ojb.odmg.locking
Class AbstractLockStrategy

java.lang.Object
  |
  +--ojb.odmg.locking.AbstractLockStrategy

All Implemented Interfaces:

LockStrategy

Direct Known Subclasses:

ReadCommittedStrategy, ReadUncommittedStrategy, RepeatableReadStrategy, SerializableStrategy

public abstract class AbstractLockStrategy

extends java.lang.Object

implements LockStrategy

The base class of all LockingStrategies. It provides the basic infrastructure to read and write locks to the persistent storage.

Author:

Thomas Mahler

Field Summary

static long

DEFAULT_LOCK_TIMEOUT the timeout for lock entries

Constructor Summary

AbstractLockStrategy()

Method Summary

protected boolean	addReader(TransactionImpl tx, java.lang.Object obj) Add a reader lock entry for transaction tx on object obj to the persistent storage.
protected java.util.Collection	getReaders(java.lang.Object obj) returns a collection of Reader LockEntries for object obj.
protected LockEntry	getWriter(java.lang.Object obj) returns the LockEntry for the Writer of object obj.
protected boolean	hasReadLock(TransactionImpl tx, java.lang.Object obj) check if there is a reader lock entry for transaction tx on object obj in the persistent storage.
protected void	removeReader(TransactionImpl tx, java.lang.Object obj) remove a reader lock entry for transaction tx on object obj from the persistent storage.
protected void	removeWriter(LockEntry writer) remove a writer lock entry for transaction tx on object obj from the persistent storage.
protected boolean	setWriter(TransactionImpl tx, java.lang.Object obj) generate a writer lock entry for transaction tx on object obj and write it to the persistent storage.
protected boolean	upgradeLock(LockEntry reader) upgrade a reader lock entry for transaction tx on object obj and write it to the persistent storage.

Methods inherited from class java.lang.Object

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

Methods inherited from interface ojb.odmg.locking.LockStrategy

checkRead, checkWrite, readLock, releaseLock, upgradeLock, writeLock

Field Detail

DEFAULT_LOCK_TIMEOUT

public static long DEFAULT_LOCK_TIMEOUT

the timeout for lock entries

Constructor Detail

AbstractLockStrategy

public AbstractLockStrategy()

Method Detail

getWriter

protected LockEntry getWriter(java.lang.Object obj)

returns the LockEntry for the Writer of object obj. If now writer exists, null is returned.

getReaders

protected java.util.Collection getReaders(java.lang.Object obj)

returns a collection of Reader LockEntries for object obj. If now LockEntries could be found an empty Vector is returned.

addReader

protected boolean addReader(TransactionImpl tx,
                            java.lang.Object obj)

Add a reader lock entry for transaction tx on object obj to the persistent storage.

removeReader

protected void removeReader(TransactionImpl tx,
                            java.lang.Object obj)

remove a reader lock entry for transaction tx on object obj from the persistent storage.

removeWriter

protected void removeWriter(LockEntry writer)

remove a writer lock entry for transaction tx on object obj from the persistent storage.

upgradeLock

protected boolean upgradeLock(LockEntry reader)

upgrade a reader lock entry for transaction tx on object obj and write it to the persistent storage.

setWriter

protected boolean setWriter(TransactionImpl tx,
                            java.lang.Object obj)

generate a writer lock entry for transaction tx on object obj and write it to the persistent storage.

hasReadLock

protected boolean hasReadLock(TransactionImpl tx,
                              java.lang.Object obj)

check if there is a reader lock entry for transaction tx on object obj in the persistent storage.