example: add tcp port scanner

examples/tcp-port-scanner/main.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"github.com/WangYihang/gojob"
+)
+
+func main() {
+	var commonPorts = []uint16{
+		21, 22, 23, 25, 53, 80, 110, 135, 139, 143, 443, 445, 993, 995,
+		1723, 3306, 3389, 5900, 8080,
+	}
+	var ips = []string{
+		"192.168.200.1",
+		"192.168.200.254",
+	}
+	scheduler := gojob.New(
+		gojob.WithNumWorkers(8),
+		gojob.WithMaxRetries(4),
+		gojob.WithMaxRuntimePerTaskSeconds(16),
+		gojob.WithNumShards(1),
+		gojob.WithShard(0),
+		gojob.WithTotalTasks(int64(len(ips)*len(commonPorts))),
+		gojob.WithStatusFilePath("status.json"),
+		gojob.WithResultFilePath("result.json"),
+		gojob.WithMetadataFilePath("metadata.json"),
+	).
+		Start()
+	for _, ip := range ips {
+		for _, port := range commonPorts {
+			scheduler.Submit(New(ip, port))
+		}
+	}
+	scheduler.Wait()
+}

examples/tcp-port-scanner/status.go

@@ -0,0 +1,22 @@
+package main
+
+type Status uint8
+
+const (
+	Unknown Status = iota
+	Open
+	Closed
+)
+
+func (s Status) String() string {
+	statuses := map[Status]string{
+		Unknown: "Undefined",
+		Open:    "Open",
+		Closed:  "Closed",
+	}
+	return statuses[s]
+}
+
+func (s Status) MarshalJSON() ([]byte, error) {
+	return []byte(`"` + s.String() + `"`), nil
+}

examples/tcp-port-scanner/task.go

@@ -0,0 +1,31 @@
+package main
+
+import "net"
+
+type MyTask struct {
+	IP     string `json:"ip"`
+	Port   uint16 `json:"port"`
+	Status Status `json:"status"`
+}
+
+func New(ip string, port uint16) *MyTask {
+	return &MyTask{
+		IP:     ip,
+		Port:   port,
+		Status: Unknown,
+	}
+}
+
+func (t *MyTask) Do() error {
+	conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
+		IP:   net.ParseIP(t.IP),
+		Port: int(t.Port),
+	})
+	if err != nil {
+		t.Status = Closed
+		return nil
+	}
+	defer conn.Close()
+	t.Status = Open
+	return nil
+}