Function AcquireInstanceLock

utils/lockfile.go:28–63

AcquireInstanceLock attempts to acquire an exclusive lock for the given instance. Returns an InstanceLock if successful, or an error if the lock cannot be acquired. Uses O_EXCL for atomicity; stale locks (>30 min or dead process) are automatically cleaned up.

(instanceID string)

// Returns an InstanceLock if successful, or an error if the lock cannot be acquired.
// Uses O_EXCL for atomicity; stale locks (>30 min or dead process) are automatically cleaned up.
func AcquireInstanceLock(instanceID string) (*InstanceLock, error) {
	lockDir := GetLockDir()
	if err := os.MkdirAll(lockDir, 0700); err != nil {
		return nil, fmt.Errorf("failed to create locks directory: %w", err)
	}

	lockPath := GetInstanceLockPath(instanceID)

	if data, err := os.ReadFile(lockPath); err == nil {
		lines := strings.Split(strings.TrimSpace(string(data)), "\n")
		if len(lines) >= 2 {
			if pid, err := strconv.Atoi(lines[0]); err == nil {
				if timestamp, err := strconv.ParseInt(lines[1], 10, 64); err == nil {
					lockAge := time.Since(time.Unix(timestamp, 0))
					if isProcessAlive(pid) && lockAge < 30*time.Minute {
						return nil, fmt.Errorf("another 'tnr connect' session is already in progress for this instance")
					}
				}
			}
		}
		_ = os.Remove(lockPath) // Stale lock
	}

	file, err := os.OpenFile(lockPath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0600)
	if err != nil {
		if os.IsExist(err) {
			return nil, fmt.Errorf("another 'tnr connect' session is already in progress for this instance")
		}
		return nil, fmt.Errorf("failed to create lock file: %w", err)
	}

	_, _ = file.WriteString(fmt.Sprintf("%d\n%d\n", os.Getpid(), time.Now().Unix()))
	file.Close()

	return &InstanceLock{lockPath: lockPath}, nil
}

// Release releases the instance lock and removes the lock file.
func (l *InstanceLock) Release() error {