org.sourceforge.jemm.database.components
Class UserLockInfo

java.lang.Object
  org.sourceforge.jemm.database.components.UserLockInfo

public class UserLockInfo
extends java.lang.Object

Constructor Summary

UserLockInfo(ID id)

UserLockInfo(ID id, ClientThreadId lockHolder, java.util.LinkedList<ClientThreadId> lockQueue)

Method Summary

boolean	acquireLock(ClientThreadId clientThreadId) Attempts to acquire the lock.
boolean	equals(java.lang.Object obj)
ClientThreadId	getHolder()
ID	getId()
java.util.LinkedList<ClientThreadId>	getLockQueue()
int	hashCode()
boolean	isUnused()
ClientThreadId	releaseLock(ClientThreadId releasingThreadId) Release the lock on this object.
ClientThreadId	releaseOrClearFromQueue(ClientThreadId clientThreadId) Release the lock on this object if it is held by this thread, or removed the thread from the waiting queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

UserLockInfo

public UserLockInfo(ID id)

UserLockInfo

public UserLockInfo(ID id,
                    ClientThreadId lockHolder,
                    java.util.LinkedList<ClientThreadId> lockQueue)

Method Detail

acquireLock

public boolean acquireLock(ClientThreadId clientThreadId)

Attempts to acquire the lock. Returns true if the lock is acquired, otherwise returns false and the requestor is added to the lock waiting queue.

Parameters:

clientThreadId - The client thread attempted to acquire the lock.

Returns:

True if the requesting thread acquired the lock, false if it is waiting.

Throws:

LockInfoDeadException - If the lock is dead and a new one should be created

releaseLock

public ClientThreadId releaseLock(ClientThreadId releasingThreadId)

Release the lock on this object. This must be performed by the current lock holder. If there is any waiters on the lock the first will immediately acquire the lock. The new lock owner is returned by the method and it is the responsibility of the caller to notify the new owner.

Parameters:

releasingThreadId - The current lock holder.

Returns:

The ClientThreadId who now holds the lock, or null if none.

releaseOrClearFromQueue

public ClientThreadId releaseOrClearFromQueue(ClientThreadId clientThreadId)

Release the lock on this object if it is held by this thread, or removed the thread from the waiting queue. If the owner had changed it will be returned by this method and it is the responsibility of the caller to notify the new owner.

Parameters:

clientThreadId - The thread being cleared.

Returns:

The ClientThreadId of the new lock holder (if the lock holder has changed)

isUnused

public boolean isUnused()

getLockQueue

public java.util.LinkedList<ClientThreadId> getLockQueue()

getHolder

public ClientThreadId getHolder()

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

getId

public ID getId()