/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.cassandra.io.sstable; import java.util.ArrayList; import java.util.Collection; import java.util.Iterator; import org.apache.cassandra.db.DecoratedKey; import org.apache.cassandra.io.sstable.format.SSTableReader; import org.apache.cassandra.utils.CloseableIterator; import org.apache.cassandra.utils.IMergeIterator; import org.apache.cassandra.utils.MergeIterator; /** * Caller must acquire and release references to the sstables used here. */ public class ReducingKeyIterator implements CloseableIterator<DecoratedKey> { private final ArrayList<KeyIterator> iters; private IMergeIterator<DecoratedKey,DecoratedKey> mi; public ReducingKeyIterator(Collection<SSTableReader> sstables) { iters = new ArrayList<>(sstables.size()); for (SSTableReader sstable : sstables) iters.add(new KeyIterator(sstable.descriptor, sstable.metadata())); } private void maybeInit() { if (mi == null) { mi = MergeIterator.get(iters, DecoratedKey.comparator, new MergeIterator.Reducer<DecoratedKey,DecoratedKey>() { DecoratedKey reduced = null; @Override public boolean trivialReduceIsTrivial() { return true; } public void reduce(int idx, DecoratedKey current) { reduced = current; } protected DecoratedKey getReduced() { return reduced; } }); } } public void close() { if (mi != null) mi.close(); } public long getTotalBytes() { maybeInit(); long m = 0; for (Iterator<DecoratedKey> iter : mi.iterators()) { m += ((KeyIterator) iter).getTotalBytes(); } return m; } public long getBytesRead() { maybeInit(); long m = 0; for (Iterator<DecoratedKey> iter : mi.iterators()) { m += ((KeyIterator) iter).getBytesRead(); } return m; } public boolean hasNext() { maybeInit(); return mi.hasNext(); } public DecoratedKey next() { maybeInit(); return mi.next(); } public void remove() { throw new UnsupportedOperationException(); } }