Yes Clinton, is just for performance.
2010/1/1 Clinton Begin <clinton.be...@gmail.com> > What problem are you trying to solve, or goal you're trying to achieve by > doing this? Is it strictly a performance consideration? > > Clinton > > > > On Fri, Jan 1, 2010 at 7:31 AM, Eduardo Macarron < > eduardo.macar...@gmail.com> wrote: > >> Fist of all happy new year! >> >> Some work has been doing on Spring 3 and Ibatis 3 integration. >> >> Having a look at mappers internals we saw that a new MapperMethod is >> created (with some introspection work) on each call to a mapper method. I >> wonder if it would be better to build them all during startup or maybe cache >> them somehow. >> >> this is the Jira issue (http://jira.springframework.org/browse/SPR-5991) >> Grabriel Axel posted it here some months ago (he opened the issue) >> >> The main problem with this task is that MapperMethods are not thread safe >> and that they hold an SqlSession. Enabling cache would require to make some >> changes to MapperMethods. SqlSession should be passed as an argument to >> execute instead to its constructor. >> >> public MapperMethod(Method method, Configuration configuration) { >> paramNames = new ArrayList<String>(); >> paramPositions = new ArrayList<Integer>(); >> ... >> >> public Object execute(Object[] args, SqlSession sqlSession) { >> Object result; >> if (SqlCommandType.INSERT == type) { >> ... >> >> And MapperProxy >> >> public Object invoke(Object proxy, Method method, Object[] args) throws >> Throwable { >> return new MapperMethod(method, >> sqlSession.getConfiguration()).execute(args, sqlSession); >> } >> >> >> So for example Spring could have this code to use directly injected >> Mappers where SqlSession is got from spring's transaction context. >> >> private Map<Method, MapperMethod> mapperMethods = new >> ConcurrentHashMap<Method, MapperMethod>(); >> >> public <T> T getMapper(final Class<T> type) { >> // mimic iBATIS MapperProxy >> return (T) >> java.lang.reflect.Proxy.newProxyInstance(type.getClassLoader(), new Class[] >> { type }, >> new InvocationHandler() { >> @Override >> public Object invoke(final Object proxy, final Method >> method, final Object[] args) throws Throwable { >> return execute(new SqlSessionCallback<T>() { >> @Override >> public T doInSqlSession(SqlSession sqlSession) >> throws SQLException { >> // mimic iBATIS MapperProxy >> Class<?> type = method.getDeclaringClass(); >> if >> (!sqlSession.getConfiguration().hasMapper(type)) { >> throw new BindingException("Type " + type >> + " is not known to the MapperRegistry."); >> } >> >> MapperMethod mm = mapperMethods.get(method); >> if (mm == null) { >> mm = new MapperMethod(method, >> sqlSession.getConfiguration()); >> mapperMethods.put(method, mm); >> } else { >> logger.debug("Returning a cached >> mapper method"); >> } >> >> return (T) mm.execute(args, sqlSession); >> } >> }); >> } >> }); >> } >> >> Or maybe avoid using directly MapperMethods and access to them thought the >> "standard" api SqlSession.getConfiguration().getMapper(impl, sesion) but in >> that case caching should be done inside. >> >> what do you think about this? >> >> >> >
