Package org.apache.derby.iapi.store.raw

Interface LockingPolicy

All Known Implementing Classes:

ContainerLocking2, ContainerLocking3, NoLocking, RowLocking1, RowLocking2, RowLocking2nohold, RowLocking3, RowLocking3Escalate, RowLockingRR

public interface LockingPolicy

Any object that implements this interface can be used as a locking policy for accessing a container.

The locking policy must use the defined lock qualifiers (ContainerLock.CIS, RowLock.RS, etc.) and the standard lock manager. (A locking policy that just performs no locking wouldn't need to use these :-)

A locking policy must use the object that is an instance of Transaction (originally obtained via startTransaction() in RawStoreFactory) as the compatibilitySpace for the LockFactory calls.
A locking policy must use the passed in transaction as the compatability space and the lock group. This chain (group) of locks has the following defined behaviour

• Locks are released at transaction.commit()
• Locks are released at transaction.abort()

MT - Thread Safe

See Also:

ContainerHandle, RecordHandle, LockFactory, Lockable

Field Summary

Fields

Modifier and Type	Field	Description
static int	MODE_CONTAINER	ContainerHandle level locking.
static int	MODE_NONE	No locking what so ever, isolation parameter will be ignored by getLockingPolicy().
static int	MODE_RECORD	Record level locking.

Method Summary

Modifier and Type	Method	Description
int	getMode()	Get the mode of this policy
boolean	lockContainer(Transaction t, ContainerHandle container, boolean waitForLock, boolean forUpdate)	Called when a container is opened.
boolean	lockRecordForRead(Transaction t, ContainerHandle container, RecordHandle record, boolean waitForLock, boolean forUpdate)	Called before a record is fetched.
boolean	lockRecordForWrite(Transaction t, RecordHandle record, boolean lockForInsert, boolean waitForLock)	Called before a record is inserted, updated or deleted.
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 lockForPreviousKey, boolean waitForLock)	Request a write lock which will be released immediately upon grant.

Field Detail

MODE_NONE

static final int MODE_NONE

No locking what so ever, isolation parameter will be ignored by getLockingPolicy().

See Also:

RawStoreFactory, Constant Field Values

MODE_RECORD

static final int MODE_RECORD

Record level locking.

See Also:

Constant Field Values

MODE_CONTAINER

static final int MODE_CONTAINER

ContainerHandle level locking.

See Also:

Constant Field Values

Method Detail

lockContainer

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

Called when a container is opened.

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 Derby error policy

See Also:

ContainerHandle

unlockContainer

void unlockContainer(Transaction t,
                     ContainerHandle container)

Called when a container is closed.

See Also:

ContainerHandle, ContainerHandle.close()

lockRecordForRead

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

Called before a record is fetched.

Parameters:

t - Transaction to associate lock with.

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

record - Record to lock.

waitForLock - Should lock request wait until granted?

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

Throws:

StandardException - Standard Derby error policy

See Also:

Page

zeroDurationLockRecordForWrite

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

Request a write lock which will be released immediately upon grant.

Parameters:

t - Transaction to associate lock with.

record - Record to lock.

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

waitForLock - Should lock request wait until granted?

Returns:

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

Throws:

StandardException - Standard Derby error policy

See Also:

Page

lockRecordForWrite

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

Called before a record is inserted, updated or deleted. If zeroDuration is true then lock is released immediately after it has been granted.

Parameters:

t - Transaction to associate lock with.

record - Record to lock.

lockForInsert - Lock is for an insert.

waitForLock - Should lock request wait until granted?

Returns:

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

Throws:

StandardException - Standard Derby error policy

See Also:

Page

unlockRecordAfterRead

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

Called after a record has been fetched.

Throws:

StandardException - Standard Derby error policy

See Also:

Page

getMode

int getMode()

Get the mode of this policy