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

Class RowLocking3

java.lang.Object

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

All Implemented Interfaces:

LockingPolicy

Direct Known Subclasses:

RowLockingRR

public class RowLocking3
extends java.lang.Object

A locking policy that implements row level locking with isolation degree 3.

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
int	getMode() Get the mode of this policy
boolean	lockContainer(Transaction t, ContainerHandle container, boolean waitForLock, boolean forUpdate) Obtain container level intent lock.
boolean	lockRecordForRead(Transaction t, ContainerHandle container_handle, RecordHandle record, boolean waitForLock, boolean forUpdate) Obtain lock on record being read.
boolean	lockRecordForWrite(Transaction t, RecordHandle record, boolean lockForInsert, boolean waitForLock) Obtain lock on record being written.
void	unlockContainer(Transaction t, ContainerHandle container) Called when a container is closed.
void	unlockRecordAfterRead(Transaction t, ContainerHandle container, RecordHandle record, boolean forUpdate, boolean row_qualified) Called after a record has been fetched.
boolean	zeroDurationLockRecordForWrite(Transaction t, RecordHandle record, boolean lockForInsertPreviousKey, boolean waitForLock) Obtain lock on record being written.

Methods inherited from class java.lang.Object

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

Method Detail

lockContainer

public boolean lockContainer(Transaction t,
                             ContainerHandle container,
                             boolean waitForLock,
                             boolean forUpdate)
                      throws StandardException

Obtain container level intent lock.

This implementation of row locking is 2 level, ie. table and row locking. It will interact correctly with tables opened with ContainerLocking3 locking mode.

Updater's will get table level IX locks, and X row locks.

Reader's will get table level IS locks, and S row locks.

Specified by:

lockContainer in interface LockingPolicy

Parameters:

t - Transaction to associate lock with.

container - Container to lock.

waitForLock - Should lock request wait until granted?

forUpdate - Should container be locked for update, or read?

Returns:

true if the lock was obtained, false if it wasn't. False should only be returned if the waitForLock policy was set to "false," and the lock was unavailable.

Throws:

StandardException - Standard exception policy.

See Also:

ContainerHandle

lockRecordForRead

public boolean lockRecordForRead(Transaction t,
                                 ContainerHandle container_handle,
                                 RecordHandle record,
                                 boolean waitForLock,
                                 boolean forUpdate)
                          throws StandardException

Obtain lock on record being read.

Assumes that a table level IS has been acquired. Will acquire a Shared or Update lock on the row, depending on the "forUpdate" parameter.

Specified by:

lockRecordForRead in interface LockingPolicy

Parameters:

t - The transaction to associate the lock with.

record - The record to be locked.

waitForLock - Should lock request wait until granted?

forUpdate - Whether to open for read or write access.

container_handle - Open Container used to get record. Will be used to row locks by the container they belong to.

Returns:

true if the lock was granted, false if waitForLock was false and the lock could not be granted.

Throws:

StandardException - Standard exception policy.

See Also:

Page

zeroDurationLockRecordForWrite

public boolean zeroDurationLockRecordForWrite(Transaction t,
                                              RecordHandle record,
                                              boolean lockForInsertPreviousKey,
                                              boolean waitForLock)
                                       throws StandardException

Obtain lock on record being written.

Assumes that a table level IX has been acquired. Will acquire an Exclusive (X) lock on the row.

Specified by:

zeroDurationLockRecordForWrite in interface LockingPolicy

Parameters:

t - transaction to associate the lock with.

record - The record to be locked.

lockForInsertPreviousKey - Lock is for a previous key of a insert.

waitForLock - Should lock request wait until granted?

Returns:

true if the lock was granted, false if waitForLock was false and the lock could not be granted.

Throws:

StandardException - Standard exception policy.

See Also:

Page

lockRecordForWrite

public boolean lockRecordForWrite(Transaction t,
                                  RecordHandle record,
                                  boolean lockForInsert,
                                  boolean waitForLock)
                           throws StandardException

Obtain lock on record being written.

Assumes that a table level IX has been acquired. Will acquire an Exclusive (X) lock on the row.

Specified by:

lockRecordForWrite in interface LockingPolicy

Parameters:

t - The transaction to associate the lock with.

record - The record to be locked.

lockForInsert - Lock is for an insert.

waitForLock - Should lock request wait until granted?

Returns:

true if the lock was granted, false if waitForLock was false and the lock could not be granted.

Throws:

StandardException - Standard exception policy.

See Also:

Page

getMode

public int getMode()

Description copied from interface: LockingPolicy

Get the mode of this policy

Specified by:

getMode in interface LockingPolicy

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()

unlockRecordAfterRead

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

Description copied from interface: LockingPolicy

Called after a record has been fetched.

Specified by:

unlockRecordAfterRead in interface LockingPolicy

Throws:

StandardException - Standard Derby error policy

See Also:

Page