| /* |
| * 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.db.rows; |
| |
| import org.apache.cassandra.utils.AbstractIterator; |
| |
| import org.apache.cassandra.config.CFMetaData; |
| import org.apache.cassandra.db.*; |
| |
| /** |
| * Abstract class to create UnfilteredRowIterator that lazily initialize themselves. |
| * |
| * This is used during partition range queries when we know the partition key but want |
| * to defer the initialization of the rest of the UnfilteredRowIterator until we need those informations. |
| * See {@link org.apache.cassandra.io.sstable.format.big.BigTableScanner#KeyScanningIterator} for instance. |
| */ |
| public abstract class LazilyInitializedUnfilteredRowIterator extends AbstractIterator<Unfiltered> implements UnfilteredRowIterator |
| { |
| private final DecoratedKey partitionKey; |
| |
| private UnfilteredRowIterator iterator; |
| |
| public LazilyInitializedUnfilteredRowIterator(DecoratedKey partitionKey) |
| { |
| this.partitionKey = partitionKey; |
| } |
| |
| protected abstract UnfilteredRowIterator initializeIterator(); |
| |
| protected void maybeInit() |
| { |
| if (iterator == null) |
| iterator = initializeIterator(); |
| } |
| |
| public boolean initialized() |
| { |
| return iterator != null; |
| } |
| |
| public CFMetaData metadata() |
| { |
| maybeInit(); |
| return iterator.metadata(); |
| } |
| |
| public PartitionColumns columns() |
| { |
| maybeInit(); |
| return iterator.columns(); |
| } |
| |
| public boolean isReverseOrder() |
| { |
| maybeInit(); |
| return iterator.isReverseOrder(); |
| } |
| |
| public DecoratedKey partitionKey() |
| { |
| return partitionKey; |
| } |
| |
| public DeletionTime partitionLevelDeletion() |
| { |
| maybeInit(); |
| return iterator.partitionLevelDeletion(); |
| } |
| |
| public Row staticRow() |
| { |
| maybeInit(); |
| return iterator.staticRow(); |
| } |
| |
| public EncodingStats stats() |
| { |
| maybeInit(); |
| return iterator.stats(); |
| } |
| |
| protected Unfiltered computeNext() |
| { |
| maybeInit(); |
| return iterator.hasNext() ? iterator.next() : endOfData(); |
| } |
| |
| public void close() |
| { |
| if (iterator != null) |
| iterator.close(); |
| } |
| } |