good good study, day day up!

vendor/gopl.io/ch9/memotest/memotest.go

@@ -0,0 +1,102 @@
+// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+// See page 272.
+
+// Package memotest provides common functions for
+// testing various designs of the memo package.
+package memotest
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"sync"
+	"testing"
+	"time"
+)
+
+//!+httpRequestBody
+func httpGetBody(url string) (interface{}, error) {
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	return ioutil.ReadAll(resp.Body)
+}
+
+//!-httpRequestBody
+
+var HTTPGetBody = httpGetBody
+
+func incomingURLs() <-chan string {
+	ch := make(chan string)
+	go func() {
+		for _, url := range []string{
+			"https://golang.org",
+			"https://godoc.org",
+			"https://play.golang.org",
+			"http://gopl.io",
+			"https://golang.org",
+			"https://godoc.org",
+			"https://play.golang.org",
+			"http://gopl.io",
+		} {
+			ch <- url
+		}
+		close(ch)
+	}()
+	return ch
+}
+
+type M interface {
+	Get(key string) (interface{}, error)
+}
+
+/*
+//!+seq
+	m := memo.New(httpGetBody)
+//!-seq
+*/
+
+func Sequential(t *testing.T, m M) {
+	//!+seq
+	for url := range incomingURLs() {
+		start := time.Now()
+		value, err := m.Get(url)
+		if err != nil {
+			log.Print(err)
+		}
+		fmt.Printf("%s, %s, %d bytes\n",
+			url, time.Since(start), len(value.([]byte)))
+	}
+	//!-seq
+}
+
+/*
+//!+conc
+	m := memo.New(httpGetBody)
+//!-conc
+*/
+
+func Concurrent(t *testing.T, m M) {
+	//!+conc
+	var n sync.WaitGroup
+	for url := range incomingURLs() {
+		n.Add(1)
+		go func(url string) {
+			start := time.Now()
+			value, err := m.Get(url)
+			if err != nil {
+				log.Print(err)
+			}
+			fmt.Printf("%s, %s, %d bytes\n",
+				url, time.Since(start), len(value.([]byte)))
+			n.Done()
+		}(url)
+	}
+	n.Wait()
+	//!-conc
+}