org.datanucleus.state

Interface LockManager

All Known Implementing Classes:

LockManagerImpl

public interface LockManager

Interface defining a manager for locking of objects. There are currently two modes to a LockManager.

1. Where the user has the object and wants it locking. In this case they provide the ObjectProvider and we lock it (by a call to the datastore where appropriate).
2. Where the user wants to do a find of an object with a particular id. In this case we register the identity as needing this lock level, and the datastore will be called to retrieve the object and will check back what lock level to use.

Field Summary

Fields

Modifier and Type	Field and Description
static short	LOCK_MODE_NONE Lock mode representing no locking.
static short	LOCK_MODE_OPTIMISTIC_READ Lock mode for optimistic reads.
static short	LOCK_MODE_OPTIMISTIC_WRITE Lock mode for optimistic writes.
static short	LOCK_MODE_PESSIMISTIC_READ Lock mode for pessimistic reads.
static short	LOCK_MODE_PESSIMISTIC_WRITE Lock mode for pessimistic writes.

Method Summary

Modifier and Type	Method and Description
void	clear() Method to clear all settings of required lock level for object ids (mode 2).
void	close() Method to close the manager and release resources.
short	getLockMode(Object id) Accessor for what locking should be applied to the object with the specified identity (mode 2).
short	getLockMode(ObjectProvider op) Accessor for the current lock mode for the object managed by the passed ObjectProvider (mode 1).
void	lock(ObjectProvider op, short lockMode) Method to lock the object managed by the passed ObjectProvider (mode 1).
void	lock(Object id, short lockMode) Method to lock the object with the provided identity (mode 2).
void	unlock(ObjectProvider op) Method to unlock the object managed by the passed ObjectProvider (mode 1).

Field Detail

LOCK_MODE_NONE

static final short LOCK_MODE_NONE

Lock mode representing no locking.

See Also:

Constant Field Values

LOCK_MODE_OPTIMISTIC_READ

static final short LOCK_MODE_OPTIMISTIC_READ

Lock mode for optimistic reads. Same as LOCK_MODE_OPTIMISTIC_WRITE for DataNucleus.

See Also:

Constant Field Values

LOCK_MODE_OPTIMISTIC_WRITE

static final short LOCK_MODE_OPTIMISTIC_WRITE

Lock mode for optimistic writes.

See Also:

Constant Field Values

LOCK_MODE_PESSIMISTIC_READ

static final short LOCK_MODE_PESSIMISTIC_READ

Lock mode for pessimistic reads. Same as LOCK_MODE_PESSIMISTIC_WRITE for DataNucleus.

See Also:

Constant Field Values

LOCK_MODE_PESSIMISTIC_WRITE

static final short LOCK_MODE_PESSIMISTIC_WRITE

Lock mode for pessimistic writes.

See Also:

Constant Field Values

Method Detail

lock

void lock(Object id,
          short lockMode)

Method to lock the object with the provided identity (mode 2).

Parameters:

id - Identity of the object

lockMode - mode for locking

getLockMode

short getLockMode(Object id)

Accessor for what locking should be applied to the object with the specified identity (mode 2).

Parameters:

id - The identity

Returns:

The lock mode to apply (NONE if nothing defined)

clear

void clear()

Method to clear all settings of required lock level for object ids (mode 2).

lock

void lock(ObjectProvider op,
          short lockMode)

Method to lock the object managed by the passed ObjectProvider (mode 1).

Parameters:

op - ObjectProvider for the object

lockMode - mode for locking

unlock

void unlock(ObjectProvider op)

Method to unlock the object managed by the passed ObjectProvider (mode 1).

Parameters:

op - ObjectProvider for the object

getLockMode

short getLockMode(ObjectProvider op)

Accessor for the current lock mode for the object managed by the passed ObjectProvider (mode 1).

Parameters:

op - ObjectProvider for the object

Returns:

The lock mode

close

void close()

Method to close the manager and release resources.