122 lines
2.6 KiB
Go
122 lines
2.6 KiB
Go
package process
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import (
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"fmt"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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"sync"
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"syscall"
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coreio "dappco.re/go/core/io"
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coreerr "dappco.re/go/core/log"
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)
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// PIDFile manages a process ID file for single-instance enforcement.
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//
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// Example:
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//
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// pidFile := process.NewPIDFile("/var/run/myapp.pid")
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type PIDFile struct {
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path string
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mu sync.Mutex
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}
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// NewPIDFile creates a PID file manager.
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//
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// Example:
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//
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// pidFile := process.NewPIDFile("/var/run/myapp.pid")
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func NewPIDFile(path string) *PIDFile {
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return &PIDFile{path: path}
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}
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// Acquire writes the current PID to the file.
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// Returns error if another instance is running.
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//
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// Example:
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//
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// if err := pidFile.Acquire(); err != nil { return err }
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func (p *PIDFile) Acquire() error {
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p.mu.Lock()
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defer p.mu.Unlock()
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if data, err := coreio.Local.Read(p.path); err == nil {
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pid, err := strconv.Atoi(strings.TrimSpace(data))
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if err == nil && pid > 0 {
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if proc, err := os.FindProcess(pid); err == nil {
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if err := proc.Signal(syscall.Signal(0)); err == nil {
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return coreerr.E("PIDFile.Acquire", fmt.Sprintf("another instance is running (PID %d)", pid), nil)
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}
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}
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}
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_ = coreio.Local.Delete(p.path)
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}
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if dir := filepath.Dir(p.path); dir != "." {
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if err := coreio.Local.EnsureDir(dir); err != nil {
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return coreerr.E("PIDFile.Acquire", "failed to create PID directory", err)
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}
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}
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pid := os.Getpid()
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if err := coreio.Local.Write(p.path, strconv.Itoa(pid)); err != nil {
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return coreerr.E("PIDFile.Acquire", "failed to write PID file", err)
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}
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return nil
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}
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// Release removes the PID file.
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//
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// Example:
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//
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// _ = pidFile.Release()
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func (p *PIDFile) Release() error {
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p.mu.Lock()
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defer p.mu.Unlock()
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if err := coreio.Local.Delete(p.path); err != nil {
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return coreerr.E("PIDFile.Release", "failed to remove PID file", err)
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}
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return nil
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}
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// Path returns the PID file path.
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//
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// Example:
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//
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// path := pidFile.Path()
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func (p *PIDFile) Path() string {
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return p.path
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}
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// ReadPID reads a PID file and checks if the process is still running.
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// Returns (pid, true) if the process is alive, (pid, false) if dead/stale,
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// or (0, false) if the file doesn't exist or is invalid.
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//
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// Example:
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//
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// pid, running := process.ReadPID("/var/run/myapp.pid")
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func ReadPID(path string) (int, bool) {
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data, err := coreio.Local.Read(path)
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if err != nil {
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return 0, false
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}
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pid, err := strconv.Atoi(strings.TrimSpace(data))
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if err != nil || pid <= 0 {
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return 0, false
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}
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proc, err := os.FindProcess(pid)
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if err != nil {
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return pid, false
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}
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if err := proc.Signal(syscall.Signal(0)); err != nil {
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return pid, false
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}
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return pid, true
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}
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