| /* |
| * 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; |
| |
| import java.util.NoSuchElementException; |
| |
| import org.apache.cassandra.config.CFMetaData; |
| import org.apache.cassandra.db.partitions.BasePartitionIterator; |
| import org.apache.cassandra.db.partitions.PartitionIterator; |
| import org.apache.cassandra.db.partitions.UnfilteredPartitionIterator; |
| import org.apache.cassandra.db.rows.*; |
| |
| public class EmptyIterators |
| { |
| |
| private static class EmptyBasePartitionIterator<R extends BaseRowIterator<?>> implements BasePartitionIterator<R> |
| { |
| EmptyBasePartitionIterator() |
| { |
| } |
| |
| public void close() |
| { |
| } |
| |
| public boolean hasNext() |
| { |
| return false; |
| } |
| |
| public R next() |
| { |
| throw new NoSuchElementException(); |
| } |
| } |
| |
| private static class EmptyUnfilteredPartitionIterator extends EmptyBasePartitionIterator<UnfilteredRowIterator> implements UnfilteredPartitionIterator |
| { |
| final CFMetaData metadata; |
| final boolean isForThrift; |
| |
| public EmptyUnfilteredPartitionIterator(CFMetaData metadata, boolean isForThrift) |
| { |
| this.metadata = metadata; |
| this.isForThrift = isForThrift; |
| } |
| |
| public boolean isForThrift() |
| { |
| return isForThrift; |
| } |
| |
| public CFMetaData metadata() |
| { |
| return metadata; |
| } |
| } |
| |
| private static class EmptyPartitionIterator extends EmptyBasePartitionIterator<RowIterator> implements PartitionIterator |
| { |
| public static final EmptyPartitionIterator instance = new EmptyPartitionIterator(); |
| private EmptyPartitionIterator() |
| { |
| super(); |
| } |
| } |
| |
| private static class EmptyBaseRowIterator<U extends Unfiltered> implements BaseRowIterator<U> |
| { |
| final PartitionColumns columns; |
| final CFMetaData metadata; |
| final DecoratedKey partitionKey; |
| final boolean isReverseOrder; |
| final Row staticRow; |
| |
| EmptyBaseRowIterator(PartitionColumns columns, CFMetaData metadata, DecoratedKey partitionKey, boolean isReverseOrder, Row staticRow) |
| { |
| this.columns = columns; |
| this.metadata = metadata; |
| this.partitionKey = partitionKey; |
| this.isReverseOrder = isReverseOrder; |
| this.staticRow = staticRow; |
| } |
| |
| public CFMetaData metadata() |
| { |
| return metadata; |
| } |
| |
| public boolean isReverseOrder() |
| { |
| return isReverseOrder; |
| } |
| |
| public PartitionColumns columns() |
| { |
| return columns; |
| } |
| |
| public DecoratedKey partitionKey() |
| { |
| return partitionKey; |
| } |
| |
| public Row staticRow() |
| { |
| return staticRow; |
| } |
| |
| public void close() |
| { |
| } |
| |
| public boolean isEmpty() |
| { |
| return staticRow == Rows.EMPTY_STATIC_ROW; |
| } |
| |
| public boolean hasNext() |
| { |
| return false; |
| } |
| |
| public U next() |
| { |
| throw new NoSuchElementException(); |
| } |
| } |
| |
| private static class EmptyUnfilteredRowIterator extends EmptyBaseRowIterator<Unfiltered> implements UnfilteredRowIterator |
| { |
| final DeletionTime partitionLevelDeletion; |
| public EmptyUnfilteredRowIterator(PartitionColumns columns, CFMetaData metadata, DecoratedKey partitionKey, |
| boolean isReverseOrder, Row staticRow, DeletionTime partitionLevelDeletion) |
| { |
| super(columns, metadata, partitionKey, isReverseOrder, staticRow); |
| this.partitionLevelDeletion = partitionLevelDeletion; |
| } |
| |
| public boolean isEmpty() |
| { |
| return partitionLevelDeletion == DeletionTime.LIVE && super.isEmpty(); |
| } |
| |
| public DeletionTime partitionLevelDeletion() |
| { |
| return partitionLevelDeletion; |
| } |
| |
| public EncodingStats stats() |
| { |
| return EncodingStats.NO_STATS; |
| } |
| } |
| |
| private static class EmptyRowIterator extends EmptyBaseRowIterator<Row> implements RowIterator |
| { |
| public EmptyRowIterator(CFMetaData metadata, DecoratedKey partitionKey, boolean isReverseOrder, Row staticRow) |
| { |
| super(PartitionColumns.NONE, metadata, partitionKey, isReverseOrder, staticRow); |
| } |
| } |
| |
| public static UnfilteredPartitionIterator unfilteredPartition(CFMetaData metadata, boolean isForThrift) |
| { |
| return new EmptyUnfilteredPartitionIterator(metadata, isForThrift); |
| } |
| |
| public static PartitionIterator partition() |
| { |
| return EmptyPartitionIterator.instance; |
| } |
| |
| // this method is the only one that can return a non-empty iterator, but it still has no rows, so it seems cleanest to keep it here |
| public static UnfilteredRowIterator unfilteredRow(CFMetaData metadata, DecoratedKey partitionKey, boolean isReverseOrder, Row staticRow, DeletionTime partitionDeletion) |
| { |
| PartitionColumns columns = PartitionColumns.NONE; |
| if (!staticRow.isEmpty()) |
| columns = new PartitionColumns(Columns.from(staticRow.columns()), Columns.NONE); |
| else |
| staticRow = Rows.EMPTY_STATIC_ROW; |
| |
| if (partitionDeletion.isLive()) |
| partitionDeletion = DeletionTime.LIVE; |
| |
| return new EmptyUnfilteredRowIterator(columns, metadata, partitionKey, isReverseOrder, staticRow, partitionDeletion); |
| } |
| |
| public static UnfilteredRowIterator unfilteredRow(CFMetaData metadata, DecoratedKey partitionKey, boolean isReverseOrder) |
| { |
| return new EmptyUnfilteredRowIterator(PartitionColumns.NONE, metadata, partitionKey, isReverseOrder, Rows.EMPTY_STATIC_ROW, DeletionTime.LIVE); |
| } |
| |
| public static RowIterator row(CFMetaData metadata, DecoratedKey partitionKey, boolean isReverseOrder) |
| { |
| return new EmptyRowIterator(metadata, partitionKey, isReverseOrder, Rows.EMPTY_STATIC_ROW); |
| } |
| } |