org.hibernate

Class LockMode

java.lang.Object

org.hibernate.LockMode

All Implemented Interfaces:

java.io.Serializable

public final class LockMode
extends java.lang.Object
implements java.io.Serializable

Instances represent a lock mode for a row of a relational database table. It is not intended that users spend much time worrying about locking since Hibernate usually obtains exactly the right lock level automatically. Some "advanced" users may wish to explicitly specify lock levels.

Author:

Gavin King

See Also:

Session.lock(Object,LockMode), Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static LockMode	FORCE Deprecated. instead use PESSIMISTIC_FORCE_INCREMENT
static LockMode	NONE No lock required.
static LockMode	OPTIMISTIC Optimisticly assume that transaction will not experience contention for entities.
static LockMode	OPTIMISTIC_FORCE_INCREMENT Optimisticly assume that transaction will not experience contention for entities.
static LockMode	PESSIMISTIC_FORCE_INCREMENT Transaction will immediately increment the entity version.
static LockMode	PESSIMISTIC_READ Implemented as PESSIMISTIC_WRITE.
static LockMode	PESSIMISTIC_WRITE Transaction will obtain a database lock immediately.
static LockMode	READ A shared lock.
static LockMode	UPGRADE Deprecated. instead use PESSIMISTIC_WRITE
static LockMode	UPGRADE_NOWAIT Attempt to obtain an upgrade lock, using an Oracle-style select for update nowait.
static LockMode	WRITE A WRITE lock is obtained when an object is updated or inserted.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	greaterThan(LockMode mode) Check if this lock mode is more restrictive than the given lock mode.
boolean	lessThan(LockMode mode) Check if this lock mode is less restrictive than the given lock mode.
static LockMode	parse(java.lang.String name)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

NONE

public static final LockMode NONE

No lock required. If an object is requested with this lock mode, a READ lock will be obtained if it is necessary to actually read the state from the database, rather than pull it from a cache.

This is the "default" lock mode.

READ

public static final LockMode READ

A shared lock. Objects in this lock mode were read from the database in the current transaction, rather than being pulled from a cache.

UPGRADE

public static final LockMode UPGRADE

Deprecated. instead use PESSIMISTIC_WRITE

An upgrade lock. Objects loaded in this lock mode are materialized using an SQL select ... for update.

UPGRADE_NOWAIT

public static final LockMode UPGRADE_NOWAIT

Attempt to obtain an upgrade lock, using an Oracle-style select for update nowait. The semantics of this lock mode, once obtained, are the same as UPGRADE.

WRITE

public static final LockMode WRITE

A WRITE lock is obtained when an object is updated or inserted. This lock mode is for internal use only and is not a valid mode for load() or lock() (both of which throw exceptions if WRITE is specified).

FORCE

public static final LockMode FORCE

Deprecated. instead use PESSIMISTIC_FORCE_INCREMENT

Similiar to UPGRADE except that, for versioned entities, it results in a forced version increment.

OPTIMISTIC

public static final LockMode OPTIMISTIC

Optimisticly assume that transaction will not experience contention for entities. The entity version will be verified near the transaction end.

OPTIMISTIC_FORCE_INCREMENT

public static final LockMode OPTIMISTIC_FORCE_INCREMENT

Optimisticly assume that transaction will not experience contention for entities. The entity version will be verified and incremented near the transaction end.

PESSIMISTIC_READ

public static final LockMode PESSIMISTIC_READ

Implemented as PESSIMISTIC_WRITE. TODO: introduce separate support for PESSIMISTIC_READ

PESSIMISTIC_WRITE

public static final LockMode PESSIMISTIC_WRITE

Transaction will obtain a database lock immediately. TODO: add PESSIMISTIC_WRITE_NOWAIT

PESSIMISTIC_FORCE_INCREMENT

public static final LockMode PESSIMISTIC_FORCE_INCREMENT

Transaction will immediately increment the entity version.

Method Detail

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

greaterThan

public boolean greaterThan(LockMode mode)

Check if this lock mode is more restrictive than the given lock mode.

Parameters:

mode - LockMode to check

Returns:

true if this lock mode is more restrictive than given lock mode

lessThan

public boolean lessThan(LockMode mode)

Check if this lock mode is less restrictive than the given lock mode.

Parameters:

mode - LockMode to check

Returns:

true if this lock mode is less restrictive than given lock mode

parse

public static LockMode parse(java.lang.String name)