org.apache.derby.impl.services.locks
Class Lock

java.lang.Object
  org.apache.derby.impl.services.locks.Lock

All Implemented Interfaces:

Control, Latch

Direct Known Subclasses:

ActiveLock

public class Lock

extends java.lang.Object

implements Latch, Control

A Lock represents a granted or waiting lock request.
MT - Mutable - Immutable identity : Thread Aware

Field Summary

(package private) int	count
private java.lang.Object	qualifier Qualifier used in the lock request..
private Lockable	ref Object being locked.
private java.lang.Object	space Compatibility space the object is locked in.

Constructor Summary

protected

Lock(java.lang.Object space, Lockable ref, java.lang.Object qualifier)

Method Summary

void	addWaiters(java.util.Dictionary waiters)
(package private) Lock	copy()
boolean	equals(java.lang.Object other)
ActiveLock	firstWaiter()
java.lang.Object	getCompatabilitySpace() Return the compatability space this lock is held in MT - Thread safe
int	getCount() Return the count of locks.
Lock	getFirstGrant()
java.util.List	getGranted()
Lock	getLock(java.lang.Object compatabilitySpace, java.lang.Object qualifier)
Lockable	getLockable() Return the object this lock is held on MT - Thread safe
LockControl	getLockControl()
java.lang.Object	getQualifier() Return the qualifier lock was obtained with.
java.util.List	getWaiting()
(package private) void	grant()
int	hashCode()
boolean	isEmpty()
boolean	isGrantable(boolean noWaitersBeforeMe, java.lang.Object compatabilitySpace, java.lang.Object requestQualifier)
Control	shallowClone() We can return ourselves here because our identity is immutable and what we returned will not be accessed as a Lock, so the count cannot be changed.
(package private) int	unlock(int unlockCount)
boolean	unlock(Latch lockInGroup, int unlockCount)

Methods inherited from class java.lang.Object

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

Field Detail

space

private final java.lang.Object space

Compatibility space the object is locked in. MT - immutable - reference only

ref

private final Lockable ref

Object being locked. MT - immutable - reference only

qualifier

private final java.lang.Object qualifier

Qualifier used in the lock request.. MT - immutable - reference only

count

int count

Constructor Detail

Lock

protected Lock(java.lang.Object space,
               Lockable ref,
               java.lang.Object qualifier)

Method Detail

getLockable

public final Lockable getLockable()

Return the object this lock is held on MT - Thread safe

Specified by:

getLockable in interface Latch

getCompatabilitySpace

public final java.lang.Object getCompatabilitySpace()

Return the compatability space this lock is held in MT - Thread safe

Specified by:

getCompatabilitySpace in interface Latch

getQualifier

public final java.lang.Object getQualifier()

Return the qualifier lock was obtained with. MT - Thread safe

Specified by:

getQualifier in interface Latch

getCount

public final int getCount()

Return the count of locks. MT - Thread safe

Specified by:

getCount in interface Latch

copy

final Lock copy()

grant

void grant()

unlock

int unlock(int unlockCount)

hashCode

public final int hashCode()

equals

public final boolean equals(java.lang.Object other)

getLockControl

public LockControl getLockControl()

Specified by:

getLockControl in interface Control

getLock

public Lock getLock(java.lang.Object compatabilitySpace,
                    java.lang.Object qualifier)

Specified by:

getLock in interface Control

shallowClone

public Control shallowClone()

We can return ourselves here because our identity is immutable and what we returned will not be accessed as a Lock, so the count cannot be changed.

Specified by:

shallowClone in interface Control

firstWaiter

public ActiveLock firstWaiter()

Specified by:

firstWaiter in interface Control

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Control

unlock

public boolean unlock(Latch lockInGroup,
                      int unlockCount)

Specified by:

unlock in interface Control

addWaiters

public void addWaiters(java.util.Dictionary waiters)

Specified by:

addWaiters in interface Control

getFirstGrant

public Lock getFirstGrant()

Specified by:

getFirstGrant in interface Control

getGranted

public java.util.List getGranted()

Specified by:

getGranted in interface Control

getWaiting

public java.util.List getWaiting()

Specified by:

getWaiting in interface Control

isGrantable

public boolean isGrantable(boolean noWaitersBeforeMe,
                           java.lang.Object compatabilitySpace,
                           java.lang.Object requestQualifier)

Specified by:

isGrantable in interface Control