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/*
 * 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
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package org.apache.cassandra.db.aggregation;

import java.io.IOException;
import java.nio.ByteBuffer;

import org.apache.cassandra.db.Clustering;
import org.apache.cassandra.db.ClusteringComparator;
import org.apache.cassandra.db.TypeSizes;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.utils.ByteBufferUtil;

/**
 * {@code GroupMaker} state.
 *
 * 

The state contains the primary key of the last row that has been processed by the previous * {@code GroupMaker} used. It can be passed to a {@code GroupMaker} to allow to resuming the grouping. *

*

* {@code GroupingState} is only used for internal paging. When a new page is requested by a client the initial state * will always be empty.

*

* If the state has a partition key but no clustering, it means that the previous group ended at the end of the * previous partition. If the clustering is not null it means that we are in the middle of a group. *

*/ public final class GroupingState { public static final GroupingState.Serializer serializer = new Serializer(); public static final GroupingState EMPTY_STATE = new GroupingState(null, null); /** * The last row partition key. */ private final ByteBuffer partitionKey; /** * The last row clustering */ final Clustering clustering; public GroupingState(ByteBuffer partitionKey, Clustering clustering) { this.partitionKey = partitionKey; this.clustering = clustering; } /** * Returns the last row partition key or null if no rows has been processed yet. * @return the last row partition key or null if no rows has been processed yet */ public ByteBuffer partitionKey() { return partitionKey; } /** * Returns the last row clustering or null if either no rows has been processed yet or the last * row was a static row. * @return he last row clustering or null if either no rows has been processed yet or the last * row was a static row */ public Clustering clustering() { return clustering; } /** * Checks if the state contains a Clustering for the last row that has been processed. * @return true if the state contains a Clustering for the last row that has been processed, * false otherwise. */ public boolean hasClustering() { return clustering != null; } public static class Serializer { public void serialize(GroupingState state, DataOutputPlus out, int version, ClusteringComparator comparator) throws IOException { boolean hasPartitionKey = state.partitionKey != null; out.writeBoolean(hasPartitionKey); if (hasPartitionKey) { ByteBufferUtil.writeWithVIntLength(state.partitionKey, out); boolean hasClustering = state.hasClustering(); out.writeBoolean(hasClustering); if (hasClustering) Clustering.serializer.serialize(state.clustering, out, version, comparator.subtypes()); } } public GroupingState deserialize(DataInputPlus in, int version, ClusteringComparator comparator) throws IOException { if (!in.readBoolean()) return GroupingState.EMPTY_STATE; ByteBuffer partitionKey = ByteBufferUtil.readWithVIntLength(in); Clustering clustering = null; if (in.readBoolean()) clustering = Clustering.serializer.deserialize(in, version, comparator.subtypes()); return new GroupingState(partitionKey, clustering); } public long serializedSize(GroupingState state, int version, ClusteringComparator comparator) { boolean hasPartitionKey = state.partitionKey != null; long size = TypeSizes.sizeof(hasPartitionKey); if (hasPartitionKey) { size += ByteBufferUtil.serializedSizeWithVIntLength(state.partitionKey); boolean hasClustering = state.hasClustering(); size += TypeSizes.sizeof(hasClustering); if (hasClustering) { size += Clustering.serializer.serializedSize(state.clustering, version, comparator.subtypes()); } } return size; } } }




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