org.apache.ojb.odmg.locking
Class ReadCommittedStrategy

java.lang.Object
  org.apache.ojb.odmg.locking.AbstractLockStrategy
      org.apache.ojb.odmg.locking.ReadCommittedStrategy

All Implemented Interfaces:

LockStrategy

public class ReadCommittedStrategy
extends AbstractLockStrategy

The implementation of the Commited Reads Locking stra ReadCommitted - Reads and Writes require locks. Locks are acquired for reading and modifying the database. Locks are released after reading but locks on modified objects are held until EOT. Allows: Non-Repeatable Reads Phantom Readstegy.

Author:

Thomas Mahler & David Dixon-Peugh

Field Summary

Fields inherited from class org.apache.ojb.odmg.locking.AbstractLockStrategy

DEFAULT_LOCK_TIMEOUT

Constructor Summary

ReadCommittedStrategy()

Method Summary

boolean	checkRead(TransactionImpl tx, Object obj) checks whether the specified Object obj is read-locked by Transaction tx.
boolean	checkWrite(TransactionImpl tx, Object obj) checks whether the specified Object obj is write-locked by Transaction tx.
boolean	readLock(TransactionImpl tx, Object obj) acquire a read lock on Object obj for Transaction tx.
boolean	releaseLock(TransactionImpl tx, Object obj) release a lock on Object obj for Transaction tx.
boolean	upgradeLock(TransactionImpl tx, Object obj) acquire a lock upgrade (from read to write) lock on Object obj for Transaction tx.
boolean	writeLock(TransactionImpl tx, Object obj) acquire a write lock on Object obj for Transaction tx.

Methods inherited from class org.apache.ojb.odmg.locking.AbstractLockStrategy

addReader, getReaders, getWriter, hasReadLock, removeReader, removeWriter, setWriter, upgradeLock

Methods inherited from class java.lang.Object

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

Constructor Detail

ReadCommittedStrategy

public ReadCommittedStrategy()

Method Detail

readLock

public boolean readLock(TransactionImpl tx,
                        Object obj)

acquire a read lock on Object obj for Transaction tx.

Parameters:

tx - the transaction requesting the lock

obj - the Object to be locked

Returns:

true if successful, else false

writeLock

public boolean writeLock(TransactionImpl tx,
                         Object obj)

acquire a write lock on Object obj for Transaction tx.

Parameters:

tx - the transaction requesting the lock

obj - the Object to be locked

Returns:

true if successful, else false

upgradeLock

public boolean upgradeLock(TransactionImpl tx,
                           Object obj)

acquire a lock upgrade (from read to write) lock on Object obj for Transaction tx.

Parameters:

tx - the transaction requesting the lock

obj - the Object to be locked

Returns:

true if successful, else false

releaseLock

public boolean releaseLock(TransactionImpl tx,
                           Object obj)

release a lock on Object obj for Transaction tx.

Parameters:

tx - the transaction releasing the lock

obj - the Object to be unlocked

Returns:

true if successful, else false

checkRead

public boolean checkRead(TransactionImpl tx,
                         Object obj)

checks whether the specified Object obj is read-locked by Transaction tx.

Parameters:

tx - the transaction

obj - the Object to be checked

Returns:

true if lock exists, else false

checkWrite

public boolean checkWrite(TransactionImpl tx,
                          Object obj)

checks whether the specified Object obj is write-locked by Transaction tx.

Parameters:

tx - the transaction

obj - the Object to be checked

Returns:

true if lock exists, else false