool when all of connections are in use, rather than raising a :py:class:`~redis.ConnectionError` (as the default :py:class:`~redis.ConnectionPool` implementation does), it makes the client wait ("blocks") for a specified number of seconds until a connection becomes available. Use ``max_connections`` to increase / decrease the pool size:: >>> pool = BlockingConnectionPool(max_connections=10) Use ``timeout`` to tell it either how many seconds to wait for a connection to become available, or to block forever: >>> # Block forever. >>> pool = BlockingConnectionPool(timeout=None) >>> # Raise a ``ConnectionError`` after five seconds if a connection is >>> # not available. >>> pool = BlockingConnectionPool(timeout=5) """ def __init__( self, max_connections=50, timeout=20, connection_class=Connection, queue_class=LifoQueue, **connection_kwargs, ): self.queue_class = queue_class self.timeout = timeout self._in_maintenance = False self._locked = False super().__init__( connection_class=connection_class, max_connections=max_connections, **connection_kwargs, ) def reset(self): # Create and fill up a thread safe queue with ``None`` values. try: if self._in_maintenance: self._lock.acquire() self._locked = True self.pool = self.queue_class(self.max_connections) while True: try: self.pool.put_nowait(None) except Full: break # Keep a list of actual connection instances so that we can # disconnect them later. self._connections = [] finally: if self._locked: try: self._lock.release() except Exception: pass self._locked = False # this must be the last operation in this method. while reset() is # called when holding _fork_lock, other threads in this process # can call _checkpid() which compares self.pid and os.getpid() without # holding any lock (for performance reasons). keeping this assignment # as the last operation ensures that those other threads will also # notice a pid difference and block waiting for the first thread to # release _fork_lock. when each of these threads eventually acquire # _fork_lock, they will notice that another thread already called # reset() and they will immediately release _fork_lock and continue on. self.pid = os.getpid() def make_connection(self): "Make a fresh connection." try: if self._in_maintenance: self._lock.acquire() self._locked = True if self.cache is not None: connection = CacheProxyConnection( self.connection_class(**self.connection_kwargs), self.cache, self._lock, ) else: connection = self.connection_class(**self.connection_kwargs) self._connections.append(connection) return connection finally: if self._locked: try: self._lock.release() except Exception: pass self._locked = False @deprecated_args( args_to_warn=["*"], reason="Use get_connection() without args instead", version="5.3.0", ) def get_connection(self, command_name=None, *keys, **options): """ Get a connection, blocking for ``self.timeout`` until a connection is available from the pool. If the connection returned is ``None`` then creates a new connection. Because we use a last-in first-out queue, the existing connections (having been returned to the pool after the initial ``None`` values were added) will be returned before ``None`` values. This means we only create new connections when we need to, i.e.: the actual number of connections will only increase in response to demand. """ # Make sure we haven't changed process. self._checkpid() # Try and get a connection from the pool. If one isn't available within # self.timeout then raise a ``ConnectionError``. connection = None try: if self._in_maintenance: self._lock.acquire() self._locked = True try: connection = self.pool.get(block=True, timeout=self.timeout) except Empty: # Note that this is not caught by the redis client and will be # raised unless handled by application code. If you want never to raise ConnectionError("No connection available.") # If the ``connection`` is actually ``None`` then that's a cue to make # a new connection to add to the pool. if connection is None: connection = self.make_connection() finally: if self._locked: try: self._lock.release() except Exception: pass self._locked = False try: # ensure this connection is connected to Redis connection.connect() # connections that the pool provides should be ready to send # a command. if not, the connection was either returned to the # pool before all data has been read or the socket has been # closed. either way, reconnect and verify everything is good. try: if connection.can_read(): raise ConnectionError("Connection has data") except (ConnectionError, TimeoutError, OSError): connection.disconnect() connection.connect() if connection.can_read(): raise ConnectionError("Connection not ready") except BaseException: # release the connection back to the pool so that we don't leak it self.release(connection) raise return connection def release(self, connection): "Releases the connection back to the pool." # Make sure we haven't changed process. self._checkpid() try: if self._in_maintenance: self._lock.acquire() self._locked = True if not self.owns_connection(connection): # pool doesn't own this connection. do not add it back # to the pool. instead add a None value which is a placeholder # that will cause the pool to recreate the connection if # its needed. connection.disconnect() self.pool.put_nowait(None) return if connection.should_reconnect(): connection.disconnect() # Put the connection back into the pool. try: self.pool.put_nowait(connection) except Full: # perhaps the pool has been reset() after a fork? regardless, # we don't want this connection pass finally: if self._locked: try: self._lock.release() except Exception: pass self._locked = False def disconnect(self, inuse_connections: bool = True): "Disconnects either all connections in the pool or just the free connections." self._checkpid() try: if self._in_maintenance: self._lock.acquire() self._locked = True if inuse_connections: connections = self._connections else: connections = self._get_free_connections() for connection in connections: connection.disconnect() finally: if self._locked: try: self._lock.release() except Exception: pass self._locked = False def _get_free_connections(self): with self._lock: return {conn for conn in self.pool.queue if conn} def _get_in_use_connections(self): with self._lock: # free connections connections_in_queue = {conn for conn in self.pool.queue if conn} # in self._connections we keep all created connections # so the ones that are not in the queue are the in use ones return { conn for conn in self._connections if conn not in connections_in_queue } def set_in_maintenance(self, in_maintenance: bool): """ Sets a flag that this Blocking ConnectionPool is in maintenance mode. This is used to prevent new connections from being created while we are in maintenance mode. The pool will be in maintenance mode only when we are processing a MOVING notification. """ self._in_maintenance = in_maintenance