Updating default retry strategy for standalone clients. 3 retries with ExponentialWithJitterBackoff become the default config. (#3614)

* Changing the default retry configuration for Redis standalone clients.

* Updating default retry strategy for standalone clients. 3 retries with ExponentialWithJitterBackoff become the default config.

* Applying review comments - removing unused methods from retry objects, updating pydocs of error handler method

Author: petyaslavova

redis/asyncio/client.py

@@ -39,6 +39,7 @@
 )
 from redis.asyncio.lock import Lock
 from redis.asyncio.retry import Retry
+from redis.backoff import ExponentialWithJitterBackoff
 from redis.client import (
     EMPTY_RESPONSE,
     NEVER_DECODE,
@@ -65,14 +66,14 @@
     PubSubError,
     RedisError,
     ResponseError,
-    TimeoutError,
     WatchError,
 )
 from redis.typing import ChannelT, EncodableT, KeyT
 from redis.utils import (
     HIREDIS_AVAILABLE,
     SSL_AVAILABLE,
     _set_info_logger,
+    deprecated_args,
     deprecated_function,
     get_lib_version,
     safe_str,
@@ -208,6 +209,11 @@ def from_pool(
         client.auto_close_connection_pool = True
         return client
 
+    @deprecated_args(
+        args_to_warn=["retry_on_timeout"],
+        reason="TimeoutError is included by default.",
+        version="6.0.0",
+    )
     def __init__(
         self,
         *,
@@ -225,6 +231,9 @@ def __init__(
         encoding_errors: str = "strict",
         decode_responses: bool = False,
         retry_on_timeout: bool = False,
+        retry: Retry = Retry(
+            backoff=ExponentialWithJitterBackoff(base=1, cap=10), retries=3
+        ),
         retry_on_error: Optional[list] = None,
         ssl: bool = False,
         ssl_keyfile: Optional[str] = None,
@@ -242,7 +251,6 @@ def __init__(
         lib_name: Optional[str] = "redis-py",
         lib_version: Optional[str] = get_lib_version(),
         username: Optional[str] = None,
-        retry: Optional[Retry] = None,
         auto_close_connection_pool: Optional[bool] = None,
         redis_connect_func=None,
         credential_provider: Optional[CredentialProvider] = None,
@@ -251,10 +259,24 @@ def __init__(
     ):
         """
         Initialize a new Redis client.
-        To specify a retry policy for specific errors, first set
-        `retry_on_error` to a list of the error/s to retry on, then set
-        `retry` to a valid `Retry` object.
-        To retry on TimeoutError, `retry_on_timeout` can also be set to `True`.
+
+        To specify a retry policy for specific errors, you have two options:
+
+        1. Set the `retry_on_error` to a list of the error/s to retry on, and
+        you can also set `retry` to a valid `Retry` object(in case the default
+        one is not appropriate) - with this approach the retries will be triggered
+        on the default errors specified in the Retry object enriched with the
+        errors specified in `retry_on_error`.
+
+        2. Define a `Retry` object with configured 'supported_errors' and set
+        it to the `retry` parameter - with this approach you completely redefine
+        the errors on which retries will happen.
+
+        `retry_on_timeout` is deprecated - please include the TimeoutError
+        either in the Retry object or in the `retry_on_error` list.
+
+        When 'connection_pool' is provided - the retry configuration of the
+        provided pool will be used.
         """
         kwargs: Dict[str, Any]
         if event_dispatcher is None:
@@ -280,8 +302,6 @@ def __init__(
             # Create internal connection pool, expected to be closed by Redis instance
             if not retry_on_error:
                 retry_on_error = []
-            if retry_on_timeout is True:
-                retry_on_error.append(TimeoutError)
             kwargs = {
                 "db": db,
                 "username": username,
@@ -291,7 +311,6 @@ def __init__(
                 "encoding": encoding,
                 "encoding_errors": encoding_errors,
                 "decode_responses": decode_responses,
-                "retry_on_timeout": retry_on_timeout,
                 "retry_on_error": retry_on_error,
                 "retry": copy.deepcopy(retry),
                 "max_connections": max_connections,
@@ -403,10 +422,10 @@ def get_connection_kwargs(self):
         """Get the connection's key-word arguments"""
         return self.connection_pool.connection_kwargs
 
-    def get_retry(self) -> Optional["Retry"]:
+    def get_retry(self) -> Optional[Retry]:
         return self.get_connection_kwargs().get("retry")
 
-    def set_retry(self, retry: "Retry") -> None:
+    def set_retry(self, retry: Retry) -> None:
         self.get_connection_kwargs().update({"retry": retry})
         self.connection_pool.set_retry(retry)
 
@@ -633,18 +652,17 @@ async def _send_command_parse_response(self, conn, command_name, *args, **option
         await conn.send_command(*args)
         return await self.parse_response(conn, command_name, **options)
 
-    async def _disconnect_raise(self, conn: Connection, error: Exception):
+    async def _close_connection(self, conn: Connection):
         """
-        Close the connection and raise an exception
-        if retry_on_error is not set or the error
-        is not one of the specified error types
+        Close the connection before retrying.
+
+        The supported exceptions are already checked in the
+        retry object so we don't need to do it here.
+
+        After we disconnect the connection, it will try to reconnect and
+        do a health check as part of the send_command logic(on connection level).
         """
         await conn.disconnect()
-        if (
-            conn.retry_on_error is None
-            or isinstance(error, tuple(conn.retry_on_error)) is False
-        ):
-            raise error
 
     # COMMAND EXECUTION AND PROTOCOL PARSING
     async def execute_command(self, *args, **options):
@@ -661,7 +679,7 @@ async def execute_command(self, *args, **options):
                 lambda: self._send_command_parse_response(
                     conn, command_name, *args, **options
                 ),
-                lambda error: self._disconnect_raise(conn, error),
+                lambda _: self._close_connection(conn),
             )
         finally:
             if self.single_connection_client:
@@ -929,19 +947,11 @@ async def connect(self):
             )
         )
 
-    async def _disconnect_raise_connect(self, conn, error):
+    async def _reconnect(self, conn):
         """
-        Close the connection and raise an exception
-        if retry_on_error is not set or the error is not one
-        of the specified error types. Otherwise, try to
-        reconnect
+        Try to reconnect
         """
         await conn.disconnect()
-        if (
-            conn.retry_on_error is None
-            or isinstance(error, tuple(conn.retry_on_error)) is False
-        ):
-            raise error
         await conn.connect()
 
     async def _execute(self, conn, command, *args, **kwargs):
@@ -954,7 +964,7 @@ async def _execute(self, conn, command, *args, **kwargs):
         """
         return await conn.retry.call_with_retry(
             lambda: command(*args, **kwargs),
-            lambda error: self._disconnect_raise_connect(conn, error),
+            lambda _: self._reconnect(conn),
         )
 
     async def parse_response(self, block: bool = True, timeout: float = 0):
@@ -1245,7 +1255,8 @@ class Pipeline(Redis):  # lgtm [py/init-calls-subclass]
     in one transmission.  This is convenient for batch processing, such as
     saving all the values in a list to Redis.
 
-    All commands executed within a pipeline are wrapped with MULTI and EXEC
+    All commands executed within a pipeline(when running in transactional mode,
+    which is the default behavior) are wrapped with MULTI and EXEC
     calls. This guarantees all commands executed in the pipeline will be
     executed atomically.
 
@@ -1274,7 +1285,7 @@ def __init__(
         self.shard_hint = shard_hint
         self.watching = False
         self.command_stack: CommandStackT = []
-        self.scripts: Set["Script"] = set()
+        self.scripts: Set[Script] = set()
         self.explicit_transaction = False
 
     async def __aenter__(self: _RedisT) -> _RedisT:
@@ -1346,36 +1357,36 @@ def execute_command(
             return self.immediate_execute_command(*args, **kwargs)
         return self.pipeline_execute_command(*args, **kwargs)
 
-    async def _disconnect_reset_raise(self, conn, error):
+    async def _disconnect_reset_raise_on_watching(
+        self,
+        conn: Connection,
+        error: Exception,
+    ):
         """
-        Close the connection, reset watching state and
-        raise an exception if we were watching,
-        if retry_on_error is not set or the error is not one
-        of the specified error types.
+        Close the connection reset watching state and
+        raise an exception if we were watching.
+
+        The supported exceptions are already checked in the
+        retry object so we don't need to do it here.
+
+        After we disconnect the connection, it will try to reconnect and
+        do a health check as part of the send_command logic(on connection level).
         """
         await conn.disconnect()
         # if we were already watching a variable, the watch is no longer
         # valid since this connection has died. raise a WatchError, which
         # indicates the user should retry this transaction.
         if self.watching:
-            await self.aclose()
+            await self.reset()
             raise WatchError(
-                "A ConnectionError occurred on while watching one or more keys"
+                f"A {type(error).__name__} occurred while watching one or more keys"
             )
-        # if retry_on_error is not set or the error is not one
-        # of the specified error types, raise it
-        if (
-            conn.retry_on_error is None
-            or isinstance(error, tuple(conn.retry_on_error)) is False
-        ):
-            await self.aclose()
-            raise
 
     async def immediate_execute_command(self, *args, **options):
         """
-        Execute a command immediately, but don't auto-retry on a
-        ConnectionError if we're already WATCHing a variable. Used when
-        issuing WATCH or subsequent commands retrieving their values but before
+        Execute a command immediately, but don't auto-retry on the supported
+        errors for retry if we're already WATCHing a variable.
+        Used when issuing WATCH or subsequent commands retrieving their values but before
         MULTI is called.
         """
         command_name = args[0]
@@ -1389,7 +1400,7 @@ async def immediate_execute_command(self, *args, **options):
             lambda: self._send_command_parse_response(
                 conn, command_name, *args, **options
             ),
-            lambda error: self._disconnect_reset_raise(conn, error),
+            lambda error: self._disconnect_reset_raise_on_watching(conn, error),
         )
 
     def pipeline_execute_command(self, *args, **options):
@@ -1544,28 +1555,24 @@ async def load_scripts(self):
                 if not exist:
                     s.sha = await immediate("SCRIPT LOAD", s.script)
 
-    async def _disconnect_raise_reset(self, conn: Connection, error: Exception):
+    async def _disconnect_raise_on_watching(self, conn: Connection, error: Exception):
         """
-        Close the connection, raise an exception if we were watching,
-        and raise an exception if retry_on_error is not set or the
-        error is not one of the specified error types.
+        Close the connection, raise an exception if we were watching.
+
+        The supported exceptions are already checked in the
+        retry object so we don't need to do it here.
+
+        After we disconnect the connection, it will try to reconnect and
+        do a health check as part of the send_command logic(on connection level).
         """
         await conn.disconnect()
         # if we were watching a variable, the watch is no longer valid
         # since this connection has died. raise a WatchError, which
         # indicates the user should retry this transaction.
         if self.watching:
             raise WatchError(
-                "A ConnectionError occurred on while watching one or more keys"
+                f"A {type(error).__name__} occurred while watching one or more keys"
             )
-        # if retry_on_error is not set or the error is not one
-        # of the specified error types, raise it
-        if (
-            conn.retry_on_error is None
-            or isinstance(error, tuple(conn.retry_on_error)) is False
-        ):
-            await self.reset()
-            raise
 
     async def execute(self, raise_on_error: bool = True) -> List[Any]:
         """Execute all the commands in the current pipeline"""
@@ -1590,7 +1597,7 @@ async def execute(self, raise_on_error: bool = True) -> List[Any]:
         try:
             return await conn.retry.call_with_retry(
                 lambda: execute(conn, stack, raise_on_error),
-                lambda error: self._disconnect_raise_reset(conn, error),
+                lambda error: self._disconnect_raise_on_watching(conn, error),
             )
         finally:
             await self.reset()