org.backsource.utils.io
Class DotLock

java.lang.Object
  org.backsource.utils.io.DotLock

public class DotLock

extends java.lang.Object

Simple, portable file locking using .lock files.

WARNING. This lock implementation has several flaws:

• It goes against the recomendations in the JDK: Note: this method should not be used for file-locking, as the resulting protocol cannot be made to work reliably. The FileLock facility should be used instead.
• It is not thread safe when used with the File.list method.

Example

 File f = new File("apa");
 DotLocl.aquire(f);
 // do stuff with f
 DotLocl.release(f);
 

Version:

$Id: DotLock.java,v 1.1.1.1 2004/05/19 12:07:30 pra Exp $

Author:

Jens Askengren

Field Summary

static java.lang.String	LOCK_SUFFIX
static long	POLL_TIME

Constructor Summary

DotLock()

Method Summary

static void	aquire(java.io.File f) Aquire the lock for the file @param f.
static boolean	aquire(java.io.File f, long timeout) Aquire the lock for the file @param f, wait a most @param timeout milliseconds for the lock to be released.
static long	getLockAge(java.io.File f)
static java.io.File	getLockFile(java.io.File f)
static boolean	isLocked(java.io.File f)
static boolean	release(java.io.File f) Release the lock for file @param f
static boolean	tryLock(java.io.File f) Try to aquire the lock for file @param f.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOCK_SUFFIX

public static final java.lang.String LOCK_SUFFIX

See Also:

Constant Field Values

POLL_TIME

public static final long POLL_TIME

See Also:

Constant Field Values

Constructor Detail

DotLock

public DotLock()

Method Detail

tryLock

public static boolean tryLock(java.io.File f)
                       throws java.io.IOException

Try to aquire the lock for file @param f. Fail emediately if the file is already locked.

Throws:

java.io.IOException - if the lockfile could not be created

aquire

public static void aquire(java.io.File f)
                   throws java.io.IOException

Aquire the lock for the file @param f. If the file is locked, wait until the lock is released.

Throws:

java.io.IOException - if the lockfile could not be created

java.lang.SecurityException - if the securitymanager denies write access to the lock file

aquire

public static boolean aquire(java.io.File f,
                             long timeout)
                      throws java.io.IOException

Aquire the lock for the file @param f, wait a most @param timeout milliseconds for the lock to be released.

Throws:

java.io.IOException - if the lockfile could not be created

java.lang.SecurityException - if the securitymanager denies write access to the lock file

release

public static boolean release(java.io.File f)

Release the lock for file @param f

isLocked

public static boolean isLocked(java.io.File f)

getLockFile

public static java.io.File getLockFile(java.io.File f)

getLockAge

public static long getLockAge(java.io.File f)