add easeprobe pid file

cmd/easeprobe/main.go

@@ -26,6 +26,7 @@ import (
  "time"
 
  "github.com/megaease/easeprobe/conf"
+ "github.com/megaease/easeprobe/daemon"
  "github.com/megaease/easeprobe/global"
  "github.com/megaease/easeprobe/notify"
  "github.com/megaease/easeprobe/probe"
@@ -54,6 +55,13 @@ func main() {
  os.Exit(-1)
  }
 
+ d, err := daemon.NewPIDFile()
+ if err != nil {
+ log.Errorf("Error: Cannot create the PID file: %s", err)
+ } else {
+ defer d.RemovePIDFile()
+ }
+
  // if dry notification mode is specificed in command line, overwrite the configuration
  if *dryNotify {
  c.Settings.Notify.Dry = *dryNotify

daemon/daemon.go

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2022, MegaEase
+ * 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:https://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 daemon
+
+import (
+ "fmt"
+ "os"
+ "path/filepath"
+ "strconv"
+ "strings"
+
+ "github.com/megaease/easeprobe/global"
+)
+
+// Config is the daemon config
+type Config struct {
+ PidFile string
+ pidFd *os.File
+}
+
+// NewPIDFile create a new pid file
+func NewPIDFile() (*Config, error) {
+ c := &Config{}
+ c.PidFile = filepath.Join(global.GetWorkDir(), global.DefaultPIDFile)
+ _, err := c.CheckPIDFile()
+ if err != nil {
+ return nil, err
+ }
+
+ if err := os.MkdirAll(filepath.Dir(c.PidFile), 0755); err != nil {
+ return nil, err
+ }
+
+ pidstr := fmt.Sprintf("%d", os.Getpid())
+ if err := os.WriteFile(c.PidFile, []byte(pidstr), 0600); err != nil {
+ return nil, err
+ }
+
+ c.pidFd, _ = os.OpenFile(c.PidFile, os.O_APPEND|os.O_EXCL, 0600)
+ return c, nil
+}
+
+// CheckPIDFile check if the pid file exists
+// if the PID file exists, return the PID of the process
+// if the PID file does not exist, return -1
+func (c *Config) CheckPIDFile() (int, error) {
+ buf, err := os.ReadFile(c.PidFile)
+ if err != nil {
+ return -1, nil
+ }
+
+ pidstr := strings.TrimSpace(string(buf))
+ pid, err := strconv.Atoi(pidstr)
+ if err != nil {
+ return -1, nil
+ }
+
+ if processExists(pid) {
+ return pid, fmt.Errorf("pid file(%s) found, ensure %s(%d) is not running", c.PidFile, global.Prog, pid)
+ }
+
+ return -1, nil
+}
+
+// RemovePIDFile remove the pid file
+func (c *Config) RemovePIDFile() error {
+ c.pidFd.Close()
+ return os.Remove(c.PidFile)
+}

daemon/daemon_darwin.go

@@ -0,0 +1,30 @@
+//go:build darwin
+// +build darwin
+
+/*
+ * Copyright (c) 2022, MegaEase
+ * 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:https://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 daemon
+
+import "golang.org/x/sys/unix"
+
+func processExists(pid int) bool {
+ // OS X does not have a proc filesystem.
+ // Use kill -0 pid to judge if the process exists.
+ err := unix.Kill(pid, 0)
+ return err == nil
+}

daemon/daemon_linux.go

@@ -0,0 +1,32 @@
+//go:build !windows && !darwin
+// +build !windows,!darwin
+
+/*
+ * Copyright (c) 2022, MegaEase
+ * 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:https://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 daemon
+
+import (
+ "os"
+ "path/filepath"
+ "strconv"
+)
+
+func processExists(pid int) bool {
+ _, err := os.Stat(filepath.Join("/proc", strconv.Itoa(pid)))
+ return err == nil // err is nil if file exists
+}

daemon/daemon_test.go

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2022, MegaEase
+ * 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:https://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 daemon
+
+import (
+ "testing"
+)
+
+func TestPIDFile(t *testing.T) {
+
+ c, err := NewPIDFile()
+ if err != nil {
+ t.Fatalf("Could not create the pid file, %v", err)
+ }
+
+ _, err = c.CheckPIDFile()
+ if err == nil {
+ t.Fatalf("Could not found the pid file, %v", err)
+ }
+
+ _, err = NewPIDFile()
+ if err == nil {
+ t.Fatalf("PIDFile could be overwritten, %v", err)
+ }
+
+ if err := c.RemovePIDFile(); err != nil {
+ t.Fatalf("Could not remove the pid file, %v", err)
+ }
+
+}

daemon/daemon_windows.go

@@ -0,0 +1,46 @@
+//go: build windows
+//go:build windows
+// +build windows
+
+/*
+ * Copyright (c) 2022, MegaEase
+ * 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:https://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 daemon
+
+import (
+ "golang.org/x/sys/windows"
+)
+
+const (
+ processQueryLimitedInformation = 0x1000
+
+ stillActive = 259
+)
+
+func processExists(pid int) bool {
+ h, err := windows.OpenProcess(processQueryLimitedInformation, false, uint32(pid))
+ if err != nil {
+ return false
+ }
+ var c uint32
+ err = windows.GetExitCodeProcess(h, &c)
+ windows.Close(h)
+ if err != nil {
+ return c == stillActive
+ }
+ return true
+}

global/global.go

@@ -70,6 +70,8 @@ const (
  DefaultAccessLogFile = "access.log"
  // DefaultDataFile is the default data file name
  DefaultDataFile = "data.yaml"
+ // DefaultPIDFile is the default pid file name
+ DefaultPIDFile = "easeprobe.pid"
 )
 
 const (