vaultik/internal/pidlock/pidlock.go
sneak badc0c07e0 Add pluggable storage backend, PID locking, and improved scan progress
Storage backend:
- Add internal/storage package with Storer interface
- Implement FileStorer for local filesystem storage (file:// URLs)
- Implement S3Storer wrapping existing s3.Client
- Support storage_url config field (s3:// or file://)
- Migrate all consumers to use storage.Storer interface

PID locking:
- Add internal/pidlock package to prevent concurrent instances
- Acquire lock before app start, release on exit
- Detect stale locks from crashed processes

Scan progress improvements:
- Add fast file enumeration pass before stat() phase
- Use enumerated set for deletion detection (no extra filesystem access)
- Show progress with percentage, files/sec, elapsed time, and ETA
- Change "changed" to "changed/new" for clarity

Config improvements:
- Add tilde expansion for paths (~/)
- Use xdg library for platform-specific default index path
2025-12-19 11:52:51 +07:00

109 lines
2.8 KiB
Go

// Package pidlock provides process-level locking using PID files.
// It prevents multiple instances of vaultik from running simultaneously,
// which would cause database locking conflicts.
package pidlock
import (
"errors"
"fmt"
"os"
"path/filepath"
"strconv"
"strings"
"syscall"
)
// ErrAlreadyRunning indicates another vaultik instance is running.
var ErrAlreadyRunning = errors.New("another vaultik instance is already running")
// Lock represents an acquired PID lock.
type Lock struct {
path string
}
// Acquire attempts to acquire a PID lock in the specified directory.
// If the lock file exists and the process is still running, it returns
// ErrAlreadyRunning with details about the existing process.
// On success, it writes the current PID to the lock file and returns
// a Lock that must be released with Release().
func Acquire(lockDir string) (*Lock, error) {
// Ensure lock directory exists
if err := os.MkdirAll(lockDir, 0700); err != nil {
return nil, fmt.Errorf("creating lock directory: %w", err)
}
lockPath := filepath.Join(lockDir, "vaultik.pid")
// Check for existing lock
existingPID, err := readPIDFile(lockPath)
if err == nil {
// Lock file exists, check if process is running
if isProcessRunning(existingPID) {
return nil, fmt.Errorf("%w (PID %d)", ErrAlreadyRunning, existingPID)
}
// Process is not running, stale lock file - we can take over
}
// Write our PID
pid := os.Getpid()
if err := os.WriteFile(lockPath, []byte(strconv.Itoa(pid)), 0600); err != nil {
return nil, fmt.Errorf("writing PID file: %w", err)
}
return &Lock{path: lockPath}, nil
}
// Release removes the PID lock file.
// It is safe to call Release multiple times.
func (l *Lock) Release() error {
if l == nil || l.path == "" {
return nil
}
// Verify we still own the lock (our PID is in the file)
existingPID, err := readPIDFile(l.path)
if err != nil {
// File already gone or unreadable - that's fine
return nil
}
if existingPID != os.Getpid() {
// Someone else wrote to our lock file - don't remove it
return nil
}
if err := os.Remove(l.path); err != nil && !os.IsNotExist(err) {
return fmt.Errorf("removing PID file: %w", err)
}
l.path = "" // Prevent double-release
return nil
}
// readPIDFile reads and parses the PID from a lock file.
func readPIDFile(path string) (int, error) {
data, err := os.ReadFile(path)
if err != nil {
return 0, err
}
pid, err := strconv.Atoi(strings.TrimSpace(string(data)))
if err != nil {
return 0, fmt.Errorf("parsing PID: %w", err)
}
return pid, nil
}
// isProcessRunning checks if a process with the given PID is running.
func isProcessRunning(pid int) bool {
process, err := os.FindProcess(pid)
if err != nil {
return false
}
// On Unix, FindProcess always succeeds. We need to send signal 0 to check.
err = process.Signal(syscall.Signal(0))
return err == nil
}