Fan out Fan in

07-data-pipelines/02-fan-out-fan-in/main.go

@@ -0,0 +1,64 @@
+// Squaring numbers.
+
+package main
+
+import (
+ "fmt"
+ "sync"
+)
+
+func generator(nums ...int) <-chan int {
+ out := make(chan int)
+ go func() {
+ for _, n := range nums {
+ out <- n
+ }
+ close(out)
+ }()
+ return out
+}
+
+func square(in <-chan int) <-chan int {
+ out := make(chan int)
+ go func() {
+ for n := range in {
+ out <- n * n
+ }
+ close(out)
+ }()
+ return out
+}
+
+func merge(cs ...<-chan int) <-chan int {
+ out := make(chan int)
+ var wg sync.WaitGroup
+
+ output := func(c <-chan int) {
+ for n := range c {
+ out <- n
+ }
+ wg.Done()
+ }
+
+ wg.Add(len(cs))
+ for _, c := range cs {
+ go output(c)
+ }
+
+ go func() {
+ wg.Wait()
+ close(out)
+ }()
+ return out
+}
+
+func main() {
+ in := generator(2, 3)
+
+ c1 := square(in)
+ c2 := square(in)
+
+ for n := range merge(c1, c2) {
+ fmt.Println(n)
+ }
+}