Tim's Question

tims-question.go

package main

import (
	"fmt"
	"net/http"
	"io/ioutil"
	"time"
)

type QueryResponse struct {
	Id      int
	Body    string
	Started time.Time
	Finished time.Time
	Error   error
}

func main() {
	size := 10
	headroom := 1

	res := make(chan *QueryResponse, size)

	for i := 0; i < size - headroom; i++ {
		fmt.Println("First: ", i)
		go Query(i, res)
	}

	coll := make([]*QueryResponse, 0, size)
DONE:
	for {
		select {
		case r := <-res:
			fmt.Println("received: ", r.Id)
			coll = append(coll, r)
			if len(coll) == size {
				fmt.Println("done got 5")
				break DONE;
			}
			if len(coll) == (size - headroom) {
				fmt.Println("Last 1")
				go Query(size - 1, res)
			}
			continue
		case <-time.After(300*time.Millisecond):
			fmt.Println("done timed out.")
			break DONE;
		}
	}

	for _,c := range coll {
		fmt.Println(c.Id)
	}
}

func Query(id int, results chan *QueryResponse) {
	started := time.Now()
	if id == 3 {
		<-time.After(400*time.Millisecond)
	}
	resp, err := http.Get("http://example.com/")
	if err != nil {
		results <- &QueryResponse{
			Error:err,
			Started:started,
			Finished: time.Now(),
		}
		return
	}
	res, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		results <- &QueryResponse{
			Error:err,
			Started:started,
			Finished: time.Now(),
		}
		return
	}
	results <- &QueryResponse{
		Id: id,
		Body: string(res),
		Error: nil,
		Started: started,
		Finished: time.Now(),
	}
}