refactor: combine multiple packages into one main package

debug.go

@@ -0,0 +1,9 @@
+package main
+
+import "log"
+
+func debug(format string, v ...interface{}) {
+	if debugFlag {
+		log.Printf(format, v...)
+	}
+}

debug_test.go

@@ -0,0 +1,7 @@
+package main
+
+import "testing"
+
+func TestDebug(t *testing.T) {
+	debug("%s %d", "test", 123)
+}

flag.go

@@ -0,0 +1,83 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"strconv"
+	"time"
+)
+
+var (
+	debugFlag         bool
+	urlFlag           string
+	cycleFlag         time.Duration
+	timeoutFlag       time.Duration
+	headerTimeoutFlag time.Duration
+
+	mailFromNameFlag   string
+	mailFromAddrFlag   string
+	mailFromPwdFlag    string
+	mailToAddrFlag     string
+	mailAuthHostFlag   string
+	mailServerAddrFlag string
+)
+
+func init() {
+	var cycle, timeout, headerTimeout int
+
+	flag.BoolVar(&debugFlag, "debug", false, "turn on debug mode")
+
+	flag.StringVar(&urlFlag, "url", "", "HTTP URL to monitor")
+	flag.IntVar(&cycle, "cycle", 20000, "detection cycle in milliseconds")
+	flag.IntVar(&timeout, "timeout", 5000, "timeout for waiting for HTTP response, in milliseconds")
+	flag.IntVar(&headerTimeout, "header-timeout", 2000, "timeout for waiting for HTTP response headers after establishing a connection, in milliseconds")
+
+	flag.StringVar(&mailFromNameFlag, "mail-fname", "Site Monitor", "mail sender's name")
+	flag.StringVar(&mailFromAddrFlag, "mail-faddr", "", "mail sender's address")
+	flag.StringVar(&mailFromPwdFlag, "mail-fpwd", "", "mail sender's SMTP password")
+	flag.StringVar(&mailToAddrFlag, "mail-taddr", "", "mail recipient address")
+	flag.StringVar(&mailAuthHostFlag, "mail-auth", "", "SMTP authentication host address")
+	flag.StringVar(&mailServerAddrFlag, "mail-server", "", "SMTP server address")
+
+	//testing.Init() // uncomment when executing unit tests
+	flag.Parse()
+
+	var miss string
+
+	if urlFlag == "" {
+		miss += "-url, "
+	}
+	if mailFromNameFlag == "" {
+		miss += "-mail-fname, "
+	}
+	if mailFromAddrFlag == "" {
+		miss += "-mail-faddr, "
+	}
+	if mailFromPwdFlag == "" {
+		miss += "-mail-fpwd, "
+	}
+	if mailToAddrFlag == "" {
+		miss += "-mail-taddr, "
+	}
+	if mailAuthHostFlag == "" {
+		miss += "-mail-auth, "
+	}
+	if mailServerAddrFlag == "" {
+		miss += "-mail-server, "
+	}
+	if miss != "" {
+		log.Fatalf("missing the necessary flag(s): %srun \"site-monitor -h\" for more information about each flag.", miss)
+	}
+
+	convertDuration(cycle, &cycleFlag)
+	convertDuration(timeout, &timeoutFlag)
+	convertDuration(headerTimeout, &headerTimeoutFlag)
+}
+
+func convertDuration(n int, du *time.Duration) {
+	d, err := time.ParseDuration(strconv.Itoa(n) + "ms")
+	if err != nil {
+		log.Fatal("the input time format is not available")
+	}
+	*du = d
+}

flag_test.go

@@ -0,0 +1,13 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+func TestConvertDuration(t *testing.T) {
+	var du time.Duration
+	if convertDuration(10, &du); du.String() != "10ms" {
+		t.Fail()
+	}
+}

http.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"net/http"
+	"time"
+)
+
+func newHTTPClient(timeout, responseHeaderTimeout time.Duration) http.Client {
+	tr := http.Transport{
+		DisableKeepAlives:     true,
+		ResponseHeaderTimeout: responseHeaderTimeout,
+	}
+	client := http.Client{
+		Transport: &tr,
+		Timeout:   timeout,
+	}
+
+	return client
+}

http_test.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+	"time"
+)
+
+func TestNewHTTPClient(t *testing.T) {
+	c := newHTTPClient(time.Second*5, time.Second*2)
+	if c.Timeout.String() != "5s" {
+		t.Fail()
+		return
+	}
+	if tr := c.Transport.(*http.Transport); tr.ResponseHeaderTimeout.String() != "2s" {
+		t.Fail()
+		return
+	}
+	resp, err := c.Get("https://jsonplaceholder.typicode.com/users/1")
+	if err != nil {
+		t.Log(err)
+		t.Fail()
+		return
+	}
+	defer resp.Body.Close()
+	fmt.Println(resp.StatusCode)
+}

logger.go

@@ -0,0 +1,66 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+	"time"
+)
+
+var (
+	loggerInstance logger
+)
+
+type logRecord struct {
+	time       time.Time
+	isNormal   bool
+	statusCode int
+	isTimeout  bool
+	err        error
+}
+
+type logger struct {
+	sync.Mutex
+	records []logRecord
+}
+
+func (l *logger) string() string {
+	var msg string
+	for _, record := range l.records {
+		msg += fmt.Sprintf("* %s\tnormal: %v\tstatus code: %d\ttimeout: %v\terror: %v\n",
+			record.time.Format("2006-01-02 15:04:05"), record.isNormal, record.statusCode, record.isTimeout, record.err)
+	}
+	return msg
+}
+
+func logPush(record logRecord) {
+	loggerInstance.Lock()
+	defer loggerInstance.Unlock()
+
+	if len(loggerInstance.records) >= 10 {
+		loggerInstance.records = loggerInstance.records[1:]
+	}
+	loggerInstance.records = append(loggerInstance.records, record)
+
+	logCheck()
+}
+
+func logCheck() {
+	var unNormal int
+	for _, r := range loggerInstance.records {
+		if !r.isNormal {
+			unNormal++
+		}
+	}
+	if unNormal >= 5 {
+		debug("* Site status: unhealthy")
+		go sendMail(loggerInstance.string())
+	} else if float64(unNormal)/float64(len(loggerInstance.records)) > 0.5 {
+		debug("* Site status: unhealthy")
+	} else {
+		debug("* Site status: healthy")
+	}
+}
+
+func init() {
+	loggerInstance.records = make([]logRecord, 0, 10)
+}