added futrue

go_design_pattern_book/concurrent_pattern/future/main.go

@@ -0,0 +1,35 @@
+package main
+
+func main() {
+
+}
+
+type SuccessFunc func(string)
+type FailFunc func(error)
+type ExecuteStringFunc func() (string, error)
+
+type MaybeString struct {
+	successFunc SuccessFunc
+	failFunc    FailFunc
+}
+
+func (s *MaybeString) Success(f SuccessFunc) *MaybeString {
+	s.successFunc = f
+	return s
+}
+
+func (s *MaybeString) Fail(f FailFunc) *MaybeString {
+	s.failFunc = f
+	return s
+}
+
+func (s *MaybeString) Execute(f ExecuteStringFunc) {
+	go func(s *MaybeString) {
+		str, err := f()
+		if err != nil {
+			s.failFunc(err)
+		} else {
+			s.successFunc(str)
+		}
+	}(s)
+}

go_design_pattern_book/concurrent_pattern/future/main_test.go

@@ -0,0 +1,39 @@
+package main
+
+import "testing"
+import "sync"
+
+func TestStringorError_Execute(t *testing.T) {
+	future := &MaybeString{}
+	t.Run("Success Result", func(t *testing.T) {
+		var wg sync.WaitGroup
+		wg.Add(1)
+		future.Success(func(s string) {
+			t.Log(s)
+			wg.Done()
+		}).Fail(func(e error) {
+			t.Fail()
+			wg.Done()
+		})
+		future.Execute(func() (string, error) {
+			return "Hello World", nil
+		})
+		wg.Wait()
+	})
+	t.Run("Failed Result", func(t *testing.T) {
+		var wg sync.WaitGroup
+		wg.Add(1)
+		future.Success(func(s string) {
+			t.Fail()
+			wg.Done()
+
+		}).Fail(func(e error) {
+			t.Log(e.Error())
+			wg.Done()
+		})
+		future.Execute(func() (string, error) {
+			return "", nil
+		})
+		wg.Wait()
+	})
+}

go_design_pattern_book/concurrent_pattern/futurev1/main.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net/http"
+)
+
+// A Future indicates any data that is needed in future but its computation
+// can be started in parallel so that it can be fetched from the background when needed.
+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("http://test.future.com")
+	// do many other things
+	body := <-future
+	fmt.Printf("response: %#v", string(body.Body))
+	fmt.Printf("error: %#v", body.Error)
+}