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* @module @onlineapps/conn-base-cache
* @description Redis cache connector with TTL, invalidation, and namespace support for OA Drive microservices.
* This connector provides a high-level abstraction over Redis operations with automatic key prefixing,
* statistics tracking, and namespace isolation.
*
* IMPORTANT: This connector uses "cache:" prefix for all keys.
* Never accesses "obs:" namespace (reserved for monitoring).
*
* @see {@link https://github.com/onlineapps/oa-drive/tree/main/shared/connector/conn-base-cache|GitHub Repository}
* @author OA Drive Team
* @license MIT
* @since 1.0.0
*/
const Redis = require('ioredis');
const crypto = require('crypto');
/**
* Redis cache connector providing caching operations with automatic key management
*
* @class CacheConnector
*
* @example <caption>Basic Usage</caption>
* const cache = new CacheConnector({
* host: 'localhost',
* port: 6379,
* defaultTTL: 3600
* });
* await cache.connect();
* await cache.set('user:123', { name: 'John' }, 600);
* const user = await cache.get('user:123');
*
* @example <caption>With Namespace</caption>
* const cache = new CacheConnector({
* namespace: 'invoice-service'
* });
* await cache.set('inv:123', data); // Actual key: cache:invoice-service:inv:123
*/
class CacheConnector {
/**
* Creates a new CacheConnector instance
*
* @constructor
* @param {Object} [config={}] - Configuration options
* @param {string} [config.host='localhost'] - Redis server host
* @param {number} [config.port=6379] - Redis server port
* @param {string} [config.password] - Redis password for authentication
* @param {number} [config.db=0] - Redis database number to use
* @param {number} [config.defaultTTL=3600] - Default TTL in seconds for cached items
* @param {string} [config.namespace=''] - Namespace prefix for all keys
* @param {number} [config.maxRetries=3] - Maximum connection retry attempts
* @param {number} [config.retryDelay=100] - Initial retry delay in milliseconds
* @param {boolean} [config.enableOfflineQueue=true] - Queue commands when disconnected
* @param {boolean} [config.lazyConnect=false] - Delay connection until first operation
*
* @throws {TypeError} If configuration is invalid
*
* @example <caption>Full Configuration</caption>
* const cache = new CacheConnector({
* host: 'redis.example.com',
* port: 6380,
* password: 'secret',
* namespace: 'my-service',
* defaultTTL: 1800,
* maxRetries: 5,
* enableOfflineQueue: false
* });
*/
constructor(config = {}) {
// Configuration
this.config = {
host: config.host || process.env.REDIS_HOST || 'localhost',
port: config.port || process.env.REDIS_PORT || 6379,
password: config.password || process.env.REDIS_PASSWORD,
db: config.db || process.env.REDIS_DB || 0,
keyPrefix: 'cache:', // ALWAYS use cache: prefix
defaultTTL: config.defaultTTL || 3600, // 1 hour default
maxRetries: config.maxRetries || 3,
retryDelay: config.retryDelay || 100,
enableOfflineQueue: config.enableOfflineQueue !== false,
lazyConnect: config.lazyConnect || false
};
// Namespace configuration
this.namespace = config.namespace || '';
// Redis client
this.client = null;
// Connection state
this.connected = false;
this.connecting = false;
// Statistics
this.stats = {
hits: 0,
misses: 0,
sets: 0,
deletes: 0,
errors: 0
};
}
/**
* Establishes connection to Redis server
*
* @async
* @method connect
* @returns {Promise<boolean>} Returns true when connection is established
*
* @throws {Error} Throws error if connection fails after all retries
*
* @fires CacheConnector#connect
* @fires CacheConnector#error
* @fires CacheConnector#close
*
* @example <caption>Simple Connection</caption>
* try {
* await cache.connect();
* console.log('Connected to Redis');
* } catch (error) {
* console.error('Failed to connect:', error);
* }
*
* @example <caption>With Event Handlers</caption>
* cache.client.on('connect', () => {
* console.log('Redis connected');
* });
*
* cache.client.on('error', (err) => {
* console.error('Redis error:', err);
* });
*
* await cache.connect();
*/
async connect() {
if (this.connected || this.connecting) {
return true;
}
this.connecting = true;
try {
this.client = new Redis({
host: this.config.host,
port: this.config.port,
password: this.config.password,
db: this.config.db,
keyPrefix: this.config.keyPrefix,
retryStrategy: (times) => {
if (times > this.config.maxRetries) {
return null; // Stop retrying
}
return Math.min(times * this.config.retryDelay, 2000);
},
enableOfflineQueue: this.config.enableOfflineQueue,
lazyConnect: this.config.lazyConnect
});
// Handle events
this.client.on('connect', () => {
this.connected = true;
this.connecting = false;
console.log('Redis cache connected');
});
this.client.on('error', (err) => {
this.stats.errors++;
console.error('Redis cache error:', err);
});
this.client.on('close', () => {
this.connected = false;
console.log('Redis cache connection closed');
});
// Wait for connection if not lazy
Eif (!this.config.lazyConnect) {
await this.client.connect();
}
this.connected = true;
this.connecting = false;
return true;
} catch (error) {
this.connecting = false;
throw new Error(`Failed to connect to Redis: ${error.message}`);
}
}
/**
* Disconnect from Redis server gracefully
*
* @async
* @method disconnect
* @returns {Promise<void>}
*
* @example
* await cache.disconnect();
* console.log('Disconnected from Redis');
*/
async disconnect() {
if (this.client) {
await this.client.quit();
this.client = null;
this.connected = false;
}
}
/**
* Build cache key with namespace
* @private
*/
buildKey(key) {
if (this.namespace) {
return `${this.namespace}:${key}`;
}
return key;
}
/**
* Retrieves a value from cache by key
*
* @async
* @method get
* @param {string} key - Cache key to retrieve
* @returns {Promise<*|null>} The cached value (parsed from JSON if applicable) or null if not found
*
* @throws {Error} Throws error if Redis operation fails
*
* @fires CacheConnector#hit - When cache hit occurs
* @fires CacheConnector#miss - When cache miss occurs
*
* @example <caption>Get Simple Value</caption>
* const value = await cache.get('user:123');
* if (value) {
* console.log('User found:', value);
* }
*
* @example <caption>Get with Fallback</caption>
* let user = await cache.get('user:123');
* if (!user) {
* user = await fetchFromDatabase(123);
* await cache.set('user:123', user, 600);
* }
*/
async get(key) {
try {
const fullKey = this.buildKey(key);
const value = await this.client.get(fullKey);
if (value === null) {
this.stats.misses++;
return null;
}
this.stats.hits++;
// Try to parse JSON
try {
return JSON.parse(value);
} catch {
// Return as string if not JSON
return value;
}
} catch (error) {
this.stats.errors++;
throw new Error(`Cache get failed: ${error.message}`);
}
}
/**
* Stores a value in cache with optional TTL
*
* @async
* @method set
* @param {string} key - Cache key
* @param {*} value - Value to cache (will be JSON stringified if not a string)
* @param {number} [ttl] - Time to live in seconds (uses defaultTTL if not specified)
* @returns {Promise<boolean>} Returns true on successful storage
*
* @throws {Error} Throws error if Redis operation fails
*
* @example <caption>Set with Default TTL</caption>
* await cache.set('config', { theme: 'dark' });
*
* @example <caption>Set with Custom TTL</caption>
* await cache.set('session:abc', sessionData, 1800); // 30 minutes
*
* @example <caption>Set Permanent (no expiry)</caption>
* await cache.set('permanent:data', data, 0);
*/
async set(key, value, ttl) {
try {
const fullKey = this.buildKey(key);
const serialized = typeof value === 'string' ? value : JSON.stringify(value);
const expiry = ttl || this.config.defaultTTL;
if (expiry > 0) {
await this.client.setex(fullKey, expiry, serialized);
} else E{
await this.client.set(fullKey, serialized);
}
this.stats.sets++;
return true;
} catch (error) {
this.stats.errors++;
throw new Error(`Cache set failed: ${error.message}`);
}
}
/**
* Delete a single key from cache
*
* @async
* @method delete
* @param {string} key - Cache key to delete
* @returns {Promise<boolean>} Returns true if key was deleted
*
* @throws {Error} Throws error if Redis operation fails
*
* @example
* const deleted = await cache.delete('user:123');
* if (deleted) {
* console.log('Key deleted');
* }
*/
async delete(key) {
try {
const fullKey = this.buildKey(key);
const result = await this.client.del(fullKey);
this.stats.deletes++;
return result > 0;
} catch (error) {
this.stats.errors++;
throw new Error(`Cache delete failed: ${error.message}`);
}
}
/**
* Deletes keys matching a pattern
*
* @async
* @method deleteByPattern
* @param {string} pattern - Redis key pattern (e.g., "user:*", "session:*")
* @returns {Promise<number>} Number of deleted keys
*
* @throws {Error} Throws error if pattern deletion fails
*
* @warning This operation can be expensive on large datasets
*
* @example <caption>Delete All User Cache Entries</caption>
* const deleted = await cache.deleteByPattern('user:*');
* console.log(`Deleted ${deleted} user entries`);
*
* @example <caption>Delete Specific Session Pattern</caption>
* await cache.deleteByPattern('session:user:123:*');
*/
async deleteByPattern(pattern) {
try {
const fullPattern = this.buildKey(pattern);
const keys = await this.client.keys(`${this.config.keyPrefix}${fullPattern}`);
if (keys.length === 0) {
return 0;
}
// Remove key prefix for del command
const cleanKeys = keys.map(k => k.replace(this.config.keyPrefix, ''));
const result = await this.client.del(...cleanKeys);
this.stats.deletes += result;
return result;
} catch (error) {
this.stats.errors++;
throw new Error(`Pattern delete failed: ${error.message}`);
}
}
/**
* Check if key exists in cache
*
* @async
* @method exists
* @param {string} key - Cache key to check
* @returns {Promise<boolean>} Returns true if key exists
*
* @throws {Error} Throws error if Redis operation fails
*
* @example
* if (await cache.exists('user:123')) {
* console.log('User is cached');
* }
*/
async exists(key) {
try {
const fullKey = this.buildKey(key);
const result = await this.client.exists(fullKey);
return result === 1;
} catch (error) {
this.stats.errors++;
throw new Error(`Cache exists check failed: ${error.message}`);
}
}
/**
* Get remaining TTL for key
*
* @async
* @method ttl
* @param {string} key - Cache key
* @returns {Promise<number>} TTL in seconds, -1 if no TTL, -2 if not exists
*
* @throws {Error} Throws error if Redis operation fails
*
* @example
* const ttl = await cache.ttl('session:abc');
* if (ttl > 0) {
* console.log(`Session expires in ${ttl} seconds`);
* } else if (ttl === -1) {
* console.log('Session has no expiry');
* } else {
* console.log('Session does not exist');
* }
*/
async ttl(key) {
try {
const fullKey = this.buildKey(key);
return await this.client.ttl(fullKey);
} catch (error) {
this.stats.errors++;
throw new Error(`TTL check failed: ${error.message}`);
}
}
/**
* Update TTL for existing key
*
* @async
* @method expire
* @param {string} key - Cache key
* @param {number} ttl - New TTL in seconds
* @returns {Promise<boolean>} Returns true if TTL was set
*
* @throws {Error} Throws error if Redis operation fails
*
* @example
* // Extend session by 30 minutes
* await cache.expire('session:abc', 1800);
*/
async expire(key, ttl) {
try {
const fullKey = this.buildKey(key);
const result = await this.client.expire(fullKey, ttl);
return result === 1;
} catch (error) {
this.stats.errors++;
throw new Error(`Expire failed: ${error.message}`);
}
}
/**
* Increment numeric value atomically
*
* @async
* @method incr
* @param {string} key - Cache key
* @param {number} [increment=1] - Increment value
* @returns {Promise<number>} New value after increment
*
* @throws {Error} Throws error if Redis operation fails
*
* @example <caption>Simple Counter</caption>
* const count = await cache.incr('page:views');
* console.log(`Page views: ${count}`);
*
* @example <caption>Increment by Value</caption>
* const score = await cache.incr('user:score', 10);
*/
async incr(key, increment = 1) {
try {
const fullKey = this.buildKey(key);
if (increment === 1) {
return await this.client.incr(fullKey);
} else {
return await this.client.incrby(fullKey, increment);
}
} catch (error) {
this.stats.errors++;
throw new Error(`Increment failed: ${error.message}`);
}
}
/**
* Decrement numeric value atomically
*
* @async
* @method decr
* @param {string} key - Cache key
* @param {number} [decrement=1] - Decrement value
* @returns {Promise<number>} New value after decrement
*
* @throws {Error} Throws error if Redis operation fails
*
* @example
* const remaining = await cache.decr('inventory:count', 1);
* if (remaining < 0) {
* console.log('Out of stock');
* }
*/
async decr(key, decrement = 1) {
try {
const fullKey = this.buildKey(key);
if (decrement === 1) {
return await this.client.decr(fullKey);
} else {
return await this.client.decrby(fullKey, decrement);
}
} catch (error) {
this.stats.errors++;
throw new Error(`Decrement failed: ${error.message}`);
}
}
/**
* Get multiple values at once
*
* @async
* @method mget
* @param {string[]} keys - Array of cache keys
* @returns {Promise<Object>} Key-value object with found values
*
* @throws {Error} Throws error if Redis operation fails
*
* @example
* const result = await cache.mget(['user:1', 'user:2', 'user:3']);
* // Returns: { 'user:1': {...}, 'user:2': {...} }
* // Missing keys are not included in result
*/
async mget(keys) {
try {
const fullKeys = keys.map(k => this.buildKey(k));
const values = await this.client.mget(...fullKeys);
const result = {};
keys.forEach((key, index) => {
if (values[index] !== null) {
try {
result[key] = JSON.parse(values[index]);
this.stats.hits++;
} catch {
result[key] = values[index];
this.stats.hits++;
}
} else {
this.stats.misses++;
}
});
return result;
} catch (error) {
this.stats.errors++;
throw new Error(`Multi-get failed: ${error.message}`);
}
}
/**
* Set multiple values at once
*
* @async
* @method mset
* @param {Object} keyValues - Key-value pairs to set
* @param {number} [ttl] - TTL in seconds for all keys
* @returns {Promise<boolean>} Returns true on success
*
* @throws {Error} Throws error if Redis operation fails
*
* @example
* await cache.mset({
* 'user:1': { name: 'Alice' },
* 'user:2': { name: 'Bob' },
* 'user:3': { name: 'Charlie' }
* }, 3600);
*/
async mset(keyValues, ttl) {
try {
const pipeline = this.client.pipeline();
for (const [key, value] of Object.entries(keyValues)) {
const fullKey = this.buildKey(key);
const serialized = typeof value === 'string' ? value : JSON.stringify(value);
const expiry = ttl || this.config.defaultTTL;
if (expiry > 0) {
pipeline.setex(fullKey, expiry, serialized);
} else E{
pipeline.set(fullKey, serialized);
}
this.stats.sets++;
}
await pipeline.exec();
return true;
} catch (error) {
this.stats.errors++;
throw new Error(`Multi-set failed: ${error.message}`);
}
}
/**
* Flush all cache keys (dangerous!)
*
* @async
* @method flush
* @param {boolean} [confirm=false] - Must be true to execute
* @returns {Promise<boolean>} Returns true on success
*
* @throws {Error} If confirmation not provided or flush fails
*
* @warning This will delete ALL cache keys with the configured prefix
*
* @example
* // Safety check required
* await cache.flush(true);
* console.log('All cache cleared');
*/
async flush(confirm = false) {
if (!confirm) {
throw new Error('Flush requires confirmation parameter to be true');
}
try {
// Only flush keys with our prefix
const keys = await this.client.keys(`${this.config.keyPrefix}*`);
Eif (keys.length > 0) {
const cleanKeys = keys.map(k => k.replace(this.config.keyPrefix, ''));
await this.client.del(...cleanKeys);
}
return true;
} catch (error) {
this.stats.errors++;
throw new Error(`Flush failed: ${error.message}`);
}
}
/**
* Get cache statistics
*
* @method getStats
* @returns {CacheStats} Current statistics
* @returns {number} stats.hits - Number of cache hits
* @returns {number} stats.misses - Number of cache misses
* @returns {number} stats.sets - Number of set operations
* @returns {number} stats.deletes - Number of delete operations
* @returns {number} stats.errors - Number of errors
* @returns {string} stats.hitRate - Hit rate percentage
*
* @example
* const stats = cache.getStats();
* console.log(`Hit rate: ${stats.hitRate}`);
* console.log(`Total operations: ${stats.hits + stats.misses}`);
*/
getStats() {
return {
...this.stats,
hitRate: this.stats.hits + this.stats.misses > 0
? (this.stats.hits / (this.stats.hits + this.stats.misses) * 100).toFixed(2) + '%'
: '0%'
};
}
/**
* Reset statistics counters
*
* @method resetStats
* @returns {void}
*
* @example
* cache.resetStats();
* // All counters set to 0
*/
resetStats() {
this.stats = {
hits: 0,
misses: 0,
sets: 0,
deletes: 0,
errors: 0
};
}
/**
* Creates a new CacheConnector instance with additional namespace
*
* @method withNamespace
* @param {string} namespace - Additional namespace to append
* @returns {CacheConnector} New instance with combined namespace
*
* @example
* const baseCache = new CacheConnector({ namespace: 'app' });
* const userCache = baseCache.withNamespace('users');
* const sessionCache = baseCache.withNamespace('sessions');
*
* // userCache keys: cache:app:users:*
* // sessionCache keys: cache:app:sessions:*
*/
withNamespace(namespace) {
return new CacheConnector({
...this.config,
namespace: this.namespace ? `${this.namespace}:${namespace}` : namespace
});
}
/**
* Wraps a function with caching (memoization)
*
* @method wrap
* @param {Function} fn - Async function to wrap
* @param {Object} [options={}] - Wrapping options
* @param {number} [options.ttl] - Cache TTL in seconds
* @param {string} [options.keyPrefix] - Prefix for cache keys
* @param {Function} [options.keyGenerator] - Custom key generation function
* @returns {Function} Wrapped function with caching
*
* @example <caption>Basic Function Wrapping</caption>
* const expensiveOperation = async (userId) => {
* // Complex database query
* return await db.query('SELECT * FROM users WHERE id = ?', [userId]);
* };
*
* const cachedOperation = cache.wrap(expensiveOperation, {
* ttl: 600,
* keyPrefix: 'expensive-op'
* });
*
* // First call hits database
* const result1 = await cachedOperation(123);
*
* // Second call returns from cache
* const result2 = await cachedOperation(123);
*
* @example <caption>Custom Key Generation</caption>
* const searchUsers = cache.wrap(async (filters) => {
* return await db.searchUsers(filters);
* }, {
* ttl: 300,
* keyGenerator: (filters) => `search:${JSON.stringify(filters)}`
* });
*/
wrap(fn, options = {}) {
const ttl = options.ttl || this.config.defaultTTL;
const keyPrefix = options.keyPrefix || fn.name || 'wrapped';
const keyGenerator = options.keyGenerator || ((...args) => {
const hash = crypto.createHash('sha256');
hash.update(JSON.stringify(args));
return `${keyPrefix}:${hash.digest('hex')}`;
});
return async (...args) => {
const key = keyGenerator(...args);
// Try to get from cache
const cached = await this.get(key);
if (cached !== null) {
return cached;
}
// Execute function
const result = await fn(...args);
// Cache result
await this.set(key, result, ttl);
return result;
};
}
/**
* Perform health check on Redis connection
*
* @async
* @method healthCheck
* @returns {Promise<boolean>} Returns true if healthy
*
* @example
* if (await cache.healthCheck()) {
* console.log('Redis is healthy');
* } else {
* console.error('Redis is down');
* }
*/
async healthCheck() {
try {
await this.client.ping();
return true;
} catch {
return false;
}
}
}
/**
* @typedef {Object} CacheConfig
* @property {string} [host='localhost'] - Redis host
* @property {number} [port=6379] - Redis port
* @property {string} [password] - Redis password
* @property {number} [db=0] - Redis database
* @property {number} [defaultTTL=3600] - Default TTL in seconds
* @property {string} [namespace=''] - Key namespace
* @property {number} [maxRetries=3] - Max connection retries
* @property {number} [retryDelay=100] - Retry delay in ms
* @property {boolean} [enableOfflineQueue=true] - Queue commands when disconnected
* @property {boolean} [lazyConnect=false] - Delay connection
*/
/**
* @typedef {Object} CacheStats
* @property {number} hits - Number of cache hits
* @property {number} misses - Number of cache misses
* @property {number} sets - Number of set operations
* @property {number} deletes - Number of delete operations
* @property {number} errors - Number of errors
* @property {string} hitRate - Hit rate percentage
*/
/**
* Connection established event
*
* @event CacheConnector#connect
* @type {void}
*/
/**
* Error event
*
* @event CacheConnector#error
* @type {Error}
*/
/**
* Connection closed event
*
* @event CacheConnector#close
* @type {void}
*/
// Export main class
module.exports = CacheConnector;
/**
* Factory function to create cache instance
*
* @function create
* @param {CacheConfig} config - Configuration object
* @returns {CacheConnector} New cache connector instance
*
* @example
* const cache = CacheConnector.create({
* host: 'localhost',
* namespace: 'my-service'
* });
*/
module.exports.create = (config) => new CacheConnector(config);
/**
* Current version
* @constant {string}
*/
module.exports.VERSION = '1.0.0';
// Export mock for testing
module.exports.MockCacheConnector = class MockCacheConnector {
constructor() {
this.cache = new Map();
this.stats = { hits: 0, misses: 0, sets: 0, deletes: 0, errors: 0 };
}
async connect() { return true; }
async disconnect() { return true; }
async get(key) {
if (this.cache.has(key)) {
this.stats.hits++;
return this.cache.get(key);
}
this.stats.misses++;
return null;
}
async set(key, value, ttl) {
this.cache.set(key, value);
this.stats.sets++;
// Simulate TTL
if (ttl > 0) {
setTimeout(() => this.cache.delete(key), ttl * 1000);
}
return true;
}
async delete(key) {
this.stats.deletes++;
return this.cache.delete(key);
}
async flush() {
this.cache.clear();
return true;
}
getStats() { return this.stats; }
resetStats() {
this.stats = { hits: 0, misses: 0, sets: 0, deletes: 0, errors: 0 };
}
}; |