public SharedIteratorSQLDataProviderDecorator(SQLDataProvider<T> sqlDataProvider,long timeToLive){
  _sqlDataProvider=sqlDataProvider;
  _timeToLive=timeToLive;
  _queryToSources=new ConcurrentHashMap<SQLQuery<T>,SharedDataIteratorSource<T>>();
  _sourcesToQuery=new ConcurrentHashMap<SharedDataIteratorSource<T>,SQLQuery<T>>();
}

public SharedIteratorSQLDataProviderDecorator ( SQLDataProvider < T > sqlDataProvider , long timeToLive ) { _sqlDataProvider = sqlDataProvider ; _timeToLive = timeToLive ; _queryToSources = new ConcurrentHashMap < SQLQuery < T > , SharedDataIteratorSource < T > > ( ) ; _sourcesToQuery = new ConcurrentHashMap < SharedDataIteratorSource < T > , SQLQuery < T > > ( ) ; }
create a new instance
