blob: dde0ffa974dfdb2329a388d55e4d4acdde7e9b46 [file] [log] [blame]
// +build OMIT
package main
import (
"fmt"
"math/rand"
"time"
"golang.org/x/net/context"
)
type Result struct {
Hit string
Err error
}
// START1 OMIT
// Search runs query on a backend and returns the result.
type Search func(ctx context.Context, query string) Result // HL
// First runs query on replicas and returns the first result.
func First(ctx context.Context, query string, replicas ...Search) Result {
c := make(chan Result, len(replicas))
ctx, cancel := context.WithCancel(ctx) // HL
defer cancel() // HL
search := func(replica Search) { c <- replica(ctx, query) } // HL
for _, replica := range replicas {
go search(replica)
}
select {
case <-ctx.Done(): // HL
return Result{Err: ctx.Err()} // HL
case r := <-c:
return r
}
}
// STOP1 OMIT
// START2 OMIT
func main() {
rand.Seed(time.Now().UnixNano())
start := time.Now()
result := First(context.Background(),
"golang",
fakeSearch("replica 1"),
fakeSearch("replica 2"))
elapsed := time.Since(start)
fmt.Printf("%+v\n", result)
fmt.Println(elapsed)
}
// STOP2 OMIT
func fakeSearch(kind string) Search {
return func(ctx context.Context, query string) Result {
time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
return Result{Hit: fmt.Sprintf("%s result for %q\n", kind, query)}
}
}