Upload examples for articles 35~37.

src/puzzlers/article35/q0/demo90.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+	"syscall"
+)
+
+func main() {
+	fd1, err := syscall.Socket(
+		syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)
+	if err != nil {
+		fmt.Printf("socket error: %v\n", err)
+		return
+	}
+	defer syscall.Close(fd1)
+	fmt.Printf("The file descriptor of socket：%d\n", fd1)
+
+	// 省略若干代码。
+	// 如果真要完全使用syscall包中的程序实体建立网络连接的话，
+	// 过程太过繁琐而且完全没有必要。
+	// 所以，我在这里就不做展示了。
+}

src/puzzlers/article35/q1/demo91.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"bufio"
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net"
+	"runtime"
+)
+
+func main() {
+	network := "tcp"
+	host := "google.cn"
+	reqStrTpl := `HEAD / HTTP/1.1
+Accept: */*
+Accept-Encoding: gzip, deflate
+Connection: keep-alive
+Host: %s
+User-Agent: Dialer/%s
+
+
+
+`
+
+	// 示例1。
+	network1 := network + "4"
+	address1 := host + ":80"
+	fmt.Printf("Dial %q with network %q ...\n", address1, network1)
+	conn1, err := net.Dial(network1, address1)
+	if err != nil {
+		fmt.Printf("dial error: %v\n", err)
+		return
+	}
+	defer conn1.Close()
+
+	reqStr1 := fmt.Sprintf(reqStrTpl, host, runtime.Version())
+	fmt.Printf("The request:\n%s\n", reqStr1)
+	_, err = io.WriteString(conn1, reqStr1)
+	if err != nil {
+		fmt.Printf("write error: %v\n", err)
+		return
+	}
+	fmt.Println()
+
+	reader1 := bufio.NewReader(conn1)
+	line1, err := reader1.ReadString('\n')
+	if err != nil {
+		fmt.Printf("read error: %v\n", err)
+		return
+	}
+	fmt.Printf("The first line of response:\n%s\n", line1)
+	fmt.Println()
+
+	// 示例2。
+	tlsConf := &tls.Config{
+		InsecureSkipVerify: true,
+		MinVersion:         tls.VersionTLS10,
+	}
+	network2 := network
+	address2 := host + ":443"
+	fmt.Printf("Dial %q with network %q ...\n", address2, network2)
+	conn2, err := tls.Dial(network2, address2, tlsConf)
+	if err != nil {
+		fmt.Printf("dial error: %v\n", err)
+		return
+	}
+	defer conn2.Close()
+
+	reqStr2 := fmt.Sprintf(reqStrTpl, host, runtime.Version())
+	fmt.Printf("The request:\n%s\n", reqStr2)
+	_, err = io.WriteString(conn2, reqStr2)
+	if err != nil {
+		fmt.Printf("write error: %v\n", err)
+		return
+	}
+
+	reader2 := bufio.NewReader(conn2)
+	line2, err := reader2.ReadString('\n')
+	if err != nil {
+		fmt.Printf("read error: %v\n", err)
+		return
+	}
+	fmt.Printf("The first line of response:\n%s\n", line2)
+	fmt.Println()
+}

src/puzzlers/article35/q2/demo92.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"fmt"
+	"net"
+	"time"
+)
+
+type dailArgs struct {
+	network string
+	address string
+	timeout time.Duration
+}
+
+func main() {
+	dialArgsList := []dailArgs{
+		{
+			"tcp",
+			"google.cn:80",
+			time.Millisecond * 500,
+		},
+		{
+			"tcp",
+			"google.com:80",
+			time.Second * 2,
+		},
+		{
+			// 如果在这种情况下发生的错误是：
+			// "connect: operation timed out"，
+			// 那么代表着什么呢？
+			//
+			// 简单来说，此错误表示底层的socket在连接网络服务的时候先超时了。
+			// 这时抛出的其实是'syscall.ETIMEDOUT'常量代表的错误值。
+			"tcp",
+			"google.com:80",
+			time.Minute * 4,
+		},
+	}
+	for _, args := range dialArgsList {
+		fmt.Printf("Dial %q with network %q and timeout %s ...\n",
+			args.address, args.network, args.timeout)
+		ts1 := time.Now()
+		conn, err := net.DialTimeout(args.network, args.address, args.timeout)
+		ts2 := time.Now()
+		fmt.Printf("Elapsed time: %s\n", time.Duration(ts2.Sub(ts1)))
+		if err != nil {
+			fmt.Printf("dial error: %v\n", err)
+			fmt.Println()
+			continue
+		}
+		defer conn.Close()
+		fmt.Printf("The local address: %s\n", conn.LocalAddr())
+		fmt.Printf("The remote address: %s\n", conn.RemoteAddr())
+		fmt.Println()
+	}
+}

src/puzzlers/article36/q0/demo93.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func main() {
+	host := "google.cn"
+
+	// 示例1。
+	url1 := "http://" + host
+	fmt.Printf("Send request to %q with method GET ...\n", url1)
+	resp1, err := http.Get(url1)
+	if err != nil {
+		fmt.Printf("request sending error: %v\n", err)
+		return
+	}
+	defer resp1.Body.Close()
+	line1 := resp1.Proto + " " + resp1.Status
+	fmt.Printf("The first line of response:\n%s\n", line1)
+	fmt.Println()
+
+	// 示例2。
+	url2 := "https://golang." + host
+	fmt.Printf("Send request to %q with method GET ...\n", url2)
+	var httpClient1 http.Client
+	resp2, err := httpClient1.Get(url2)
+	if err != nil {
+		fmt.Printf("request sending error: %v\n", err)
+		return
+	}
+	defer resp2.Body.Close()
+	line2 := resp2.Proto + " " + resp2.Status
+	fmt.Printf("The first line of response:\n%s\n", line2)
+}

src/puzzlers/article36/q1/demo94.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+)
+
+// domains 包含了我们将要访问的一些网络域名。
+// 你可以随意地对它们进行增、删、改，
+// 不过这会影响到后面的输出内容。
+var domains = []string{
+	"google.com",
+	"google.com.hk",
+	"google.cn",
+	"golang.org",
+	"golang.google.cn",
+}
+
+func main() {
+	// 你可以改变myTransport中的各个字段的值，
+	// 并观察后面的输出会有什么不同。
+	myTransport := &http.Transport{
+		Proxy: http.ProxyFromEnvironment,
+		DialContext: (&net.Dialer{
+			Timeout:   15 * time.Second,
+			KeepAlive: 15 * time.Second,
+			DualStack: true,
+		}).DialContext,
+		MaxConnsPerHost:       2,
+		MaxIdleConns:          10,
+		MaxIdleConnsPerHost:   2,
+		IdleConnTimeout:       30 * time.Second,
+		ResponseHeaderTimeout: 0,
+		ExpectContinueTimeout: 1 * time.Second,
+		TLSHandshakeTimeout:   10 * time.Second,
+	}
+	// 你可以改变myClient中的各个字段的值，
+	// 并观察后面的输出会有什么不同。
+	myClient := http.Client{
+		Transport: myTransport,
+		Timeout:   20 * time.Second,
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(len(domains))
+	for _, domain := range domains {
+		go func(domain string) {
+			var logBuf strings.Builder
+			var diff time.Duration
+			defer func() {
+				logBuf.WriteString(
+					fmt.Sprintf("(elapsed time: %s)\n", diff))
+				fmt.Println(logBuf.String())
+				wg.Done()
+			}()
+			url := "https://" + domain
+			logBuf.WriteString(
+				fmt.Sprintf("Send request to %q with method GET ...\n", url))
+			t1 := time.Now()
+			resp, err := myClient.Get(url)
+			diff = time.Now().Sub(t1)
+			if err != nil {
+				logBuf.WriteString(
+					fmt.Sprintf("request sending error: %v\n", err))
+				return
+			}
+			defer resp.Body.Close()
+			line2 := resp.Proto + " " + resp.Status
+			logBuf.WriteString(
+				fmt.Sprintf("The first line of response:\n%s\n", line2))
+		}(domain)
+	}
+	wg.Wait()
+}

src/puzzlers/article36/q2/demo95.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"sync"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	wg.Add(2)
+
+	// 示例1。
+	go startServer1(&wg)
+
+	// 示例2。
+	go startServer2(&wg)
+
+	wg.Wait()
+}
+
+func startServer1(wg *sync.WaitGroup) {
+	defer wg.Done()
+	var httpServer1 http.Server
+	httpServer1.Addr = "127.0.0.1:8080"
+	// 由于我们没有定制handler，所以这个网络服务对任何请求都只会响应404。
+	if err := httpServer1.ListenAndServe(); err != nil {
+		if err == http.ErrServerClosed {
+			log.Println("HTTP server 1 closed.")
+		} else {
+			log.Printf("HTTP server 1 error: %v\n", err)
+		}
+	}
+}
+
+func startServer2(wg *sync.WaitGroup) {
+	defer wg.Done()
+	mux1 := http.NewServeMux()
+	mux1.HandleFunc("/hi", func(w http.ResponseWriter, req *http.Request) {
+		if req.URL.Path != "/hi" {
+			http.NotFound(w, req)
+			return
+		}
+		name := req.FormValue("name")
+		if name == "" {
+			fmt.Fprint(w, "Welcome!")
+		} else {
+			fmt.Fprintf(w, "Welcome, %s!", name)
+		}
+	})
+	httpServer2 := http.Server{
+		Addr:    "127.0.0.1:8081",
+		Handler: mux1,
+	}
+	if err := httpServer2.ListenAndServe(); err != nil {
+		if err == http.ErrServerClosed {
+			log.Println("HTTP server 2 closed.")
+		} else {
+			log.Printf("HTTP server 2 error: %v\n", err)
+		}
+	}
+}

src/puzzlers/article37/common/common.go

@@ -0,0 +1,52 @@
+package common
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+// OpFunc 代表包含高负载操作的函数。
+type OpFunc func() error
+
+// Execute 用于执行可以产生高负载的操作。
+func Execute(op OpFunc, times int) (err error) {
+	if op == nil {
+		return errors.New("nil operation function")
+	}
+	if times <= 0 {
+		return fmt.Errorf("invalid times: %d", times)
+	}
+	var t1 time.Time
+	defer func() {
+		diff := time.Now().Sub(t1)
+		fmt.Printf("(elapsed time: %s)\n", diff)
+		if p := recover(); p != nil {
+			err = fmt.Errorf("fatal error: %v", p)
+		}
+	}()
+	t1 = time.Now()
+	for i := 0; i < times; i++ {
+		if err = op(); err != nil {
+			return
+		}
+		time.Sleep(time.Microsecond)
+	}
+	return
+}
+
+// CreateFile 用于在当前目录下创建一个指定名称的文件。
+// 若同名文件已存在，则清空并复用。
+func CreateFile(dir, name string) (*os.File, error) {
+	if dir == "" {
+		var err error
+		dir, err = os.Getwd()
+		if err != nil {
+			return nil, err
+		}
+	}
+	path := filepath.Join(dir, name)
+	return os.Create(path)
+}