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我正在学习 GO 并想做一个简单的 rest API。

我想要做的是在处理 api 请求后启动一个 goroutine 并在后台异步完成工作。

到目前为止，这是我的实现：

package main

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

    "github.com/julienschmidt/httprouter"
)

// APIResponse represents common structure of every api call response
type APIResponse struct {
    Status string `json:"status"`
    Error  string `json:"error,omitempty"`
    Data   string `json:"data,omitempty"`
}

// Action represents what could be passed to the goroutine
type Action = func()

// ActionQueue represents a buffered channel
type ActionQueue = chan Action

func main() {
    r := httprouter.New()
    r.GET("/test", test)

    var apiServerPort = ":80"
    err := http.ListenAndServe(apiServerPort, r)
    if err != nil {
        log.Fatal("ListenAndServe:", err)
    } else {
        log.Printf("Started server on port %s", apiServerPort)
    }

    var queueSize = 10
    queue := make(ActionQueue, queueSize)
    for i := 0; i < queueSize; i++ {
        go worker(queue)
    }
    log.Printf("Started %d queue workers", queueSize)
}

func test(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
    successResponse(w, http.StatusOK, "Hello World")
    queue <- func() {
        log.Println("Hello from queue worker, initiated by api call")
    }
}

func successResponse(w http.ResponseWriter, statusCode int, successData string) {
    sendResponse(w, statusCode, "", successData)
}

func errorResponse(w http.ResponseWriter, statusCode int, errorData string) {
    sendResponse(w, statusCode, errorData, "")
}

func sendResponse(w http.ResponseWriter, statusCode int, errorData string, responseData string) {
    w.WriteHeader(statusCode)
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(&APIResponse{Status: http.StatusText(statusCode), Error: errorData, Data: responseData})
}

func worker(queue ActionQueue) {
    for action := range queue {
        action()
    }
}

当我尝试运行此代码时，我收到以下错误（在此行queue <- func() { ... }）：

./main.go:46:2：未定义：队列

如何使queue通道对我的请求处理程序可用（即 httprouter GET 请求处理程序函数）？

其次，我在控制台输出（stdout）中看不到我的log.Printf()调用输出，例如应用程序运行时的服务器状态消息。任何想法为什么？

4

1 回答 1

1

有几件事是错误的，首先你的主要功能没有正确排序，你想在运行之前初始化你的频道并启动工作人员，err := http.ListenAndServe(apiServerPort, r)所以像这样

func main() {
    var queueSize = 10
    queue := make(ActionQueue, queueSize)
    for i := 0; i < queueSize; i++ {
        go worker(queue)
    }
    log.Printf("Started %d queue workers", queueSize)

    // routers and stuff...
}

然后queue变量没有在test()函数中定义，这就是你得到./main.go:46:2: undefined: queue. 您可以使用更高阶函数来修复它，例如

func test(queue ActionQueue) httprouter.Handle {
    return func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
        successResponse(w, http.StatusOK, "Hello World")
        queue <- func() {
            log.Println("Hello from queue worker, initiated by api call")
        }
    }
}

然后将其绑定到路线r.GET("/test", test(queue))

于 2018-07-25T22:28:07.680 回答