| // +build ignore,OMIT | |
| package main | |
| import ( | |
| "fmt" | |
| "time" | |
| "math/rand" | |
| ) | |
| func waiter(i int, block, done chan struct{}) { | |
| time.Sleep(time.Duration(rand.Intn(3000)) * time.Millisecond) | |
| fmt.Println(i, "waiting...") | |
| <-block // HL | |
| fmt.Println(i, "done!") | |
| done <- struct{}{} | |
| } | |
| func main() { | |
| block, done := make(chan struct{}), make(chan struct{}) | |
| for i := 0; i < 4; i++ { | |
| go waiter(i, block, done) | |
| } | |
| time.Sleep(5 * time.Second) | |
| close(block) // HL | |
| for i := 0; i < 4; i++ { | |
| <-done | |
| } | |
| } | |
| // endmain OMIT |