🏦 refactor: Centralize Caching & Redis Key Prefixing (#8457)

* 🔧 Overhauled caching feature:
- Refactored caching logic.
- Fixed redis prefix, namespace, tls, ttl, and cluster.
- Added REDIS_KEY_PREFIX_VAR

* # refactor: Rename redisCache to standardCache

* # Add Redis pinging mechanism to maintain connection.

* # docs: Add warning about Keyv Redis client prefix support

api/cache/cacheFactory.js

@@ -0,0 +1,66 @@
+const KeyvRedis = require('@keyv/redis').default;
+const { Keyv } = require('keyv');
+const { cacheConfig } = require('./cacheConfig');
+const { keyvRedisClient, ioredisClient, GLOBAL_PREFIX_SEPARATOR } = require('./redisClients');
+const { Time } = require('librechat-data-provider');
+const ConnectRedis = require('connect-redis').default;
+const MemoryStore = require('memorystore')(require('express-session'));
+const { violationFile } = require('./keyvFiles');
+const { RedisStore } = require('rate-limit-redis');
+
+/**
+ * Creates a cache instance using Redis or a fallback store. Suitable for general caching needs.
+ * @param {string} namespace - The cache namespace.
+ * @param {number} [ttl] - Time to live for cache entries.
+ * @param {object} [fallbackStore] - Optional fallback store if Redis is not used.
+ * @returns {Keyv} Cache instance.
+ */
+const standardCache = (namespace, ttl = undefined, fallbackStore = undefined) => {
+  if (cacheConfig.USE_REDIS) {
+    const keyvRedis = new KeyvRedis(keyvRedisClient);
+    const cache = new Keyv(keyvRedis, { namespace, ttl });
+    keyvRedis.namespace = cacheConfig.REDIS_KEY_PREFIX;
+    keyvRedis.keyPrefixSeparator = GLOBAL_PREFIX_SEPARATOR;
+    return cache;
+  }
+  if (fallbackStore) return new Keyv({ store: fallbackStore, namespace, ttl });
+  return new Keyv({ namespace, ttl });
+};
+
+/**
+ * Creates a cache instance for storing violation data.
+ * Uses a file-based fallback store if Redis is not enabled.
+ * @param {string} namespace - The cache namespace for violations.
+ * @param {number} [ttl] - Time to live for cache entries.
+ * @returns {Keyv} Cache instance for violations.
+ */
+const violationCache = (namespace, ttl = undefined) => {
+  return standardCache(`violations:${namespace}`, ttl, violationFile);
+};
+
+/**
+ * Creates a session cache instance using Redis or in-memory store.
+ * @param {string} namespace - The session namespace.
+ * @param {number} [ttl] - Time to live for session entries.
+ * @returns {MemoryStore | ConnectRedis} Session store instance.
+ */
+const sessionCache = (namespace, ttl = undefined) => {
+  namespace = namespace.endsWith(':') ? namespace : `${namespace}:`;
+  if (!cacheConfig.USE_REDIS) return new MemoryStore({ ttl, checkPeriod: Time.ONE_DAY });
+  return new ConnectRedis({ client: ioredisClient, ttl, prefix: namespace });
+};
+
+/**
+ * Creates a rate limiter cache using Redis.
+ * @param {string} prefix - The key prefix for rate limiting.
+ * @returns {RedisStore|undefined} RedisStore instance or undefined if Redis is not used.
+ */
+const limiterCache = (prefix) => {
+  if (!prefix) throw new Error('prefix is required');
+  if (!cacheConfig.USE_REDIS) return undefined;
+  prefix = prefix.endsWith(':') ? prefix : `${prefix}:`;
+  return new RedisStore({ sendCommand, prefix });
+};
+const sendCommand = (...args) => ioredisClient?.call(...args);
+
+module.exports = { standardCache, sessionCache, violationCache, limiterCache };