main.go

package main

import (
	"context"
	"encoding/json"
	"github.com/google/uuid"
	"github.com/grpc-ecosystem/go-grpc-middleware/logging/logrus/ctxlogrus"
	"github.com/sirupsen/logrus"
	"log"
	"math/rand"
	"net/http"
	"time"
)

func init() {
	// 全局设置
	logrus.SetFormatter(&logrus.JSONFormatter{})
	//logrus.SetReportCaller(true)
}

// model
type Product struct {
	ID    string
	Name  string
	Price float64
}

// biz logic
func Do(ctx context.Context, userID, productID string) (*Product, error) {
	ctxlogrus.Extract(ctx).Info("do biz logic")

	// pretend to read user
	userType := "admin"
	if len(userID) >= 3 {
		userType = "normal"
	}

	// add new fields
	ctxlogrus.AddFields(ctx, map[string]interface{}{
		"userType": userType,
	})

	product, err := GetProductByID(ctx, productID)
	if err != nil {
		return nil, err
	}

	// 1~99原价，100号以后涨价
	if len(userID) >= 3 {
		product.Price *= 1.1
	}

	ctxlogrus.Extract(ctx).Infof("product price: %v", product.Price)

	return product, nil
}

// mock read db
func GetProductByID(ctx context.Context, productID string) (*Product, error) {
	ctxlogrus.Extract(ctx).Info("get product from db")

	ms := rand.Intn(5) * 1000
	time.Sleep(time.Duration(ms) * time.Millisecond)

	return &Product{
		ID:    productID,
		Name:  "cat",
		Price: 100,
	}, nil
}

// http handler
type productHandler struct {
}

func (h *productHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	userID := r.URL.Query().Get("uid")
	productID := r.URL.Query().Get("pid")

	// prepare context
	// StandardLogger 是全局的logger
	// logrus.New() 会创建新的logger，需要另外设置formatter
	ctx := ctxlogrus.ToContext(r.Context(), logrus.NewEntry(logrus.StandardLogger()))
	ctxlogrus.AddFields(ctx, map[string]interface{}{
		"requestID": uuid.New().String(),
		"userID":    userID,
		"productID": productID,
	})

	product, err := Do(ctx, userID, productID)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	encoder := json.NewEncoder(w)
	_ = encoder.Encode(product)
}

// demo
// go run .
// curl http://localhost:8080/product?pid=10&uid=10
// curl http://localhost:8080/product?pid=10&uid=100
func main() {
	http.Handle("/product", new(productHandler))
	log.Fatal(http.ListenAndServe(":8080", nil))
}