Optimize cache structure

[zz-zhi54]

Question?

When I read the source code of mybatis recently,Discover the occurrence attribute of mapper ->cache And type,
Cache is used . However, evaluation is an elimination strategy. A cache is required in the construction method,
such as

public FifoCache(Cache delegate)

My idea is to add a layer of baseCache to the middle of the cache.
eviction:
Add a method to verify the existence of the cache and a method to set the cache when creating the cache of the evaluation Or use the construction method

Then it is divided into real cache and occurrence cache.
I don't know whether this direction is feasible. If so, I would be happy to submit pull requests

MyBatis version

3.x.x

[harawata]

Hello @poo0054 ,

I couldn't follow your explanation.
What are the "real cache" and "occurrence cache"?
And how does dividing those caches help MyBatis users?

Please show us some example code before and after the change so that we can understand the benefit of your proposal.

[zz-zhi54]

For example, the data actually cached in FifoCache is the attribute delegate, and the data is actually cached in PerpetualCache. At the beginning, I could not accurately distinguish between the two. The correct writing should be, but I wrote.

My idea is to add abstract classes between the occurrence type and the type type to distinguish the differences between them

Error parsing Mapper XML. The XML location is 'resources/mapper/TableAttributeDao.xml'. Cause: org.apache.ibatis.cache.CacheException: Invalid base cache implementation (class org.apache.ibatis.cache.decorators.FifoCache). Base cache implementations must have a constructor that takes a String id as a parameter. Cause: java.lang.NoSuchMethodException: org.apache.ibatis.cache.decorators.FifoCache.(java.lang.String)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:120)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.parse(XMLMapperBuilder.java:86)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.mapperElement(XMLConfigBuilder.java:380)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:117)
... 31 more
Caused by: org.apache.ibatis.cache.CacheException: Invalid base cache implementation (class org.apache.ibatis.cache.decorators.FifoCache). Base cache implementations must have a constructor that takes a String id as a parameter. Cause: java.lang.NoSuchMethodException: org.apache.ibatis.cache.decorators.FifoCache.(java.lang.String)
at org.apache.ibatis.mapping.CacheBuilder.getBaseCacheConstructor(CacheBuilder.java:202)
at org.apache.ibatis.mapping.CacheBuilder.newBaseCacheInstance(CacheBuilder.java:190)
at org.apache.ibatis.mapping.CacheBuilder.build(CacheBuilder.java:94)
at org.apache.ibatis.builder.MapperBuilderAssistant.useNewCache(MapperBuilderAssistant.java:119)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.cacheElement(XMLMapperBuilder.java:219)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:112)
... 34 more
Caused by: java.lang.NoSuchMethodException: org.apache.ibatis.cache.decorators.FifoCache.(java.lang.String)