org.jasig.cas.ticket.registry.support
Class JdbcLockingStrategy

java.lang.Object
  org.jasig.cas.ticket.registry.support.JdbcLockingStrategy

All Implemented Interfaces:

LockingStrategy, org.springframework.beans.factory.InitializingBean

public class JdbcLockingStrategy
extends java.lang.Object
implements LockingStrategy, org.springframework.beans.factory.InitializingBean

Locking strategy that uses database storage for lock state that has the following properties:

• Exclusivity - Only only client at a time may acquire the lock.
• Non-reentrant - An attempt to re-acquire the lock by the current holder will fail.
• Lock expiration - Locks are acquired with an expiration such that a request to acquire the lock after the expiration date will succeed even if it is currently held by another client.

This class requires a backing database table to exist based on the following template:

 CREATE TABLE LOCKS (
   APPLICATION_ID VARCHAR(50) NOT NULL,
   UNIQUE_ID VARCHAR(50) NULL,
   EXPIRATION_DATE TIMESTAMP NULL
 );
 ALTER TABLE LOCKS ADD CONSTRAINT LOCKS_PK
 PRIMARY KEY (APPLICATION_ID);
 

Note that table and column names can be controlled through instance properties, but the create table script above is consistent with defaults.

Since:

3.3.6

Version:

$Revision: 47522 $

Author:

Marvin S. Addison

Nested Class Summary

static class

JdbcLockingStrategy.DatabasePlatform Supported database platforms provides support for platform-specific behavior such as locking semantics.

Field Summary

static int

DEFAULT_LOCK_TIMEOUT Default lock timeout is 1 hour

Constructor Summary

JdbcLockingStrategy()

Method Summary

boolean	acquire() Attempt to acquire the lock.
void	afterPropertiesSet()
void	release() Release the lock if held.
void	setApplicationId(java.lang.String id)
void	setApplicationIdColumnName(java.lang.String name)
void	setDataSource(javax.sql.DataSource dataSource)
void	setExpirationDateColumnName(java.lang.String name)
void	setLockTimeout(int seconds)
void	setPlatform(JdbcLockingStrategy.DatabasePlatform platform)
void	setTableName(java.lang.String name)
void	setUniqueId(java.lang.String id)
void	setUniqueIdColumnName(java.lang.String name)

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_LOCK_TIMEOUT

public static final int DEFAULT_LOCK_TIMEOUT

Default lock timeout is 1 hour

See Also:

Constant Field Values

Constructor Detail

JdbcLockingStrategy

public JdbcLockingStrategy()

Method Detail

setUniqueId

public void setUniqueId(java.lang.String id)

Parameters:

id - Identifier used to identify this instance in a row of the lock table. Must be unique across all clients vying for locks for a given application ID.

setApplicationId

public void setApplicationId(java.lang.String id)

Parameters:

id - Application identifier that identifies a row in the lock table for which multiple clients vie to hold the lock.

setLockTimeout

public void setLockTimeout(int seconds)

Parameters:

seconds - Maximum amount of time in seconds lock may be held.

setTableName

public void setTableName(java.lang.String name)

Parameters:

name - Name of database table holding locks.

setApplicationIdColumnName

public void setApplicationIdColumnName(java.lang.String name)

Parameters:

name - Name of database column that stores application ID.

setUniqueIdColumnName

public void setUniqueIdColumnName(java.lang.String name)

Parameters:

name - Name of database column that stores unique ID.

setExpirationDateColumnName

public void setExpirationDateColumnName(java.lang.String name)

Parameters:

name - Name of database column that stores lock expiration date.

setDataSource

public void setDataSource(javax.sql.DataSource dataSource)

Parameters:

dataSource - JDBC data source.

setPlatform

public void setPlatform(JdbcLockingStrategy.DatabasePlatform platform)

Parameters:

platform - Database platform that indicates when special syntax is needed for database operations.

afterPropertiesSet

public void afterPropertiesSet()

Specified by:

afterPropertiesSet in interface org.springframework.beans.factory.InitializingBean

acquire

@Transactional
public boolean acquire()

Description copied from interface: LockingStrategy

Attempt to acquire the lock.

Specified by:

acquire in interface LockingStrategy

Returns:

True if lock was successfully acquired, false otherwise.

See Also:

LockingStrategy.acquire()

release

@Transactional
public void release()

Description copied from interface: LockingStrategy

Release the lock if held. If the lock is not held nothing is done.

Specified by:

release in interface LockingStrategy

See Also:

LockingStrategy.release()