select

go/05-concurrency/select.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"math/rand"
 	"time"
 )
@@ -8,12 +9,46 @@ import (
 func main() {
 
 	ch1 := make(chan string)
+	ch2 := make(chan string)
 
 	go func() {
 		time.Sleep(time.Duration(rand.Intn(5)+1) * time.Second)
 		ch1 <- "Message from channel 1"
 	}()
 
-	msg1 := <-ch1
-	println("Received:", msg1)
+	go func() {
+		time.Sleep(time.Duration(rand.Intn(5)+1) * time.Second)
+		ch2 <- "Message from channel 2"
+	}()
+
+	count := 10
+	var channels []chan string
+	for i := range count {
+		ch := make(chan string)
+		channels = append(channels, ch)
+		go func() {
+			time.Sleep(time.Duration(rand.Intn(5)+1) * time.Second)
+			ch <- fmt.Sprintf("Message from dynamic channel %d", i)
+		}()
+	}
+
+	fanIn := make(chan string)
+	for _, ch := range channels {
+		go func(c chan string) {
+			fanIn <- <-c
+		}(ch)
+	}
+
+	select {
+	case msg1 := <-ch1:
+		println("Received:", msg1)
+	case msg2 := <-ch2:
+		println("Received:", msg2)
+	case msg := <-fanIn:
+		println("Received:", msg)
+	case <-time.After(3 * time.Second):
+		println("Timeout occurred")
+	default:
+		println("Nothing")
+	}
 }