golang-exercises/ping-pong/main.go

package main

import (
	"fmt"
	"time"
)

var ball int = 0

// Credits to this tutorial for actually teaching how to work with channels
// https://riptutorial.com/go/example/6056/ping-pong-with-two-goroutines

// Okay so from what I'm gathering here, the function input for the channel takes in an arrow depending on whether
// or not it's getting a value from the channel, or sending a value into the channel, here it's pulling from
// pingChan since the arrow is at the left

// For the second input value it's gonna be pulling the value from the pong Channel instead of sending to it
func ping(pingChan <-chan int, pongChan chan<- int) {
	for {
		<-pingChan
		fmt.Println("PING:", ball)
		fmt.Printf("Current goroutine: %v\n\n", pingChan)
		ball = ball + 1
		time.Sleep(time.Second)
		// Instead of calling each other's function, we seem to initialize each goroutine by directing a value
		// into its channel
		pongChan <- 1
	}
}

// Over here it should be opposite, since the ping func sends its value into pingChan, then here we need to
// pull the value from pingChan, and in the case of pongChan it's the opposite
func pong(pingChan chan<- int, pongChan <-chan int) {
	for {
		<-pongChan
		fmt.Println("PONG:", ball)
		fmt.Printf("Current goroutine: %v\n\n", pongChan)
		ball = ball + 1
		time.Sleep(time.Second)
		pingChan <- 1
	}
}

// This is some black magic
func main() {

	// Here we initialize both channels, and provide both to each function called through "go"
	pingChannel := make(chan int)
	pongChannel := make(chan int)
	go ping(pingChannel, pongChannel)
	go pong(pingChannel, pongChannel)

	// Now we're just initalizing them with a 1
	pingChannel <- 1

	for {
		time.Sleep(time.Second)
		if ball >= 10 {
			break
		}
	}

	fmt.Println("Finished")

}

// WARNING: Do not read the following if you don't wish to have your retinas burned!

// var pingChannel chan int
// var ball int
//
// func main() {
// 	pingChannel := make(chan int)
// 	fmt.Println("Hello world")
// 	ball := 0
// 	go ping(pingChannel)
// 	//go pong(ball, pingChannel)
// 	ping <- 1
//
// 	for {
// 		if ball >= 10 {
// 			fmt.Println("Ball value above 10")
// 			os.Exit(0)
// 		}
// 	}
// }
//
// func ping(ballChannel <-chan int, ponger chan<- int) {
// 	pingChannel := make(chan int)
//
// 	ball = <-ballChannel
// 	fmt.Println("PING", ball)
// 	ball = +1
//
// 	ballChannel <- ball
// 	go pong(pingChannel)
// }
//
// func pong(ballChannel chan int, ponger chan<- int) {
// 	pingChannel := make(chan int)
//
// 	ball = <-ballChannel
// 	fmt.Println("PONG", ball)
//
// 	ballChannel <- ball
// 	go ping(pingChannel)
// }