org.codehaus.wadi.core.util
Interface Lease

All Superinterfaces:

java.util.concurrent.locks.Lock

All Known Implementing Classes:

ExtendableLease, SimpleLease

public interface Lease
extends java.util.concurrent.locks.Lock

Lease - like a Sync, but locks are only granted for a given period after which they automatically unlock themselves. This is an important construct in a distributed, HA system as, even in the case of failure, a locked resource will be correctly unlocked.

Version:

$Revision$

Author:

jules

Nested Class Summary

static interface

Lease.Handle

Method Summary

Lease.Handle	acquire(long leasePeriod) acquire a lease for a given period
Lease.Handle	attempt(long timeframe, long leasePeriod) attempt the acquisition of a lease for a given period within a given timeframe
boolean	release(Lease.Handle handle) A misleading name - 'release' as in 'unlock' the lease corresponding to the given handle

Methods inherited from interface java.util.concurrent.locks.Lock

lock, lockInterruptibly, newCondition, tryLock, tryLock, unlock

Method Detail

acquire

Lease.Handle acquire(long leasePeriod)
                     throws java.lang.InterruptedException

acquire a lease for a given period

Parameters:

leasePeriod - the given period (in millis)

Returns:

the handle of the lease acquired

Throws:

java.lang.InterruptedException

attempt

Lease.Handle attempt(long timeframe,
                     long leasePeriod)
                     throws java.lang.InterruptedException

attempt the acquisition of a lease for a given period within a given timeframe

Parameters:

timeframe - the timeframe within which to try to acquire the lease (in millis)

leasePeriod - the period for which the lease is required (in millis)

Returns:

the handle of the lease acquire or null in the case of failure

Throws:

java.lang.InterruptedException

release

boolean release(Lease.Handle handle)

A misleading name - 'release' as in 'unlock' the lease corresponding to the given handle

Parameters:

handle - the handle of the Lease to be 'released'

Returns:

whether or not the lease in question was still active at the point of 'release'