first commit

backend/venv/lib/python3.9/site-packages/redis/asyncio/__init__.py

@@ -0,0 +1,64 @@
+from redis.asyncio.client import Redis, StrictRedis
+from redis.asyncio.cluster import RedisCluster
+from redis.asyncio.connection import (
+    BlockingConnectionPool,
+    Connection,
+    ConnectionPool,
+    SSLConnection,
+    UnixDomainSocketConnection,
+)
+from redis.asyncio.sentinel import (
+    Sentinel,
+    SentinelConnectionPool,
+    SentinelManagedConnection,
+    SentinelManagedSSLConnection,
+)
+from redis.asyncio.utils import from_url
+from redis.backoff import default_backoff
+from redis.exceptions import (
+    AuthenticationError,
+    AuthenticationWrongNumberOfArgsError,
+    BusyLoadingError,
+    ChildDeadlockedError,
+    ConnectionError,
+    DataError,
+    InvalidResponse,
+    OutOfMemoryError,
+    PubSubError,
+    ReadOnlyError,
+    RedisError,
+    ResponseError,
+    TimeoutError,
+    WatchError,
+)
+
+__all__ = [
+    "AuthenticationError",
+    "AuthenticationWrongNumberOfArgsError",
+    "BlockingConnectionPool",
+    "BusyLoadingError",
+    "ChildDeadlockedError",
+    "Connection",
+    "ConnectionError",
+    "ConnectionPool",
+    "DataError",
+    "from_url",
+    "default_backoff",
+    "InvalidResponse",
+    "PubSubError",
+    "OutOfMemoryError",
+    "ReadOnlyError",
+    "Redis",
+    "RedisCluster",
+    "RedisError",
+    "ResponseError",
+    "Sentinel",
+    "SentinelConnectionPool",
+    "SentinelManagedConnection",
+    "SentinelManagedSSLConnection",
+    "SSLConnection",
+    "StrictRedis",
+    "TimeoutError",
+    "UnixDomainSocketConnection",
+    "WatchError",
+]

backend/venv/lib/python3.9/site-packages/redis/asyncio/http/http_client.py

@@ -0,0 +1,265 @@
+import asyncio
+from abc import ABC, abstractmethod
+from concurrent.futures import ThreadPoolExecutor
+from typing import Any, Mapping, Optional, Union
+
+from redis.http.http_client import HttpClient, HttpResponse
+
+DEFAULT_USER_AGENT = "HttpClient/1.0 (+https://example.invalid)"
+DEFAULT_TIMEOUT = 30.0
+RETRY_STATUS_CODES = {429, 500, 502, 503, 504}
+
+
+class AsyncHTTPClient(ABC):
+    @abstractmethod
+    async def get(
+        self,
+        path: str,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        """
+        Invoke HTTP GET request."""
+        pass
+
+    @abstractmethod
+    async def delete(
+        self,
+        path: str,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        """
+        Invoke HTTP DELETE request."""
+        pass
+
+    @abstractmethod
+    async def post(
+        self,
+        path: str,
+        json_body: Optional[Any] = None,
+        data: Optional[Union[bytes, str]] = None,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        """
+        Invoke HTTP POST request."""
+        pass
+
+    @abstractmethod
+    async def put(
+        self,
+        path: str,
+        json_body: Optional[Any] = None,
+        data: Optional[Union[bytes, str]] = None,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        """
+        Invoke HTTP PUT request."""
+        pass
+
+    @abstractmethod
+    async def patch(
+        self,
+        path: str,
+        json_body: Optional[Any] = None,
+        data: Optional[Union[bytes, str]] = None,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        """
+        Invoke HTTP PATCH request."""
+        pass
+
+    @abstractmethod
+    async def request(
+        self,
+        method: str,
+        path: str,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        body: Optional[Union[bytes, str]] = None,
+        timeout: Optional[float] = None,
+    ) -> HttpResponse:
+        """
+        Invoke HTTP request with given method."""
+        pass
+
+
+class AsyncHTTPClientWrapper(AsyncHTTPClient):
+    """
+    An async wrapper around sync HTTP client with thread pool execution.
+    """
+
+    def __init__(self, client: HttpClient, max_workers: int = 10) -> None:
+        """
+        Initialize a new HTTP client instance.
+
+        Args:
+            client: Sync HTTP client instance.
+            max_workers: Maximum number of concurrent requests.
+
+        The client supports both regular HTTPS with server verification and mutual TLS
+        authentication. For server verification, provide CA certificate information via
+        ca_file, ca_path or ca_data. For mutual TLS, additionally provide a client
+        certificate and key via client_cert_file and client_key_file.
+        """
+        self.client = client
+        self._executor = ThreadPoolExecutor(max_workers=max_workers)
+
+    async def get(
+        self,
+        path: str,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        loop = asyncio.get_event_loop()
+        return await loop.run_in_executor(
+            self._executor, self.client.get, path, params, headers, timeout, expect_json
+        )
+
+    async def delete(
+        self,
+        path: str,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        loop = asyncio.get_event_loop()
+        return await loop.run_in_executor(
+            self._executor,
+            self.client.delete,
+            path,
+            params,
+            headers,
+            timeout,
+            expect_json,
+        )
+
+    async def post(
+        self,
+        path: str,
+        json_body: Optional[Any] = None,
+        data: Optional[Union[bytes, str]] = None,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        loop = asyncio.get_event_loop()
+        return await loop.run_in_executor(
+            self._executor,
+            self.client.post,
+            path,
+            json_body,
+            data,
+            params,
+            headers,
+            timeout,
+            expect_json,
+        )
+
+    async def put(
+        self,
+        path: str,
+        json_body: Optional[Any] = None,
+        data: Optional[Union[bytes, str]] = None,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        loop = asyncio.get_event_loop()
+        return await loop.run_in_executor(
+            self._executor,
+            self.client.put,
+            path,
+            json_body,
+            data,
+            params,
+            headers,
+            timeout,
+            expect_json,
+        )
+
+    async def patch(
+        self,
+        path: str,
+        json_body: Optional[Any] = None,
+        data: Optional[Union[bytes, str]] = None,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        timeout: Optional[float] = None,
+        expect_json: bool = True,
+    ) -> Union[HttpResponse, Any]:
+        loop = asyncio.get_event_loop()
+        return await loop.run_in_executor(
+            self._executor,
+            self.client.patch,
+            path,
+            json_body,
+            data,
+            params,
+            headers,
+            timeout,
+            expect_json,
+        )
+
+    async def request(
+        self,
+        method: str,
+        path: str,
+        params: Optional[
+            Mapping[str, Union[None, str, int, float, bool, list, tuple]]
+        ] = None,
+        headers: Optional[Mapping[str, str]] = None,
+        body: Optional[Union[bytes, str]] = None,
+        timeout: Optional[float] = None,
+    ) -> HttpResponse:
+        loop = asyncio.get_event_loop()
+        return await loop.run_in_executor(
+            self._executor,
+            self.client.request,
+            method,
+            path,
+            params,
+            headers,
+            body,
+            timeout,
+        )

backend/venv/lib/python3.9/site-packages/redis/asyncio/lock.py

@@ -0,0 +1,334 @@
+import asyncio
+import logging
+import threading
+import uuid
+from types import SimpleNamespace
+from typing import TYPE_CHECKING, Awaitable, Optional, Union
+
+from redis.exceptions import LockError, LockNotOwnedError
+from redis.typing import Number
+
+if TYPE_CHECKING:
+    from redis.asyncio import Redis, RedisCluster
+
+logger = logging.getLogger(__name__)
+
+
+class Lock:
+    """
+    A shared, distributed Lock. Using Redis for locking allows the Lock
+    to be shared across processes and/or machines.
+
+    It's left to the user to resolve deadlock issues and make sure
+    multiple clients play nicely together.
+    """
+
+    lua_release = None
+    lua_extend = None
+    lua_reacquire = None
+
+    # KEYS[1] - lock name
+    # ARGV[1] - token
+    # return 1 if the lock was released, otherwise 0
+    LUA_RELEASE_SCRIPT = """
+        local token = redis.call('get', KEYS[1])
+        if not token or token ~= ARGV[1] then
+            return 0
+        end
+        redis.call('del', KEYS[1])
+        return 1
+    """
+
+    # KEYS[1] - lock name
+    # ARGV[1] - token
+    # ARGV[2] - additional milliseconds
+    # ARGV[3] - "0" if the additional time should be added to the lock's
+    #           existing ttl or "1" if the existing ttl should be replaced
+    # return 1 if the locks time was extended, otherwise 0
+    LUA_EXTEND_SCRIPT = """
+        local token = redis.call('get', KEYS[1])
+        if not token or token ~= ARGV[1] then
+            return 0
+        end
+        local expiration = redis.call('pttl', KEYS[1])
+        if not expiration then
+            expiration = 0
+        end
+        if expiration < 0 then
+            return 0
+        end
+
+        local newttl = ARGV[2]
+        if ARGV[3] == "0" then
+            newttl = ARGV[2] + expiration
+        end
+        redis.call('pexpire', KEYS[1], newttl)
+        return 1
+    """
+
+    # KEYS[1] - lock name
+    # ARGV[1] - token
+    # ARGV[2] - milliseconds
+    # return 1 if the locks time was reacquired, otherwise 0
+    LUA_REACQUIRE_SCRIPT = """
+        local token = redis.call('get', KEYS[1])
+        if not token or token ~= ARGV[1] then
+            return 0
+        end
+        redis.call('pexpire', KEYS[1], ARGV[2])
+        return 1
+    """
+
+    def __init__(
+        self,
+        redis: Union["Redis", "RedisCluster"],
+        name: Union[str, bytes, memoryview],
+        timeout: Optional[float] = None,
+        sleep: float = 0.1,
+        blocking: bool = True,
+        blocking_timeout: Optional[Number] = None,
+        thread_local: bool = True,
+        raise_on_release_error: bool = True,
+    ):
+        """
+        Create a new Lock instance named ``name`` using the Redis client
+        supplied by ``redis``.
+
+        ``timeout`` indicates a maximum life for the lock in seconds.
+        By default, it will remain locked until release() is called.
+        ``timeout`` can be specified as a float or integer, both representing
+        the number of seconds to wait.
+
+        ``sleep`` indicates the amount of time to sleep in seconds 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.
+
+        ``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.
+
+        ``raise_on_release_error`` indicates whether to raise an exception when
+        the lock is no longer owned when exiting the context manager. By default,
+        this is True, meaning an exception will be raised. If False, the warning
+        will be logged and the exception will be suppressed.
+
+        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.
+        """
+        self.redis = redis
+        self.name = name
+        self.timeout = timeout
+        self.sleep = sleep
+        self.blocking = blocking
+        self.blocking_timeout = blocking_timeout
+        self.thread_local = bool(thread_local)
+        self.local = threading.local() if self.thread_local else SimpleNamespace()
+        self.raise_on_release_error = raise_on_release_error
+        self.local.token = None
+        self.register_scripts()
+
+    def register_scripts(self):
+        cls = self.__class__
+        client = self.redis
+        if cls.lua_release is None:
+            cls.lua_release = client.register_script(cls.LUA_RELEASE_SCRIPT)
+        if cls.lua_extend is None:
+            cls.lua_extend = client.register_script(cls.LUA_EXTEND_SCRIPT)
+        if cls.lua_reacquire is None:
+            cls.lua_reacquire = client.register_script(cls.LUA_REACQUIRE_SCRIPT)
+
+    async def __aenter__(self):
+        if await self.acquire():
+            return self
+        raise LockError("Unable to acquire lock within the time specified")
+
+    async def __aexit__(self, exc_type, exc_value, traceback):
+        try:
+            await self.release()
+        except LockError:
+            if self.raise_on_release_error:
+                raise
+            logger.warning(
+                "Lock was unlocked or no longer owned when exiting context manager."
+            )
+
+    async def acquire(
+        self,
+        blocking: Optional[bool] = None,
+        blocking_timeout: Optional[Number] = None,
+        token: Optional[Union[str, bytes]] = None,
+    ):
+        """
+        Use Redis to hold a shared, distributed lock named ``name``.
+        Returns True once the lock is acquired.
+
+        If ``blocking`` is False, always return immediately. If the lock
+        was acquired, return True, otherwise return False.
+
+        ``blocking_timeout`` specifies the maximum number of seconds to
+        wait trying to acquire the lock.
+
+        ``token`` specifies the token value to be used. If provided, token
+        must be a bytes object or a string that can be encoded to a bytes
+        object with the default encoding. If a token isn't specified, a UUID
+        will be generated.
+        """
+        sleep = self.sleep
+        if token is None:
+            token = uuid.uuid1().hex.encode()
+        else:
+            try:
+                encoder = self.redis.connection_pool.get_encoder()
+            except AttributeError:
+                # Cluster
+                encoder = self.redis.get_encoder()
+            token = encoder.encode(token)
+        if blocking is None:
+            blocking = self.blocking
+        if blocking_timeout is None:
+            blocking_timeout = self.blocking_timeout
+        stop_trying_at = None
+        if blocking_timeout is not None:
+            stop_trying_at = asyncio.get_running_loop().time() + blocking_timeout
+        while True:
+            if await self.do_acquire(token):
+                self.local.token = token
+                return True
+            if not blocking:
+                return False
+            next_try_at = asyncio.get_running_loop().time() + sleep
+            if stop_trying_at is not None and next_try_at > stop_trying_at:
+                return False
+            await asyncio.sleep(sleep)
+
+    async def do_acquire(self, token: Union[str, bytes]) -> bool:
+        if self.timeout:
+            # convert to milliseconds
+            timeout = int(self.timeout * 1000)
+        else:
+            timeout = None
+        if await self.redis.set(self.name, token, nx=True, px=timeout):
+            return True
+        return False
+
+    async def locked(self) -> bool:
+        """
+        Returns True if this key is locked by any process, otherwise False.
+        """
+        return await self.redis.get(self.name) is not None
+
+    async def owned(self) -> bool:
+        """
+        Returns True if this key is locked by this lock, otherwise False.
+        """
+        stored_token = await self.redis.get(self.name)
+        # need to always compare bytes to bytes
+        # TODO: this can be simplified when the context manager is finished
+        if stored_token and not isinstance(stored_token, bytes):
+            try:
+                encoder = self.redis.connection_pool.get_encoder()
+            except AttributeError:
+                # Cluster
+                encoder = self.redis.get_encoder()
+            stored_token = encoder.encode(stored_token)
+        return self.local.token is not None and stored_token == self.local.token
+
+    def release(self) -> Awaitable[None]:
+        """Releases the already acquired lock"""
+        expected_token = self.local.token
+        if expected_token is None:
+            raise LockError(
+                "Cannot release a lock that's not owned or is already unlocked.",
+                lock_name=self.name,
+            )
+        self.local.token = None
+        return self.do_release(expected_token)
+
+    async def do_release(self, expected_token: bytes) -> None:
+        if not bool(
+            await self.lua_release(
+                keys=[self.name], args=[expected_token], client=self.redis
+            )
+        ):
+            raise LockNotOwnedError("Cannot release a lock that's no longer owned")
+
+    def extend(
+        self, additional_time: Number, replace_ttl: bool = False
+    ) -> Awaitable[bool]:
+        """
+        Adds more time to an already acquired lock.
+
+        ``additional_time`` can be specified as an integer or a float, both
+        representing the number of seconds to add.
+
+        ``replace_ttl`` if False (the default), add `additional_time` to
+        the lock's existing ttl. If True, replace the lock's ttl with
+        `additional_time`.
+        """
+        if self.local.token is None:
+            raise LockError("Cannot extend an unlocked lock")
+        if self.timeout is None:
+            raise LockError("Cannot extend a lock with no timeout")
+        return self.do_extend(additional_time, replace_ttl)
+
+    async def do_extend(self, additional_time, replace_ttl) -> bool:
+        additional_time = int(additional_time * 1000)
+        if not bool(
+            await self.lua_extend(
+                keys=[self.name],
+                args=[self.local.token, additional_time, replace_ttl and "1" or "0"],
+                client=self.redis,
+            )
+        ):
+            raise LockNotOwnedError("Cannot extend a lock that's no longer owned")
+        return True
+
+    def reacquire(self) -> Awaitable[bool]:
+        """
+        Resets a TTL of an already acquired lock back to a timeout value.
+        """
+        if self.local.token is None:
+            raise LockError("Cannot reacquire an unlocked lock")
+        if self.timeout is None:
+            raise LockError("Cannot reacquire a lock with no timeout")
+        return self.do_reacquire()
+
+    async def do_reacquire(self) -> bool:
+        timeout = int(self.timeout * 1000)
+        if not bool(
+            await self.lua_reacquire(
+                keys=[self.name], args=[self.local.token, timeout], client=self.redis
+            )
+        ):
+            raise LockNotOwnedError("Cannot reacquire a lock that's no longer owned")
+        return True

backend/venv/lib/python3.9/site-packages/redis/asyncio/multidb/client.py

@@ -0,0 +1,530 @@
+import asyncio
+import logging
+from typing import Any, Awaitable, Callable, Coroutine, List, Optional, Union
+
+from redis.asyncio.client import PubSubHandler
+from redis.asyncio.multidb.command_executor import DefaultCommandExecutor
+from redis.asyncio.multidb.config import DEFAULT_GRACE_PERIOD, MultiDbConfig
+from redis.asyncio.multidb.database import AsyncDatabase, Databases
+from redis.asyncio.multidb.failure_detector import AsyncFailureDetector
+from redis.asyncio.multidb.healthcheck import HealthCheck, HealthCheckPolicy
+from redis.background import BackgroundScheduler
+from redis.commands import AsyncCoreCommands, AsyncRedisModuleCommands
+from redis.multidb.circuit import CircuitBreaker
+from redis.multidb.circuit import State as CBState
+from redis.multidb.exception import NoValidDatabaseException, UnhealthyDatabaseException
+from redis.typing import ChannelT, EncodableT, KeyT
+from redis.utils import experimental
+
+logger = logging.getLogger(__name__)
+
+
+@experimental
+class MultiDBClient(AsyncRedisModuleCommands, AsyncCoreCommands):
+    """
+    Client that operates on multiple logical Redis databases.
+    Should be used in Active-Active database setups.
+    """
+
+    def __init__(self, config: MultiDbConfig):
+        self._databases = config.databases()
+        self._health_checks = config.default_health_checks()
+
+        if config.health_checks is not None:
+            self._health_checks.extend(config.health_checks)
+
+        self._health_check_interval = config.health_check_interval
+        self._health_check_policy: HealthCheckPolicy = config.health_check_policy.value(
+            config.health_check_probes, config.health_check_delay
+        )
+        self._failure_detectors = config.default_failure_detectors()
+
+        if config.failure_detectors is not None:
+            self._failure_detectors.extend(config.failure_detectors)
+
+        self._failover_strategy = (
+            config.default_failover_strategy()
+            if config.failover_strategy is None
+            else config.failover_strategy
+        )
+        self._failover_strategy.set_databases(self._databases)
+        self._auto_fallback_interval = config.auto_fallback_interval
+        self._event_dispatcher = config.event_dispatcher
+        self._command_retry = config.command_retry
+        self._command_retry.update_supported_errors([ConnectionRefusedError])
+        self.command_executor = DefaultCommandExecutor(
+            failure_detectors=self._failure_detectors,
+            databases=self._databases,
+            command_retry=self._command_retry,
+            failover_strategy=self._failover_strategy,
+            failover_attempts=config.failover_attempts,
+            failover_delay=config.failover_delay,
+            event_dispatcher=self._event_dispatcher,
+            auto_fallback_interval=self._auto_fallback_interval,
+        )
+        self.initialized = False
+        self._hc_lock = asyncio.Lock()
+        self._bg_scheduler = BackgroundScheduler()
+        self._config = config
+        self._recurring_hc_task = None
+        self._hc_tasks = []
+        self._half_open_state_task = None
+
+    async def __aenter__(self: "MultiDBClient") -> "MultiDBClient":
+        if not self.initialized:
+            await self.initialize()
+        return self
+
+    async def __aexit__(self, exc_type, exc_value, traceback):
+        if self._recurring_hc_task:
+            self._recurring_hc_task.cancel()
+        if self._half_open_state_task:
+            self._half_open_state_task.cancel()
+        for hc_task in self._hc_tasks:
+            hc_task.cancel()
+
+    async def initialize(self):
+        """
+        Perform initialization of databases to define their initial state.
+        """
+
+        async def raise_exception_on_failed_hc(error):
+            raise error
+
+        # Initial databases check to define initial state
+        await self._check_databases_health(on_error=raise_exception_on_failed_hc)
+
+        # Starts recurring health checks on the background.
+        self._recurring_hc_task = asyncio.create_task(
+            self._bg_scheduler.run_recurring_async(
+                self._health_check_interval,
+                self._check_databases_health,
+            )
+        )
+
+        is_active_db_found = False
+
+        for database, weight in self._databases:
+            # Set on state changed callback for each circuit.
+            database.circuit.on_state_changed(self._on_circuit_state_change_callback)
+
+            # Set states according to a weights and circuit state
+            if database.circuit.state == CBState.CLOSED and not is_active_db_found:
+                await self.command_executor.set_active_database(database)
+                is_active_db_found = True
+
+        if not is_active_db_found:
+            raise NoValidDatabaseException(
+                "Initial connection failed - no active database found"
+            )
+
+        self.initialized = True
+
+    def get_databases(self) -> Databases:
+        """
+        Returns a sorted (by weight) list of all databases.
+        """
+        return self._databases
+
+    async def set_active_database(self, database: AsyncDatabase) -> None:
+        """
+        Promote one of the existing databases to become an active.
+        """
+        exists = None
+
+        for existing_db, _ in self._databases:
+            if existing_db == database:
+                exists = True
+                break
+
+        if not exists:
+            raise ValueError("Given database is not a member of database list")
+
+        await self._check_db_health(database)
+
+        if database.circuit.state == CBState.CLOSED:
+            highest_weighted_db, _ = self._databases.get_top_n(1)[0]
+            await self.command_executor.set_active_database(database)
+            return
+
+        raise NoValidDatabaseException(
+            "Cannot set active database, database is unhealthy"
+        )
+
+    async def add_database(self, database: AsyncDatabase):
+        """
+        Adds a new database to the database list.
+        """
+        for existing_db, _ in self._databases:
+            if existing_db == database:
+                raise ValueError("Given database already exists")
+
+        await self._check_db_health(database)
+
+        highest_weighted_db, highest_weight = self._databases.get_top_n(1)[0]
+        self._databases.add(database, database.weight)
+        await self._change_active_database(database, highest_weighted_db)
+
+    async def _change_active_database(
+        self, new_database: AsyncDatabase, highest_weight_database: AsyncDatabase
+    ):
+        if (
+            new_database.weight > highest_weight_database.weight
+            and new_database.circuit.state == CBState.CLOSED
+        ):
+            await self.command_executor.set_active_database(new_database)
+
+    async def remove_database(self, database: AsyncDatabase):
+        """
+        Removes a database from the database list.
+        """
+        weight = self._databases.remove(database)
+        highest_weighted_db, highest_weight = self._databases.get_top_n(1)[0]
+
+        if (
+            highest_weight <= weight
+            and highest_weighted_db.circuit.state == CBState.CLOSED
+        ):
+            await self.command_executor.set_active_database(highest_weighted_db)
+
+    async def update_database_weight(self, database: AsyncDatabase, weight: float):
+        """
+        Updates a database from the database list.
+        """
+        exists = None
+
+        for existing_db, _ in self._databases:
+            if existing_db == database:
+                exists = True
+                break
+
+        if not exists:
+            raise ValueError("Given database is not a member of database list")
+
+        highest_weighted_db, highest_weight = self._databases.get_top_n(1)[0]
+        self._databases.update_weight(database, weight)
+        database.weight = weight
+        await self._change_active_database(database, highest_weighted_db)
+
+    def add_failure_detector(self, failure_detector: AsyncFailureDetector):
+        """
+        Adds a new failure detector to the database.
+        """
+        self._failure_detectors.append(failure_detector)
+
+    async def add_health_check(self, healthcheck: HealthCheck):
+        """
+        Adds a new health check to the database.
+        """
+        async with self._hc_lock:
+            self._health_checks.append(healthcheck)
+
+    async def execute_command(self, *args, **options):
+        """
+        Executes a single command and return its result.
+        """
+        if not self.initialized:
+            await self.initialize()
+
+        return await self.command_executor.execute_command(*args, **options)
+
+    def pipeline(self):
+        """
+        Enters into pipeline mode of the client.
+        """
+        return Pipeline(self)
+
+    async def transaction(
+        self,
+        func: Callable[["Pipeline"], Union[Any, Awaitable[Any]]],
+        *watches: KeyT,
+        shard_hint: Optional[str] = None,
+        value_from_callable: bool = False,
+        watch_delay: Optional[float] = None,
+    ):
+        """
+        Executes callable as transaction.
+        """
+        if not self.initialized:
+            await self.initialize()
+
+        return await self.command_executor.execute_transaction(
+            func,
+            *watches,
+            shard_hint=shard_hint,
+            value_from_callable=value_from_callable,
+            watch_delay=watch_delay,
+        )
+
+    async 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.
+        """
+        if not self.initialized:
+            await self.initialize()
+
+        return PubSub(self, **kwargs)
+
+    async def _check_databases_health(
+        self,
+        on_error: Optional[Callable[[Exception], Coroutine[Any, Any, None]]] = None,
+    ):
+        """
+        Runs health checks as a recurring task.
+        Runs health checks against all databases.
+        """
+        try:
+            self._hc_tasks = [
+                asyncio.create_task(self._check_db_health(database))
+                for database, _ in self._databases
+            ]
+            results = await asyncio.wait_for(
+                asyncio.gather(
+                    *self._hc_tasks,
+                    return_exceptions=True,
+                ),
+                timeout=self._health_check_interval,
+            )
+        except asyncio.TimeoutError:
+            raise asyncio.TimeoutError(
+                "Health check execution exceeds health_check_interval"
+            )
+
+        for result in results:
+            if isinstance(result, UnhealthyDatabaseException):
+                unhealthy_db = result.database
+                unhealthy_db.circuit.state = CBState.OPEN
+
+                logger.exception(
+                    "Health check failed, due to exception",
+                    exc_info=result.original_exception,
+                )
+
+                if on_error:
+                    on_error(result.original_exception)
+
+    async def _check_db_health(self, database: AsyncDatabase) -> bool:
+        """
+        Runs health checks on the given database until first failure.
+        """
+        # Health check will setup circuit state
+        is_healthy = await self._health_check_policy.execute(
+            self._health_checks, database
+        )
+
+        if not is_healthy:
+            if database.circuit.state != CBState.OPEN:
+                database.circuit.state = CBState.OPEN
+            return is_healthy
+        elif is_healthy and database.circuit.state != CBState.CLOSED:
+            database.circuit.state = CBState.CLOSED
+
+        return is_healthy
+
+    def _on_circuit_state_change_callback(
+        self, circuit: CircuitBreaker, old_state: CBState, new_state: CBState
+    ):
+        loop = asyncio.get_running_loop()
+
+        if new_state == CBState.HALF_OPEN:
+            self._half_open_state_task = asyncio.create_task(
+                self._check_db_health(circuit.database)
+            )
+            return
+
+        if old_state == CBState.CLOSED and new_state == CBState.OPEN:
+            loop.call_later(DEFAULT_GRACE_PERIOD, _half_open_circuit, circuit)
+
+    async def aclose(self):
+        if self.command_executor.active_database:
+            await self.command_executor.active_database.client.aclose()
+
+
+def _half_open_circuit(circuit: CircuitBreaker):
+    circuit.state = CBState.HALF_OPEN
+
+
+class Pipeline(AsyncRedisModuleCommands, AsyncCoreCommands):
+    """
+    Pipeline implementation for multiple logical Redis databases.
+    """
+
+    def __init__(self, client: MultiDBClient):
+        self._command_stack = []
+        self._client = client
+
+    async def __aenter__(self: "Pipeline") -> "Pipeline":
+        return self
+
+    async def __aexit__(self, exc_type, exc_value, traceback):
+        await self.reset()
+        await self._client.__aexit__(exc_type, exc_value, traceback)
+
+    def __await__(self):
+        return self._async_self().__await__()
+
+    async def _async_self(self):
+        return self
+
+    def __len__(self) -> int:
+        return len(self._command_stack)
+
+    def __bool__(self) -> bool:
+        """Pipeline instances should always evaluate to True"""
+        return True
+
+    async def reset(self) -> None:
+        self._command_stack = []
+
+    async def aclose(self) -> None:
+        """Close the pipeline"""
+        await self.reset()
+
+    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_command(self, *args, **kwargs):
+        """Adds a command to the stack"""
+        return self.pipeline_execute_command(*args, **kwargs)
+
+    async def execute(self) -> List[Any]:
+        """Execute all the commands in the current pipeline"""
+        if not self._client.initialized:
+            await self._client.initialize()
+
+        try:
+            return await self._client.command_executor.execute_pipeline(
+                tuple(self._command_stack)
+            )
+        finally:
+            await self.reset()
+
+
+class PubSub:
+    """
+    PubSub object for multi database client.
+    """
+
+    def __init__(self, client: MultiDBClient, **kwargs):
+        """Initialize the PubSub object for a multi-database client.
+
+        Args:
+            client: MultiDBClient instance to use for pub/sub operations
+            **kwargs: Additional keyword arguments to pass to the underlying pubsub implementation
+        """
+
+        self._client = client
+        self._client.command_executor.pubsub(**kwargs)
+
+    async def __aenter__(self) -> "PubSub":
+        return self
+
+    async def __aexit__(self, exc_type, exc_value, traceback) -> None:
+        await self.aclose()
+
+    async def aclose(self):
+        return await self._client.command_executor.execute_pubsub_method("aclose")
+
+    @property
+    def subscribed(self) -> bool:
+        return self._client.command_executor.active_pubsub.subscribed
+
+    async def execute_command(self, *args: EncodableT):
+        return await self._client.command_executor.execute_pubsub_method(
+            "execute_command", *args
+        )
+
+    async def psubscribe(self, *args: ChannelT, **kwargs: PubSubHandler):
+        """
+        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()``.
+        """
+        return await self._client.command_executor.execute_pubsub_method(
+            "psubscribe", *args, **kwargs
+        )
+
+    async def punsubscribe(self, *args: ChannelT):
+        """
+        Unsubscribe from the supplied patterns. If empty, unsubscribe from
+        all patterns.
+        """
+        return await self._client.command_executor.execute_pubsub_method(
+            "punsubscribe", *args
+        )
+
+    async def subscribe(self, *args: ChannelT, **kwargs: Callable):
+        """
+        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()``.
+        """
+        return await self._client.command_executor.execute_pubsub_method(
+            "subscribe", *args, **kwargs
+        )
+
+    async def unsubscribe(self, *args):
+        """
+        Unsubscribe from the supplied channels. If empty, unsubscribe from
+        all channels
+        """
+        return await self._client.command_executor.execute_pubsub_method(
+            "unsubscribe", *args
+        )
+
+    async def get_message(
+        self, ignore_subscribe_messages: bool = False, timeout: Optional[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.
+        """
+        return await self._client.command_executor.execute_pubsub_method(
+            "get_message",
+            ignore_subscribe_messages=ignore_subscribe_messages,
+            timeout=timeout,
+        )
+
+    async def run(
+        self,
+        *,
+        exception_handler=None,
+        poll_timeout: float = 1.0,
+    ) -> None:
+        """Process pub/sub messages using registered callbacks.
+
+        This is the equivalent of :py:meth:`redis.PubSub.run_in_thread` in
+        redis-py, but it is a coroutine. To launch it as a separate task, use
+        ``asyncio.create_task``:
+
+            >>> task = asyncio.create_task(pubsub.run())
+
+        To shut it down, use asyncio cancellation:
+
+            >>> task.cancel()
+            >>> await task
+        """
+        return await self._client.command_executor.execute_pubsub_run(
+            sleep_time=poll_timeout, exception_handler=exception_handler, pubsub=self
+        )

backend/venv/lib/python3.9/site-packages/redis/asyncio/multidb/command_executor.py

@@ -0,0 +1,339 @@
+from abc import abstractmethod
+from asyncio import iscoroutinefunction
+from datetime import datetime
+from typing import Any, Awaitable, Callable, List, Optional, Union
+
+from redis.asyncio import RedisCluster
+from redis.asyncio.client import Pipeline, PubSub
+from redis.asyncio.multidb.database import AsyncDatabase, Database, Databases
+from redis.asyncio.multidb.event import (
+    AsyncActiveDatabaseChanged,
+    CloseConnectionOnActiveDatabaseChanged,
+    RegisterCommandFailure,
+    ResubscribeOnActiveDatabaseChanged,
+)
+from redis.asyncio.multidb.failover import (
+    DEFAULT_FAILOVER_ATTEMPTS,
+    DEFAULT_FAILOVER_DELAY,
+    AsyncFailoverStrategy,
+    DefaultFailoverStrategyExecutor,
+    FailoverStrategyExecutor,
+)
+from redis.asyncio.multidb.failure_detector import AsyncFailureDetector
+from redis.asyncio.retry import Retry
+from redis.event import AsyncOnCommandsFailEvent, EventDispatcherInterface
+from redis.multidb.circuit import State as CBState
+from redis.multidb.command_executor import BaseCommandExecutor, CommandExecutor
+from redis.multidb.config import DEFAULT_AUTO_FALLBACK_INTERVAL
+from redis.typing import KeyT
+
+
+class AsyncCommandExecutor(CommandExecutor):
+    @property
+    @abstractmethod
+    def databases(self) -> Databases:
+        """Returns a list of databases."""
+        pass
+
+    @property
+    @abstractmethod
+    def failure_detectors(self) -> List[AsyncFailureDetector]:
+        """Returns a list of failure detectors."""
+        pass
+
+    @abstractmethod
+    def add_failure_detector(self, failure_detector: AsyncFailureDetector) -> None:
+        """Adds a new failure detector to the list of failure detectors."""
+        pass
+
+    @property
+    @abstractmethod
+    def active_database(self) -> Optional[AsyncDatabase]:
+        """Returns currently active database."""
+        pass
+
+    @abstractmethod
+    async def set_active_database(self, database: AsyncDatabase) -> None:
+        """Sets the currently active database."""
+        pass
+
+    @property
+    @abstractmethod
+    def active_pubsub(self) -> Optional[PubSub]:
+        """Returns currently active pubsub."""
+        pass
+
+    @active_pubsub.setter
+    @abstractmethod
+    def active_pubsub(self, pubsub: PubSub) -> None:
+        """Sets currently active pubsub."""
+        pass
+
+    @property
+    @abstractmethod
+    def failover_strategy_executor(self) -> FailoverStrategyExecutor:
+        """Returns failover strategy executor."""
+        pass
+
+    @property
+    @abstractmethod
+    def command_retry(self) -> Retry:
+        """Returns command retry object."""
+        pass
+
+    @abstractmethod
+    async def pubsub(self, **kwargs):
+        """Initializes a PubSub object on a currently active database"""
+        pass
+
+    @abstractmethod
+    async def execute_command(self, *args, **options):
+        """Executes a command and returns the result."""
+        pass
+
+    @abstractmethod
+    async def execute_pipeline(self, command_stack: tuple):
+        """Executes a stack of commands in pipeline."""
+        pass
+
+    @abstractmethod
+    async def execute_transaction(
+        self, transaction: Callable[[Pipeline], None], *watches, **options
+    ):
+        """Executes a transaction block wrapped in callback."""
+        pass
+
+    @abstractmethod
+    async def execute_pubsub_method(self, method_name: str, *args, **kwargs):
+        """Executes a given method on active pub/sub."""
+        pass
+
+    @abstractmethod
+    async def execute_pubsub_run(self, sleep_time: float, **kwargs) -> Any:
+        """Executes pub/sub run in a thread."""
+        pass
+
+
+class DefaultCommandExecutor(BaseCommandExecutor, AsyncCommandExecutor):
+    def __init__(
+        self,
+        failure_detectors: List[AsyncFailureDetector],
+        databases: Databases,
+        command_retry: Retry,
+        failover_strategy: AsyncFailoverStrategy,
+        event_dispatcher: EventDispatcherInterface,
+        failover_attempts: int = DEFAULT_FAILOVER_ATTEMPTS,
+        failover_delay: float = DEFAULT_FAILOVER_DELAY,
+        auto_fallback_interval: float = DEFAULT_AUTO_FALLBACK_INTERVAL,
+    ):
+        """
+        Initialize the DefaultCommandExecutor instance.
+
+        Args:
+            failure_detectors: List of failure detector instances to monitor database health
+            databases: Collection of available databases to execute commands on
+            command_retry: Retry policy for failed command execution
+            failover_strategy: Strategy for handling database failover
+            event_dispatcher: Interface for dispatching events
+            failover_attempts: Number of failover attempts
+            failover_delay: Delay between failover attempts
+            auto_fallback_interval: Time interval in seconds between attempts to fall back to a primary database
+        """
+        super().__init__(auto_fallback_interval)
+
+        for fd in failure_detectors:
+            fd.set_command_executor(command_executor=self)
+
+        self._databases = databases
+        self._failure_detectors = failure_detectors
+        self._command_retry = command_retry
+        self._failover_strategy_executor = DefaultFailoverStrategyExecutor(
+            failover_strategy, failover_attempts, failover_delay
+        )
+        self._event_dispatcher = event_dispatcher
+        self._active_database: Optional[Database] = None
+        self._active_pubsub: Optional[PubSub] = None
+        self._active_pubsub_kwargs = {}
+        self._setup_event_dispatcher()
+        self._schedule_next_fallback()
+
+    @property
+    def databases(self) -> Databases:
+        return self._databases
+
+    @property
+    def failure_detectors(self) -> List[AsyncFailureDetector]:
+        return self._failure_detectors
+
+    def add_failure_detector(self, failure_detector: AsyncFailureDetector) -> None:
+        self._failure_detectors.append(failure_detector)
+
+    @property
+    def active_database(self) -> Optional[AsyncDatabase]:
+        return self._active_database
+
+    async def set_active_database(self, database: AsyncDatabase) -> None:
+        old_active = self._active_database
+        self._active_database = database
+
+        if old_active is not None and old_active is not database:
+            await self._event_dispatcher.dispatch_async(
+                AsyncActiveDatabaseChanged(
+                    old_active,
+                    self._active_database,
+                    self,
+                    **self._active_pubsub_kwargs,
+                )
+            )
+
+    @property
+    def active_pubsub(self) -> Optional[PubSub]:
+        return self._active_pubsub
+
+    @active_pubsub.setter
+    def active_pubsub(self, pubsub: PubSub) -> None:
+        self._active_pubsub = pubsub
+
+    @property
+    def failover_strategy_executor(self) -> FailoverStrategyExecutor:
+        return self._failover_strategy_executor
+
+    @property
+    def command_retry(self) -> Retry:
+        return self._command_retry
+
+    def pubsub(self, **kwargs):
+        if self._active_pubsub is None:
+            if isinstance(self._active_database.client, RedisCluster):
+                raise ValueError("PubSub is not supported for RedisCluster")
+
+            self._active_pubsub = self._active_database.client.pubsub(**kwargs)
+            self._active_pubsub_kwargs = kwargs
+
+    async def execute_command(self, *args, **options):
+        async def callback():
+            response = await self._active_database.client.execute_command(
+                *args, **options
+            )
+            await self._register_command_execution(args)
+            return response
+
+        return await self._execute_with_failure_detection(callback, args)
+
+    async def execute_pipeline(self, command_stack: tuple):
+        async def callback():
+            async with self._active_database.client.pipeline() as pipe:
+                for command, options in command_stack:
+                    pipe.execute_command(*command, **options)
+
+                response = await pipe.execute()
+                await self._register_command_execution(command_stack)
+                return response
+
+        return await self._execute_with_failure_detection(callback, command_stack)
+
+    async def execute_transaction(
+        self,
+        func: Callable[["Pipeline"], Union[Any, Awaitable[Any]]],
+        *watches: KeyT,
+        shard_hint: Optional[str] = None,
+        value_from_callable: bool = False,
+        watch_delay: Optional[float] = None,
+    ):
+        async def callback():
+            response = await self._active_database.client.transaction(
+                func,
+                *watches,
+                shard_hint=shard_hint,
+                value_from_callable=value_from_callable,
+                watch_delay=watch_delay,
+            )
+            await self._register_command_execution(())
+            return response
+
+        return await self._execute_with_failure_detection(callback)
+
+    async def execute_pubsub_method(self, method_name: str, *args, **kwargs):
+        async def callback():
+            method = getattr(self.active_pubsub, method_name)
+            if iscoroutinefunction(method):
+                response = await method(*args, **kwargs)
+            else:
+                response = method(*args, **kwargs)
+
+            await self._register_command_execution(args)
+            return response
+
+        return await self._execute_with_failure_detection(callback, *args)
+
+    async def execute_pubsub_run(
+        self, sleep_time: float, exception_handler=None, pubsub=None
+    ) -> Any:
+        async def callback():
+            return await self._active_pubsub.run(
+                poll_timeout=sleep_time,
+                exception_handler=exception_handler,
+                pubsub=pubsub,
+            )
+
+        return await self._execute_with_failure_detection(callback)
+
+    async def _execute_with_failure_detection(
+        self, callback: Callable, cmds: tuple = ()
+    ):
+        """
+        Execute a commands execution callback with failure detection.
+        """
+
+        async def wrapper():
+            # On each retry we need to check active database as it might change.
+            await self._check_active_database()
+            return await callback()
+
+        return await self._command_retry.call_with_retry(
+            lambda: wrapper(),
+            lambda error: self._on_command_fail(error, *cmds),
+        )
+
+    async def _check_active_database(self):
+        """
+        Checks if active a database needs to be updated.
+        """
+        if (
+            self._active_database is None
+            or self._active_database.circuit.state != CBState.CLOSED
+            or (
+                self._auto_fallback_interval != DEFAULT_AUTO_FALLBACK_INTERVAL
+                and self._next_fallback_attempt <= datetime.now()
+            )
+        ):
+            await self.set_active_database(
+                await self._failover_strategy_executor.execute()
+            )
+            self._schedule_next_fallback()
+
+    async def _on_command_fail(self, error, *args):
+        await self._event_dispatcher.dispatch_async(
+            AsyncOnCommandsFailEvent(args, error)
+        )
+
+    async def _register_command_execution(self, cmd: tuple):
+        for detector in self._failure_detectors:
+            await detector.register_command_execution(cmd)
+
+    def _setup_event_dispatcher(self):
+        """
+        Registers necessary listeners.
+        """
+        failure_listener = RegisterCommandFailure(self._failure_detectors)
+        resubscribe_listener = ResubscribeOnActiveDatabaseChanged()
+        close_connection_listener = CloseConnectionOnActiveDatabaseChanged()
+        self._event_dispatcher.register_listeners(
+            {
+                AsyncOnCommandsFailEvent: [failure_listener],
+                AsyncActiveDatabaseChanged: [
+                    close_connection_listener,
+                    resubscribe_listener,
+                ],
+            }
+        )

backend/venv/lib/python3.9/site-packages/redis/asyncio/multidb/config.py

@@ -0,0 +1,210 @@
+from dataclasses import dataclass, field
+from typing import List, Optional, Type, Union
+
+import pybreaker
+
+from redis.asyncio import ConnectionPool, Redis, RedisCluster
+from redis.asyncio.multidb.database import Database, Databases
+from redis.asyncio.multidb.failover import (
+    DEFAULT_FAILOVER_ATTEMPTS,
+    DEFAULT_FAILOVER_DELAY,
+    AsyncFailoverStrategy,
+    WeightBasedFailoverStrategy,
+)
+from redis.asyncio.multidb.failure_detector import (
+    AsyncFailureDetector,
+    FailureDetectorAsyncWrapper,
+)
+from redis.asyncio.multidb.healthcheck import (
+    DEFAULT_HEALTH_CHECK_DELAY,
+    DEFAULT_HEALTH_CHECK_INTERVAL,
+    DEFAULT_HEALTH_CHECK_POLICY,
+    DEFAULT_HEALTH_CHECK_PROBES,
+    HealthCheck,
+    HealthCheckPolicies,
+    PingHealthCheck,
+)
+from redis.asyncio.retry import Retry
+from redis.backoff import ExponentialWithJitterBackoff, NoBackoff
+from redis.data_structure import WeightedList
+from redis.event import EventDispatcher, EventDispatcherInterface
+from redis.multidb.circuit import (
+    DEFAULT_GRACE_PERIOD,
+    CircuitBreaker,
+    PBCircuitBreakerAdapter,
+)
+from redis.multidb.failure_detector import (
+    DEFAULT_FAILURE_RATE_THRESHOLD,
+    DEFAULT_FAILURES_DETECTION_WINDOW,
+    DEFAULT_MIN_NUM_FAILURES,
+    CommandFailureDetector,
+)
+
+DEFAULT_AUTO_FALLBACK_INTERVAL = 120
+
+
+def default_event_dispatcher() -> EventDispatcherInterface:
+    return EventDispatcher()
+
+
+@dataclass
+class DatabaseConfig:
+    """
+    Dataclass representing the configuration for a database connection.
+
+    This class is used to store configuration settings for a database connection,
+    including client options, connection sourcing details, circuit breaker settings,
+    and cluster-specific properties. It provides a structure for defining these
+    attributes and allows for the creation of customized configurations for various
+    database setups.
+
+    Attributes:
+        weight (float): Weight of the database to define the active one.
+        client_kwargs (dict): Additional parameters for the database client connection.
+        from_url (Optional[str]): Redis URL way of connecting to the database.
+        from_pool (Optional[ConnectionPool]): A pre-configured connection pool to use.
+        circuit (Optional[CircuitBreaker]): Custom circuit breaker implementation.
+        grace_period (float): Grace period after which we need to check if the circuit could be closed again.
+        health_check_url (Optional[str]): URL for health checks. Cluster FQDN is typically used
+            on public Redis Enterprise endpoints.
+
+    Methods:
+        default_circuit_breaker:
+            Generates and returns a default CircuitBreaker instance adapted for use.
+    """
+
+    weight: float = 1.0
+    client_kwargs: dict = field(default_factory=dict)
+    from_url: Optional[str] = None
+    from_pool: Optional[ConnectionPool] = None
+    circuit: Optional[CircuitBreaker] = None
+    grace_period: float = DEFAULT_GRACE_PERIOD
+    health_check_url: Optional[str] = None
+
+    def default_circuit_breaker(self) -> CircuitBreaker:
+        circuit_breaker = pybreaker.CircuitBreaker(reset_timeout=self.grace_period)
+        return PBCircuitBreakerAdapter(circuit_breaker)
+
+
+@dataclass
+class MultiDbConfig:
+    """
+    Configuration class for managing multiple database connections in a resilient and fail-safe manner.
+
+    Attributes:
+        databases_config: A list of database configurations.
+        client_class: The client class used to manage database connections.
+        command_retry: Retry strategy for executing database commands.
+        failure_detectors: Optional list of additional failure detectors for monitoring database failures.
+        min_num_failures: Minimal count of failures required for failover
+        failure_rate_threshold: Percentage of failures required for failover
+        failures_detection_window: Time interval for tracking database failures.
+        health_checks: Optional list of additional health checks performed on databases.
+        health_check_interval: Time interval for executing health checks.
+        health_check_probes: Number of attempts to evaluate the health of a database.
+        health_check_delay: Delay between health check attempts.
+        failover_strategy: Optional strategy for handling database failover scenarios.
+        failover_attempts: Number of retries allowed for failover operations.
+        failover_delay: Delay between failover attempts.
+        auto_fallback_interval: Time interval to trigger automatic fallback.
+        event_dispatcher: Interface for dispatching events related to database operations.
+
+    Methods:
+        databases:
+            Retrieves a collection of database clients managed by weighted configurations.
+            Initializes database clients based on the provided configuration and removes
+            redundant retry objects for lower-level clients to rely on global retry logic.
+
+        default_failure_detectors:
+            Returns the default list of failure detectors used to monitor database failures.
+
+        default_health_checks:
+            Returns the default list of health checks used to monitor database health
+            with specific retry and backoff strategies.
+
+        default_failover_strategy:
+            Provides the default failover strategy used for handling failover scenarios
+            with defined retry and backoff configurations.
+    """
+
+    databases_config: List[DatabaseConfig]
+    client_class: Type[Union[Redis, RedisCluster]] = Redis
+    command_retry: Retry = Retry(
+        backoff=ExponentialWithJitterBackoff(base=1, cap=10), retries=3
+    )
+    failure_detectors: Optional[List[AsyncFailureDetector]] = None
+    min_num_failures: int = DEFAULT_MIN_NUM_FAILURES
+    failure_rate_threshold: float = DEFAULT_FAILURE_RATE_THRESHOLD
+    failures_detection_window: float = DEFAULT_FAILURES_DETECTION_WINDOW
+    health_checks: Optional[List[HealthCheck]] = None
+    health_check_interval: float = DEFAULT_HEALTH_CHECK_INTERVAL
+    health_check_probes: int = DEFAULT_HEALTH_CHECK_PROBES
+    health_check_delay: float = DEFAULT_HEALTH_CHECK_DELAY
+    health_check_policy: HealthCheckPolicies = DEFAULT_HEALTH_CHECK_POLICY
+    failover_strategy: Optional[AsyncFailoverStrategy] = None
+    failover_attempts: int = DEFAULT_FAILOVER_ATTEMPTS
+    failover_delay: float = DEFAULT_FAILOVER_DELAY
+    auto_fallback_interval: float = DEFAULT_AUTO_FALLBACK_INTERVAL
+    event_dispatcher: EventDispatcherInterface = field(
+        default_factory=default_event_dispatcher
+    )
+
+    def databases(self) -> Databases:
+        databases = WeightedList()
+
+        for database_config in self.databases_config:
+            # The retry object is not used in the lower level clients, so we can safely remove it.
+            # We rely on command_retry in terms of global retries.
+            database_config.client_kwargs.update(
+                {"retry": Retry(retries=0, backoff=NoBackoff())}
+            )
+
+            if database_config.from_url:
+                client = self.client_class.from_url(
+                    database_config.from_url, **database_config.client_kwargs
+                )
+            elif database_config.from_pool:
+                database_config.from_pool.set_retry(
+                    Retry(retries=0, backoff=NoBackoff())
+                )
+                client = self.client_class.from_pool(
+                    connection_pool=database_config.from_pool
+                )
+            else:
+                client = self.client_class(**database_config.client_kwargs)
+
+            circuit = (
+                database_config.default_circuit_breaker()
+                if database_config.circuit is None
+                else database_config.circuit
+            )
+            databases.add(
+                Database(
+                    client=client,
+                    circuit=circuit,
+                    weight=database_config.weight,
+                    health_check_url=database_config.health_check_url,
+                ),
+                database_config.weight,
+            )
+
+        return databases
+
+    def default_failure_detectors(self) -> List[AsyncFailureDetector]:
+        return [
+            FailureDetectorAsyncWrapper(
+                CommandFailureDetector(
+                    min_num_failures=self.min_num_failures,
+                    failure_rate_threshold=self.failure_rate_threshold,
+                    failure_detection_window=self.failures_detection_window,
+                )
+            ),
+        ]
+
+    def default_health_checks(self) -> List[HealthCheck]:
+        return [
+            PingHealthCheck(),
+        ]
+
+    def default_failover_strategy(self) -> AsyncFailoverStrategy:
+        return WeightBasedFailoverStrategy()

backend/venv/lib/python3.9/site-packages/redis/asyncio/multidb/database.py

@@ -0,0 +1,69 @@
+from abc import abstractmethod
+from typing import Optional, Union
+
+from redis.asyncio import Redis, RedisCluster
+from redis.data_structure import WeightedList
+from redis.multidb.circuit import CircuitBreaker
+from redis.multidb.database import AbstractDatabase, BaseDatabase
+from redis.typing import Number
+
+
+class AsyncDatabase(AbstractDatabase):
+    """Database with an underlying asynchronous redis client."""
+
+    @property
+    @abstractmethod
+    def client(self) -> Union[Redis, RedisCluster]:
+        """The underlying redis client."""
+        pass
+
+    @client.setter
+    @abstractmethod
+    def client(self, client: Union[Redis, RedisCluster]):
+        """Set the underlying redis client."""
+        pass
+
+    @property
+    @abstractmethod
+    def circuit(self) -> CircuitBreaker:
+        """Circuit breaker for the current database."""
+        pass
+
+    @circuit.setter
+    @abstractmethod
+    def circuit(self, circuit: CircuitBreaker):
+        """Set the circuit breaker for the current database."""
+        pass
+
+
+Databases = WeightedList[tuple[AsyncDatabase, Number]]
+
+
+class Database(BaseDatabase, AsyncDatabase):
+    def __init__(
+        self,
+        client: Union[Redis, RedisCluster],
+        circuit: CircuitBreaker,
+        weight: float,
+        health_check_url: Optional[str] = None,
+    ):
+        self._client = client
+        self._cb = circuit
+        self._cb.database = self
+        super().__init__(weight, health_check_url)
+
+    @property
+    def client(self) -> Union[Redis, RedisCluster]:
+        return self._client
+
+    @client.setter
+    def client(self, client: Union[Redis, RedisCluster]):
+        self._client = client
+
+    @property
+    def circuit(self) -> CircuitBreaker:
+        return self._cb
+
+    @circuit.setter
+    def circuit(self, circuit: CircuitBreaker):
+        self._cb = circuit

backend/venv/lib/python3.9/site-packages/redis/asyncio/multidb/event.py

@@ -0,0 +1,84 @@
+from typing import List
+
+from redis.asyncio import Redis
+from redis.asyncio.multidb.database import AsyncDatabase
+from redis.asyncio.multidb.failure_detector import AsyncFailureDetector
+from redis.event import AsyncEventListenerInterface, AsyncOnCommandsFailEvent
+
+
+class AsyncActiveDatabaseChanged:
+    """
+    Event fired when an async active database has been changed.
+    """
+
+    def __init__(
+        self,
+        old_database: AsyncDatabase,
+        new_database: AsyncDatabase,
+        command_executor,
+        **kwargs,
+    ):
+        self._old_database = old_database
+        self._new_database = new_database
+        self._command_executor = command_executor
+        self._kwargs = kwargs
+
+    @property
+    def old_database(self) -> AsyncDatabase:
+        return self._old_database
+
+    @property
+    def new_database(self) -> AsyncDatabase:
+        return self._new_database
+
+    @property
+    def command_executor(self):
+        return self._command_executor
+
+    @property
+    def kwargs(self):
+        return self._kwargs
+
+
+class ResubscribeOnActiveDatabaseChanged(AsyncEventListenerInterface):
+    """
+    Re-subscribe the currently active pub / sub to a new active database.
+    """
+
+    async def listen(self, event: AsyncActiveDatabaseChanged):
+        old_pubsub = event.command_executor.active_pubsub
+
+        if old_pubsub is not None:
+            # Re-assign old channels and patterns so they will be automatically subscribed on connection.
+            new_pubsub = event.new_database.client.pubsub(**event.kwargs)
+            new_pubsub.channels = old_pubsub.channels
+            new_pubsub.patterns = old_pubsub.patterns
+            await new_pubsub.on_connect(None)
+            event.command_executor.active_pubsub = new_pubsub
+            await old_pubsub.aclose()
+
+
+class CloseConnectionOnActiveDatabaseChanged(AsyncEventListenerInterface):
+    """
+    Close connection to the old active database.
+    """
+
+    async def listen(self, event: AsyncActiveDatabaseChanged):
+        await event.old_database.client.aclose()
+
+        if isinstance(event.old_database.client, Redis):
+            await event.old_database.client.connection_pool.update_active_connections_for_reconnect()
+            await event.old_database.client.connection_pool.disconnect()
+
+
+class RegisterCommandFailure(AsyncEventListenerInterface):
+    """
+    Event listener that registers command failures and passing it to the failure detectors.
+    """
+
+    def __init__(self, failure_detectors: List[AsyncFailureDetector]):
+        self._failure_detectors = failure_detectors
+
+    async def listen(self, event: AsyncOnCommandsFailEvent) -> None:
+        for failure_detector in self._failure_detectors:
+            await failure_detector.register_failure(event.exception, event.commands)

backend/venv/lib/python3.9/site-packages/redis/asyncio/multidb/failover.py

@@ -0,0 +1,125 @@
+import time
+from abc import ABC, abstractmethod
+
+from redis.asyncio.multidb.database import AsyncDatabase, Databases
+from redis.data_structure import WeightedList
+from redis.multidb.circuit import State as CBState
+from redis.multidb.exception import (
+    NoValidDatabaseException,
+    TemporaryUnavailableException,
+)
+
+DEFAULT_FAILOVER_ATTEMPTS = 10
+DEFAULT_FAILOVER_DELAY = 12
+
+
+class AsyncFailoverStrategy(ABC):
+    @abstractmethod
+    async def database(self) -> AsyncDatabase:
+        """Select the database according to the strategy."""
+        pass
+
+    @abstractmethod
+    def set_databases(self, databases: Databases) -> None:
+        """Set the database strategy operates on."""
+        pass
+
+
+class FailoverStrategyExecutor(ABC):
+    @property
+    @abstractmethod
+    def failover_attempts(self) -> int:
+        """The number of failover attempts."""
+        pass
+
+    @property
+    @abstractmethod
+    def failover_delay(self) -> float:
+        """The delay between failover attempts."""
+        pass
+
+    @property
+    @abstractmethod
+    def strategy(self) -> AsyncFailoverStrategy:
+        """The strategy to execute."""
+        pass
+
+    @abstractmethod
+    async def execute(self) -> AsyncDatabase:
+        """Execute the failover strategy."""
+        pass
+
+
+class WeightBasedFailoverStrategy(AsyncFailoverStrategy):
+    """
+    Failover strategy based on database weights.
+    """
+
+    def __init__(self):
+        self._databases = WeightedList()
+
+    async def database(self) -> AsyncDatabase:
+        for database, _ in self._databases:
+            if database.circuit.state == CBState.CLOSED:
+                return database
+
+        raise NoValidDatabaseException("No valid database available for communication")
+
+    def set_databases(self, databases: Databases) -> None:
+        self._databases = databases
+
+
+class DefaultFailoverStrategyExecutor(FailoverStrategyExecutor):
+    """
+    Executes given failover strategy.
+    """
+
+    def __init__(
+        self,
+        strategy: AsyncFailoverStrategy,
+        failover_attempts: int = DEFAULT_FAILOVER_ATTEMPTS,
+        failover_delay: float = DEFAULT_FAILOVER_DELAY,
+    ):
+        self._strategy = strategy
+        self._failover_attempts = failover_attempts
+        self._failover_delay = failover_delay
+        self._next_attempt_ts: int = 0
+        self._failover_counter: int = 0
+
+    @property
+    def failover_attempts(self) -> int:
+        return self._failover_attempts
+
+    @property
+    def failover_delay(self) -> float:
+        return self._failover_delay
+
+    @property
+    def strategy(self) -> AsyncFailoverStrategy:
+        return self._strategy
+
+    async def execute(self) -> AsyncDatabase:
+        try:
+            database = await self._strategy.database()
+            self._reset()
+            return database
+        except NoValidDatabaseException as e:
+            if self._next_attempt_ts == 0:
+                self._next_attempt_ts = time.time() + self._failover_delay
+                self._failover_counter += 1
+            elif time.time() >= self._next_attempt_ts:
+                self._next_attempt_ts += self._failover_delay
+                self._failover_counter += 1
+
+            if self._failover_counter > self._failover_attempts:
+                self._reset()
+                raise e
+            else:
+                raise TemporaryUnavailableException(
+                    "No database connections currently available. "
+                    "This is a temporary condition - please retry the operation."
+                )
+
+    def _reset(self) -> None:
+        self._next_attempt_ts = 0
+        self._failover_counter = 0

backend/venv/lib/python3.9/site-packages/redis/asyncio/multidb/failure_detector.py

@@ -0,0 +1,38 @@
+from abc import ABC, abstractmethod
+
+from redis.multidb.failure_detector import FailureDetector
+
+
+class AsyncFailureDetector(ABC):
+    @abstractmethod
+    async def register_failure(self, exception: Exception, cmd: tuple) -> None:
+        """Register a failure that occurred during command execution."""
+        pass
+
+    @abstractmethod
+    async def register_command_execution(self, cmd: tuple) -> None:
+        """Register a command execution."""
+        pass
+
+    @abstractmethod
+    def set_command_executor(self, command_executor) -> None:
+        """Set the command executor for this failure."""
+        pass
+
+
+class FailureDetectorAsyncWrapper(AsyncFailureDetector):
+    """
+    Async wrapper for the failure detector.
+    """
+
+    def __init__(self, failure_detector: FailureDetector) -> None:
+        self._failure_detector = failure_detector
+
+    async def register_failure(self, exception: Exception, cmd: tuple) -> None:
+        self._failure_detector.register_failure(exception, cmd)
+
+    async def register_command_execution(self, cmd: tuple) -> None:
+        self._failure_detector.register_command_execution(cmd)
+
+    def set_command_executor(self, command_executor) -> None:
+        self._failure_detector.set_command_executor(command_executor)

backend/venv/lib/python3.9/site-packages/redis/asyncio/multidb/healthcheck.py

@@ -0,0 +1,285 @@
+import asyncio
+import logging
+from abc import ABC, abstractmethod
+from enum import Enum
+from typing import List, Optional, Tuple, Union
+
+from redis.asyncio import Redis
+from redis.asyncio.http.http_client import DEFAULT_TIMEOUT, AsyncHTTPClientWrapper
+from redis.backoff import NoBackoff
+from redis.http.http_client import HttpClient
+from redis.multidb.exception import UnhealthyDatabaseException
+from redis.retry import Retry
+
+DEFAULT_HEALTH_CHECK_PROBES = 3
+DEFAULT_HEALTH_CHECK_INTERVAL = 5
+DEFAULT_HEALTH_CHECK_DELAY = 0.5
+DEFAULT_LAG_AWARE_TOLERANCE = 5000
+
+logger = logging.getLogger(__name__)
+
+
+class HealthCheck(ABC):
+    @abstractmethod
+    async def check_health(self, database) -> bool:
+        """Function to determine the health status."""
+        pass
+
+
+class HealthCheckPolicy(ABC):
+    """
+    Health checks execution policy.
+    """
+
+    @property
+    @abstractmethod
+    def health_check_probes(self) -> int:
+        """Number of probes to execute health checks."""
+        pass
+
+    @property
+    @abstractmethod
+    def health_check_delay(self) -> float:
+        """Delay between health check probes."""
+        pass
+
+    @abstractmethod
+    async def execute(self, health_checks: List[HealthCheck], database) -> bool:
+        """Execute health checks and return database health status."""
+        pass
+
+
+class AbstractHealthCheckPolicy(HealthCheckPolicy):
+    def __init__(self, health_check_probes: int, health_check_delay: float):
+        if health_check_probes < 1:
+            raise ValueError("health_check_probes must be greater than 0")
+        self._health_check_probes = health_check_probes
+        self._health_check_delay = health_check_delay
+
+    @property
+    def health_check_probes(self) -> int:
+        return self._health_check_probes
+
+    @property
+    def health_check_delay(self) -> float:
+        return self._health_check_delay
+
+    @abstractmethod
+    async def execute(self, health_checks: List[HealthCheck], database) -> bool:
+        pass
+
+
+class HealthyAllPolicy(AbstractHealthCheckPolicy):
+    """
+    Policy that returns True if all health check probes are successful.
+    """
+
+    def __init__(self, health_check_probes: int, health_check_delay: float):
+        super().__init__(health_check_probes, health_check_delay)
+
+    async def execute(self, health_checks: List[HealthCheck], database) -> bool:
+        for health_check in health_checks:
+            for attempt in range(self.health_check_probes):
+                try:
+                    if not await health_check.check_health(database):
+                        return False
+                except Exception as e:
+                    raise UnhealthyDatabaseException("Unhealthy database", database, e)
+
+                if attempt < self.health_check_probes - 1:
+                    await asyncio.sleep(self._health_check_delay)
+        return True
+
+
+class HealthyMajorityPolicy(AbstractHealthCheckPolicy):
+    """
+    Policy that returns True if a majority of health check probes are successful.
+    """
+
+    def __init__(self, health_check_probes: int, health_check_delay: float):
+        super().__init__(health_check_probes, health_check_delay)
+
+    async def execute(self, health_checks: List[HealthCheck], database) -> bool:
+        for health_check in health_checks:
+            if self.health_check_probes % 2 == 0:
+                allowed_unsuccessful_probes = self.health_check_probes / 2
+            else:
+                allowed_unsuccessful_probes = (self.health_check_probes + 1) / 2
+
+            for attempt in range(self.health_check_probes):
+                try:
+                    if not await health_check.check_health(database):
+                        allowed_unsuccessful_probes -= 1
+                        if allowed_unsuccessful_probes <= 0:
+                            return False
+                except Exception as e:
+                    allowed_unsuccessful_probes -= 1
+                    if allowed_unsuccessful_probes <= 0:
+                        raise UnhealthyDatabaseException(
+                            "Unhealthy database", database, e
+                        )
+
+                if attempt < self.health_check_probes - 1:
+                    await asyncio.sleep(self._health_check_delay)
+        return True
+
+
+class HealthyAnyPolicy(AbstractHealthCheckPolicy):
+    """
+    Policy that returns True if at least one health check probe is successful.
+    """
+
+    def __init__(self, health_check_probes: int, health_check_delay: float):
+        super().__init__(health_check_probes, health_check_delay)
+
+    async def execute(self, health_checks: List[HealthCheck], database) -> bool:
+        is_healthy = False
+
+        for health_check in health_checks:
+            exception = None
+
+            for attempt in range(self.health_check_probes):
+                try:
+                    if await health_check.check_health(database):
+                        is_healthy = True
+                        break
+                    else:
+                        is_healthy = False
+                except Exception as e:
+                    exception = UnhealthyDatabaseException(
+                        "Unhealthy database", database, e
+                    )
+
+                if attempt < self.health_check_probes - 1:
+                    await asyncio.sleep(self._health_check_delay)
+
+            if not is_healthy and not exception:
+                return is_healthy
+            elif not is_healthy and exception:
+                raise exception
+
+        return is_healthy
+
+
+class HealthCheckPolicies(Enum):
+    HEALTHY_ALL = HealthyAllPolicy
+    HEALTHY_MAJORITY = HealthyMajorityPolicy
+    HEALTHY_ANY = HealthyAnyPolicy
+
+
+DEFAULT_HEALTH_CHECK_POLICY: HealthCheckPolicies = HealthCheckPolicies.HEALTHY_ALL
+
+
+class PingHealthCheck(HealthCheck):
+    """
+    Health check based on PING command.
+    """
+
+    async def check_health(self, database) -> bool:
+        if isinstance(database.client, Redis):
+            return await database.client.execute_command("PING")
+        else:
+            # For a cluster checks if all nodes are healthy.
+            all_nodes = database.client.get_nodes()
+            for node in all_nodes:
+                if not await node.redis_connection.execute_command("PING"):
+                    return False
+
+            return True
+
+
+class LagAwareHealthCheck(HealthCheck):
+    """
+    Health check available for Redis Enterprise deployments.
+    Verify via REST API that the database is healthy based on different lags.
+    """
+
+    def __init__(
+        self,
+        rest_api_port: int = 9443,
+        lag_aware_tolerance: int = DEFAULT_LAG_AWARE_TOLERANCE,
+        timeout: float = DEFAULT_TIMEOUT,
+        auth_basic: Optional[Tuple[str, str]] = None,
+        verify_tls: bool = True,
+        # TLS verification (server) options
+        ca_file: Optional[str] = None,
+        ca_path: Optional[str] = None,
+        ca_data: Optional[Union[str, bytes]] = None,
+        # Mutual TLS (client cert) options
+        client_cert_file: Optional[str] = None,
+        client_key_file: Optional[str] = None,
+        client_key_password: Optional[str] = None,
+    ):
+        """
+        Initialize LagAwareHealthCheck with the specified parameters.
+
+        Args:
+            rest_api_port: Port number for Redis Enterprise REST API (default: 9443)
+            lag_aware_tolerance: Tolerance in lag between databases in MS (default: 100)
+            timeout: Request timeout in seconds (default: DEFAULT_TIMEOUT)
+            auth_basic: Tuple of (username, password) for basic authentication
+            verify_tls: Whether to verify TLS certificates (default: True)
+            ca_file: Path to CA certificate file for TLS verification
+            ca_path: Path to CA certificates directory for TLS verification
+            ca_data: CA certificate data as string or bytes
+            client_cert_file: Path to client certificate file for mutual TLS
+            client_key_file: Path to client private key file for mutual TLS
+            client_key_password: Password for encrypted client private key
+        """
+        self._http_client = AsyncHTTPClientWrapper(
+            HttpClient(
+                timeout=timeout,
+                auth_basic=auth_basic,
+                retry=Retry(NoBackoff(), retries=0),
+                verify_tls=verify_tls,
+                ca_file=ca_file,
+                ca_path=ca_path,
+                ca_data=ca_data,
+                client_cert_file=client_cert_file,
+                client_key_file=client_key_file,
+                client_key_password=client_key_password,
+            )
+        )
+        self._rest_api_port = rest_api_port
+        self._lag_aware_tolerance = lag_aware_tolerance
+
+    async def check_health(self, database) -> bool:
+        if database.health_check_url is None:
+            raise ValueError(
+                "Database health check url is not set. Please check DatabaseConfig for the current database."
+            )
+
+        if isinstance(database.client, Redis):
+            db_host = database.client.get_connection_kwargs()["host"]
+        else:
+            db_host = database.client.startup_nodes[0].host
+
+        base_url = f"{database.health_check_url}:{self._rest_api_port}"
+        self._http_client.client.base_url = base_url
+
+        # Find bdb matching to the current database host
+        matching_bdb = None
+        for bdb in await self._http_client.get("/v1/bdbs"):
+            for endpoint in bdb["endpoints"]:
+                if endpoint["dns_name"] == db_host:
+                    matching_bdb = bdb
+                    break
+
+                # In case if the host was set as public IP
+                for addr in endpoint["addr"]:
+                    if addr == db_host:
+                        matching_bdb = bdb
+                        break
+
+        if matching_bdb is None:
+            logger.warning("LagAwareHealthCheck failed: Couldn't find a matching bdb")
+            raise ValueError("Could not find a matching bdb")
+
+        url = (
+            f"/v1/bdbs/{matching_bdb['uid']}/availability"
+            f"?extend_check=lag&availability_lag_tolerance_ms={self._lag_aware_tolerance}"
+        )
+        await self._http_client.get(url, expect_json=False)
+
+        # Status checked in an http client, otherwise HttpError will be raised
+        return True

backend/venv/lib/python3.9/site-packages/redis/asyncio/retry.py

@@ -0,0 +1,58 @@
+from asyncio import sleep
+from typing import TYPE_CHECKING, Any, Awaitable, Callable, Tuple, Type, TypeVar
+
+from redis.exceptions import ConnectionError, RedisError, TimeoutError
+from redis.retry import AbstractRetry
+
+T = TypeVar("T")
+
+if TYPE_CHECKING:
+    from redis.backoff import AbstractBackoff
+
+
+class Retry(AbstractRetry[RedisError]):
+    __hash__ = AbstractRetry.__hash__
+
+    def __init__(
+        self,
+        backoff: "AbstractBackoff",
+        retries: int,
+        supported_errors: Tuple[Type[RedisError], ...] = (
+            ConnectionError,
+            TimeoutError,
+        ),
+    ):
+        super().__init__(backoff, retries, supported_errors)
+
+    def __eq__(self, other: Any) -> bool:
+        if not isinstance(other, Retry):
+            return NotImplemented
+
+        return (
+            self._backoff == other._backoff
+            and self._retries == other._retries
+            and set(self._supported_errors) == set(other._supported_errors)
+        )
+
+    async def call_with_retry(
+        self, do: Callable[[], Awaitable[T]], fail: Callable[[RedisError], Any]
+    ) -> T:
+        """
+        Execute an operation that might fail and returns its result, or
+        raise the exception that was thrown depending on the `Backoff` object.
+        `do`: the operation to call. Expects no argument.
+        `fail`: the failure handler, expects the last error that was thrown
+        """
+        self._backoff.reset()
+        failures = 0
+        while True:
+            try:
+                return await do()
+            except self._supported_errors as error:
+                failures += 1
+                await fail(error)
+                if self._retries >= 0 and failures > self._retries:
+                    raise error
+                backoff = self._backoff.compute(failures)
+                if backoff > 0:
+                    await sleep(backoff)

backend/venv/lib/python3.9/site-packages/redis/asyncio/sentinel.py

@@ -0,0 +1,404 @@
+import asyncio
+import random
+import weakref
+from typing import AsyncIterator, Iterable, Mapping, Optional, Sequence, Tuple, Type
+
+from redis.asyncio.client import Redis
+from redis.asyncio.connection import (
+    Connection,
+    ConnectionPool,
+    EncodableT,
+    SSLConnection,
+)
+from redis.commands import AsyncSentinelCommands
+from redis.exceptions import (
+    ConnectionError,
+    ReadOnlyError,
+    ResponseError,
+    TimeoutError,
+)
+
+
+class MasterNotFoundError(ConnectionError):
+    pass
+
+
+class SlaveNotFoundError(ConnectionError):
+    pass
+
+
+class SentinelManagedConnection(Connection):
+    def __init__(self, **kwargs):
+        self.connection_pool = kwargs.pop("connection_pool")
+        super().__init__(**kwargs)
+
+    def __repr__(self):
+        s = f"<{self.__class__.__module__}.{self.__class__.__name__}"
+        if self.host:
+            host_info = f",host={self.host},port={self.port}"
+            s += host_info
+        return s + ")>"
+
+    async def connect_to(self, address):
+        self.host, self.port = address
+        await self.connect_check_health(
+            check_health=self.connection_pool.check_connection,
+            retry_socket_connect=False,
+        )
+
+    async def _connect_retry(self):
+        if self._reader:
+            return  # already connected
+        if self.connection_pool.is_master:
+            await self.connect_to(await self.connection_pool.get_master_address())
+        else:
+            async for slave in self.connection_pool.rotate_slaves():
+                try:
+                    return await self.connect_to(slave)
+                except ConnectionError:
+                    continue
+            raise SlaveNotFoundError  # Never be here
+
+    async def connect(self):
+        return await self.retry.call_with_retry(
+            self._connect_retry,
+            lambda error: asyncio.sleep(0),
+        )
+
+    async def read_response(
+        self,
+        disable_decoding: bool = False,
+        timeout: Optional[float] = None,
+        *,
+        disconnect_on_error: Optional[float] = True,
+        push_request: Optional[bool] = False,
+    ):
+        try:
+            return await super().read_response(
+                disable_decoding=disable_decoding,
+                timeout=timeout,
+                disconnect_on_error=disconnect_on_error,
+                push_request=push_request,
+            )
+        except ReadOnlyError:
+            if self.connection_pool.is_master:
+                # When talking to a master, a ReadOnlyError when likely
+                # indicates that the previous master that we're still connected
+                # to has been demoted to a slave and there's a new master.
+                # calling disconnect will force the connection to re-query
+                # sentinel during the next connect() attempt.
+                await self.disconnect()
+                raise ConnectionError("The previous master is now a slave")
+            raise
+
+
+class SentinelManagedSSLConnection(SentinelManagedConnection, SSLConnection):
+    pass
+
+
+class SentinelConnectionPool(ConnectionPool):
+    """
+    Sentinel backed connection pool.
+
+    If ``check_connection`` flag is set to True, SentinelManagedConnection
+    sends a PING command right after establishing the connection.
+    """
+
+    def __init__(self, service_name, sentinel_manager, **kwargs):
+        kwargs["connection_class"] = kwargs.get(
+            "connection_class",
+            (
+                SentinelManagedSSLConnection
+                if kwargs.pop("ssl", False)
+                else SentinelManagedConnection
+            ),
+        )
+        self.is_master = kwargs.pop("is_master", True)
+        self.check_connection = kwargs.pop("check_connection", False)
+        super().__init__(**kwargs)
+        self.connection_kwargs["connection_pool"] = weakref.proxy(self)
+        self.service_name = service_name
+        self.sentinel_manager = sentinel_manager
+        self.master_address = None
+        self.slave_rr_counter = None
+
+    def __repr__(self):
+        return (
+            f"<{self.__class__.__module__}.{self.__class__.__name__}"
+            f"(service={self.service_name}({self.is_master and 'master' or 'slave'}))>"
+        )
+
+    def reset(self):
+        super().reset()
+        self.master_address = None
+        self.slave_rr_counter = None
+
+    def owns_connection(self, connection: Connection):
+        check = not self.is_master or (
+            self.is_master and self.master_address == (connection.host, connection.port)
+        )
+        return check and super().owns_connection(connection)
+
+    async def get_master_address(self):
+        master_address = await self.sentinel_manager.discover_master(self.service_name)
+        if self.is_master:
+            if self.master_address != master_address:
+                self.master_address = master_address
+                # disconnect any idle connections so that they reconnect
+                # to the new master the next time that they are used.
+                await self.disconnect(inuse_connections=False)
+        return master_address
+
+    async def rotate_slaves(self) -> AsyncIterator:
+        """Round-robin slave balancer"""
+        slaves = await self.sentinel_manager.discover_slaves(self.service_name)
+        if slaves:
+            if self.slave_rr_counter is None:
+                self.slave_rr_counter = random.randint(0, len(slaves) - 1)
+            for _ in range(len(slaves)):
+                self.slave_rr_counter = (self.slave_rr_counter + 1) % len(slaves)
+                slave = slaves[self.slave_rr_counter]
+                yield slave
+        # Fallback to the master connection
+        try:
+            yield await self.get_master_address()
+        except MasterNotFoundError:
+            pass
+        raise SlaveNotFoundError(f"No slave found for {self.service_name!r}")
+
+
+class Sentinel(AsyncSentinelCommands):
+    """
+    Redis Sentinel cluster client
+
+    >>> from redis.sentinel import Sentinel
+    >>> sentinel = Sentinel([('localhost', 26379)], socket_timeout=0.1)
+    >>> master = sentinel.master_for('mymaster', socket_timeout=0.1)
+    >>> await master.set('foo', 'bar')
+    >>> slave = sentinel.slave_for('mymaster', socket_timeout=0.1)
+    >>> await slave.get('foo')
+    b'bar'
+
+    ``sentinels`` is a list of sentinel nodes. Each node is represented by
+    a pair (hostname, port).
+
+    ``min_other_sentinels`` defined a minimum number of peers for a sentinel.
+    When querying a sentinel, if it doesn't meet this threshold, responses
+    from that sentinel won't be considered valid.
+
+    ``sentinel_kwargs`` is a dictionary of connection arguments used when
+    connecting to sentinel instances. Any argument that can be passed to
+    a normal Redis connection can be specified here. If ``sentinel_kwargs`` is
+    not specified, any socket_timeout and socket_keepalive options specified
+    in ``connection_kwargs`` will be used.
+
+    ``connection_kwargs`` are keyword arguments that will be used when
+    establishing a connection to a Redis server.
+    """
+
+    def __init__(
+        self,
+        sentinels,
+        min_other_sentinels=0,
+        sentinel_kwargs=None,
+        force_master_ip=None,
+        **connection_kwargs,
+    ):
+        # if sentinel_kwargs isn't defined, use the socket_* options from
+        # connection_kwargs
+        if sentinel_kwargs is None:
+            sentinel_kwargs = {
+                k: v for k, v in connection_kwargs.items() if k.startswith("socket_")
+            }
+        self.sentinel_kwargs = sentinel_kwargs
+
+        self.sentinels = [
+            Redis(host=hostname, port=port, **self.sentinel_kwargs)
+            for hostname, port in sentinels
+        ]
+        self.min_other_sentinels = min_other_sentinels
+        self.connection_kwargs = connection_kwargs
+        self._force_master_ip = force_master_ip
+
+    async def execute_command(self, *args, **kwargs):
+        """
+        Execute Sentinel command in sentinel nodes.
+        once - If set to True, then execute the resulting command on a single
+               node at random, rather than across the entire sentinel cluster.
+        """
+        once = bool(kwargs.pop("once", False))
+
+        # Check if command is supposed to return the original
+        # responses instead of boolean value.
+        return_responses = bool(kwargs.pop("return_responses", False))
+
+        if once:
+            response = await random.choice(self.sentinels).execute_command(
+                *args, **kwargs
+            )
+            if return_responses:
+                return [response]
+            else:
+                return True if response else False
+
+        tasks = [
+            asyncio.Task(sentinel.execute_command(*args, **kwargs))
+            for sentinel in self.sentinels
+        ]
+        responses = await asyncio.gather(*tasks)
+
+        if return_responses:
+            return responses
+
+        return all(responses)
+
+    def __repr__(self):
+        sentinel_addresses = []
+        for sentinel in self.sentinels:
+            sentinel_addresses.append(
+                f"{sentinel.connection_pool.connection_kwargs['host']}:"
+                f"{sentinel.connection_pool.connection_kwargs['port']}"
+            )
+        return (
+            f"<{self.__class__}.{self.__class__.__name__}"
+            f"(sentinels=[{','.join(sentinel_addresses)}])>"
+        )
+
+    def check_master_state(self, state: dict, service_name: str) -> bool:
+        if not state["is_master"] or state["is_sdown"] or state["is_odown"]:
+            return False
+        # Check if our sentinel doesn't see other nodes
+        if state["num-other-sentinels"] < self.min_other_sentinels:
+            return False
+        return True
+
+    async def discover_master(self, service_name: str):
+        """
+        Asks sentinel servers for the Redis master's address corresponding
+        to the service labeled ``service_name``.
+
+        Returns a pair (address, port) or raises MasterNotFoundError if no
+        master is found.
+        """
+        collected_errors = list()
+        for sentinel_no, sentinel in enumerate(self.sentinels):
+            try:
+                masters = await sentinel.sentinel_masters()
+            except (ConnectionError, TimeoutError) as e:
+                collected_errors.append(f"{sentinel} - {e!r}")
+                continue
+            state = masters.get(service_name)
+            if state and self.check_master_state(state, service_name):
+                # Put this sentinel at the top of the list
+                self.sentinels[0], self.sentinels[sentinel_no] = (
+                    sentinel,
+                    self.sentinels[0],
+                )
+
+                ip = (
+                    self._force_master_ip
+                    if self._force_master_ip is not None
+                    else state["ip"]
+                )
+                return ip, state["port"]
+
+        error_info = ""
+        if len(collected_errors) > 0:
+            error_info = f" : {', '.join(collected_errors)}"
+        raise MasterNotFoundError(f"No master found for {service_name!r}{error_info}")
+
+    def filter_slaves(
+        self, slaves: Iterable[Mapping]
+    ) -> Sequence[Tuple[EncodableT, EncodableT]]:
+        """Remove slaves that are in an ODOWN or SDOWN state"""
+        slaves_alive = []
+        for slave in slaves:
+            if slave["is_odown"] or slave["is_sdown"]:
+                continue
+            slaves_alive.append((slave["ip"], slave["port"]))
+        return slaves_alive
+
+    async def discover_slaves(
+        self, service_name: str
+    ) -> Sequence[Tuple[EncodableT, EncodableT]]:
+        """Returns a list of alive slaves for service ``service_name``"""
+        for sentinel in self.sentinels:
+            try:
+                slaves = await sentinel.sentinel_slaves(service_name)
+            except (ConnectionError, ResponseError, TimeoutError):
+                continue
+            slaves = self.filter_slaves(slaves)
+            if slaves:
+                return slaves
+        return []
+
+    def master_for(
+        self,
+        service_name: str,
+        redis_class: Type[Redis] = Redis,
+        connection_pool_class: Type[SentinelConnectionPool] = SentinelConnectionPool,
+        **kwargs,
+    ):
+        """
+        Returns a redis client instance for the ``service_name`` master.
+        Sentinel client will detect failover and reconnect Redis clients
+        automatically.
+
+        A :py:class:`~redis.sentinel.SentinelConnectionPool` class is
+        used to retrieve the master's address before establishing a new
+        connection.
+
+        NOTE: If the master's address has changed, any cached connections to
+        the old master are closed.
+
+        By default clients will be a :py:class:`~redis.Redis` instance.
+        Specify a different class to the ``redis_class`` argument if you
+        desire something different.
+
+        The ``connection_pool_class`` specifies the connection pool to
+        use.  The :py:class:`~redis.sentinel.SentinelConnectionPool`
+        will be used by default.
+
+        All other keyword arguments are merged with any connection_kwargs
+        passed to this class and passed to the connection pool as keyword
+        arguments to be used to initialize Redis connections.
+        """
+        kwargs["is_master"] = True
+        connection_kwargs = dict(self.connection_kwargs)
+        connection_kwargs.update(kwargs)
+
+        connection_pool = connection_pool_class(service_name, self, **connection_kwargs)
+        # The Redis object "owns" the pool
+        return redis_class.from_pool(connection_pool)
+
+    def slave_for(
+        self,
+        service_name: str,
+        redis_class: Type[Redis] = Redis,
+        connection_pool_class: Type[SentinelConnectionPool] = SentinelConnectionPool,
+        **kwargs,
+    ):
+        """
+        Returns redis client instance for the ``service_name`` slave(s).
+
+        A SentinelConnectionPool class is used to retrieve the slave's
+        address before establishing a new connection.
+
+        By default clients will be a :py:class:`~redis.Redis` instance.
+        Specify a different class to the ``redis_class`` argument if you
+        desire something different.
+
+        The ``connection_pool_class`` specifies the connection pool to use.
+        The SentinelConnectionPool will be used by default.
+
+        All other keyword arguments are merged with any connection_kwargs
+        passed to this class and passed to the connection pool as keyword
+        arguments to be used to initialize Redis connections.
+        """
+        kwargs["is_master"] = False
+        connection_kwargs = dict(self.connection_kwargs)
+        connection_kwargs.update(kwargs)
+
+        connection_pool = connection_pool_class(service_name, self, **connection_kwargs)
+        # The Redis object "owns" the pool
+        return redis_class.from_pool(connection_pool)

backend/venv/lib/python3.9/site-packages/redis/asyncio/utils.py

@@ -0,0 +1,28 @@
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from redis.asyncio.client import Pipeline, Redis
+
+
+def from_url(url, **kwargs):
+    """
+    Returns an active Redis client generated from the given database URL.
+
+    Will attempt to extract the database id from the path url fragment, if
+    none is provided.
+    """
+    from redis.asyncio.client import Redis
+
+    return Redis.from_url(url, **kwargs)
+
+
+class pipeline:  # noqa: N801
+    def __init__(self, redis_obj: "Redis"):
+        self.p: "Pipeline" = redis_obj.pipeline()
+
+    async def __aenter__(self) -> "Pipeline":
+        return self.p
+
+    async def __aexit__(self, exc_type, exc_value, traceback):
+        await self.p.execute()
+        del self.p