MethodCache.md

The method caching in JetCache is similar like Spring Cache. JetCache provide naitve TTL support and two level cache support.

Add @Cached on a method of a Spring bean to enable method caching. Since 2.4 @CacheUpdate and @CacheInvalidate are introduced for removing and updating method cache. You can even add the annotation on the interface that the bean implements.

public interface UserService {
    @Cached(name="userCache.", key="#userId", expire = 3600)
    User getUserById(long userId);

    @CacheUpdate(name="userCache.", key="#user.userId", value="#user")
    void updateUser(User user);

    @CacheInvalidate(name="userCache.", key="#userId")
    void deleteUser(long userId);
}

the key and value attribute use SpEL script. To enable use parameter name such as key="#userId", you javac compiler target must be 1.8 and the -parameters should be set, otherwise use index to access parameters like key="args[0]".

The attributes of @Cached are similar with @CreateCache except @Cached has more attributes:

attribute	default value	description
area	“default”	If you want to use multi backend cache system, you can setup multi "cache area" in configuration, this attribute specifies the name of the "cache area" you want to use.
name	undefined	The unique name of this Cache instance in an area, optional. If you do not specify, JetCache will auto generate one. The name is used to display statistics information and as part of key prefix when using a remote cache.
key	undefined	use SpEL script to specify the key. If not specified, JetCache will auto generate one using all method parameters.
expire	undefined	The expire time. Use global config if the attribute value is absent, and if the global config is not defined either, use infinity instead.
timeUnit	TimeUnit.SECONDS	Specify the time unit of expire
cacheType	CacheType.REMOTE	Type of the Cache instance. May be CacheType.REMOTE, CacheType.LOCAL, CacheType.BOTH. Create a two level cache (local+remote) when value is CacheType.BOTH.
localLimit	undefined	Specify max elements in local memory when cacheType is CacheType.LOCAL or CacheType.BOTH. Use global config if the attribute value is absent, and if the global config is not defined either, use 100 instead.
localExpire	undefined	Only use with cacheType=CacheType.BOTH, specify a different local expire (typically less than expire) for local cache
serialPolicy	undefined	Specify the serialization policy of remote cache when cacheType is CacheType.REMOTE or CacheType.BOTH. The JetCache build-in serialPolicy are SerialPolicy.JAVA or SerialPolicy.KRYO. Use global config if the attribute value is absent, and if the global config is not defined either, use SerialPolicy.JAVA instead.
keyConvertor	undefined	Specify the key convertor. Used to convert the complex key object. The JetCache build-in keyConvertor are KeyConvertor.FASTJSON or KeyConvertor.NONE. NONE indicate do not convert, FASTJSON will use fastjson to convert key object to a string. Use global config if the attribute value is absent.
enabled	true	Specify whether the method caching is enabled. If set to false, you can enable it in thread context using CacheContext.enableCache(Supplier<T> callback)
cacheNullValue	false	Specify whether a null value should be cached.
condition	undefined	Expression script used for conditioning the method caching, the cache is not used when evaluation result is false. Can't refer return value of real method.
postCondition	undefined	Expression script used for conditioning the method cache updating, the cache updating action is vetoed when the evaluation result is false. Evaluation occurs after real method invocation so we can refer #result in script.

@CacheInvalidate attribute table:

attribute	default value	description
area	“default”	If you want to use multi backend cache system, you can setup multi "cache area" in configuration, this attribute specifies the name of the "cache area" you want to use.
name	undefined	The unique name of this Cache instance in an area. refer to name of @Cached.
key	undefined	use SpEL script to specify the key.
condition	undefined	Expression script used for conditioning the cache operation, the operation is vetoed when evaluation result is false. Evaluation occurs after real method invocation so we can refer #result in script.

@CacheUpdate attribute table:

attribute	default value	description
area	“default”	If you want to use multi backend cache system, you can setup multi "cache area" in configuration, this attribute specifies the name of the "cache area" you want to use.
name	undefined	The unique name of this Cache instance in an area. refer to name of @Cached.
key	undefined	use SpEL script to specify the key.
value	undefined	use SpEL script to specify the value.
condition	undefined	Expression script used for conditioning the cache operation, the operation is vetoed when evaluation result is false. Evaluation occurs after real method invocation so we can refer #result in script.

Note that remote cache operation related to @CacheUpdate and @CacheInvalidate may fail, so it is important to set the '''expire''' attribute.

@CacheRefresh attribute table:

attribute	default value	description
refresh	undefined	interval of refreshment
timeUnit	TimeUnit.SECONDS	time unit
stopRefreshAfterLastAccess	undefined	if specified, refresh action will stop if the associated key is not accessed after specified time unit
refreshLockTimeout	60 seconds	the distributed lock timeout when cacheType is REMOTE or BOTH

@CachePenetrationProtect:

This annotation used to synchronize concurrent cache loading operation. Currently it only take effect only in each single JVM, that is, in one JVM there is only one thread load for same key, other threads wait for the result.

There are some attributes in the above table has no default value. JetCache will use global config when you not specify the value in annotation. See Configuration details for more information about global config.