add english version

en/code/src/apps/ch.2.7/buffered_channel/main.go

@@ -0,0 +1,13 @@
+// Example code for Chapter 2.7 from "Build Web Application with Golang"
+// Purpose: Shows how to use a buffered channel
+package main
+
+import "fmt"
+
+func main() {
+	c := make(chan int, 2) // change 2 to 1 will have runtime error, but 3 is fine
+	c <- 1
+	c <- 2
+	fmt.Println(<-c)
+	fmt.Println(<-c)
+}

en/code/src/apps/ch.2.7/goroutine/main.go

@@ -0,0 +1,20 @@
+// Example code for Chapter 2.7 from "Build Web Application with Golang"
+// Purpose: Shows how to launch a simple gorountine
+package main
+
+import (
+	"fmt"
+	"runtime"
+)
+
+func say(s string) {
+	for i := 0; i < 5; i++ {
+		runtime.Gosched()
+		fmt.Println(s)
+	}
+}
+
+func main() {
+	go say("world") // create a new goroutine
+	say("hello")    // current goroutine
+}

en/code/src/apps/ch.2.7/range_and_close_channel/main.go

@@ -0,0 +1,24 @@
+// Example code for Chapter 2.7 from "Build Web Application with Golang"
+// Purpose: Shows how to close and interate through a channel
+package main
+
+import (
+	"fmt"
+)
+
+func fibonacci(n int, c chan int) {
+	x, y := 1, 1
+	for i := 0; i < n; i++ {
+		c <- x
+		x, y = y, x+y
+	}
+	close(c)
+}
+
+func main() {
+	c := make(chan int, 10)
+	go fibonacci(cap(c), c)
+	for i := range c {
+		fmt.Println(i)
+	}
+}

en/code/src/apps/ch.2.7/select_channel/main.go

@@ -0,0 +1,30 @@
+// Example code for Chapter 2.7 from "Build Web Application with Golang"
+// Purpose: Shows how to use `select`
+package main
+
+import "fmt"
+
+func fibonacci(c, quit chan int) {
+	x, y := 1, 1
+	for {
+		select {
+		case c <- x:
+			x, y = y, x+y
+		case <-quit:
+			fmt.Println("quit")
+			return
+		}
+	}
+}
+
+func main() {
+	c := make(chan int)
+	quit := make(chan int)
+	go func() {
+		for i := 0; i < 10; i++ {
+			fmt.Println(<-c)
+		}
+		quit <- 0
+	}()
+	fibonacci(c, quit)
+}

en/code/src/apps/ch.2.7/timeout/main.go

@@ -0,0 +1,27 @@
+// Example code for Chapter 2.7 from "Build Web Application with Golang"
+// Purpose: Shows how to create and use a timeout
+package main
+
+import (
+	"fmt"
+	"time"
+)
+
+
+func main() {
+	c := make(chan int)
+	o := make(chan bool)
+	go func() {
+		for {
+			select {
+			case v := <-c:
+				fmt.Println(v)
+			case <-time.After(5 * time.Second):
+				fmt.Println("timeout")
+				o <- true
+				break
+			}
+		}
+	}()
+	<-o
+}

en/code/src/apps/ch.2.7/unbuffered_channel/main.go

@@ -0,0 +1,24 @@
+// Example code for Chapter 2.7 from "Build Web Application with Golang"
+// Purpose: Shows how to create and use a unbuffered channel
+package main
+
+import "fmt"
+
+func sum(a []int, c chan int) {
+	total := 0
+	for _, v := range a {
+		total += v
+	}
+	c <- total // send total to c
+}
+
+func main() {
+	a := []int{7, 2, 8, -9, 4, 0}
+
+	c := make(chan int)
+	go sum(a[:len(a)/2], c)
+	go sum(a[len(a)/2:], c)
+	x, y := <-c, <-c // receive from c
+
+	fmt.Println(x, y, x+y)
+}