/**
 * `redis-storage-services.ts`
 * - storage implementation on redis backend
 *
 * @author      Tim Hong <tim@lemoncloud.io>
 * @date        2020-12-08 initial version
 *
 * @copyright   (C) lemoncloud.io 2020 - All Rights Reserved.
 */
import { Redis } from 'ioredis';
import { StorageService, StorageModel } from './storage-service';
/** ********************************************************************************************************************
 *  Exported Types
 ** ********************************************************************************************************************/
/**
 * type `RedisOptions`
 */
export interface RedisOptions {
    /**
     * (optional) cache server endpoint
     */
    endpoint?: string;
    /**
     * (optional) virtual table name used as key prefix
     */
    tableName: string | number;
    /**
     * (optional) default time to live of a model in seconds. 0 for unlimited (default: 0)
     */
    defTimeout?: number;
}
/** ********************************************************************************************************************
 *  Exported Class
 ** ********************************************************************************************************************/
/**
 * class `RedisStorageService`
 */
export declare class RedisStorageService<T extends StorageModel> implements StorageService<T> {
    /**
     * Environment variable name for redis server endpoint
     * @static
     */
    static readonly ENV_REDIS_ENDPOINT = "MY_REDIS_ENDPOINT";
    /**
     * Maximum retry count of check-and-save behavior
     * @static
     */
    static readonly CAS_MAX_RETRIES = 5;
    /**
     * ioredis client
     * @protected
     */
    protected readonly redis: Redis;
    /**
     * Virtual table name
     * @private
     */
    readonly tableName: string;
    /**
     * Default time to live of a model
     * @private
     */
    readonly ttl: number;
    /**
     * Public constructor
     *
     * @options redis options
     */
    constructor(options: RedisOptions);
    /**
     * Say hello
     */
    hello(): string;
    /**
     * Disconnect from redis
     */
    quit(): Promise<void>;
    /**
     * Read model by id
     *
     * @param id
     */
    read(id: string): Promise<T>;
    /**
     * Read model or create if id does not exist
     *
     * @param id
     * @param model
     */
    readOrCreate(id: string, model: T): Promise<T>;
    /**
     * Create model and overwrite if id exists
     *
     * @param id
     * @param model
     */
    save(id: string, model: T): Promise<T>;
    /**
     * Update existing model and create if id does not exist
     * @param id
     * @param update    model to update
     * @param increment (optional) model to increment
     */
    update(id: string, update: T, increment?: T): Promise<T>;
    /**
     * Increment the integer value of a key
     *
     * @param id
     * @param increment model to increment
     * @param update    (optional) model to update
     */
    increment(id: string, increment: T, update?: T): Promise<T>;
    /**
     * Delete a key
     *
     * @param id
     * @return  true on success
     */
    delete(id: string): Promise<T>;
    /**
     * Get redis key from id
     * @param id
     * @protected
     */
    asKey(id: string): string;
    /**
     * Serialize model into internal data
     * @param model
     * @protected
     */
    serialize(model: T): Record<string, string>;
    /**
     * Deserialize internal data into model
     * @param data
     * @protected
     */
    deserialize(data: Record<string, string>): T;
    /**
     * Update key w/ check-and-save behavior and retries
     * @param id
     * @param update    (optional) model to update
     * @param increment (optional) model to increment
     * @private
     */
    private updateCAS;
    /**
     * Prepare new model - original model + update + increment
     * @param orig
     * @param update
     * @param increment
     * @private
     */
    private prepareUpdatedModel;
    /**
     * Check transaction results and throw if error occurred
     * @param results   transaction pipeline execution results
     * @private
     */
    private static throwIfTransactionError;
}
/**
 * class `DummyRedisStorageService`
 *  - Use local redis server and non-default logical database
 */
export declare class DummyRedisStorageService<T extends StorageModel> extends RedisStorageService<T> {
    /**
     * Database index. Each DummyRedisStorageService uses different logical database.
     * @private
     */
    private static dbIndex;
    /**
     * Public constructor
     */
    constructor();
    /**
     * Say hello
     */
    hello(): string;
    /**
     * Delete all data in database
     */
    truncate(): Promise<void>;
}