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/*-
* Copyright (C) 2011, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This file was distributed by Oracle as part of a version of Oracle NoSQL
* Database made available at:
*
* http://www.oracle.com/technetwork/database/database-technologies/nosqldb/downloads/index.html
*
* Please see the LICENSE file included in the top-level directory of the
* appropriate version of Oracle NoSQL Database for a copy of the license and
* additional information.
*/
package oracle.kv;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.concurrent.TimeUnit;
import oracle.kv.stats.DetailedMetrics;
/**
* Interface to the specialized Iterator type returned by the {@link
* KVStore#storeIterator(Direction, int, Key, KeyRange, Depth, Consistency, long,
* TimeUnit, StoreIteratorConfig) Parallel Scan version} of storeIterator().
*
* This Iterator adds the ability to close (terminate) a ParallelScan as well
* gather per-partition and per-shard statistics about the scan.
*
* Iterators implementing this interface can only be used safely by one thread
* at a time unless synchronized externally.
*/
public interface ParallelScanIterator extends Iterator {
/**
* Close (terminate) a Parallel Scan. This shutdowns down all related
* threads and tasks, and awaits up to 60 seconds for threads to exit.
*/
public void close();
/**
* Gets the per-partition metrics for this Parallel Scan. This may be
* called at any time during the iteration in order to obtain metrics to
* that point or it may be called at the end to obtain metrics for the
* entire scan. If there are no metrics available yet for a particular
* partition, then there will not be an entry in the list.
*
* @return the per-partition metrics for this Parallel Scan.
*/
public List getPartitionMetrics();
/**
* Gets the per-shard metrics for this Parallel Scan. This may be called at
* any time during the iteration in order to obtain metrics to that point
* or it may be called at the end to obtain metrics for the entire scan.
* If there are no metrics available yet for a particular shard, then there
* will not be an entry in the list.
*
* @return the per-shard metrics for this Parallel Scan.
*/
public List getShardMetrics();
/**
* Returns the next element in the iteration.
*
* @return the next element in the iteration.
*
* @throws NoSuchElementException - iteration has no more elements.
*
* @throws StoreIteratorException - an exception occurred during a
* retrieval as part of a multi-record iteration method. This exception
* does not necessarily close or invalidate the iterator. Repeated calls to
* next() may or may not cause an exception to be thrown. It is incumbent
* on the caller to determine the type of exception and act accordingly.
*/
@Override
public K next();
}