| /* |
| * 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.aggregation; |
| |
| import java.nio.ByteBuffer; |
| |
| import org.apache.cassandra.cql3.selection.Selector; |
| import org.apache.cassandra.db.Clustering; |
| import org.apache.cassandra.db.ClusteringComparator; |
| import org.apache.cassandra.db.DecoratedKey; |
| import org.apache.cassandra.transport.ProtocolVersion; |
| |
| /** |
| * A <code>GroupMaker</code> can be used to determine if some sorted rows belongs to the same group or not. |
| */ |
| public abstract class GroupMaker |
| { |
| /** |
| * <code>GroupMaker</code> that groups all the rows together. |
| */ |
| public static final GroupMaker GROUP_EVERYTHING = new GroupMaker() |
| { |
| public boolean isNewGroup(DecoratedKey partitionKey, Clustering<?> clustering) |
| { |
| return false; |
| } |
| |
| public boolean returnAtLeastOneRow() |
| { |
| return true; |
| } |
| }; |
| |
| public static GroupMaker newPkPrefixGroupMaker(ClusteringComparator comparator, |
| int clusteringPrefixSize, |
| GroupingState state) |
| { |
| return new PkPrefixGroupMaker(comparator, clusteringPrefixSize, state); |
| } |
| |
| public static GroupMaker newPkPrefixGroupMaker(ClusteringComparator comparator, int clusteringPrefixSize) |
| { |
| return new PkPrefixGroupMaker(comparator, clusteringPrefixSize); |
| } |
| |
| public static GroupMaker newSelectorGroupMaker(ClusteringComparator comparator, |
| int clusteringPrefixSize, |
| Selector selector, |
| GroupingState state) |
| { |
| return new SelectorGroupMaker(comparator, clusteringPrefixSize, selector, state); |
| } |
| |
| public static GroupMaker newSelectorGroupMaker(ClusteringComparator comparator, |
| int clusteringPrefixSize, |
| Selector selector) |
| { |
| return new SelectorGroupMaker(comparator, clusteringPrefixSize, selector); |
| } |
| |
| /** |
| * Checks if a given row belongs to the same group that the previous row or not. |
| * |
| * @param partitionKey the partition key. |
| * @param clustering the row clustering key |
| * @return <code>true</code> if the row belongs to the same group that the previous one, <code>false</code> |
| * otherwise. |
| */ |
| public abstract boolean isNewGroup(DecoratedKey partitionKey, Clustering<?> clustering); |
| |
| /** |
| * Specify if at least one row must be returned. If the selection is performing some aggregations on all the rows, |
| * one row should be returned even if no records were processed. |
| * |
| * @return <code>true</code> if at least one row must be returned, <code>false</code> otherwise. |
| */ |
| public boolean returnAtLeastOneRow() |
| { |
| return false; |
| } |
| |
| private static class PkPrefixGroupMaker extends GroupMaker |
| { |
| /** |
| * The size of the clustering prefix used to make the groups |
| */ |
| protected final int clusteringPrefixSize; |
| |
| /** |
| * The comparator used to compare the clustering prefixes. |
| */ |
| protected final ClusteringComparator comparator; |
| |
| /** |
| * The last partition key seen |
| */ |
| protected ByteBuffer lastPartitionKey; |
| |
| /** |
| * The last clustering seen |
| */ |
| protected Clustering<?> lastClustering; |
| |
| public PkPrefixGroupMaker(ClusteringComparator comparator, int clusteringPrefixSize, GroupingState state) |
| { |
| this(comparator, clusteringPrefixSize); |
| this.lastPartitionKey = state.partitionKey(); |
| this.lastClustering = state.clustering; |
| } |
| |
| public PkPrefixGroupMaker(ClusteringComparator comparator, int clusteringPrefixSize) |
| { |
| this.comparator = comparator; |
| this.clusteringPrefixSize = clusteringPrefixSize; |
| } |
| |
| @Override |
| public boolean isNewGroup(DecoratedKey partitionKey, Clustering<?> clustering) |
| { |
| ByteBuffer key = partitionKey.getKey(); |
| // We are entering a new group if: |
| // - the partition key is a new one |
| // - the last clustering was not null and does not have the same prefix as the new clustering one |
| boolean isNew = !key.equals(lastPartitionKey) |
| || lastClustering == null |
| || comparator.compare(lastClustering, clustering, clusteringPrefixSize) != 0; |
| |
| lastPartitionKey = key; |
| lastClustering = Clustering.STATIC_CLUSTERING == clustering ? null : clustering; |
| return isNew; |
| } |
| } |
| |
| private static class SelectorGroupMaker extends PkPrefixGroupMaker |
| { |
| /** |
| * The selector used to build the groups. |
| */ |
| private final Selector selector; |
| |
| /** |
| * The output of the selector call on the last clustering |
| */ |
| private ByteBuffer lastOutput; |
| |
| private final Selector.InputRow input = new Selector.InputRow(1, false, false); |
| |
| public SelectorGroupMaker(ClusteringComparator comparator, |
| int clusteringPrefixSize, |
| Selector selector, |
| GroupingState state) |
| { |
| super(comparator, clusteringPrefixSize, state); |
| this.selector = selector; |
| this.lastOutput = lastClustering == null ? null : |
| executeSelector(lastClustering.bufferAt(clusteringPrefixSize - 1)); |
| } |
| |
| public SelectorGroupMaker(ClusteringComparator comparator, |
| int clusteringPrefixSize, |
| Selector selector) |
| { |
| super(comparator, clusteringPrefixSize); |
| this.selector = selector; |
| } |
| |
| @Override |
| public boolean isNewGroup(DecoratedKey partitionKey, Clustering<?> clustering) |
| { |
| ByteBuffer output = |
| Clustering.STATIC_CLUSTERING == clustering ? null |
| : executeSelector(clustering.bufferAt(clusteringPrefixSize - 1)); |
| |
| ByteBuffer key = partitionKey.getKey(); |
| |
| // We are entering a new group if: |
| // - the partition key is a new one |
| // - the last clustering was not null and does not have the same prefix as the new clustering one |
| boolean isNew = !key.equals(lastPartitionKey) |
| || lastClustering == null |
| || comparator.compare(lastClustering, clustering, clusteringPrefixSize - 1) != 0 |
| || compareOutput(output) != 0; |
| |
| lastPartitionKey = key; |
| lastClustering = Clustering.STATIC_CLUSTERING == clustering ? null : clustering; |
| lastOutput = output; |
| return isNew; |
| } |
| |
| private int compareOutput(ByteBuffer output) |
| { |
| if (output == null) |
| return lastOutput == null ? 0 : -1; |
| if (lastOutput == null) |
| return 1; |
| |
| return selector.getType().compare(output, lastOutput); |
| } |
| |
| private ByteBuffer executeSelector(ByteBuffer argument) |
| { |
| input.add(argument); |
| |
| // For computing groups we do not need to use the client protocol version. |
| selector.addInput(ProtocolVersion.CURRENT, input); |
| ByteBuffer output = selector.getOutput(ProtocolVersion.CURRENT); |
| selector.reset(); |
| input.reset(false); |
| |
| return output; |
| } |
| } |
| } |