272 lines
7.7 KiB
Java
272 lines
7.7 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.cassandra.db.composites;
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import java.nio.ByteBuffer;
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import java.util.ArrayList;
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import java.util.Comparator;
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import java.util.LinkedHashSet;
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import java.util.List;
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import java.util.Set;
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import java.util.TreeSet;
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import org.apache.cassandra.db.composites.Composite.EOC;
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import static java.util.Collections.singletonList;
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/**
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* Builder that allow to build multiple composites at the same time.
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*/
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public final class CompositesBuilder
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{
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/**
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* The builder used to build the <code>Composite</code>s.
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*/
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private final CBuilder builder;
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/**
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* The comparator used to sort the returned <code>Composite</code>s.
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*/
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private final Comparator<Composite> comparator;
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/**
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* The elements of the composites
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*/
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private final List<List<ByteBuffer>> elementsList = new ArrayList<>();
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/**
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* The number of elements that still can be added.
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*/
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private int remaining;
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/**
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* <code>true</code> if the composites have been build, <code>false</code> otherwise.
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*/
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private boolean built;
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/**
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* <code>true</code> if the composites contains some <code>null</code> elements.
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*/
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private boolean containsNull;
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public CompositesBuilder(CBuilder builder, Comparator<Composite> comparator)
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{
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this.builder = builder;
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this.comparator = comparator;
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this.remaining = builder.remainingCount();
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}
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/**
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* Adds the specified element to all the composites.
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* <p>
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* If this builder contains 2 composites: A-B and A-C a call to this method to add D will result in the composites:
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* A-B-D and A-C-D.
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* </p>
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*
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* @param value the value of the next element
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* @return this <code>CompositeBuilder</code>
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*/
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public CompositesBuilder addElementToAll(ByteBuffer value)
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{
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checkUpdateable();
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if (isEmpty())
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elementsList.add(new ArrayList<ByteBuffer>());
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for (int i = 0, m = elementsList.size(); i < m; i++)
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{
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if (value == null)
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containsNull = true;
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elementsList.get(i).add(value);
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}
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remaining--;
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return this;
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}
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/**
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* Adds individually each of the specified elements to the end of all of the existing composites.
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* <p>
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* If this builder contains 2 composites: A-B and A-C a call to this method to add D and E will result in the 4
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* composites: A-B-D, A-B-E, A-C-D and A-C-E.
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* </p>
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*
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* @param values the elements to add
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* @return this <code>CompositeBuilder</code>
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*/
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public CompositesBuilder addEachElementToAll(List<ByteBuffer> values)
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{
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checkUpdateable();
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if (isEmpty())
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elementsList.add(new ArrayList<ByteBuffer>());
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for (int i = 0, m = elementsList.size(); i < m; i++)
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{
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List<ByteBuffer> oldComposite = elementsList.remove(0);
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for (int j = 0, n = values.size(); j < n; j++)
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{
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List<ByteBuffer> newComposite = new ArrayList<>(oldComposite);
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elementsList.add(newComposite);
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ByteBuffer value = values.get(j);
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if (value == null)
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containsNull = true;
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newComposite.add(values.get(j));
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}
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}
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remaining--;
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return this;
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}
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/**
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* Adds individually each of the specified list of elements to the end of all of the existing composites.
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* <p>
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* If this builder contains 2 composites: A-B and A-C a call to this method to add [[D, E], [F, G]] will result in the 4
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* composites: A-B-D-E, A-B-F-G, A-C-D-E and A-C-F-G.
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* </p>
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*
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* @param values the elements to add
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* @return this <code>CompositeBuilder</code>
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*/
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public CompositesBuilder addAllElementsToAll(List<List<ByteBuffer>> values)
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{
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assert !values.isEmpty();
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checkUpdateable();
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if (isEmpty())
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elementsList.add(new ArrayList<ByteBuffer>());
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for (int i = 0, m = elementsList.size(); i < m; i++)
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{
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List<ByteBuffer> oldComposite = elementsList.remove(0);
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for (int j = 0, n = values.size(); j < n; j++)
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{
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List<ByteBuffer> newComposite = new ArrayList<>(oldComposite);
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elementsList.add(newComposite);
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List<ByteBuffer> value = values.get(j);
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if (value.contains(null))
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containsNull = true;
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newComposite.addAll(value);
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}
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}
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remaining -= values.get(0).size();
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return this;
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}
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/**
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* Returns the number of elements that can be added to the composites.
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*
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* @return the number of elements that can be added to the composites.
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*/
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public int remainingCount()
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{
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return remaining;
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}
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/**
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* Checks if some elements can still be added to the composites.
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*
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* @return <code>true</code> if it is possible to add more elements to the composites, <code>false</code> otherwise.
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*/
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public boolean hasRemaining()
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{
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return remaining > 0;
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}
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/**
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* Checks if this builder is empty.
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*
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* @return <code>true</code> if this builder is empty, <code>false</code> otherwise.
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*/
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public boolean isEmpty()
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{
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return elementsList.isEmpty();
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}
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/**
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* Checks if the composites contains null elements.
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*
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* @return <code>true</code> if the composites contains <code>null</code> elements, <code>false</code> otherwise.
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*/
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public boolean containsNull()
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{
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return containsNull;
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}
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/**
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* Builds the <code>Composites</code>.
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*
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* @return the composites
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*/
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public List<Composite> build()
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{
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return buildWithEOC(EOC.NONE);
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}
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/**
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* Builds the <code>Composites</code> with the specified EOC.
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*
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* @return the composites
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*/
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public List<Composite> buildWithEOC(EOC eoc)
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{
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built = true;
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if (elementsList.isEmpty())
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return singletonList(builder.build().withEOC(eoc));
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// Use a Set to sort if needed and eliminate duplicates
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Set<Composite> set = newSet();
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for (int i = 0, m = elementsList.size(); i < m; i++)
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{
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List<ByteBuffer> elements = elementsList.get(i);
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set.add(builder.buildWith(elements).withEOC(eoc));
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}
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return new ArrayList<>(set);
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}
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/**
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* Returns a new <code>Set</code> instance that will be used to eliminate duplicates and sort the results.
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*
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* @return a new <code>Set</code> instance.
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*/
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private Set<Composite> newSet()
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{
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return comparator == null ? new LinkedHashSet<Composite>() : new TreeSet<Composite>(comparator);
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}
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private void checkUpdateable()
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{
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if (!hasRemaining() || built)
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throw new IllegalStateException("this CompositesBuilder cannot be updated anymore");
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}
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}
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