How to rigger a channel inside the loop where the same channel is consumed. Below is a sample code that does not work. How is this achievable?
https://go.dev/play/p/o5ZhNfw4IFu
package main
import (
"context"
"fmt"
"time"
)
func main() {
ch1 := make(chan struct{})
ch2 := make(chan struct{})
defer close(ch1)
defer close(ch2)
ctx, cancel := context.WithTimeout(context.Background(), time.Second*3)
defer cancel()
go func() {
time.Sleep(time.Second * 1)
ch1 <- struct{}{}
}()
loop:
for {
select {
case <-ctx.Done():
fmt.Println("timeout")
break loop
case <-ch1:
fmt.Println("ch1")
ch2 <- struct{}{} // This here does not work!
case <-ch2:
fmt.Println("ch2")
}
}
}
>Solution :
1. send data to ch2 inside goroutine
package main
import (
"context"
"fmt"
"time"
)
func main() {
ch1 := make(chan struct{})
ch2 := make(chan struct{})
defer close(ch1)
defer close(ch2)
ctx, cancel := context.WithTimeout(context.Background(), time.Second*3)
defer cancel()
go func() {
time.Sleep(time.Second * 1)
ch1 <- struct{}{}
}()
loop:
for {
select {
case <-ctx.Done():
fmt.Println("timeout")
break loop
case <-ch1:
fmt.Println("ch1")
go func() {
ch2 <- struct{}{}
}()
case <-ch2:
fmt.Println("ch2")
}
}
}
or
2. make ch2 buffered
package main
import (
"context"
"fmt"
"time"
)
func main() {
ch1 := make(chan struct{})
ch2 := make(chan struct{}, 1)
defer close(ch1)
defer close(ch2)
ctx, cancel := context.WithTimeout(context.Background(), time.Second*3)
defer cancel()
go func() {
time.Sleep(time.Second * 1)
ch1 <- struct{}{}
}()
loop:
for {
select {
case <-ctx.Done():
fmt.Println("timeout")
break loop
case <-ch1:
fmt.Println("ch1")
ch2 <- struct{}{}
case <-ch2:
fmt.Println("ch2")
}
}
}