feat: Make ENABLE_WEBSOCKET_SUPPORT disable polling entirely to allow multiple replicas without sticky sessions.

See https://socket.io/docs/v4/using-multiple-nodes/ for details why this was done.

Also create a redis key to track which replica is running the cleanup job

backend/open_webui/socket/utils.py

@@ -1,5 +1,33 @@
 import json
 import redis
+import uuid
+
+
+class RedisLock:
+    def __init__(self, redis_url, lock_name, timeout_secs):
+        self.lock_name = lock_name
+        self.lock_id = str(uuid.uuid4())
+        self.timeout_secs = timeout_secs
+        self.lock_obtained = False
+        self.redis = redis.Redis.from_url(redis_url, decode_responses=True)
+
+    def aquire_lock(self):
+        # nx=True will only set this key if it _hasn't_ already been set
+        self.lock_obtained = self.redis.set(
+            self.lock_name, self.lock_id, nx=True, ex=self.timeout_secs
+        )
+        return self.lock_obtained
+
+    def renew_lock(self):
+        # xx=True will only set this key if it _has_ already been set
+        return self.redis.set(
+            self.lock_name, self.lock_id, xx=True, ex=self.timeout_secs
+        )
+
+    def release_lock(self):
+        lock_value = self.redis.get(self.lock_name)
+        if lock_value and lock_value.decode("utf-8") == self.lock_id:
+            self.redis.delete(self.lock_name)
 
 
 class RedisDict: