golang框架在分布式系统中的扩展性分析

import (
    "encoding/json"
    "log"
    "net/http"
    "sync"

    "github.com/labstack/echo/v4"
    "github.com/valyala/fasttemplate"
)

var (
    mu     sync.Mutex
    cache  = make(map[int]string)
    tmpl   *fasttemplate.Template
    client *http.Client
)

func init() {
    tmpl = fasttemplate.New("templates/users.html", "{{.Users}}", "{{.}}")
    client = http.DefaultClient
}

// UserController handles requests for the "/users" path
func UserController(c echo.Context) error {
    mu.Lock()
    defer mu.Unlock()

    // Check if the users are already in the cache
    if users, ok := cache[1]; ok {
        return c.String(http.StatusOK, users)
    }

    // Fetch the users from an external API
    resp, err := client.Get("http://example.com/api/users")
    if err != nil {
        return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
    }
    defer resp.Body.Close()

    // Parse the JSON response
    var users []string
    if err := json.NewDecoder(resp.Body).Decode(&users); err != nil {
        return echo.NewHTTPError(http.StatusInternalServerError, err.Error())
    }

    // Store the users in the cache
    cache[1] = tmpl.ExecuteString(users)

    // Return the users to the client
    return c.JSON(http.StatusOK, users)
}