Package org.apache.ibatis.cache.decorators

Class BlockingCache

java.lang.Object

org.apache.ibatis.cache.decorators.BlockingCache

All Implemented Interfaces:

Cache

public class BlockingCache
extends Object
implements Cache

Simple blocking decorator

Simple and inefficient version of EhCache's BlockingCache decorator. It sets a lock over a cache key when the element is not found in cache. This way, other threads will wait until this element is filled instead of hitting the database.

By its nature, this implementation can cause deadlock when used incorrectly.

Author:

Eduardo Macarron

Constructor Summary

Constructors

Constructor	Description
BlockingCache(Cache delegate)

Method Summary

Modifier and Type	Method	Description
void	clear()	Clears this cache instance.
String	getId()
Object	getObject(Object key)
int	getSize()	Optional.
long	getTimeout()
void	putObject(Object key, Object value)
Object	removeObject(Object key)	As of 3.3.0 this method is only called during a rollback for any previous value that was missing in the cache.
void	setTimeout(long timeout)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.ibatis.cache.Cache

getReadWriteLock

Constructor Details

BlockingCache

public BlockingCache(Cache delegate)

Method Details

getId

public String getId()

Specified by:

getId in interface Cache

Returns:

The identifier of this cache

getSize

public int getSize()

Description copied from interface: Cache

Optional. This method is not called by the core.

Specified by:

getSize in interface Cache

Returns:

The number of elements stored in the cache (not its capacity).

putObject

public void putObject(Object key,
 Object value)

Specified by:

putObject in interface Cache

Parameters:

key - Can be any object but usually it is a CacheKey

value - The result of a select.

getObject

public Object getObject(Object key)

Specified by:

getObject in interface Cache

Parameters:

key - The key

Returns:

The object stored in the cache.

removeObject

public Object removeObject(Object key)

Description copied from interface: Cache

As of 3.3.0 this method is only called during a rollback for any previous value that was missing in the cache. This lets any blocking cache to release the lock that may have previously put on the key. A blocking cache puts a lock when a value is null and releases it when the value is back again. This way other threads will wait for the value to be available instead of hitting the database.

Specified by:

removeObject in interface Cache

Parameters:

key - The key

Returns:

Not used

clear

public void clear()

Description copied from interface: Cache

Clears this cache instance.

Specified by:

clear in interface Cache

getTimeout

public long getTimeout()

setTimeout

public void setTimeout(long timeout)