Hello!
Today I demonstrating concurrency design pattern FANin.
In this sample concurrency design pattern FANin is being demonstrated using GoRoutine, Channels, Range, Select
Imp points
Range will keep iterating and fetching the value until channel will be closed
Select is useful which we are dealing with multiple channels together and we need to fetch from the channel whichever is ready with value.
In this design pattern a single channel accepts inputs from multiple output channels.
package main
import "fmt"
func main() {
even := make(chan int)
odd := make(chan int)
fanin := make(chan int)
// Send, this will alunch a go routine, which will execute saparatly from mai routine
go sendChannel(even, odd)
go receiveChannel(even, odd, fanin)
// range on channel will iterate until channel will be closed
for v := range fanin {
fmt.Printf("FanIn Channel value %v \n", v)
}
fmt.Printf("About to Exit")
}
func sendChannel(e, o chan<- int) {
defer close(e)
defer close(o)
for index := 0; index < 10; index++ {
if index%2 == 0 {
e <- index
} else {
o <- index
}
}
}
func receiveChannel(e, o <-chan int, f int) {
var okay int
for {
select {
case v, ok := <-e: // v will capture the channel value and ok will capture the state of channel
if !ok { // If channel is closed then increase okay
fmt.Printf("Even channel closed: %v \n", ok)
okay++
} else {
fmt.Printf("Even channel Value received: %v \n", v)
f <- v // Assign the value to fanin channel
}
case v, ok := <-o:
if !ok {
fmt.Printf("Odd channel closed: %v \n", ok)
okay++
} else {
fmt.Printf("Odd channel Value received: %v \n", v)
f <- v
}
}
// Loop exit condition
if okay == 2 {
fmt.Printf("Loop ends: %v \n", okay)
close(f)
return
}
}
}
Cheers
Dev