Add Go Concurrency tutorial source code

Author: jakewright

go/02-go-concurrency/01-goroutine.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+	go count("sheep")
+	count("fish")
+}
+
+func count(thing string) {
+	for i := 1; true; i++ {
+		fmt.Println(i, thing)
+		time.Sleep(time.Millisecond * 500)
+	}
+}

go/02-go-concurrency/02-wait-group.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+	"time"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	wg.Add(1)
+
+	go func() {
+		count("sheep")
+		wg.Done()
+	}()
+
+	wg.Wait()
+}
+
+func count(thing string) {
+	for i := 1; i <= 5; i++ {
+		fmt.Println(i, thing)
+		time.Sleep(time.Millisecond * 500)
+	}
+}

go/02-go-concurrency/03-channels.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+	c := make(chan string, 50)
+	go count("sheep", c)
+
+	for msg := range c {
+		fmt.Println(msg)
+	}
+}
+
+func count(thing string, c chan string) {
+	for i := 1; i <= 5; i++ {
+		c <- thing
+		time.Sleep(time.Millisecond * 500)
+	}
+
+	close(c)
+}

go/02-go-concurrency/04-select.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+func main() {
+	c1 := make(chan string)
+	c2 := make(chan string)
+
+	go func() {
+		for {
+			time.Sleep(time.Millisecond * 500)
+			c1 <- "Every 500ms"
+		}
+	}()
+
+	go func() {
+		for {
+			time.Sleep(time.Second * 2)
+			c2 <- "Every two seconds"
+		}
+	}()
+
+	for {
+		select {
+		case msg1 := <-c1:
+			fmt.Println(msg1)
+		case msg2 := <-c2:
+			fmt.Println(msg2)
+		}
+	}
+}

go/02-go-concurrency/05-fib.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	jobs := make(chan int, 100)
+	results := make(chan int, 100)
+
+	go worker(jobs, results)
+	go worker(jobs, results)
+	go worker(jobs, results)
+	go worker(jobs, results)
+
+	for i := 0; i < 100; i++ {
+		jobs <- i
+	}
+	close(jobs)
+
+	for j := 0; j < 100; j++ {
+		fmt.Println(<-results)
+	}
+}
+
+func worker(jobs <-chan int, results chan<- int) {
+	for n := range jobs {
+		results <- fib(n)
+	}
+}
+
+func fib(n int) int {
+	if n <= 1 {
+		return n
+	}
+
+	return fib(n-1) + fib(n-2)
+}