Adding hibernate-memcached to your applicationIf 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... Configuring HibernateThe 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 SettingsThe cache wide settings all have defaults can mostly be overwritten at a cache-region level. | 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 region 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.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.NATIVE_HASH | Which hash algorithm to use when adding items to the cache. Prior to hibernate-memcached 1.2 this defaulted to HashAlgorithm.KETAMA_HASH | | hibernate.memcached.connectionFactory (since 1.2) | DefaultConnectionFactory | The "simple" name of the ConnectionFactory class to use from spymemcached. Must be one of DefaultConnectionFactory, KetamaConnectionFactory, or BinaryConnectionFactory | | 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. |
Cache Region SettingsCache region 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. Note: that the square brackets are there to denote the text you need to replace, they are not part of the property name. | Property | Default | Description | | hibernate.memcached.YOUR_REGION_NAME.cacheTimeSeconds | none, see hibernate.memcached.cacheTimeSeconds | Set the cache time for this cache region, overriding the cache-wide setting. | | hibernate.memcached.YOUR_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.YOUR_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. |
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Due to limitations in the JVM implementation of Enum.hashCode(), it is recommended that no keyed class rely on Enum.hashCode(). Instead, use Enum.name().hashCode instead, as in:
class MyClass { private String mVar1; private MyEnum mVar2; public int hashCode() { int result = mVar1.hashCode(); result = result + 31 * mVar2.name().hashCode(); return result; } }