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The Way to Go

Channel Factory and Producer-Consumer Pattern

Explore how to use the channel factory pattern where functions return channels, and apply the producer-consumer pattern with separate goroutines producing and consuming data. Understand how to manage these patterns using for-range loops over channels and synchronization in Go concurrency.

We'll cover the following...

Channel factory pattern

Another common pattern in this style of programming is that, instead of passing a channel as a parameter to a goroutine, the function makes the channel and returns it (so it plays the role of a factory). Inside the function, a lambda function is called a goroutine. The following code is an implementation of this pattern:

Go (1.6.2)
package main
import (
  "fmt"
  "time"
)
func main() {
  stream := pump()
  go suck(stream)
  // the above 2 lines can be shortened to: go suck( pump() )
  time.Sleep(1e9)
}
func pump() chan int {
  ch := make(chan int)
  go func() {
    for i := 0; ; i++ {
      ch <- i
    }
  }()
  return ch
}
func suck(ch chan int) {
  for {
    fmt.Println(<-ch)
  }
}

At line 8, the main() goroutine starts the function pump(). As we see from line 14, pump() returns a channel of ints, which is received in the stream variable.

Look at the header of pump() at line 14. It makes a local channel ch at line ...