lockfile

Documentation

Index

• Variables
• type Lockfile
  • func New(path string) (*Lockfile, error)
  • func (l *Lockfile) GetOwner() (*os.Process, error)
  • func (l *Lockfile) TryLock() error
  • func (l *Lockfile) Unlock() error

Examples

• Lockfile

Variables

var (
	ErrBusy        = errors.New("Locked by other process") // If you get this, retry after a short sleep might help
	ErrNeedAbsPath = errors.New("Lockfiles must be given as absolute path names")
	ErrInvalidPid  = errors.New("Lockfile contains invalid pid for system")
	ErrDeadOwner   = errors.New("Lockfile contains pid of process not existent on this system anymore")
)

Types

type Lockfile

type Lockfile struct {
	Path string
}

Example

package main

import (
	"fmt"
	"github.com/dropbox/changes-client/common/lockfile"
)

func main() {
	lock, err := lockfile.New("/tmp/lock.me.now.lck")
	if err != nil {
		fmt.Printf("Cannot init lock. reason: %s\n", err)
		panic(err)
	}
	err = lock.TryLock()

	// Error handling is essential, as we only try to get the lock.
	if err != nil {
		fmt.Printf("Cannot lock \"%v\", reason: %s\n", lock, err)
		panic(err)
	}

	defer lock.Unlock()

	fmt.Println("Do stuff under lock")
}

Output:

Do stuff under lock

func New

func New(path string) (*Lockfile, error)

Describe a new filename located at path. It is expected to be an absolute path

func (*Lockfile) GetOwner

func (l *Lockfile) GetOwner() (*os.Process, error)

Who owns the lockfile?

func (*Lockfile) TryLock

func (l *Lockfile) TryLock() error

Try to get Lockfile lock. Returns nil, if successful and and error describing the reason, it didn't work out. Please note, that existing lockfiles containing pids of dead processes and lockfiles containing no pid at all are deleted.

func (*Lockfile) Unlock

func (l *Lockfile) Unlock() error

Release a lock again. Returns any error that happend during release of lock.