A template for an HTTP Request dispatcher and worker 'pool' (sharing channels with the Dispatcher)

http_dispatcher_and_workers.go

package main

import (
//	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"strings"

)

const (
	numWorkers = 4
)

var c = make(chan *http.Request)

func main() {
	flag.Parse()
	quit := make(chan bool)
	go produce("", c, quit)
	d := &Dispatcher{quit: quit}
	d.Init()
	d.Dispatch()
	<-quit
}

func produce(msg string, c chan *http.Request, quit chan bool) {
	for i := 0; i <= numWorkers; i++ {
		c <- cPost() // Expression to be sent can be any suitable value.
	}
	// this is actually useless since the producer should not call the quit channel
	// but a 'global' counter that oversees that the number of jobs the workers received had
	// been fulfilled plus a reasonable timeout for them to fetch
	quit <- true
}

type Worker struct {
	workers  chan chan *http.Request
	requests chan *http.Request
	quit     chan bool
}

type Dispatcher struct {
	workers chan chan *http.Request
	quit    chan bool
}

func (d *Dispatcher) Init() {
	d.workers = make(chan chan *http.Request, numWorkers)

}

func (d *Dispatcher) Dispatch() {
	for i := 0; i <= numWorkers; i++ {
		log.Printf("Dispatcher initalizing worker %d\n", i)
		worker := &Worker{workers: d.workers, quit: d.quit}
		worker.Init()
		worker.Work()
	}
	go d.Listen()
}

func (d *Dispatcher) Listen() {
	for {
		select {
		case job := <-c:
			go func(j *http.Request) {
				workerChan := <-d.workers
				workerChan <- j
			}(job)
		}
	}
}

func (w *Worker) Init() {
	w.requests = make(chan *http.Request)
}

func (w *Worker) Work() {
	go func() {
		for {
			w.workers <- w.requests
			select {
			case <-w.requests: // todo: assign the fetched chan value
				fmt.Println("Doing the actual I/O request")
			case <-w.quit:
				return
				// when done, I'm putting my channel back to the dispatcher so she can send me more jobs

			}
		}
	}()
}

func cPost() *http.Request {
	req, err := http.NewRequest(
		"POST",
		`/`,
		strings.NewReader(`{"time":1111, "msg":"aaaaaa"}`),
	)
	if err != nil {
		log.Fatalf("%v", err)
	}
	req.Header.Set(
		"Content-Type",
		"application/x-www-form-urlencoded; param=value",
	)
	return req
}