first

course/13-channels/challenges/1-channels_practice/code.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func pingPong(numPings int) {
+	pings := make(chan struct{})
+	pongs := make(chan struct{})
+	go ponger(pings, pongs)
+	go pinger(pings, pongs, numPings)
+}
+
+// TEST SUITE - Don't touch below this line
+
+func pinger(pings, pongs chan struct{}, numPings int) {
+	go func() {
+		sleepTime := 50 * time.Millisecond
+		for i := 0; i < numPings; i++ {
+			fmt.Println("ping", i, "sent")
+			pings <- struct{}{}
+			time.Sleep(sleepTime)
+			sleepTime *= 2
+		}
+		close(pings)
+	}()
+	i := 0
+	for range pongs {
+		fmt.Println("pong", i, "got")
+		i++
+	}
+	fmt.Println("pongs done")
+}
+
+func ponger(pings, pongs chan struct{}) {
+	i := 0
+	for range pings {
+		fmt.Println("ping", i, "got", "pong", i, "sent")
+		pongs <- struct{}{}
+		i++
+	}
+	fmt.Println("pings done")
+	close(pongs)
+}
+
+func test(numPings int) {
+	fmt.Println("Starting game...")
+	pingPong(numPings)
+	fmt.Println("===== Game over =====")
+}
+
+func main() {
+	test(4)
+	test(3)
+	test(2)
+}

course/13-channels/challenges/1-channels_practice/complete.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func pingPong(numPings int) {
+	pings := make(chan struct{})
+	pongs := make(chan struct{})
+	go ponger(pings, pongs)
+	pinger(pings, pongs, numPings)
+}
+
+// TEST SUITE - Don't touch below this line
+
+func pinger(pings, pongs chan struct{}, numPings int) {
+	go func() {
+		sleepTime := 50 * time.Millisecond
+		for i := 0; i < numPings; i++ {
+			fmt.Println("ping", i, "sent")
+			pings <- struct{}{}
+			time.Sleep(sleepTime)
+			sleepTime *= 2
+		}
+		close(pings)
+	}()
+	i := 0
+	for range pongs {
+		fmt.Println("pong", i, "got")
+		i++
+	}
+	fmt.Println("pongs done")
+}
+
+func ponger(pings, pongs chan struct{}) {
+	i := 0
+	for range pings {
+		fmt.Println("ping", i, "got", "pong", i, "sent")
+		pongs <- struct{}{}
+		i++
+	}
+	fmt.Println("pings done")
+	close(pongs)
+}
+
+func test(numPings int) {
+	fmt.Println("Starting game...")
+	pingPong(numPings)
+	fmt.Println("===== Game over =====")
+}
+
+func main() {
+	test(4)
+	test(3)
+	test(2)
+}

course/13-channels/challenges/1-channels_practice/expected.txt

@@ -0,0 +1,39 @@
+Starting game...
+ping 0 sent
+ping 0 got pong 0 sent
+pong 0 got
+ping 1 sent
+ping 1 got pong 1 sent
+pong 1 got
+ping 2 sent
+ping 2 got pong 2 sent
+pong 2 got
+ping 3 sent
+ping 3 got pong 3 sent
+pong 3 got
+pings done
+pongs done
+===== Game over =====
+Starting game...
+ping 0 sent
+ping 0 got pong 0 sent
+pong 0 got
+ping 1 sent
+ping 1 got pong 1 sent
+pong 1 got
+ping 2 sent
+ping 2 got pong 2 sent
+pong 2 got
+pings done
+pongs done
+===== Game over =====
+Starting game...
+ping 0 sent
+ping 0 got pong 0 sent
+pong 0 got
+ping 1 sent
+ping 1 got pong 1 sent
+pong 1 got
+pings done
+pongs done
+===== Game over =====

course/13-channels/challenges/1-channels_practice/readme.md

@@ -0,0 +1,7 @@
+# Ping Pong
+
+Many tech companies play ping pong in the office during break time. At Mailio, we play virtual ping pong using channels.
+
+## Assignment
+
+Fix the bug in the `pingPong` function. It shouldn't `return` until the entire game of ping pong is complete.