org.apache.flink.api.java.operators.translation

Class RichCombineToGroupCombineWrapper<IN,OUT,F extends RichGroupReduceFunction<IN,OUT> & CombineFunction<IN,IN>>

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.api.common.functions.RichGroupCombineFunction<IN,IN>

org.apache.flink.api.java.operators.translation.RichCombineToGroupCombineWrapper<IN,OUT,F>

All Implemented Interfaces:

Serializable, Function, GroupCombineFunction<IN,IN>, GroupReduceFunction<IN,OUT>, RichFunction

public class RichCombineToGroupCombineWrapper<IN,OUT,F extends RichGroupReduceFunction<IN,OUT> & CombineFunction<IN,IN>>
extends RichGroupCombineFunction<IN,IN>
implements GroupReduceFunction<IN,OUT>

A wrapper the wraps a function that implements both CombineFunction and GroupReduceFunction interfaces and makes it look like a function that implements GroupCombineFunction and GroupReduceFunction to the runtime.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
RichCombineToGroupCombineWrapper(F wrappedFunction)

Method Summary

Modifier and Type	Method and Description
void	combine(Iterable<IN> values, Collector<IN> out) The combine method, called (potentially multiple timed) with subgroups of elements.
void	open(OpenContext openContext) Initialization method for the function.
void	reduce(Iterable<IN> values, Collector<OUT> out) The reduce method.

Methods inherited from class org.apache.flink.api.common.functions.AbstractRichFunction

close, getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RichCombineToGroupCombineWrapper

public RichCombineToGroupCombineWrapper(F wrappedFunction)

Method Detail

open

public void open(OpenContext openContext)
          throws Exception

Description copied from interface: RichFunction

Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

The openContext object passed to the function can be used for configuration and initialization. The openContext contains some necessary information that were configured on the function in the program composition.

 public class MyFilter extends RichFilterFunction<String> {

     private String searchString;

     public void open(OpenContext openContext) {
         // initialize the value of searchString
     }

     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
 

Specified by:

open in interface RichFunction

Overrides:

open in class AbstractRichFunction

Parameters:

openContext - The context containing information about the context in which the function is opened.

Throws:

Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the task and lets the fail-over logic decide whether to retry the task execution.

combine

public void combine(Iterable<IN> values,
                    Collector<IN> out)
             throws Exception

Description copied from interface: GroupCombineFunction

The combine method, called (potentially multiple timed) with subgroups of elements.

Specified by:

combine in interface GroupCombineFunction<IN,IN>

Specified by:

combine in class RichGroupCombineFunction<IN,IN>

Parameters:

values - The elements to be combined.

out - The collector to use to return values from the function.

Throws:

Exception - The function may throw Exceptions, which will cause the program to cancel, and may trigger the recovery logic.

reduce

public void reduce(Iterable<IN> values,
                   Collector<OUT> out)
            throws Exception

Description copied from interface: GroupReduceFunction

The reduce method. The function receives one call per group of elements.

Specified by:

reduce in interface GroupReduceFunction<IN,OUT>

Parameters:

values - All records that belong to the given input key.

out - The collector to hand results to.

Throws:

Exception - This method may throw exceptions. Throwing an exception will cause the operation to fail and may trigger recovery.