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Core package for Neo4j Procedures
package apoc.index;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.BlockingQueue;
import java.util.function.BiConsumer;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;
/**
* Populate a {@link BlockingQueue} with a poison element after a stream iteration has been finished.
* Defacto a noop collector expect adding the poison in the finisher.
* @param
*/
public class QueuePoisoningCollector implements Collector {
private final BlockingQueue queue;
private final E poison;
public QueuePoisoningCollector(BlockingQueue queue, E poison) {
this.queue = queue;
this.poison = poison;
}
@Override
public Supplier supplier() {
return () -> null;
}
@Override
public BiConsumer accumulator() {
return (integer, integer2) -> {
};
}
@Override
public BinaryOperator combiner() {
return null;
}
@Override
public Function finisher() {
return integer -> {
try {
queue.put(poison);
return null;
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
};
}
@Override
public Set characteristics() {
Set characteristics = new HashSet<>();
characteristics.add(Characteristics.UNORDERED);
characteristics.add(Characteristics.CONCURRENT);
return characteristics;
}
}