feat: support StopOldInstance() to kill old process on startup (#96)

Author: Copilot

main.go

@@ -15,6 +15,8 @@
 package main
 
 import (
+	"fmt"
+
 	"github.com/beego/beego"
 	"github.com/beego/beego/plugins/cors"
 	_ "github.com/beego/beego/session/redis"
@@ -25,6 +27,7 @@ import (
 	"github.com/casbin/caswaf/routers"
 	"github.com/casbin/caswaf/run"
 	"github.com/casbin/caswaf/service"
+	"github.com/casbin/caswaf/util"
 )
 
 func main() {
@@ -67,5 +70,12 @@ func main() {
 
 	service.Start()
 
-	beego.Run()
+	port := beego.AppConfig.DefaultInt("httpport", 17000)
+
+	err := util.StopOldInstance(port)
+	if err != nil {
+		panic(err)
+	}
+
+	beego.Run(fmt.Sprintf(":%v", port))
 }

util/process.go

@@ -0,0 +1,95 @@
+// Copyright 2023 The casbin Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package util
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"runtime"
+	"strconv"
+	"strings"
+)
+
+func getPidByPort(port int) (int, error) {
+	var cmd *exec.Cmd
+	switch runtime.GOOS {
+	case "windows":
+		cmd = exec.Command("cmd", "/c", "netstat -ano | findstr :"+strconv.Itoa(port))
+	case "darwin", "linux":
+		cmd = exec.Command("lsof", "-t", "-i", ":"+strconv.Itoa(port))
+	default:
+		return 0, fmt.Errorf("unsupported OS: %s", runtime.GOOS)
+	}
+
+	output, err := cmd.Output()
+	if err != nil {
+		if exitErr, ok := err.(*exec.ExitError); ok {
+			if exitErr.ExitCode() == 1 {
+				return 0, nil
+			}
+		}
+		return 0, err
+	}
+
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		fields := strings.Fields(line)
+		if len(fields) > 0 {
+			if runtime.GOOS == "windows" {
+				if len(fields) >= 2 && fields[1] == "0.0.0.0:"+strconv.Itoa(port) {
+					pid, err := strconv.Atoi(fields[len(fields)-1])
+					if err != nil {
+						return 0, err
+					}
+
+					return pid, nil
+				}
+			} else {
+				pid, err := strconv.Atoi(fields[0])
+				if err != nil {
+					return 0, err
+				}
+
+				return pid, nil
+			}
+		}
+	}
+
+	return 0, nil
+}
+
+func StopOldInstance(port int) error {
+	pid, err := getPidByPort(port)
+	if err != nil {
+		return err
+	}
+	if pid == 0 {
+		return nil
+	}
+
+	process, err := os.FindProcess(pid)
+	if err != nil {
+		return err
+	}
+
+	err = process.Kill()
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("The old instance with pid: %d has been stopped\n", pid)
+	return nil
+}