hibernate-memcached补丁：支持Whalin的MemCached Java客户端

hibernate-memcached（http://code.google.com/p/hibernate-memcached/ ）是允许hibernate使用MemCached作为二级缓存的项目，它用到了spymemcached（http://code.google.com/p/spymemcached/ ）这个MemCached的Java客户端。花了一点时间做了个补丁，让它也支持Whalin的Java客户端（http://whalin.com/memcached/ ）。

所有的代码（包括原hibernate-memcached的所有源码）、javadoc及重新制作的发布包请见附件，限于篇幅就不具体说明了。以下是我更新过的hibernate-memcached的配置说明，原配置说明请参见http://code.google.com/p/hibernate-memcached/wiki/Configuration

 

Adding hibernate-memcached to your application

If you are using Maven2 for your application build you can follow the instructions on the MavenRepository page. For those that aren't using Maven2 you'll need to collect a few simple jars for yourself. I am going to assume you already have hibenrnate3 setup before you came here.

You'll need...

• hibernate-memcached-<version>.jar
• commons-codec 1.3
• slf4j-1.5.0.jar
• An slf4j implementation for your preferred logging framework. For log4j you can use slf4j-log4j12-1.5.0.jar .

If you are using spymemcached as the MemCached client, you also need

• memcached-2.1.jar
• spy-2.4.jar

or if you prefer Whalin's memcached client for java , you need to download java_memcached-release_2.0.1.jar from the download page according to your Java VM version.

Configuring Hibernate

The first thing to do is to tell hibernate which cache provider you'd like to use, and to enable the second level cache.

hibernate.cache.provider_class

com.googlecode.hibernate.memcached.MemcachedCacheProvider

Using just the property above you get basic entity caching by default. The hibernate-memcached library supports query caching, but you have to enable query caching separately.

hibernate.cache.use_query_cache

true

!Now you can start setting up the hibernate-memcached specific properties. The hibernate-memcached properties are divided into two categories; cache-wide settings and cache-region settings.

Cache Wide Settings

The cache wide settings all have defaults can mostly be overwritten at a cache-region level. For both spymemcached and Whalin's client, you can set:

Property	Default	Description
hibernate.memcached.servers	localhost:11211	Space delimited list of memcached instances in host:port format
hibernate.memcached.cacheTimeSeconds	300	The default number of seconds items should be cached. Can be overriden at the regon level.
hibernate.memcached.keyStrategy	HashCodeKeyStrategy	Sets the strategy class to to use for generating cache keys. Must provide a class name that implements KeyStrategy
hibernate.memcached.clearSupported	false	Enables support for the MemcachedCache.clear() method for all cache regions. The way clear is implemented for memcached is expensive and adds overhead to all get/set operations. It is not recommended for production use.

For spymemcached, you can set:

hibernate.memcached.readBufferSize	DefaultConnectionFactory.DEFAULT_READ_BUFFER_SIZE	The read buffer size for each server connection from this factory
hibernate.memcached.operationQueueLength	DefaultConnectionFactory.DEFAULT_OP_QUEUE_LEN	Maximum length of the operation queue returned by this connection factory
hibernate.memcached.operationTimeout	DefaultConnectionFactory.DEFAULT_OPERATION_TIMEOUT	Default operation timeout in milliseconds
hibernate.memcached.hashAlgorithm	HashAlgorithm.KETAMA_HASH	Which hash algorithm to use when adding items to the cache. Note: the MemcachedClient defaults to using HashAlgorithm.NATIVE_HASH, while the hibernate-memcached cache defaults to KETAMA_HASH for "consistent hashing"

For Whalin's client, you can set:

hibernate.memcached.weights		Space delimited list of server weights. If not set, all servers get the same weight
hibernate.memcached.errorHandler	com.googlecode.hibernate.memcached. dangamemcached.SimpleErrorHandler	Error handler used by Whalin's client internally
hibernate.memcached.poolName	default	The name of SockIOPool
hibernate.memcached.initConn	1	Initial pool size
hibernate.memcached.minConn	1	Min pool size
hibernate.memcached.maxConn	10	Max pool size
hibernate.memcached.maxIdle	3000000	Max idle time for available sockets. Default 5 minutes
hibernate.memcached.socketTimeout	30000	Default timeout of socket reads. Default 30 seconds
hibernate.memcached.socketConnectTimeout	3000	Default timeout of socket connections. Default 3 seconds
hibernate.memcached.maintSleep	30000	Maintenance thread sleep time. Default 30 seconds
hibernate.memcached.compressEnable	true	If compression enabled
hibernate.memcached.defaultEncoding	UTF-8	Default encoding

Cache Region Settings

Cache regon properties are set by giving your cached data a "region name" in hibernate. You can tune the MemcachedCache instance for your region using the following properties. These properties essentially override the cache-wide properties above.

Property	Default	Description
hibernate.memcached.[region-name].cacheTimeSeconds	none, see hibernate.memcached.cacheTimeSeconds	Set the cache time for this cache region, overriding the cache-wide setting.
hibernate.memcached.[region-name].keyStrategy	none, see hibernate.memcached.keyStrategy	Overrides the strategy class to to use for generating cache keys in this cache region. Must provide a class name that implements KeyStrategy
hibernate.memcached.[region-name].clearSupported	none, see hibernate.memcached.clearSupported	Enables clear() operations for this cache region only. Again, the clear operation incurs cost on every get/set operation.