import KeyvRedis from '@keyv/redis';
import { type ClusterNode, type ClusterOptions } from 'ioredis';
/**
 * Singleton connection pool for Redis connections.
 * Ensures multiple Cache instances pointing to the same Redis instance
 * share the same underlying Redis client, avoiding connection exhaustion.
 * Each Cache gets its own KeyvRedis wrapper but shares the client.
 */
export declare class RedisConnectionPool {
    private static instance;
    private pool;
    private constructor();
    static getInstance(): RedisConnectionPool;
    /**
     * Get a Redis store from the pool. Creates a new KeyvRedis instance that uses
     * a shared Redis client if one exists, or creates a new client if not.
     *
     * For `rediss://` (TLS) URLs, automatically adds `tls: { rejectUnauthorized: false }`
     * so that connections to Redis instances using non-public CA certificates (e.g., GCP
     * Memorystore with Google-managed certs) work without disabling TLS validation
     * process-wide via NODE_TLS_REJECT_UNAUTHORIZED.
     *
     * @param connectionString The Redis connection string
     * @returns KeyvRedis store instance
     */
    getConnection(connectionString: string): KeyvRedis;
    /**
     * Get a Redis store backed by an ioredis Cluster instance.
     * Pools the underlying Cluster connection by a key derived from the sorted node list.
     *
     * IMPORTANT: Uses `useRedisSets: false` because MULTI/EXEC (used by the default
     * useRedisSets: true) is not supported across slots in Redis Cluster.
     *
     * @param nodes Cluster seed nodes
     * @param options ioredis ClusterOptions
     * @returns KeyvRedis store wrapping the shared Cluster instance
     */
    getClusterConnection(nodes: ClusterNode[], options?: ClusterOptions): KeyvRedis;
    /**
     * Release a Redis connection. When reference count reaches 0,
     * the connection is kept in the pool for reuse.
     * @param connectionString The Redis connection string
     */
    releaseConnection(connectionString: string): void;
    /**
     * Disconnect and remove a connection from the pool.
     * This should be called when you're certain no more instances will need this connection.
     * @param connectionString The Redis connection string
     */
    disconnect(connectionString: string): Promise<void>;
    /**
     * Disconnect all connections in the pool.
     * Useful for cleanup during application shutdown.
     */
    disconnectAll(): Promise<void>;
    /**
     * Get the reference count for a connection.
     * Useful for testing and debugging.
     * @param connectionString The Redis connection string
     */
    getRefCount(connectionString: string): number;
    /**
     * Get the number of connections in the pool.
     * Useful for testing and debugging.
     */
    getPoolSize(): number;
    /**
     * Clear the pool without disconnecting.
     * Only use this for testing purposes.
     */
    clearPool(): void;
}