netdata/netdata

// SPDX-License-Identifier: GPL-3.0-or-later

package filelock

import (
    "path/filepath"

    "github.com/gofrs/flock"
)

func New(dir string) *Locker {
    return &Locker{
        suffix: ".collector.lock",
        dir:    dir,
        locks:  make(map[string]*flock.Flock),
    }
}

type Locker struct {
    suffix string
    dir    string
    locks  map[string]*flock.Flock
}

func (l *Locker) Lock(name string) (bool, error) {
    filename := l.filename(name)

    if _, ok := l.locks[filename]; ok {
        return true, nil
    }

    locker := flock.New(filename)

    ok, err := locker.TryLock()
    if ok {
        l.locks[filename] = locker
    } else {
        _ = locker.Close()
    }

    return ok, err
}

func (l *Locker) Unlock(name string) {
    filename := l.filename(name)

    locker, ok := l.locks[filename]
    if !ok {
        return
    }

    delete(l.locks, filename)

    _ = locker.Close()
}

func (l *Locker) isLocked(name string) bool {
    _, ok := l.locks[l.filename(name)]
    return ok
}

func (l *Locker) filename(name string) string {
    return filepath.Join(l.dir, name+l.suffix)
}