性能设计篇之"边缘计算" [2026重制版]

// index.js — Cloudflare Worker 入门示例

export default {
  // 处理 HTTP 请求
  async fetch(request, env) {
    const url = new URL(request.url);

    // ====== 路由匹配 ======
    if (url.pathname === '/api/hello') {
      return handleHello(request);
    }

    if (url.pathname === '/api/time') {
      return handleTime(request, env);
    }

    if (url.pathname.startsWith('/api/ip')) {
      return handleIpInfo(request);
    }

    // 默认返回
    return new Response('Edge Function is running! 🚀', {
      headers: { 'Content-Type': 'text/plain' },
    });
  },
};

/**
 * 简单的 Hello World
 */
async function handleHello(request) {
  const data = {
    message: 'Hello from the Edge!',
    location: 'Cloudflare Worker',
    timestamp: new Date().toISOString(),
    requestHeaders: Object.fromEntries(request.headers),
  };

  return Response.json(data, {
    headers: {
      'Access-Control-Allow-Origin': '*',
      'Cache-Control': 'public, max-age=60',
    },
  });
}

/**
 * 从边缘返回精确的服务器时间
 */
async function handleTime(request, env) {
  // 使用 Cloudflare 的精确时间 API
  const start = Date.now();

  // 可以访问绑定的 KV/D1/DO 等资源
  const visitCount = await env.VISITS.put('total', {
    metadata: { visitedAt: new Date().toISOString() },
  });

  return Response.json({
    serverTime: new Date().toISOString(),
    edgeLocation: request.cf.colo || 'unknown',  // 所在边缘节点城市
    country: request.cf.country,
    processingTimeMs: Date.now() - start,
    totalVisits: visitCount.metadata?.customMetadata?.visits || 0,
  });
}

/**
 * 获取客户端 IP 信息
 */
async function handleIpInfo(request) {
  const clientIP = request.headers.get('CF-Connecting-IP');
  const country = request.cf.country;
  const city = request.cf.city;
  const colo = request.cf.colo;  // Cloudflare 节点代码

  return Response.json({
    ip: clientIP,
    country,
    city,
    edgeNode: colo,
    asn: request.cf.asn,
    httpVersion: request.httpVersion,
    tlsVersion: request.cf.tlsVersion,
  }, {
    headers: { 'Cache-Control': 'no-store' },
  });
}

# wrangler.toml — Cloudflare Workers 项目配置
name = "my-edge-app"
main = "index.js"
compatibility_date = "2024-01-01"

# ====== 绑定资源 ======
[vars]
ENVIRONMENT = "production"
APP_NAME = "My Edge App"

# KV 命名空间绑定
[[kv_namespaces]]
binding = "VISITS"
id = "xxxxxxxxxxxxxxxxxxxxxxxxxxxx"
preview_id = "xxxxxxxxxxxxxxxxxxxxxxxxxxxx"

# D1 数据库绑定 (SQLite at Edge)
[[d1_databases]]
binding = "DB"
database_name = "edge-db"
database_id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"

# Durable Objects 绑定
[[durable_objects_bindings]]
name = "COUNTER"
class_name = "Counter"

# R2 存储桶绑定
[[r2_buckets]]
binding = "BUCKET"
bucket_name = "my-edge-bucket"

# ====== 路由配置 ======
[triggers]
crons = ["*/5 * * * *"]  # 定时任务

# ====== 环境变量 ======
[env.production]
API_KEY = "${PRODUCTION_API_KEY}"
DATABASE_URL = "sqlite:///dev/null"

# ====== 构建配置 ======
[build]
command = "npm run build"
watch_dir = "src"

# ====== 部署配置 ======
[deployment]
bypass_token = "${BYPASS_TOKEN}"

// kv-demo.js — Cloudflare KV 存储操作示例

export default {
  async fetch(request, env) {
    const url = new URL(request.url);

    // 写入 KV
    if (url.pathname === '/api/kv/set' && request.method === 'POST') {
      const body = await request.json();
      await env.MY_KV.put(body.key, JSON.stringify(value), {
        expirationTtl: 3600,  // 1小时后过期
        metadata: { author: body.userId }
      });

      return Response.json({ success: true, key: body.key });
    }

    // 读取 KV
    if (url.pathname === '/api/kv/get') {
      const key = url.searchParams.get('key');
      const value = await env.MY_KV.get(key, { type: 'json' });

      if (value === null) {
        return Response.json({ error: 'Key not found' }, { status: 404 });
      }

      return Response.json({ key, value });
    }

    // 列出所有 Key
    if (url.pathname === '/api/kv/list') {
      const list = await env.MY_KV.list();
      const keys = list.keys.map(k => k.name);
      return Response.json({ keys, count: keys.length });
    }
  },
};

// middleware.ts — Next.js Edge Middleware
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export async function middleware(request: NextRequest) {
  const response = NextResponse.next();

  // ====== 1. 地理位置检测 ======
  const country = request.geo?.country || 'Unknown';
  const city = request.geo?.city || 'Unknown';

  // ====== 2. A/B 测试路由 ======
  const userId = request.cookies.get('user-id')?.value;
  const experimentGroup = hashUserId(userId) % 2; // 0 或 1

  // 设置响应头（供前端使用）
  response.headers.set('x-edge-country', country);
  response.headers.set('x-edge-city', city);
  response.headers.set('x-experiment-group', String(experimentGroup));

  // ====== 3. IP 限流 ======
  const clientIP = request.ip ?? '127.0.0.1';
  const rateLimitKey = `ratelimit:${clientIP}`;

  // 使用 Vercel Edge KV 进行限流计数
  const currentCount = await checkRateLimit(rateLimitKey, 60); // 60秒窗口

  if (currentCount > 100) {
    return new Response('Too Many Requests', {
      status: 429,
      headers: { 'Retry-After': '60' },
    });
  }

  // ====== 4. Bot 检测 ======
  const userAgent = request.headers.get('user-agent') || '';
  if (isBot(userAgent)) {
    // 返回静态页面或 CAPTCHA 挑战
    return new Response(null, {
      status: 302,
      headers: { Location: '/bot-challenge' },
    });
  }

  // ====== 5. 静态资源缓存策略 ======
  if (request.nextUrl.pathname.startsWith('/static/')) {
    response.headers.set(
      'Cache-Control',
      'public, s-maxage=86400, immutable'
    );
  }

  return response;

  export const config = {
    matcher: ['/((?!_next/static|_next/image|favicon.ico).*)'],
  };
}

/**
 * 简单哈希函数 — 用于 A/B 测试分组
 */
function hashUserId(userId?: string): number {
  if (!userId) return Math.floor(Math.random() * 2);
  let hash = 0;
  for (let i = 0; i < userId.length; i++) {
    hash = ((hash << 5) - hash) + userId.charCodeAt(i);
    hash |= 0;
  }
  return Math.abs(hash) % 2;
}

// app/api/hello/route.ts — Vercel Edge API Route
import type { APIContext } from 'astro';

export const prerender = false;

export async function GET({ request, locals }: APIContext) {
  // 获取边缘信息
  const edgeData = {
    method: request.method,
    url: request.url,
    geo: {
      country: locals.country,
      city: locals.city,
      latitude: locals.latitude,
      longitude: locals.longitude,
    },
    timing: {
      receivedAt: new Date().toISOString(),
    },
  };

  // 从边缘 KV 读取缓存数据
  const cached = await locals.kv.get('greeting');

  return Response.json({
    message: cached || 'Hello from Vercel Edge!',
    ...edgeData,
    platform: 'vercel-edge',
  }, {
    headers: {
      'x-powered-by': 'Vercel Edge Functions',
      'cache-control': 'public, s-maxage=10, stale-while-revalidate=59',
    },
  });
}

// src/lib.rs — WasmEdge 边缘函数 (Rust)

use wasmedge_sdk::http_request::HttpRequest;
use wasmedge_sdk::http_response::HttpResponse;
use wasmedge_sdk::HostFn;

#[derive(Default)]
struct Handler;

impl HostFn for Handler {
    fn call(&mut self, req: HttpRequest) -> Result<HttpResponse, String> {
        let path = req.path.unwrap_or_default();

        match path.as_str() {
            "/api/echo" => Ok(handle_echo(req)),
            "/api/json" => Ok(handle_json()),
            "/api/fibonacci" => Ok(handle_fibonacci(req)),
            _ => Ok(HttpResponse::new(404, vec![("Content-Type", "text/plain")], Some(b"Not Found"))),
        }
    }
}

fn handle_echo(_req: HttpRequest) -> Result<HttpResponse, String> {
    let body = r#"{"message":"Hello from WasmEdge!"}"#.as_bytes().to_vec();
    Ok(HttpResponse::new(
        200,
        vec![
            ("Content-Type", "application/json"),
            ("X-Powered-By", "WasmEdge/Rust"),
        ],
        Some(body),
    ))
}

fn handle_json() -> Result<HttpResponse, String> {
    let json = serde_json::json!({
        "runtime": "WasmEdge",
        "language": "Rust",
        "version": env!("CARGO_PKG_VERSION"),
        "timestamp": chrono::Utc::now().to_rfc3339(),
        "features": ["fast-startup", "sandboxed", "multi-language"]
    });

    Ok(HttpResponse::new(
        200,
        vec![("Content-Type", "application/json")],
        Some(json.to_string().into_bytes()),
    ))
}

fn handle_fibonacci(req: HttpRequest) -> Result<HttpResponse, String> {
    // 解析查询参数 ?n=10
    let query = req.query_string.unwrap_or_default();
    let n: u64 = query
        .split('&')
        .find(|p| p.starts_with("n="))
        .and_then(|p| p.split('=').nth(1))
        .and_then(|v| v.parse().ok())
        .unwrap_or(10)
        .min(93);  // 防止过大计算

    let result = fibonacci(n);

    Ok(HttpResponse::new(
        200,
        vec![("Content-Type", "application/json")],
        Some(format!(r#"{{"n":{},"result":{}"#}, n, result).into_bytes()),
    ))
}

fn fibonacci(n: u64) -> u64 {
    match n {
        0 => 0,
        1 => 1,
        n => {
            let (a, b) = (0u64, 1u64);
            for _ in 2..=n {
                let c = a + b;
                a = b;
                b = c;
            }
            b
        }
    }
}

# Dockerfile — WasmEdge 边缘服务
FROM wasmedge/wasmedge:latest AS builder

WORKDIR /app
COPY . .
RUN cargo build --target wasm32-wasi --release

FROM wasmedge/wasmedge:light
COPY --from=builder /app/target/release/*.wasm /app/
COPY --from=builder /app/modules/*.wasm /app/

EXPOSE 8080
CMD ["wasmedge-tensorflow-lite", "--dir", "/app::/app"]

┌──────────────────────────────────────────────────────┐
│         Cloudflare Workers 全球延迟分布                 │
├──────────────────────────────────────────────────────┤
│                                                      │
│   🇺🇸 美国     ████████████░░░░░  P50: 8ms       │
│   🇬🇧 英国     ██████████░░░░░░░░  P50: 12ms      │
│   🇯🇵 日本     █████████████░░░░░  P50: 15ms      │
│   🇩🇪 德国     ███████████░░░░░░░  P50: 18ms      │
│   🇦🇺 澳大利亚  ███████████████░░░  P50: 22ms      │
│   🇧🇷 巴西     █████████████████░  P50: 35ms      │
│   🇿🇳 新加坡    █████████████████  P50: 28ms      │
│                                                      │
│   全球 P95 延迟: < 50ms                               │
│   覆盖率: 95% 全球互联网用户                          │
│                                                      │
└──────────────────────────────────────────────────────┘