LockManagerDefaultImpl

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org.apache.ojb.odmg.locking
Class LockManagerDefaultImpl

java.lang.Object
  org.apache.ojb.odmg.locking.LockManagerDefaultImpl

All Implemented Interfaces:: LockManager

public class LockManagerDefaultImpl
extends java.lang.Object
implements LockManager

The OJB default implementation of a Locking mechanism. This Implementation supports 4 transaction isolation levels as specified in the interface org.apache.ojb.broker.metadata.IsolationLevels: public final int IL_READ_UNCOMMITTED = 0; public final int IL_READ_COMMITTED = 1; public final int IL_REPEATABLE_READ = 2; public final int IL_SERIALIZABLE = 3; Isolationlevels can be adjusted per class. The proper lockhandling is done in the respective LockStrategy implementation. This default implementation provides persistent Locks that are stored in a special database table. To keep the locks in the database and not in memory allows to use them accross multiple distributed ODMG clients. Of course this solution causes a lot of database reads and writes even if no real application data is written to the database. This solution may thus not be suited for all environments. As the LockManager is pluggable its possible to replace the default implementation by user defined implementations. A different solution might be to implement the LockManager as an additional standalone server, that allows to elminate additional db reads and writes.

Field Summary

private org.apache.ojb.broker.util.logging.Logger log


Constructor Summary

(package private) LockManagerDefaultImpl()
          LockManagerDefaultImpl constructor comment.

Method Summary

boolean checkRead(org.apache.ojb.odmg.TransactionImpl tx, java.lang.Object obj)
          checks if there is a readlock for transaction tx on object obj.

boolean checkWrite(org.apache.ojb.odmg.TransactionImpl tx, java.lang.Object obj)
          checks if there is a writelock for transaction tx on object obj.

boolean readLock(org.apache.ojb.odmg.TransactionImpl tx, java.lang.Object obj)
          aquires a readlock for transaction tx on object obj.

boolean releaseLock(org.apache.ojb.odmg.TransactionImpl tx, java.lang.Object obj)
          releases a lock for transaction tx on object obj.

boolean upgradeLock(org.apache.ojb.odmg.TransactionImpl tx, java.lang.Object obj)
          upgrades readlock for transaction tx on object obj to a writelock.

boolean writeLock(org.apache.ojb.odmg.TransactionImpl tx, java.lang.Object obj)
          aquires a writelock for transaction tx on object obj.

Methods inherited from class java.lang.Object

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

Field Detail

log

private org.apache.ojb.broker.util.logging.Logger log

Constructor Detail