7ea523ee7b
PIDFile manages a process ID lock file with Acquire/Release semantics. Detects stale PIDs via signal(0) probe, creates parent directories automatically. Includes standalone ReadPID helper for checking if a PID file's process is still alive. Co-Authored-By: Virgil <virgil@lethean.io>
92 lines
2 KiB
Go
92 lines
2 KiB
Go
package process
|
|
|
|
import (
|
|
"fmt"
|
|
"os"
|
|
"path/filepath"
|
|
"strconv"
|
|
"strings"
|
|
"sync"
|
|
"syscall"
|
|
)
|
|
|
|
// PIDFile manages a process ID file for single-instance enforcement.
|
|
type PIDFile struct {
|
|
path string
|
|
mu sync.Mutex
|
|
}
|
|
|
|
// NewPIDFile creates a PID file manager.
|
|
func NewPIDFile(path string) *PIDFile {
|
|
return &PIDFile{path: path}
|
|
}
|
|
|
|
// Acquire writes the current PID to the file.
|
|
// Returns error if another instance is running.
|
|
func (p *PIDFile) Acquire() error {
|
|
p.mu.Lock()
|
|
defer p.mu.Unlock()
|
|
|
|
if data, err := os.ReadFile(p.path); err == nil {
|
|
pid, err := strconv.Atoi(strings.TrimSpace(string(data)))
|
|
if err == nil && pid > 0 {
|
|
if proc, err := os.FindProcess(pid); err == nil {
|
|
if err := proc.Signal(syscall.Signal(0)); err == nil {
|
|
return fmt.Errorf("another instance is running (PID %d)", pid)
|
|
}
|
|
}
|
|
}
|
|
_ = os.Remove(p.path)
|
|
}
|
|
|
|
if dir := filepath.Dir(p.path); dir != "." {
|
|
if err := os.MkdirAll(dir, 0755); err != nil {
|
|
return fmt.Errorf("failed to create PID directory: %w", err)
|
|
}
|
|
}
|
|
|
|
pid := os.Getpid()
|
|
if err := os.WriteFile(p.path, []byte(strconv.Itoa(pid)), 0644); err != nil {
|
|
return fmt.Errorf("failed to write PID file: %w", err)
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Release removes the PID file.
|
|
func (p *PIDFile) Release() error {
|
|
p.mu.Lock()
|
|
defer p.mu.Unlock()
|
|
return os.Remove(p.path)
|
|
}
|
|
|
|
// Path returns the PID file path.
|
|
func (p *PIDFile) Path() string {
|
|
return p.path
|
|
}
|
|
|
|
// ReadPID reads a PID file and checks if the process is still running.
|
|
// Returns (pid, true) if the process is alive, (pid, false) if dead/stale,
|
|
// or (0, false) if the file doesn't exist or is invalid.
|
|
func ReadPID(path string) (int, bool) {
|
|
data, err := os.ReadFile(path)
|
|
if err != nil {
|
|
return 0, false
|
|
}
|
|
|
|
pid, err := strconv.Atoi(strings.TrimSpace(string(data)))
|
|
if err != nil || pid <= 0 {
|
|
return 0, false
|
|
}
|
|
|
|
proc, err := os.FindProcess(pid)
|
|
if err != nil {
|
|
return pid, false
|
|
}
|
|
|
|
if err := proc.Signal(syscall.Signal(0)); err != nil {
|
|
return pid, false
|
|
}
|
|
|
|
return pid, true
|
|
}
|