org.apache.flink.runtime.operators.util

Interface JoinTaskIterator<V1,V2,O>

All Known Implementing Classes:

AbstractMergeInnerJoinIterator, AbstractMergeIterator, AbstractMergeOuterJoinIterator, NonReusingBuildFirstHashJoinIterator, NonReusingBuildFirstReOpenableHashJoinIterator, NonReusingBuildSecondHashJoinIterator, NonReusingBuildSecondReOpenableHashJoinIterator, NonReusingMergeInnerJoinIterator, NonReusingMergeOuterJoinIterator, ReusingBuildFirstHashJoinIterator, ReusingBuildFirstReOpenableHashJoinIterator, ReusingBuildSecondHashJoinIterator, ReusingBuildSecondReOpenableHashJoinIterator, ReusingMergeInnerJoinIterator, ReusingMergeOuterJoinIterator

public interface JoinTaskIterator<V1,V2,O>

Interface of an iterator that performs the logic of a match task. The iterator follows the open/next/close principle. The next logic here calls the match stub with all value pairs that share the same key.

Method Summary

Modifier and Type	Method and Description
void	abort() Aborts the matching process.
boolean	callWithNextKey(FlatJoinFunction<V1,V2,O> matchFunction, Collector<O> collector) Moves the internal pointer to the next key that both inputs share.
void	close() General-purpose close method.
void	open() General-purpose open method.

Method Detail

open

void open()
   throws IOException,
          MemoryAllocationException,
          InterruptedException

General-purpose open method. Initializes the internal strategy (for example triggers the sorting of the inputs or starts building hash tables).

Throws:

IOException - Thrown, if an I/O error occurred while preparing the data. An example is a failing external sort.

MemoryAllocationException - Thrown, if the internal strategy could not allocate the memory it needs.

InterruptedException - Thrown, if the thread was interrupted during the initialization process.

close

void close()

General-purpose close method. Works after the principle of best effort. The internal structures are released, but errors that occur on the way are not reported.

callWithNextKey

boolean callWithNextKey(FlatJoinFunction<V1,V2,O> matchFunction,
                        Collector<O> collector)
                 throws Exception

Moves the internal pointer to the next key that both inputs share. It calls the match stub with the cross product of all values that share the same key.

Parameters:

matchFunction - The match stub containing the match function which is called with the keys.

collector - The collector to pass the match function.

Returns:

True, if a next key exists, false if no more keys exist.

Throws:

Exception - Exceptions from the user code are forwarded.

abort

void abort()

Aborts the matching process. This extra abort method is supplied, because a significant time may pass while calling the match stub with the cross product of all values that share the same key. A call to this abort method signals an interrupt to that procedure.