added future

concurrency/future/main.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+)
+
+type data struct {
+	Body  []byte
+	Error error
+}
+
+func futureData(url string) <-chan data {
+	c := make(chan data, 1)
+
+	go func() {
+		var body []byte
+		var err error
+
+		resp, err := http.Get(url)
+		defer resp.Body.Close()
+
+		body, err = ioutil.ReadAll(resp.Body)
+
+		c <- data{Body: body, Error: err}
+	}()
+
+	return c
+}
+
+func main() {
+	future := futureData("https://medium.com/@thejasbabu/concurrency-patterns-golang-5c5e1bcd0833")
+	future2 := futureData("https://golang.org/ref/mem")
+
+	// do many other things
+
+	body := <-future
+	fmt.Printf("response: %#v", "test")
+	fmt.Printf("error: %#v", body.Error)
+
+	body2 := <-future2
+	fmt.Printf("response: %#v", "test1")
+	fmt.Printf("error: %#v", body2.Error)
+}

concurrency/locker/main.go

@@ -18,7 +18,7 @@ import (
 )
 
 func main() {
-	lock := make(chan bool, 1)
+	lock := make(chan bool, 2)
 	for i := 1; i < 7; i++ {
 		go worker(i, lock)
 	}