core/lib/client/Redis.js

Core Libs

var Pool = require('../pattern/Pool.js').Pool;
var CredentialsProvider = require('../credentials/CredentialsProvider.js').CredentialsProvider;
var Event = require('../event/Event').Event;
var EventDispatcher = require('../event/EventDispatcher').EventDispatcher;

var redis = require('redis');
var instances = [];
var emptyFn = function () {};

var Redis = function (cp) {
    return Redis.getInstance(cp);
};

Redis.getInstance = function (cp) {
    for (var i = 0, max = instances.length; i < max; i++) {
        if (instances[i][0] === cp) {
            return instances[i][1];
        }
    }
    var obj = Object.create(Redis.prototype);
    EventDispatcher.call(obj);

    obj._debugEnabled = true;
    obj._options = {
        db: false,
        updateTimeout: 1000,
        defaultConnectionsCount: 1,
        redisConfig: {
            'hbInterval': false,
            'hbTimeout': false,
            'max_attempts': 0,
            'return_buffers': true,
            'enable_offline_queue': false
        }
    };

    obj._hosts = {};
    obj._credentials = null;
    obj._readyClients = 0;
    obj._isReady = false;
    obj._onReadyCallback = false;
    obj._sortedHosts = [];

    cp.addEventListener(CredentialsProvider.Event.LOAD, function (e) {
        obj._onCredentialsChange(null, e.data);
    }, obj);

    cp.get(function () {
        obj._onCredentialsChange.apply(obj, arguments);
    });

    obj._cp = cp;
    instances.push([cp, obj]);
    // in the old version it was running find out why?Maybe some bug with cp
    obj._updateTimeout = setTimeout(obj._onCredentialsChange.bind(obj), obj._options.updateTimeout);

    return obj;
};

Redis.prototype = Object.create(EventDispatcher.prototype);

/**
 * Enable/disable debug mode for redisClient
 *
 * @return {void}
 */
Redis.prototype._debug = function () {
    if (!this._debugEnabled) {
        return;
    }

    console.log.apply(console, arguments);
};

/**
 * Gracefully kill unused redis numConnectionss using pool release and clean host object
 *
 * @return {void}
 */
Redis.prototype._cleanDeletedHosts = function () {
    var hosts = Object.keys(this._hosts);

    for (var i = 0, hostsL = hosts.length; i < hostsL; i++) {
        var server = this._hosts[hosts[i]];

        if (!server.toDelete) {
            continue;
        }

        var clientCount = server.pool.getKnownLength();
        if (clientCount === 0) {
            delete this._hosts[hosts[i]];
            continue;
        }

        for (var j = 0; j < clientCount; j++) {
            this._deleteClient(hosts[i]);
        }
    }
};

/**
 * Check if all connections are ready.
 *
 * @return {bool} - true if ready, otherwise false
 */
Redis.prototype.isReady = function () {
    return this._isReady;
};

/**
 * Add onReady Function
 *
 * @param  {Function} callback funct to be called when all clients are connected
 * @return {void}
 */
Redis.prototype.onReady = function (callback) {
    if (typeof callback !== 'function') {
        return;
    }

    this._onReadyCallback = callback;
};

/**
 * Update redis clients to config given from credentialProvider
 *
 * @param  {Object} - Err
 * @param  {Object} - Credentials in CredentialProvider format
 * @return {void}
 */
Redis.prototype._onCredentialsChange = function (error, credentials) {
    var that = this;

    if (error) {
        console.error('Redis Credentials error', error);
        return;
    }

    if (this._updateTimeout) {
        clearTimeout(this._updateTimeout);
        this._updateTimeout = null;
    }

    this._cleanDeletedHosts();

    if (credentials) {
        if (credentials.hasOwnProperty('connect_timeout')) {
            this._options.redisConfig.connect_timeout = credentials.connect_timeout;
        }

        if (this._options.hasOwnProperty('db')) {
            this._options.db = credentials.db;
        } else {
            this._options.db = false;
        }

        this._options.redisConfig.enable_offline_queue = credentials.enable_offline_queue || false;
        redis.debug_mode = that._debugEnabled = credentials.debug || false;
        this._options.redisConfig.hbInterval = credentials.hbInterval || false;
        this._options.redisConfig.hbTimeout = credentials.hbTimeout || false;
    }

    //parse credentials to class format
    credentials = this._normalizeCredentials(credentials);

    if (!credentials || typeof credentials !== 'object') {
        if (typeof this._credentials !== 'object') {
            console.error('Redis no credentials available');
            return;
        }

        credentials = this._credentials;
    } else {
        this._credentials = credentials;
    }

    var credentialKeys = Object.keys(credentials);
    var hostsKeys = Object.keys(this._hosts);

    credentialKeys.forEach(function (i) {
        if (hostsKeys.indexOf(i) < 0) {
            that._hosts[i] = {
                connections: credentials[i],
                pool: new Pool(),
                active: 0,
                errors: 0,
                toDelete: false
            };
        }
    });

    hostsKeys.forEach(function (i) {
        if (credentialKeys.indexOf(i) < 0) {
            that._hosts[i].toDelete = true;
        }
    });

    var hosts = Object.keys(this._hosts);
    for (var j = 0, hostsL = hosts.length; j < hostsL; j++) {
        if (credentials[hosts[j]]) {
            this._hosts[hosts[j]].connections = credentials[hosts[j]];
        }

        var connected = this._hosts[hosts[j]].pool.getKnownLength();

        if (connected !== this._hosts[hosts[j]].connections) {
            this._manageConnections(hosts[j], this._hosts[hosts[j]].connections - connected);
        }
    }

    //sort host for getShard method (backward compatibility)
    this._sortedHosts = Object.keys(this._hosts).sort(function (a, b) {
        var hostA = a.split(':');
        var hostB = b.split(':');

        if (hostA[0] !== hostB[0]) {
            return hostA[0] > hostB[0] ? 1 : -1;
        }
        return hostA[1] - hostB[1];
    });

};

/**
 * Normalize params from credentialsProvider to class format
 *
 * @param  {Object}
 * @return {Object} - object with {ip:port => numConnections}
 */
Redis.prototype._normalizeCredentials = function (items) {
    if (!items || !items.hosts) {
        return false;
    }

    var result = {};

    if (typeof items.connections === 'undefined') {
        items.connections = this._options.defaultConnectionsCount;
    }

    items.connections = parseInt(items.connections);
    var connections = isNaN(items.connections) ? 0 : items.connections;

    for (var i = 0; i < items.hosts.length; i++) {
        if (items.hosts[i].host && items.hosts[i].port) {
            //if we have two ore more same entries in config we add it to existing entry
            if (result[items.hosts[i].host + ':' + items.hosts[i].port]) {
                result[items.hosts[i].host + ':' + items.hosts[i].port] += connections;
            } else {
                result[items.hosts[i].host + ':' + items.hosts[i].port] = connections;
            }
        }
    }

    return result;
};

/**
 *  Add/delete connections to redis
 *
 * @param  {string} - ip:port string
 * @param  {int} - number of connections
 * @return {void}
 */
Redis.prototype._manageConnections = function (addr, connections) {
    if (!connections) {
        return;
    }

    if (!this._validateHost(addr)) {
        console.error('Bad hostname adres:'.addr);
        return;
    }

    var toRemove = false;

    if (connections < 0) {
        toRemove = true;
        connections = (connections * -1);
    }

    for (var i = 0; i < connections; i++) {
        if (!toRemove) {
            this._createClient(addr);
        } else {
            this._deleteClient(addr);
        }
    }
};

/**
 * close single redis client
 *
 * @param  {string} - host with port
 * @return {void}
 */
Redis.prototype._deleteClient = function (addr) {
    if (!this._validateHost(addr)) {
        console.error('Bad hostname adres:', addr);
        return;
    }

    this._hosts[addr].pool.get(function (client) {
        client.quit(function (err) {
            if (err) {
                client.connection_gone('delete_client');
            }
        });
    });
};

/**
 * Simple hostname:ip string validation
 *
 * @param  {string} addr - ip:port
 * @return {bool} v-alidation result
 */
Redis.prototype._validateHost = function (addr) {
    if (!addr || typeof addr !== 'string' || addr.indexOf(':') === -1 || addr.split(':').length !== 2) {
        return false;
    }

    return true;
};

/**
 * Check if all connections are established at start and run onReady callback (only runs at client start)
 *
 * @return {void}
 */
Redis.prototype._readyCheck = function () {
    var that = this;
    var readyTmp = 0;
    if (this._isReady) {
        return;
    }

    that._readyClients++;

    Object.keys(this._hosts).forEach(function (host) {
        readyTmp += that._hosts[host].connections;
    });

    if (readyTmp === this._readyClients) {
        this._isReady = true;

        this.dispatchEvent(new Event(Redis.Event.READY));

        if (typeof this._onReadyCallback === 'function') {
            this._onReadyCallback();
        }
    }
};

/**
 * Add redis client to pool
 *
 * @param  {string} - ip:port
 * @return {void}
 */
Redis.prototype._createClient = function (addr) {
    var that = this;
    var countActive = false;

    if (!this._validateHost(addr)) {
        console.error('Bad hostname adres:', addr);
        return;
    }

    if (!that._hosts[addr]) {
        console.error('Host not found in pools');
        return;
    }

    var host = addr.split(':', 2);
    var client = redis.createClient(host[1], host[0], that._options.redisConfig);
    that._heartbeat(client);

    client.on('connect', function () {
        that._debug('Redis client connected to', addr);
    });

    client.on('ready', function () {
        //increment connection active counter and add flag that connection is connected
        //redis default flag cant be use because on end event its set to false
        that._hosts[addr].active++;
        countActive = true;

        if (that._options.db || that._options.db === 0) {
            client.select(that._options.db, function (error) {
                if (error) {
                    console.error('Redis client error', error);
                    that._hosts[addr].errors++;
                } else {
                    that._debug('Redis client', addr, 'ready');
                    that._readyCheck();
                }
            });
        } else {
            that._debug('Redis client', addr, 'ready');
            that._readyCheck();
        }
    });

    client.on('error', function (error) {
        console.error('Redis client error:', addr, 'Error:', error);
        that._hosts[addr].errors++;
        that._hosts[addr].pool.markForDeletion(client);
        that._hosts[addr].pool.release(client);
        client.connection_gone('error');
    });

    client.on('end', function () {
        //disable client reconnect by set closing var
        client.closing = true;

        //if connection was active and it disconnects remove it from active counter
        if (countActive) {
            that._hosts[addr].active--;
            countActive = false;
        }

        if (!that._hosts[addr]) {
            console.error('Cannot find host', addr, ' onRedisClientEnd');
            return;
        }

        if (that._hbTimeout) {
            clearTimeout(that._hbTimeout);
        }

        that._hosts[addr].pool.markForDeletion(client);
        that._hosts[addr].pool.release(client);
        client.end();

        //when client ends check connections count
        if (!that._updateTimeout) {
            that._updateTimeout = setTimeout(that._onCredentialsChange.bind(that), that._options.updateTimeout);
        }

        that._debug('client :', addr, 'disconnected');
    });

    that._hosts[addr].pool.add(client);
};

/**
 * Add hearbeat to redis client
 *
 * @param  {Object} client Redis Client object
 * @return {void}
 */

Redis.prototype._heartbeat = function (client) {
    var that = this;

    if (!client) {
        return;
    }

    if (client._hbTimeout) {
        clearTimeout(client._hbTimeout);
    }

    if (client.ready && client.options.hbInterval) {
        //add timeout for ping command
        if (client.options.hbTimeout) {
            client._hbWait = setTimeout(function () {
                //send event connection gone
                //its run flush_and_error <- run all queued callback with error
                //its run end event (on end we set closing to true because of disable reconnects)
                client.quit(emptyFn);
                client.connection_gone('ping');
            }, client.options.hbTimeout);
        }

        client.ping(function () {
            clearTimeout(client._hbWait);
        });
    }

    //set timer for hb
    //if hbtimer is not set, timer from credentail checking will be used
    //its because of checking if hb is enabled or not
    var timer = client.options.hbInterval || this._options.updateTimeout;

    if (!timer) {
        return;
    }

    client._hbTimeout = setTimeout(function () {
        that._heartbeat(client);
    }, timer);
};

/**
 * Returns object with connection statistics
 *
 * @return {Object}
 */
Redis.prototype.getStats = function () {
    var result = {};
    var hosts = Object.keys(this._hosts);
    for (var j = 0, hostsL = hosts.length; j < hostsL; j++) {
        var host = this._hosts[hosts[j]];

        //do not show deleted connections in stats
        if (host.toDelete) {
            continue;
        }

        //active key deprecated
        result[hosts[j]] = {
            known: host.pool.getKnownLength(),
            spare: host.pool.getSpareLength(),
            waiting: host.pool.getWaitingLength(),
            active: host.active,
            errors: host.errors,
            queued: host.pool.getQueued()
        };

        // reset error counter
        host.errors = 0;
    }

    return result;
};

/**
 * Generate crc32 hash from string
 *
 * @param  {String} - string to hash
 * @return {string}   hashed key
 */
Redis.prototype._hashKey = function (key) {
    var digest = crc32(key);
    var activeHosts = 0;
    var hosts = Object.keys(this._hosts);

    for (var i = 0, hl = hosts.length; i < hl; i++) {
        if (!this._hosts[hosts[i]].toDelete) {
            activeHosts++;
        }
    }

    if (!activeHosts) {
        return undefined;
    } else {
        return digest % activeHosts;
    }
};

/**
 * Destroy all connections and disable update interval
 *
 * @return {void}
 */
Redis.prototype.destroy = function () {
    var that = this;
    clearTimeout(this._updateTimeout);

    for (var host in this._hosts) {
        var server = that._hosts[host];
        var clientsCount = server.pool.getKnownLength();

        for (var j = 0; j < clientsCount; j++) {
            that._deleteClient();
        }
    }
};

/**
 * Get redis hostname assigned to key
 *
 * @param  {string} -
 * @return {string} -  redis  key
 */
Redis.prototype._getShard = function (key) {
    var pool = this._hashKey(key);
    var hostsL = Object.keys(this._hosts).length;

    for (var i = 0; i < hostsL; i++) {
        if (pool > hostsL) {
            pool = 0;
        }

        if (!this._sortedHosts[pool] || !this._hosts[this._sortedHosts[pool]] || this._hosts[this._sortedHosts[pool]].toDelete) {
            pool++;
            continue;
        }

        if (this._hosts[this._sortedHosts[pool]].pool.getKnownLength() > 0) {
            return this._sortedHosts[pool];
        }

        console.info('Dont know any active client for shard', this._sortedHosts[pool]);

        pool++;
    }
};

/**
 * Returns redis client by keys
 *
 * @param {string}   key      key for shard
 * @param {Function} callback call with err, client, host
 * @return {void}
 */
Redis.prototype.getConnectionByKey = function (key, callback) {
    var host = this._getShard(key);

    if (!callback) {
        console.error('Callback is required');
        return;
    }

    if (host === undefined) {
        if (callback) {
            callback('All shards are down', null);
        }
        return;
    }

    this._hosts[host].pool.get(function (client) {
        callback(null, client, host);
    });

};

/**
 * Function ovverides redis client to add shard support
 *
 * @param
 * @return {void}
 */
var cmd = function (cmd) {
    return function () {
        var that = this;
        var tmp = new Array(arguments.length);

        for (var i = 0; i < arguments.length; i++) {
            tmp[i] = arguments[i];
        }

        var key = tmp[0];
        var cb = tmp.pop();

        if (typeof cb !== 'function') {
            tmp.push(cb);
            cb = function (err) {
                if (err) {
                    console.error('Redis/Error cmd=%s error="%s"', cmd, err);
                }
            };
        }

        this.getConnectionByKey(key, function (err, client, host) {
            if (err) {
                return cb(err, null);
            }

            if (client === Pool.ERROR.MAX_QUEUED_REACHED) {
                cb(Pool.ERROR.MAX_QUEUED_REACHED, null);
                return;
            }

            tmp.push(function (err, data) {
                if (err) {
                    console.warn('Redis/Error cmd=%s error="%s"', cmd, err);
                    that._hosts[host].errors++;
                }

                that._hosts[host].pool.release(client);

                cb(err, data);
            });
            client[cmd].apply(client, tmp);
        });

    };
};
CMDS = [];

var CMDS = ['get', 'set', 'setnx', 'setex', 'append', 'strlen', 'del', 'exists',
    'setbit', 'getbit', 'setrange', 'getrange', 'substr', 'incr', 'decr', 'mget', 'rpush',
    'lpush', 'rpushx', 'lpushx', 'linsert', 'rpop', 'lpop', 'brpop', 'brpoplpush', 'blpop',
    'llen', 'lindex', 'lset', 'lrange', 'ltrim', 'lrem', 'rpoplpush', 'sadd', 'srem', 'smove',
    'sismember', 'scard', 'spop', 'srandmember', 'sinter', 'sinterstore', 'sunion', 'sunionstore',
    'sdiff', 'sdiffstore', 'smembers', 'zadd', 'zincrby', 'zrem', 'zremrangebyscore', 'zremrangebyrank',
    'zunionstore', 'zinterstore', 'zrange', 'zrangebyscore', 'zrevrangebyscore', 'zcount', 'zrevrange',
    'zcard', 'zscore', 'zrank', 'zrevrank', 'hset', 'hsetnx', 'hget', 'hmset', 'hmget', 'hincrby', 'hdel', 'hlen',
    'hkeys', 'hvals', 'hgetall', 'hexists', 'incrby', 'decrby', 'getset', 'mset', 'msetnx', 'randomkey', 'select',
    'move', 'rename', 'renamenx', 'expire', 'expireat', 'keys', 'dbsize', 'auth', 'ping', 'echo', 'save',
    'bgsave', 'bgrewriteaof', 'shutdown', 'lastsave', 'type', 'multi', 'exec', 'discard', 'sync', 'flushdb',
    'flushall', 'sort', 'info', 'monitor', 'ttl', 'persist', 'slaveof', 'debug', 'config', 'subscribe',
    'unsubscribe',
    'psubscribe', 'punsubscribe', 'publish', 'watch', 'unwatch', 'cluster', 'restore', 'migrate', 'dump', 'object',
    'client', 'eval', 'evalsha'
];

var i;
for (i = 0; i < CMDS.length; i++) {
    Redis.prototype[CMDS[i]] = cmd(CMDS[i]);
}

var crc32 = function (str, hex) {
    var crc = ~0;
    var i, l;
    for (i = 0, l = str.length; i < l; i++) {
        crc = (crc >>> 8) ^ crc32tab[(crc ^ str.charCodeAt(i)) & 0xff];
    }
    crc = Math.abs(crc ^ -1);
    return hex ? crc.toString(16) : crc;
};

var crc32tab = [
    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
    0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
    0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
    0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
    0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
    0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
    0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
    0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
    0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
    0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
    0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
    0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
    0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
    0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
    0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
    0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
    0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
    0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
    0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
    0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
    0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
    0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
    0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
    0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
    0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
    0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
    0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
    0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
    0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
    0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
    0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
    0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
    0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
    0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
    0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
    0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
    0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
    0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
    0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
    0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
    0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
    0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
    0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
    0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
    0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
    0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
    0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
    0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
    0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
    0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
    0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
    0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
    0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
    0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
];

Redis.Event = {};
Redis.Event.READY = 'Redis.Event.READY';

exports.Redis = Redis;