[GitHub] nwangtw commented on issue #3040: Nwang/refactor grouping

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nwangtw commented on issue #3040: Nwang/refactor grouping
URL: https://github.com/apache/incubator-heron/pull/3040#issuecomment-427527427
 
 
   Thanks for reviewing!
   
   Sure thing to explain a bit more:
   
   Firstly, in order to support custom operator, we need to pass in the operator object as well as specifying the grouping strategy.
   
   Currently, the implementation of Streamlet classes are like:
   
   bldr.setBolt(getName(), new FlatMapOperator<R, T>(flatMapFn),
           getNumPartitions()).shuffleGrouping(parent.getName());
   
   
   You can say the grouping is a function call with the parent name. It is ok for predefined operators because the grouping is likely to be decided, but this is tricky for custom operators (and there might be new operators that allow users to specify grouping strategy in future).
   
   One way is to pass an enum, but this is not flexible.
   
   
   

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