e291f464ee
- Implemented daemon.lock using flock (Unix) and LockFileEx (Windows) - Lock acquired before PID file, held for daemon lifetime - Eliminates race conditions in concurrent daemon starts - Backward compatible: falls back to PID check for old daemons - Updated isDaemonRunning() to check lock availability - All tests pass including new lock and backward compatibility tests Amp-Thread-ID: https://ampcode.com/threads/T-0e2627f4-03f9-4024-bb4b-21d23d296300 Co-authored-by: Amp <amp@ampcode.com>
117 lines
2.9 KiB
Go
117 lines
2.9 KiB
Go
package main
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import (
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"errors"
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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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)
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var ErrDaemonLocked = errors.New("daemon lock already held by another process")
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// DaemonLock represents a held lock on the daemon.lock file
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type DaemonLock struct {
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file *os.File
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path string
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}
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// Close releases the daemon lock
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func (l *DaemonLock) Close() error {
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if l.file == nil {
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return nil
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}
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// Closing the file descriptor automatically releases the flock
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err := l.file.Close()
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l.file = nil
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return err
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}
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// acquireDaemonLock attempts to acquire an exclusive lock on daemon.lock
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// Returns ErrDaemonLocked if another daemon is already running
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func acquireDaemonLock(beadsDir string, global bool) (*DaemonLock, error) {
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lockPath := filepath.Join(beadsDir, "daemon.lock")
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// Open or create the lock file
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f, err := os.OpenFile(lockPath, os.O_CREATE|os.O_RDWR, 0600)
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if err != nil {
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return nil, fmt.Errorf("cannot open lock file: %w", err)
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}
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// Try to acquire exclusive non-blocking lock
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if err := flockExclusive(f); err != nil {
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f.Close()
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if err == ErrDaemonLocked {
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return nil, ErrDaemonLocked
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}
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return nil, fmt.Errorf("cannot lock file: %w", err)
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}
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// Write our PID to the lock file for debugging (optional)
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f.Truncate(0)
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f.Seek(0, 0)
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fmt.Fprintf(f, "%d\n", os.Getpid())
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f.Sync()
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return &DaemonLock{file: f, path: lockPath}, nil
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}
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// tryDaemonLock attempts to acquire and immediately release the daemon lock
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// to check if a daemon is running. Returns true if daemon is running.
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// Falls back to PID file check for backward compatibility with pre-lock daemons.
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func tryDaemonLock(beadsDir string) (running bool, pid int) {
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lockPath := filepath.Join(beadsDir, "daemon.lock")
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// Try to open existing lock file
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f, err := os.Open(lockPath)
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if err != nil {
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// No lock file - could be old daemon without lock support
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// Fall back to PID file check for backward compatibility
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return checkPIDFile(beadsDir)
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}
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defer f.Close()
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// Try to acquire lock non-blocking
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if err := flockExclusive(f); err != nil {
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if err == ErrDaemonLocked {
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// Lock is held - daemon is running
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// Try to read PID for display (best effort)
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if data := make([]byte, 32); true {
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n, _ := f.Read(data)
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if n > 0 {
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fmt.Sscanf(string(data), "%d", &pid)
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}
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}
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return true, pid
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}
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// Other errors mean we can't determine status
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return false, 0
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}
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// We got the lock - no daemon running
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// Release immediately (file close will do this)
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return false, 0
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}
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// checkPIDFile checks if a daemon is running by reading the PID file.
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// This is used for backward compatibility with pre-lock daemons.
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func checkPIDFile(beadsDir string) (running bool, pid int) {
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pidFile := filepath.Join(beadsDir, "daemon.pid")
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data, err := os.ReadFile(pidFile)
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if err != nil {
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return false, 0
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}
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pidVal, err := strconv.Atoi(strings.TrimSpace(string(data)))
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if err != nil {
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return false, 0
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}
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if !isProcessRunning(pidVal) {
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return false, 0
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}
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return true, pidVal
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}
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