toysearch/search.go

package main

import (
	"fmt"
	"math/rand"
	"time"
)

type Search func(query string) Result

type Result struct {
	Goodies string
}

func fakeSearch(kind string) Search {
	return func(query string) Result {
		time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
		return Result{fmt.Sprintf("%s result for %q", kind, query)}
	}
}

func First(query string, replicas ...Search) Result {
	c := make(chan Result)
	searchReplica := func(i int) {
		c <- replicas[i](query)
	}
	for i := range replicas {
		go searchReplica(i)
	}
	return <-c
}

func Google(query string) (results []Result) {
	c := make(chan Result)
	go func() {
		c <- First(query, fakeSearch("web 1"), fakeSearch("web 2"))
	}()
	go func() {
		c <- First(query, fakeSearch("vid 1"), fakeSearch("vid 2"))
	}()
	go func() {
		c <- First(query, fakeSearch("img 1"), fakeSearch("img 2"))
	}()

	timeout := time.After(80 * time.Millisecond)
	for i := 0; i < 3; i++ {
		select {
		case result := <-c:
			results = append(results, result)
		case <-timeout:
			fmt.Println("timed out!!")
			return
		}
	}
	return
}