org.jboss.cache.lock

Class IdentityLock

java.lang.Object

org.jboss.cache.lock.IdentityLock

All Implemented Interfaces:

NodeLock

Deprecated.

will be removed when we drop support for Pessimistic Locking and Optimistic Locking

@Deprecated
public class IdentityLock
extends Object
implements NodeLock

Lock object which grants and releases locks, and associates locks with owners. The methods to acquire and release a lock require an owner (Object). When a lock is acquired, we store the current owner with the lock. When the same owner (but possibly running in a different thread) wants to acquire the lock, it is immediately granted. When an owner different from the one currently owning the lock wants to release the lock, we do nothing (no-op).

Consider the following example:

 FIFOSemaphore lock=new FIFOSemaphore(1);
 lock.acquire();
 lock.acquire();
 lock.release();
 

This would block on the second acquire() (although we currently already hold the lock) because the lock only has 1 permit. So IdentityLock will allow the following code to work properly:

 IdentityLock lock=new IdentityLock();
 lock.readLock().acquire(this, timeout);
 lock.writeLock().acquire(this, timeout);
 lock.release(this);
 

If the owner is null, then the current thread is taken by default. This allow the following code to work:

 IdentityLock lock=new IdentityLock();
 lock.readLock().attempt(null, timeout);
 lock.writeLock().attempt(null, timeout);
 lock.release(null);
 

Note that the Object given as owner is required to implement Object.equals(java.lang.Object). For a use case see the examples in the testsuite.

Author:

Bela Ban Apr 11, 2003, Ben Wang July 2003

Constructor Summary

Constructors

Constructor and Description
IdentityLock(LockStrategyFactory factory, NodeSPI node) Deprecated. Creates a new IdentityLock using the LockFactory passed in.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	acquire(Object caller, long timeout, LockType lock_type) Deprecated.
Set<NodeLock>	acquireAll(Object caller, long timeout, LockType lock_type) Deprecated. Recursively acquire locks for this node and all subnodes, including internal Fqns such as buddy backup subtrees.
Set<NodeLock>	acquireAll(Object caller, long timeout, LockType lock_type, boolean excludeInternalFqns) Deprecated. Same as the overloaded NodeLock.acquire(Object, long, LockType) except that you can optionally specify that internal Fqns - such as buddy backup subtrees - can be excluded when acquiring locks.
boolean	acquireReadLock(Object caller, long timeout) Deprecated. Acquire a read lock with a timeout period of timeout milliseconds.
boolean	acquireWriteLock(Object caller, long timeout) Deprecated. Acquire a write lock with a timeout of timeout milliseconds.
Fqn	getFqn() Deprecated. Returns the FQN this lock, may be null.
LockMap	getLockMap() Deprecated.
Node	getNode() Deprecated. Returns the node for this lock, may be null.
Collection<Object>	getReaderOwners() Deprecated. Return a copy of the reader lock owner in List.
Object	getWriterOwner() Deprecated. Return the writer lock owner object.
boolean	isLocked() Deprecated. Check if there is a read or write lock
boolean	isOwner(Object o) Deprecated. Am I a lock owner?
boolean	isReadLocked() Deprecated. Check if there is a read lock.
boolean	isWriteLocked() Deprecated. Check if there is a write lock.
void	printLockInfo(StringBuilder sb, int indent) Deprecated.
void	release(Object caller) Deprecated. Release the lock held by the owner.
void	releaseAll() Deprecated. Release all locks associated with this instance.
void	releaseAll(Object owner) Deprecated. Releases all locks with this owner.
void	releaseForce() Deprecated. Same as releaseAll now.
String	toString() Deprecated.
String	toString(boolean print_lock_details) Deprecated.
void	toString(StringBuilder sb) Deprecated.
void	toString(StringBuilder sb, boolean print_lock_details) Deprecated.

Methods inherited from class java.lang.Object

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

Constructor Detail

IdentityLock

public IdentityLock(LockStrategyFactory factory,
            NodeSPI node)

Deprecated.

Creates a new IdentityLock using the LockFactory passed in.

Parameters:

factory - to create lock strategies

node - to lock

Method Detail

getNode

public Node getNode()

Deprecated.

Returns the node for this lock, may be null.

getFqn

public Fqn getFqn()

Deprecated.

Returns the FQN this lock, may be null.

Specified by:

getFqn in interface NodeLock

getReaderOwners

public Collection<Object> getReaderOwners()

Deprecated.

Return a copy of the reader lock owner in List. Size is zero is not available. Note that this list is synchronized.

Specified by:

getReaderOwners in interface NodeLock

Returns:

Collection