go_select_channel.go

package main

import (
    "time"
    "fmt"
)

func main() {
    bundles := make(chan int, 5)
    cancelProcessing := make(chan struct{})

    go func() {
        counter := 0
        for bundle := range bundles {
            fmt.Println("[2] Counter =", counter, "Got bundle", bundle, "sleeping for 2s")
            time.Sleep(time.Second*2)
            fmt.Println("[2] Counter =", counter, "Got bundle", bundle, "WOKE UP")

            if counter > 1 {
                //time.Sleep(1 * time.Second)
                fmt.Println("[2] Closing cancelProcessing...")
                close(cancelProcessing)
                fmt.Println("[2] Closed cancelProcessing")
                break
            }
            counter++
        }
        close(bundles)
    }()

    foo(bundles, cancelProcessing)
    time.Sleep(time.Second * 10)
}

func foo(output chan<- int, cancel <-chan struct{}) {
    batches := []int{11, 22, 33, 44, 55, 66}
    for _, batch := range batches {
        fmt.Println("Iteration with batch:", batch)
        select {
        case output <- batch:
            fmt.Println("Sent batch", batch, "to output channel")
        case <-cancel:
            fmt.Println("Cancel")
            break
        case <-time.After(time.Second):
            fmt.Println("Timeout!")
            break
        }
    }
}