org.apache.derby.impl.store.raw.xact

Class RowLockingRR

java.lang.Object

org.apache.derby.impl.store.raw.xact.RowLocking3

org.apache.derby.impl.store.raw.xact.RowLockingRR

All Implemented Interfaces:

LockingPolicy

Direct Known Subclasses:

RowLocking2

public class RowLockingRR
extends RowLocking3

A locking policy that implements row level locking with repeatable read isolation. Since phantom protection with previous key locking is actually handled by the upper level access methods, the only difference in repeatable read is that read locks are of type RowLock.RS2. This type will not conflict with a previous key insert lock.

See Also:

LockingPolicy

Field Summary

Fields inherited from interface org.apache.derby.iapi.store.raw.LockingPolicy

MODE_CONTAINER, MODE_NONE, MODE_RECORD

Method Summary

Modifier and Type	Method and Description
void	unlockContainer(Transaction t, ContainerHandle container) Called when a container is closed.
void	unlockRecordAfterRead(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean forUpdate, boolean row_qualified) Unlock a record after it has been locked for read.

Methods inherited from class org.apache.derby.impl.store.raw.xact.RowLocking3

getMode, lockContainer, lockRecordForRead, lockRecordForWrite, zeroDurationLockRecordForWrite

Methods inherited from class java.lang.Object

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

Method Detail

unlockRecordAfterRead

public void unlockRecordAfterRead(Transaction t,
                                  ContainerHandle container_handle,
                                  RecordHandle record,
                                  boolean forUpdate,
                                  boolean row_qualified)
                           throws StandardException

Unlock a record after it has been locked for read.

In repeatable read only unlock records which "did not qualify". For example in a query like "select * from foo where a = 1" on a table with no index it is only necessary to hold locks on rows where a=1, but in the process of finding those rows the system will get locks on other rows to verify they are committed before applying the qualifier. Those locks can be released under repeatable read isolation.

Specified by:

unlockRecordAfterRead in interface LockingPolicy

Throws:

StandardException - Standard exception policy.

See Also:

Page

unlockContainer

public void unlockContainer(Transaction t,
                            ContainerHandle container)

Description copied from interface: LockingPolicy

Called when a container is closed.

Specified by:

unlockContainer in interface LockingPolicy

See Also:

ContainerHandle, ContainerHandle.close()