[IBATIS-761] ScheduledCache weakness

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 3.0 Beta 7
• Fix Version/s: 3.0 Beta 8
• Component/s: Core
• Assignee: Unassigned
• Reporter: Eric Vantillard
• Created: 11/Mar/10 12:56
• Updated: 11/Mar/10 13:18
• Resolved: 11/Mar/10 13:18

Description

Some times we have a NullPointerException :

java.lang.NullPointerException
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:38)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:61)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:18)

The problem is related to the ScheduledCache cleaning.

In method query of CachingExecutor class we have :

[...]
            if (cache.hasKey(key)) {
              return (List) cache.getObject(key);
            } else {
[...]
            } 

both methods cache.hasKey() and cache.getObject() of class org.apache.ibatis.cache.decorators.ScheduledCache are checking the cleaning interval by calling {{clearWhenStale()}.

Problem arrive when the timeout occur after the call to cache.hasKey()} but BEFORE the call to {{cache.getObject().

To reproduce the case, define a cache of type LRU with a small flushInterval (for exemple 10ms) and loop on a simple select query.