Redis Patterns
Implement common Redis patterns for high-performance applications.
Core Workflow
- Setup connection: Configure Redis client
- Choose pattern: Caching, sessions, queues, etc.
- Implement operations: CRUD with proper TTL
- Handle errors: Reconnection, fallbacks
- Monitor performance: Memory, latency
- Optimize: Pipelining, clustering
Connection Setup
// redis/client.ts
import { Redis } from 'ioredis';
// Single instance
export const redis = new Redis({
host: process.env.REDIS_HOST || 'localhost',
port: parseInt(process.env.REDIS_PORT || '6379'),
password: process.env.REDIS_PASSWORD,
db: parseInt(process.env.REDIS_DB || '0'),
// Connection options
maxRetriesPerRequest: 3,
retryStrategy(times) {
const delay = Math.min(times * 50, 2000);
return delay;
},
// Performance options
enableReadyCheck: true,
enableOfflineQueue: true,
connectTimeout: 10000,
// TLS for production
tls: process.env.NODE_ENV === 'production' ? {} : undefined,
});
// Event handlers
redis.on('connect', () => console.log('Redis connecting...'));
redis.on('ready', () => console.log('Redis ready'));
redis.on('error', (err) => console.error('Redis error:', err));
redis.on('close', () => console.log('Redis connection closed'));
// Cluster connection
export const cluster = new Redis.Cluster([
{ host: 'redis-node-1', port: 6379 },
{ host: 'redis-node-2', port: 6379 },
{ host: 'redis-node-3', port: 6379 },
], {
redisOptions: {
password: process.env.REDIS_PASSWORD,
},
scaleReads: 'slave',
maxRedirections: 16,
});
// Graceful shutdown
process.on('SIGTERM', async () => {
await redis.quit();
});Caching Pattern
// patterns/cache.ts
import { redis } from './client';
interface CacheOptions {
ttl?: number; // seconds
prefix?: string;
}
export class Cache {
private prefix: string;
private defaultTTL: number;
constructor(options: CacheOptions = {}) {
this.prefix = options.prefix || 'cache:';
this.defaultTTL = options.ttl || 3600;
}
private key(key: string): string {
return `${this.prefix}${key}`;
}
async get<T>(key: string): Promise<T | null> {
const data = await redis.get(this.key(key));
if (!data) return null;
try {
return JSON.parse(data) as T;
} catch {
return data as unknown as T;
}
}
async set<T>(key: string, value: T, ttl?: number): Promise<void> {
const serialized = typeof value === 'string'
? value
: JSON.stringify(value);
await redis.setex(this.key(key), ttl || this.defaultTTL, serialized);
}
async getOrSet<T>(
key: string,
fetcher: () => Promise<T>,
ttl?: number
): Promise<T> {
const cached = await this.get<T>(key);
if (cached !== null) return cached;
const value = await fetcher();
await this.set(key, value, ttl);
return value;
}
async delete(key: string): Promise<void> {
await redis.del(this.key(key));
}
async deletePattern(pattern: string): Promise<void> {
const keys = await redis.keys(this.key(pattern));
if (keys.length > 0) {
await redis.del(...keys);
}
}
// Cache with stale-while-revalidate
async getStale<T>(
key: string,
fetcher: () => Promise<T>,
options: { ttl: number; staleTTL: number }
): Promise<T> {
const cacheKey = this.key(key);
const staleKey = `${cacheKey}:stale`;
const cached = await redis.get(cacheKey);
if (cached) {
return JSON.parse(cached);
}
// Check stale data
const stale = await redis.get(staleKey);
if (stale) {
// Return stale, refresh in background
this.refreshCache(key, fetcher, options).catch(console.error);
return JSON.parse(stale);
}
return this.refreshCache(key, fetcher, options);
}
private async refreshCache<T>(
key: string,
fetcher: () => Promise<T>,
options: { ttl: number; staleTTL: number }
): Promise<T> {
const value = await fetcher();
const serialized = JSON.stringify(value);
const pipeline = redis.pipeline();
pipeline.setex(this.key(key), options.ttl, serialized);
pipeline.setex(`${this.key(key)}:stale`, options.staleTTL, serialized);
await pipeline.exec();
return value;
}
}
// Usage
const cache = new Cache({ prefix: 'user:', ttl: 3600 });
async function getUser(id: string) {
return cache.getOrSet(`profile:${id}`, async () => {
return await db.users.findById(id);
}, 1800);
}Session Storage
// patterns/session.ts
import { redis } from './client';
import { nanoid } from 'nanoid';
interface Session {
id: string;
userId: string;
data: Record<string, any>;
createdAt: number;
expiresAt: number;
}
export class SessionStore {
private prefix = 'session:';
private userPrefix = 'user:sessions:';
private ttl = 86400 * 7; // 7 days
private key(sessionId: string): string {
return `${this.prefix}${sessionId}`;
}
async create(userId: string, data: Record<string, any> = {}): Promise<Session> {
const session: Session = {
id: nanoid(32),
userId,
data,
createdAt: Date.now(),
expiresAt: Date.now() + this.ttl * 1000,
};
const pipeline = redis.pipeline();
// Store session
pipeline.setex(this.key(session.id), this.ttl, JSON.stringify(session));
// Track user's sessions
pipeline.sadd(`${this.userPrefix}${userId}`, session.id);
pipeline.expire(`${this.userPrefix}${userId}`, this.ttl);
await pipeline.exec();
return session;
}
async get(sessionId: string): Promise<Session | null> {
const data = await redis.get(this.key(sessionId));
if (!data) return null;
const session = JSON.parse(data) as Session;
// Check expiration
if (session.expiresAt < Date.now()) {
await this.destroy(sessionId);
return null;
}
return session;
}
async update(sessionId: string, data: Record<string, any>): Promise<void> {
const session = await this.get(sessionId);
if (!session) throw new Error('Session not found');
session.data = { ...session.data, ...data };
await redis.setex(
this.key(sessionId),
this.ttl,
JSON.stringify(session)
);
}
async refresh(sessionId: string): Promise<void> {
const session = await this.get(sessionId);
if (!session) return;
session.expiresAt = Date.now() + this.ttl * 1000;
await redis.setex(
this.key(sessionId),
this.ttl,
JSON.stringify(session)
);
}
async destroy(sessionId: string): Promise<void> {
const session = await this.get(sessionId);
if (!session) return;
const pipeline = redis.pipeline();
pipeline.del(this.key(sessionId));
pipeline.srem(`${this.userPrefix}${session.userId}`, sessionId);
await pipeline.exec();
}
async destroyAllForUser(userId: string): Promise<void> {
const sessionIds = await redis.smembers(`${this.userPrefix}${userId}`);
if (sessionIds.length > 0) {
const keys = sessionIds.map(id => this.key(id));
await redis.del(...keys, `${this.userPrefix}${userId}`);
}
}
}Rate Limiting
// patterns/rate-limiter.ts
import { redis } from './client';
interface RateLimitResult {
allowed: boolean;
remaining: number;
resetAt: number;
}
export class RateLimiter {
// Fixed window rate limiting
async fixedWindow(
key: string,
limit: number,
windowSeconds: number
): Promise<RateLimitResult> {
const redisKey = `ratelimit:fixed:${key}`;
const now = Math.floor(Date.now() / 1000);
const window = Math.floor(now / windowSeconds);
const windowKey = `${redisKey}:${window}`;
const count = await redis.incr(windowKey);
if (count === 1) {
await redis.expire(windowKey, windowSeconds);
}
return {
allowed: count <= limit,
remaining: Math.max(0, limit - count),
resetAt: (window + 1) * windowSeconds * 1000,
};
}
// Sliding window rate limiting
async slidingWindow(
key: string,
limit: number,
windowSeconds: number
): Promise<RateLimitResult> {
const redisKey = `ratelimit:sliding:${key}`;
const now = Date.now();
const windowStart = now - windowSeconds * 1000;
const pipeline = redis.pipeline();
// Remove old entries
pipeline.zremrangebyscore(redisKey, 0, windowStart);
// Add current request
pipeline.zadd(redisKey, now, `${now}:${Math.random()}`);
// Count requests in window
pipeline.zcard(redisKey);
// Set expiration
pipeline.expire(redisKey, windowSeconds);
const results = await pipeline.exec();
const count = results?.[2]?.[1] as number;
return {
allowed: count <= limit,
remaining: Math.max(0, limit - count),
resetAt: now + windowSeconds * 1000,
};
}
// Token bucket rate limiting
async tokenBucket(
key: string,
bucketSize: number,
refillRate: number, // tokens per second
tokensNeeded: number = 1
): Promise<RateLimitResult> {
const redisKey = `ratelimit:bucket:${key}`;
const now = Date.now();
// Lua script for atomic token bucket
const script = `
local key = KEYS[1]
local bucket_size = tonumber(ARGV[1])
local refill_rate = tonumber(ARGV[2])
local tokens_needed = tonumber(ARGV[3])
local now = tonumber(ARGV[4])
local bucket = redis.call('HMGET', key, 'tokens', 'last_refill')
local tokens = tonumber(bucket[1]) or bucket_size
local last_refill = tonumber(bucket[2]) or now
-- Calculate refill
local elapsed = (now - last_refill) / 1000
local refill = elapsed * refill_rate
tokens = math.min(bucket_size, tokens + refill)
-- Check if enough tokens
local allowed = 0
if tokens >= tokens_needed then
tokens = tokens - tokens_needed
allowed = 1
end
-- Save state
redis.call('HMSET', key, 'tokens', tokens, 'last_refill', now)
redis.call('EXPIRE', key, math.ceil(bucket_size / refill_rate) + 1)
return {allowed, tokens}
`;
const result = await redis.eval(
script,
1,
redisKey,
bucketSize,
refillRate,
tokensNeeded,
now
) as [number, number];
return {
allowed: result[0] === 1,
remaining: Math.floor(result[1]),
resetAt: now + Math.ceil((tokensNeeded - result[1]) / refillRate) * 1000,
};
}
}
// Express middleware
export function rateLimitMiddleware(
limiter: RateLimiter,
options: { limit: number; window: number }
) {
return async (req: Request, res: Response, next: NextFunction) => {
const key = req.ip || 'anonymous';
const result = await limiter.slidingWindow(key, options.limit, options.window);
res.setHeader('X-RateLimit-Limit', options.limit);
res.setHeader('X-RateLimit-Remaining', result.remaining);
res.setHeader('X-RateLimit-Reset', result.resetAt);
if (!result.allowed) {
return res.status(429).json({
error: 'Too Many Requests',
retryAfter: Math.ceil((result.resetAt - Date.now()) / 1000),
});
}
next();
};
}Distributed Locks
// patterns/lock.ts
import { redis } from './client';
import { nanoid } from 'nanoid';
export class DistributedLock {
private prefix = 'lock:';
async acquire(
resource: string,
ttlMs: number = 10000
): Promise<string | null> {
const lockKey = `${this.prefix}${resource}`;
const lockValue = nanoid();
const ttlSeconds = Math.ceil(ttlMs / 1000);
const acquired = await redis.set(
lockKey,
lockValue,
'EX',
ttlSeconds,
'NX'
);
return acquired === 'OK' ? lockValue : null;
}
async release(resource: string, lockValue: string): Promise<boolean> {
const lockKey = `${this.prefix}${resource}`;
// Lua script for atomic release
const script = `
if redis.call('GET', KEYS[1]) == ARGV[1] then
return redis.call('DEL', KEYS[1])
else
return 0
end
`;
const result = await redis.eval(script, 1, lockKey, lockValue);
return result === 1;
}
async extend(
resource: string,
lockValue: string,
ttlMs: number
): Promise<boolean> {
const lockKey = `${this.prefix}${resource}`;
const ttlSeconds = Math.ceil(ttlMs / 1000);
const script = `
if redis.call('GET', KEYS[1]) == ARGV[1] then
return redis.call('EXPIRE', KEYS[1], ARGV[2])
else
return 0
end
`;
const result = await redis.eval(script, 1, lockKey, lockValue, ttlSeconds);
return result === 1;
}
async withLock<T>(
resource: string,
fn: () => Promise<T>,
options: { ttl?: number; retries?: number; retryDelay?: number } = {}
): Promise<T> {
const { ttl = 10000, retries = 3, retryDelay = 100 } = options;
let lockValue: string | null = null;
let attempts = 0;
while (attempts < retries) {
lockValue = await this.acquire(resource, ttl);
if (lockValue) break;
attempts++;
await new Promise(resolve => setTimeout(resolve, retryDelay));
}
if (!lockValue) {
throw new Error(`Failed to acquire lock for ${resource}`);
}
try {
return await fn();
} finally {
await this.release(resource, lockValue);
}
}
}
// Usage
const lock = new DistributedLock();
async function processPayment(orderId: string) {
return lock.withLock(`order:${orderId}`, async () => {
// Critical section - only one process can execute
const order = await db.orders.findById(orderId);
if (order.status !== 'pending') {
throw new Error('Order already processed');
}
await processStripePayment(order);
await db.orders.update(orderId, { status: 'paid' });
});
}Pub/Sub Pattern
// patterns/pubsub.ts
import { Redis } from 'ioredis';
// Separate connections for pub/sub
const subscriber = new Redis(process.env.REDIS_URL!);
const publisher = new Redis(process.env.REDIS_URL!);
type MessageHandler<T> = (message: T, channel: string) => void | Promise<void>;
export class PubSub {
private handlers: Map<string, Set<MessageHandler<any>>> = new Map();
async subscribe<T>(channel: string, handler: MessageHandler<T>): Promise<void> {
if (!this.handlers.has(channel)) {
this.handlers.set(channel, new Set());
await subscriber.subscribe(channel);
}
this.handlers.get(channel)!.add(handler);
}
async unsubscribe(channel: string, handler?: MessageHandler<any>): Promise<void> {
const handlers = this.handlers.get(channel);
if (!handlers) return;
if (handler) {
handlers.delete(handler);
if (handlers.size === 0) {
this.handlers.delete(channel);
await subscriber.unsubscribe(channel);
}
} else {
this.handlers.delete(channel);
await subscriber.unsubscribe(channel);
}
}
async publish<T>(channel: string, message: T): Promise<void> {
await publisher.publish(channel, JSON.stringify(message));
}
async subscribePattern<T>(pattern: string, handler: MessageHandler<T>): Promise<void> {
if (!this.handlers.has(pattern)) {
this.handlers.set(pattern, new Set());
await subscriber.psubscribe(pattern);
}
this.handlers.get(pattern)!.add(handler);
}
}
// Initialize message handling
subscriber.on('message', (channel, message) => {
const pubsub = new PubSub();
const handlers = pubsub['handlers'].get(channel);
if (!handlers) return;
const parsed = JSON.parse(message);
handlers.forEach(handler => handler(parsed, channel));
});
// Usage
const pubsub = new PubSub();
// Subscribe to user events
await pubsub.subscribe<{ userId: string; action: string }>('user:events', async (msg) => {
console.log(`User ${msg.userId} performed ${msg.action}`);
});
// Publish event
await pubsub.publish('user:events', { userId: '123', action: 'login' });Leaderboard Pattern
// patterns/leaderboard.ts
import { redis } from './client';
export class Leaderboard {
private key: string;
constructor(name: string) {
this.key = `leaderboard:${name}`;
}
async addScore(member: string, score: number): Promise<void> {
await redis.zadd(this.key, score, member);
}
async incrementScore(member: string, increment: number): Promise<number> {
return redis.zincrby(this.key, increment, member);
}
async getTop(count: number): Promise<Array<{ member: string; score: number }>> {
const results = await redis.zrevrange(this.key, 0, count - 1, 'WITHSCORES');
const entries: Array<{ member: string; score: number }> = [];
for (let i = 0; i < results.length; i += 2) {
entries.push({
member: results[i],
score: parseFloat(results[i + 1]),
});
}
return entries;
}
async getRank(member: string): Promise<number | null> {
const rank = await redis.zrevrank(this.key, member);
return rank !== null ? rank + 1 : null;
}
async getScore(member: string): Promise<number | null> {
const score = await redis.zscore(this.key, member);
return score !== null ? parseFloat(score) : null;
}
async getAroundMember(
member: string,
count: number
): Promise<Array<{ member: string; score: number; rank: number }>> {
const rank = await redis.zrevrank(this.key, member);
if (rank === null) return [];
const start = Math.max(0, rank - Math.floor(count / 2));
const results = await redis.zrevrange(this.key, start, start + count - 1, 'WITHSCORES');
const entries: Array<{ member: string; score: number; rank: number }> = [];
for (let i = 0; i < results.length; i += 2) {
entries.push({
member: results[i],
score: parseFloat(results[i + 1]),
rank: start + i / 2 + 1,
});
}
return entries;
}
}Best Practices
- Connection pooling: Reuse connections
- Pipelining: Batch multiple commands
- TTL everywhere: Prevent memory leaks
- Key naming: Use consistent prefixes
- Lua scripts: Atomic operations
- Cluster ready: Design for horizontal scaling
- Error handling: Graceful degradation
- Memory management: Monitor and set maxmemory
Output Checklist
Every Redis implementation should include:
- Connection with retry strategy
- Proper key prefixing/namespacing
- TTL on all keys
- Error handling and fallbacks
- Graceful shutdown
- Pipelining for batch operations
- Lua scripts for atomicity
- Memory monitoring
- Cluster-safe operations
- Connection pooling