feat: add redis fallback mechanism #21043 (#21044)

Co-authored-by: tech <cto@sb>
Co-authored-by: crazywoola <100913391+crazywoola@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

api/extensions/ext_redis.py

@@ -1,6 +1,10 @@
+import functools
+import logging
+from collections.abc import Callable
 from typing import Any, Union
 
 import redis
+from redis import RedisError
 from redis.cache import CacheConfig
 from redis.cluster import ClusterNode, RedisCluster
 from redis.connection import Connection, SSLConnection
@@ -9,6 +13,8 @@ from redis.sentinel import Sentinel
 from configs import dify_config
 from dify_app import DifyApp
 
+logger = logging.getLogger(__name__)
+
 
 class RedisClientWrapper:
     """
@@ -115,3 +121,25 @@ def init_app(app: DifyApp):
         redis_client.initialize(redis.Redis(connection_pool=pool))
 
     app.extensions["redis"] = redis_client
+
+
+def redis_fallback(default_return: Any = None):
+    """
+    decorator to handle Redis operation exceptions and return a default value when Redis is unavailable.
+
+    Args:
+        default_return: The value to return when a Redis operation fails. Defaults to None.
+    """
+
+    def decorator(func: Callable):
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            try:
+                return func(*args, **kwargs)
+            except RedisError as e:
+                logger.warning(f"Redis operation failed in {func.__name__}: {str(e)}", exc_info=True)
+                return default_return
+
+        return wrapper
+
+    return decorator