Fake google search example in Go using concurrent Go routines pushing to a common Go channel. From Rob Pike's Google IO 2012 presentation: http://www.youtube.com/watch?v=f6kdp27TYZs&feature=youtu.be and adapted from Alexey Kachayev's transcription of Pike's slides: https://gist.github.com/3124594#file-go-channels-7-search-go

search-google.go

package main;

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

var (
    Web1   = fakeSearch("web1")
    Web2   = fakeSearch("web2")
    Image1 = fakeSearch("image1")
    Image2 = fakeSearch("image2")
    Video1 = fakeSearch("video1")
    Video2 = fakeSearch("video2")
)

type Result string

type Search func(query string) Result

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\n", kind, query) )
    }
}

// Replication in order to avoid timeouts
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
}


// Main search function
func Google(query string) (results []Result) {
    c := make(chan Result)

    go func() { c <- First(query, Web1, Web2) }()
    go func() { c <- First(query, Image1, Image2) }()
    go func() { c <- First(query, Video1, Video2) }()

    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 results
}

func main() {
    rand.Seed(time.Now().UnixNano())
    start := time.Now()
    results := Google("golang")
    elapsed := time.Since(start)
    fmt.Println(results)
    fmt.Println(elapsed)
}