org.apache.lucene.store
Class Lock

java.lang.Object
  org.apache.lucene.store.Lock

public abstract class Lock

extends Object

An interprocess mutex lock.

Typical use might look like:

 new Lock.With(directory.makeLock("my.lock")) {
     public Object doBody() {
       ... code to execute while locked ...
     }
   }.run();
 

Version:

$Id: Lock.java,v 1.12 2004/05/11 17:43:28 cutting Exp $

Author:

Doug Cutting

See Also:

Directory.makeLock(String)

Nested Class Summary

static class

Lock.With Utility class for executing code with exclusive access.

Field Summary

static long

LOCK_POLL_INTERVAL

Constructor Summary

Lock()

Method Summary

abstract boolean	isLocked() Returns true if the resource is currently locked.
abstract boolean	obtain() Attempts to obtain exclusive access and immediately return upon success or failure.
boolean	obtain(long lockWaitTimeout) Attempts to obtain an exclusive lock within amount of time given.
abstract void	release() Releases exclusive access.

Methods inherited from class java.lang.Object

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

Field Detail

LOCK_POLL_INTERVAL

public static long LOCK_POLL_INTERVAL

Constructor Detail

Lock

public Lock()

Method Detail

obtain

public abstract boolean obtain()
                        throws IOException

Attempts to obtain exclusive access and immediately return upon success or failure.

Returns:

true iff exclusive access is obtained

Throws:

IOException

obtain

public boolean obtain(long lockWaitTimeout)
               throws IOException

Attempts to obtain an exclusive lock within amount of time given. Currently polls once per second until lockWaitTimeout is passed.

Parameters:

lockWaitTimeout - length of time to wait in ms

Returns:

true if lock was obtained

Throws:

IOException - if lock wait times out or obtain() throws an IOException

release

public abstract void release()

Releases exclusive access.

isLocked

public abstract boolean isLocked()

Returns true if the resource is currently locked. Note that one must still call obtain() before using the resource.