I am trying to figure out whether I can reopen a channel after closing it.
Test case:
go func() {
queue <- "1"
queue <- "2"
close(queue)
}()
for i := range queue {
go func(i string) {
fmt.Println("From queue: ", i)
}(i)
}
go func() {
open(queue)
queue <- "3"
queue <- "4"
close(queue)
}()
for i := range queue {
go func(i string) {
fmt.Println("From queue: ", i)
}(i)
}
open
does not exist. How can I implement something like what I need in Go?You cannot reopen a closed channel but you can send a channel
on a channel, perhaps this is what you're looking for?
package main
import (
"fmt"
"time"
)
func main() {
queue := make(chan chan int)
defer close(queue)
go func() { // reader
for {
ch := <-queue
for i := range ch {
fmt.Println(i)
}
fmt.Println("Done with this channel")
}
}()
go func() { // writer-1
ch := make(chan int)
defer close(ch)
queue <- ch
ch <- 4
ch <- 2
}()
go func() { // writer-2
ch := make(chan int)
defer close(ch)
queue <- ch
ch <- 4
ch <- 20
}()
time.Sleep(time.Second)
}
I want to range over them therefore I need to close the channel beforehand
Nope, no need to close the channel. It'll resume iteration when another item is pushed thru the channel.
The below code accepts console input and pushes it to the channel:
main.go
package main
import (
"log"
"bufio"
"os"
"fmt"
)
func process(c chan string) {
for s := range c {
log.Println("processed", s)
}
}
func main() {
c := make(chan string, 10)
go process(c)
// get from console and process
reader := bufio.NewReader(os.Stdin)
fmt.Println("INPUT STUFF. TYPE #quit TO EXIT.")
for {
input, _, _ := reader.ReadLine()
if string(input) == "#quit" {
break
}
c <- string(input)
}
log.Println("BYE!")
}
output
INPUT STUFF. TYPE #quit TO EXIT.
hello
2018/10/23 10:43:52 processed hello
world
2018/10/23 10:43:54 processed world
#quit
2018/10/23 10:43:57 BYE!
The below sample uses Sleep()
and is runnable as a Go Playground snippet
package main
import (
"log"
"time"
)
func process(c chan string) {
for s := range c {
log.Println("processed", s)
}
}
func main() {
c := make(chan string, 10)
go process(c)
// push some data
c <- "barry allen"
c <- "iris west"
time.Sleep(time.Second * 2)
// push more data
c <- "joe west"
c <- "caitlin snow"
time.Sleep(time.Second * 3)
}
output
2009/11/10 23:00:00 processed barry allen
2009/11/10 23:00:00 processed iris west
2009/11/10 23:00:02 processed joe west
2009/11/10 23:00:02 processed caitlin snow
Hope this helps. Cheers,