mirror of
https://github.com/affaan-m/everything-claude-code.git
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599 lines
13 KiB
Markdown
599 lines
13 KiB
Markdown
---
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name: backend-patterns
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description: 后端架构模式、API设计、数据库优化以及适用于Node.js、Express和Next.js API路由的服务器端最佳实践。
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origin: ECC
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---
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# 后端开发模式
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用于可扩展服务器端应用程序的后端架构模式和最佳实践。
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## 何时激活
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* 设计 REST 或 GraphQL API 端点时
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* 实现仓储层、服务层或控制器层时
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* 优化数据库查询（N+1问题、索引、连接池）时
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* 添加缓存（Redis、内存缓存、HTTP 缓存头）时
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* 设置后台作业或异步处理时
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* 为 API 构建错误处理和验证结构时
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* 构建中间件（认证、日志记录、速率限制）时
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## API 设计模式
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### RESTful API 结构
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```typescript
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// PASS: Resource-based URLs
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GET /api/markets # List resources
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GET /api/markets/:id # Get single resource
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POST /api/markets # Create resource
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PUT /api/markets/:id # Replace resource
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PATCH /api/markets/:id # Update resource
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DELETE /api/markets/:id # Delete resource
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// PASS: Query parameters for filtering, sorting, pagination
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GET /api/markets?status=active&sort=volume&limit=20&offset=0
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```
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### 仓储模式
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```typescript
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// Abstract data access logic
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interface MarketRepository {
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findAll(filters?: MarketFilters): Promise<Market[]>
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findById(id: string): Promise<Market | null>
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create(data: CreateMarketDto): Promise<Market>
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update(id: string, data: UpdateMarketDto): Promise<Market>
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delete(id: string): Promise<void>
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}
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class SupabaseMarketRepository implements MarketRepository {
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async findAll(filters?: MarketFilters): Promise<Market[]> {
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let query = supabase.from('markets').select('*')
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if (filters?.status) {
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query = query.eq('status', filters.status)
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}
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if (filters?.limit) {
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query = query.limit(filters.limit)
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}
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const { data, error } = await query
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if (error) throw new Error(error.message)
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return data
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}
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// Other methods...
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}
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```
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### 服务层模式
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```typescript
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// Business logic separated from data access
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class MarketService {
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constructor(private marketRepo: MarketRepository) {}
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async searchMarkets(query: string, limit: number = 10): Promise<Market[]> {
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// Business logic
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const embedding = await generateEmbedding(query)
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const results = await this.vectorSearch(embedding, limit)
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// Fetch full data
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const markets = await this.marketRepo.findByIds(results.map(r => r.id))
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// Sort by similarity
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return markets.sort((a, b) => {
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const scoreA = results.find(r => r.id === a.id)?.score || 0
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const scoreB = results.find(r => r.id === b.id)?.score || 0
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return scoreA - scoreB
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})
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}
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private async vectorSearch(embedding: number[], limit: number) {
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// Vector search implementation
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}
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}
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```
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### 中间件模式
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```typescript
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// Request/response processing pipeline
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export function withAuth(handler: NextApiHandler): NextApiHandler {
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return async (req, res) => {
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const token = req.headers.authorization?.replace('Bearer ', '')
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if (!token) {
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return res.status(401).json({ error: 'Unauthorized' })
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}
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try {
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const user = await verifyToken(token)
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req.user = user
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return handler(req, res)
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} catch (error) {
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return res.status(401).json({ error: 'Invalid token' })
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}
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}
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}
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// Usage
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export default withAuth(async (req, res) => {
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// Handler has access to req.user
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})
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```
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## 数据库模式
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### 查询优化
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```typescript
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// PASS: GOOD: Select only needed columns
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const { data } = await supabase
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.from('markets')
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.select('id, name, status, volume')
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.eq('status', 'active')
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.order('volume', { ascending: false })
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.limit(10)
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// FAIL: BAD: Select everything
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const { data } = await supabase
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.from('markets')
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.select('*')
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```
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### N+1 查询预防
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```typescript
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// FAIL: BAD: N+1 query problem
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const markets = await getMarkets()
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for (const market of markets) {
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market.creator = await getUser(market.creator_id) // N queries
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}
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// PASS: GOOD: Batch fetch
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const markets = await getMarkets()
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const creatorIds = markets.map(m => m.creator_id)
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const creators = await getUsers(creatorIds) // 1 query
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const creatorMap = new Map(creators.map(c => [c.id, c]))
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markets.forEach(market => {
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market.creator = creatorMap.get(market.creator_id)
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})
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```
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### 事务模式
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```typescript
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async function createMarketWithPosition(
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marketData: CreateMarketDto,
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positionData: CreatePositionDto
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) {
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// Use Supabase transaction
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const { data, error } = await supabase.rpc('create_market_with_position', {
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market_data: marketData,
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position_data: positionData
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})
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if (error) throw new Error('Transaction failed')
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return data
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}
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// SQL function in Supabase
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CREATE OR REPLACE FUNCTION create_market_with_position(
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market_data jsonb,
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position_data jsonb
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)
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RETURNS jsonb
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LANGUAGE plpgsql
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AS $
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BEGIN
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-- Start transaction automatically
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INSERT INTO markets VALUES (market_data);
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INSERT INTO positions VALUES (position_data);
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RETURN jsonb_build_object('success', true);
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EXCEPTION
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WHEN OTHERS THEN
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-- Rollback happens automatically
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RETURN jsonb_build_object('success', false, 'error', SQLERRM);
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END;
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$;
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```
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## 缓存策略
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### Redis 缓存层
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```typescript
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class CachedMarketRepository implements MarketRepository {
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constructor(
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private baseRepo: MarketRepository,
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private redis: RedisClient
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) {}
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async findById(id: string): Promise<Market | null> {
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// Check cache first
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const cached = await this.redis.get(`market:${id}`)
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if (cached) {
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return JSON.parse(cached)
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}
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// Cache miss - fetch from database
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const market = await this.baseRepo.findById(id)
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if (market) {
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// Cache for 5 minutes
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await this.redis.setex(`market:${id}`, 300, JSON.stringify(market))
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}
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return market
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}
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async invalidateCache(id: string): Promise<void> {
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await this.redis.del(`market:${id}`)
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}
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}
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```
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### 旁路缓存模式
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```typescript
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async function getMarketWithCache(id: string): Promise<Market> {
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const cacheKey = `market:${id}`
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// Try cache
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const cached = await redis.get(cacheKey)
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if (cached) return JSON.parse(cached)
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// Cache miss - fetch from DB
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const market = await db.markets.findUnique({ where: { id } })
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if (!market) throw new Error('Market not found')
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// Update cache
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await redis.setex(cacheKey, 300, JSON.stringify(market))
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return market
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}
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```
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## 错误处理模式
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### 集中式错误处理程序
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```typescript
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class ApiError extends Error {
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constructor(
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public statusCode: number,
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public message: string,
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public isOperational = true
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) {
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super(message)
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Object.setPrototypeOf(this, ApiError.prototype)
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}
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}
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export function errorHandler(error: unknown, req: Request): Response {
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if (error instanceof ApiError) {
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return NextResponse.json({
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success: false,
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error: error.message
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}, { status: error.statusCode })
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}
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if (error instanceof z.ZodError) {
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return NextResponse.json({
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success: false,
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error: 'Validation failed',
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details: error.errors
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}, { status: 400 })
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}
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// Log unexpected errors
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console.error('Unexpected error:', error)
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return NextResponse.json({
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success: false,
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error: 'Internal server error'
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}, { status: 500 })
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}
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// Usage
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export async function GET(request: Request) {
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try {
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const data = await fetchData()
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return NextResponse.json({ success: true, data })
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} catch (error) {
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return errorHandler(error, request)
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}
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}
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```
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### 指数退避重试
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```typescript
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async function fetchWithRetry<T>(
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fn: () => Promise<T>,
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maxRetries = 3
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): Promise<T> {
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let lastError: Error
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for (let i = 0; i < maxRetries; i++) {
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try {
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return await fn()
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} catch (error) {
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lastError = error as Error
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if (i < maxRetries - 1) {
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// Exponential backoff: 1s, 2s, 4s
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const delay = Math.pow(2, i) * 1000
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await new Promise(resolve => setTimeout(resolve, delay))
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}
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}
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}
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throw lastError!
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}
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// Usage
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const data = await fetchWithRetry(() => fetchFromAPI())
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```
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## 认证与授权
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### JWT 令牌验证
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```typescript
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import jwt from 'jsonwebtoken'
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interface JWTPayload {
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userId: string
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email: string
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role: 'admin' | 'user'
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}
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export function verifyToken(token: string): JWTPayload {
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try {
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const payload = jwt.verify(token, process.env.JWT_SECRET!) as JWTPayload
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return payload
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} catch (error) {
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throw new ApiError(401, 'Invalid token')
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}
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}
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export async function requireAuth(request: Request) {
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const token = request.headers.get('authorization')?.replace('Bearer ', '')
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if (!token) {
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throw new ApiError(401, 'Missing authorization token')
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}
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return verifyToken(token)
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}
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// Usage in API route
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export async function GET(request: Request) {
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const user = await requireAuth(request)
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const data = await getDataForUser(user.userId)
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return NextResponse.json({ success: true, data })
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}
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```
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### 基于角色的访问控制
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```typescript
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type Permission = 'read' | 'write' | 'delete' | 'admin'
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interface User {
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id: string
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role: 'admin' | 'moderator' | 'user'
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}
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const rolePermissions: Record<User['role'], Permission[]> = {
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admin: ['read', 'write', 'delete', 'admin'],
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moderator: ['read', 'write', 'delete'],
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user: ['read', 'write']
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}
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export function hasPermission(user: User, permission: Permission): boolean {
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return rolePermissions[user.role].includes(permission)
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}
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export function requirePermission(permission: Permission) {
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return (handler: (request: Request, user: User) => Promise<Response>) => {
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return async (request: Request) => {
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const user = await requireAuth(request)
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if (!hasPermission(user, permission)) {
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throw new ApiError(403, 'Insufficient permissions')
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}
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return handler(request, user)
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}
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}
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}
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// Usage - HOF wraps the handler
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export const DELETE = requirePermission('delete')(
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async (request: Request, user: User) => {
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// Handler receives authenticated user with verified permission
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return new Response('Deleted', { status: 200 })
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}
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)
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```
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## 速率限制
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### 简单的内存速率限制器
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```typescript
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class RateLimiter {
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private requests = new Map<string, number[]>()
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async checkLimit(
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identifier: string,
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maxRequests: number,
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windowMs: number
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): Promise<boolean> {
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const now = Date.now()
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const requests = this.requests.get(identifier) || []
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// Remove old requests outside window
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const recentRequests = requests.filter(time => now - time < windowMs)
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if (recentRequests.length >= maxRequests) {
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return false // Rate limit exceeded
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}
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// Add current request
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recentRequests.push(now)
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this.requests.set(identifier, recentRequests)
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return true
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}
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}
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const limiter = new RateLimiter()
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export async function GET(request: Request) {
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const ip = request.headers.get('x-forwarded-for') || 'unknown'
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const allowed = await limiter.checkLimit(ip, 100, 60000) // 100 req/min
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if (!allowed) {
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return NextResponse.json({
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error: 'Rate limit exceeded'
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}, { status: 429 })
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}
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// Continue with request
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}
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```
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## 后台作业与队列
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### 简单队列模式
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```typescript
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class JobQueue<T> {
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private queue: T[] = []
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private processing = false
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async add(job: T): Promise<void> {
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this.queue.push(job)
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if (!this.processing) {
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this.process()
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}
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}
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private async process(): Promise<void> {
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this.processing = true
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while (this.queue.length > 0) {
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const job = this.queue.shift()!
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try {
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await this.execute(job)
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} catch (error) {
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console.error('Job failed:', error)
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}
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}
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this.processing = false
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}
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private async execute(job: T): Promise<void> {
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// Job execution logic
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}
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}
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// Usage for indexing markets
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interface IndexJob {
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marketId: string
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}
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const indexQueue = new JobQueue<IndexJob>()
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export async function POST(request: Request) {
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const { marketId } = await request.json()
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// Add to queue instead of blocking
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await indexQueue.add({ marketId })
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return NextResponse.json({ success: true, message: 'Job queued' })
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}
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```
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## 日志记录与监控
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### 结构化日志记录
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```typescript
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interface LogContext {
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userId?: string
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requestId?: string
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method?: string
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path?: string
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[key: string]: unknown
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}
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class Logger {
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log(level: 'info' | 'warn' | 'error', message: string, context?: LogContext) {
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const entry = {
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timestamp: new Date().toISOString(),
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level,
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message,
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...context
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}
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console.log(JSON.stringify(entry))
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}
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info(message: string, context?: LogContext) {
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this.log('info', message, context)
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}
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warn(message: string, context?: LogContext) {
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this.log('warn', message, context)
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}
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error(message: string, error: Error, context?: LogContext) {
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this.log('error', message, {
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...context,
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error: error.message,
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stack: error.stack
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})
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}
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}
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const logger = new Logger()
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// Usage
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export async function GET(request: Request) {
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const requestId = crypto.randomUUID()
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logger.info('Fetching markets', {
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requestId,
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method: 'GET',
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path: '/api/markets'
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})
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try {
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const markets = await fetchMarkets()
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return NextResponse.json({ success: true, data: markets })
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} catch (error) {
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logger.error('Failed to fetch markets', error as Error, { requestId })
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return NextResponse.json({ error: 'Internal error' }, { status: 500 })
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}
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}
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```
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**记住**：后端模式支持可扩展、可维护的服务器端应用程序。选择适合你复杂程度的模式。
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