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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.NavigableSet;
import org.apache.cassandra.schema.ColumnMetadata;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.btree.BTreeSet;
/**
* Builder that allow to build multiple Clustering/ClusteringBound at the same time.
*/
public abstract class MultiCBuilder
{
/**
* The table comparator.
*/
protected final ClusteringComparator comparator;
/**
* The number of clustering elements that have been added.
*/
protected int size;
/**
* true if the clusterings have been build, false otherwise.
*/
protected boolean built;
/**
* true if the clusterings contains some null elements.
*/
protected boolean containsNull;
/**
* true if the composites contains some unset elements.
*/
protected boolean containsUnset;
/**
* true if some empty collection have been added.
*/
protected boolean hasMissingElements;
protected MultiCBuilder(ClusteringComparator comparator)
{
this.comparator = comparator;
}
/**
* Creates a new empty {@code MultiCBuilder}.
*/
public static MultiCBuilder create(ClusteringComparator comparator, boolean forMultipleValues)
{
return forMultipleValues
? new MultiClusteringBuilder(comparator)
: new OneClusteringBuilder(comparator);
}
/**
* Adds the specified element to all the clusterings.
*
* If this builder contains 2 clustering: A-B and A-C a call to this method to add D will result in the clusterings:
* A-B-D and A-C-D.
*
*
* @param value the value of the next element
* @return this MulitCBuilder
*/
public abstract MultiCBuilder addElementToAll(ByteBuffer value);
/**
* Adds individually each of the specified elements to the end of all of the existing clusterings.
*
* If this builder contains 2 clusterings: A-B and A-C a call to this method to add D and E will result in the 4
* clusterings: A-B-D, A-B-E, A-C-D and A-C-E.
*
*
* @param values the elements to add
* @return this CompositeBuilder
*/
public abstract MultiCBuilder addEachElementToAll(List values);
/**
* Adds individually each of the specified list of elements to the end of all of the existing composites.
*
* 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
* composites: A-B-D-E, A-B-F-G, A-C-D-E and A-C-F-G.
*
*
* @param values the elements to add
* @return this CompositeBuilder
*/
public abstract MultiCBuilder addAllElementsToAll(List> values);
protected void checkUpdateable()
{
if (!hasRemaining() || built)
throw new IllegalStateException("this builder cannot be updated anymore");
}
/**
* Returns the number of elements that can be added to the clusterings.
*
* @return the number of elements that can be added to the clusterings.
*/
public int remainingCount()
{
return comparator.size() - size;
}
/**
* Returns the current number of results when {@link #build()} is called
*
* @return the current number of build results
*/
public abstract int buildSize();
/**
* Checks if the clusterings contains null elements.
*
* @return true if the clusterings contains null elements, false otherwise.
*/
public boolean containsNull()
{
return containsNull;
}
/**
* Checks if the clusterings contains unset elements.
*
* @return true if the clusterings contains unset elements, false otherwise.
*/
public boolean containsUnset()
{
return containsUnset;
}
/**
* Checks if some empty list of values have been added
* @return true if the clusterings have some missing elements, false otherwise.
*/
public boolean hasMissingElements()
{
return hasMissingElements;
}
/**
* Builds the clusterings.
*
* @return the clusterings
*/
public abstract NavigableSet> build();
/**
* Builds the ClusteringBounds for slice restrictions.
*
* @param isStart specify if the bound is a start one
* @param isInclusive specify if the bound is inclusive or not
* @param isOtherBoundInclusive specify if the other bound is inclusive or not
* @param columnDefs the columns of the slice restriction
* @return the ClusteringBounds
*/
public abstract NavigableSet> buildBoundForSlice(boolean isStart,
boolean isInclusive,
boolean isOtherBoundInclusive,
List columnDefs);
/**
* Builds the ClusteringBounds
*
* @param isStart specify if the bound is a start one
* @param isInclusive specify if the bound is inclusive or not
* @return the ClusteringBounds
*/
public abstract NavigableSet> buildBound(boolean isStart, boolean isInclusive);
/**
* Checks if some elements can still be added to the clusterings.
*
* @return true if it is possible to add more elements to the clusterings, false otherwise.
*/
public boolean hasRemaining()
{
return remainingCount() > 0;
}
/**
* Specialization of MultiCBuilder when we know only one clustering/bound is created.
*/
private static class OneClusteringBuilder extends MultiCBuilder
{
/**
* The elements of the clusterings
*/
private final ByteBuffer[] elements;
public OneClusteringBuilder(ClusteringComparator comparator)
{
super(comparator);
this.elements = new ByteBuffer[comparator.size()];
}
public MultiCBuilder addElementToAll(ByteBuffer value)
{
checkUpdateable();
if (value == null)
containsNull = true;
if (value == ByteBufferUtil.UNSET_BYTE_BUFFER)
containsUnset = true;
elements[size++] = value;
return this;
}
public MultiCBuilder addEachElementToAll(List values)
{
if (values.isEmpty())
{
hasMissingElements = true;
return this;
}
assert values.size() == 1;
return addElementToAll(values.get(0));
}
public MultiCBuilder addAllElementsToAll(List> values)
{
if (values.isEmpty())
{
hasMissingElements = true;
return this;
}
assert values.size() == 1;
return addEachElementToAll(values.get(0));
}
@Override
public int buildSize()
{
return hasMissingElements ? 0 : 1;
}
public NavigableSet> build()
{
built = true;
if (hasMissingElements)
return BTreeSet.empty(comparator);
return BTreeSet.of(comparator, size == 0 ? Clustering.EMPTY : Clustering.make(elements));
}
@Override
public NavigableSet> buildBoundForSlice(boolean isStart,
boolean isInclusive,
boolean isOtherBoundInclusive,
List columnDefs)
{
return buildBound(isStart, columnDefs.get(0).isReversedType() ? isOtherBoundInclusive : isInclusive);
}
public NavigableSet> buildBound(boolean isStart, boolean isInclusive)
{
built = true;
if (hasMissingElements)
return BTreeSet.empty(comparator);
if (size == 0)
return BTreeSet.of(comparator, isStart ? BufferClusteringBound.BOTTOM : BufferClusteringBound.TOP);
ByteBuffer[] newValues = size == elements.length
? elements
: Arrays.copyOf(elements, size);
return BTreeSet.of(comparator, BufferClusteringBound.create(ClusteringBound.boundKind(isStart, isInclusive), newValues));
}
}
/**
* MultiCBuilder implementation actually supporting the creation of multiple clustering/bound.
*/
private static class MultiClusteringBuilder extends MultiCBuilder
{
/**
* The elements of the clusterings
*/
private final List> elementsList = new ArrayList<>();
public MultiClusteringBuilder(ClusteringComparator comparator)
{
super(comparator);
}
public MultiCBuilder addElementToAll(ByteBuffer value)
{
checkUpdateable();
if (elementsList.isEmpty())
elementsList.add(new ArrayList<>());
if (value == null)
containsNull = true;
else if (value == ByteBufferUtil.UNSET_BYTE_BUFFER)
containsUnset = true;
for (int i = 0, m = elementsList.size(); i < m; i++)
elementsList.get(i).add(value);
size++;
return this;
}
public MultiCBuilder addEachElementToAll(List values)
{
checkUpdateable();
if (elementsList.isEmpty())
elementsList.add(new ArrayList<>());
if (values.isEmpty())
{
hasMissingElements = true;
}
else
{
for (int i = 0, m = elementsList.size(); i < m; i++)
{
List oldComposite = elementsList.remove(0);
for (int j = 0, n = values.size(); j < n; j++)
{
List newComposite = new ArrayList<>(oldComposite);
elementsList.add(newComposite);
ByteBuffer value = values.get(j);
if (value == null)
containsNull = true;
if (value == ByteBufferUtil.UNSET_BYTE_BUFFER)
containsUnset = true;
newComposite.add(values.get(j));
}
}
}
size++;
return this;
}
public MultiCBuilder addAllElementsToAll(List> values)
{
checkUpdateable();
if (elementsList.isEmpty())
elementsList.add(new ArrayList<>());
if (values.isEmpty())
{
hasMissingElements = true;
}
else
{
for (int i = 0, m = elementsList.size(); i < m; i++)
{
List oldComposite = elementsList.remove(0);
for (int j = 0, n = values.size(); j < n; j++)
{
List newComposite = new ArrayList<>(oldComposite);
elementsList.add(newComposite);
List value = values.get(j);
if (value.contains(null))
containsNull = true;
if (value.contains(ByteBufferUtil.UNSET_BYTE_BUFFER))
containsUnset = true;
newComposite.addAll(value);
}
}
size += values.get(0).size();
}
return this;
}
@Override
public int buildSize()
{
return hasMissingElements ? 0 : elementsList.size();
}
public NavigableSet> build()
{
built = true;
if (hasMissingElements)
return BTreeSet.empty(comparator);
CBuilder builder = CBuilder.create(comparator);
if (elementsList.isEmpty())
return BTreeSet.of(builder.comparator(), builder.build());
BTreeSet.Builder> set = BTreeSet.builder(builder.comparator());
for (int i = 0, m = elementsList.size(); i < m; i++)
{
List elements = elementsList.get(i);
set.add(builder.buildWith(elements));
}
return set.build();
}
public NavigableSet> buildBoundForSlice(boolean isStart,
boolean isInclusive,
boolean isOtherBoundInclusive,
List columnDefs)
{
built = true;
if (hasMissingElements)
return BTreeSet.empty(comparator);
CBuilder builder = CBuilder.create(comparator);
if (elementsList.isEmpty())
return BTreeSet.of(comparator, builder.buildBound(isStart, isInclusive));
// Use a TreeSet to sort and eliminate duplicates
BTreeSet.Builder> set = BTreeSet.builder(comparator);
// The first column of the slice might not be the first clustering column (e.g. clustering_0 = ? AND (clustering_1, clustering_2) >= (?, ?)
int offset = columnDefs.get(0).position();
for (int i = 0, m = elementsList.size(); i < m; i++)
{
List elements = elementsList.get(i);
// Handle the no bound case
if (elements.size() == offset)
{
set.add(builder.buildBoundWith(elements, isStart, true));
continue;
}
// In the case of mixed order columns, we will have some extra slices where the columns change directions.
// For example: if we have clustering_0 DESC and clustering_1 ASC a slice like (clustering_0, clustering_1) > (1, 2)
// will produce 2 slices: [BOTTOM, 1) and (1.2, 1]
// So, the END bound will return 2 bounds with the same values 1
ColumnMetadata lastColumn = columnDefs.get(columnDefs.size() - 1);
if (elements.size() <= lastColumn.position() && i < m - 1 && elements.equals(elementsList.get(i + 1)))
{
set.add(builder.buildBoundWith(elements, isStart, false));
set.add(builder.buildBoundWith(elementsList.get(i++), isStart, true));
continue;
}
// Handle the normal bounds
ColumnMetadata column = columnDefs.get(elements.size() - 1 - offset);
set.add(builder.buildBoundWith(elements, isStart, column.isReversedType() ? isOtherBoundInclusive : isInclusive));
}
return set.build();
}
public NavigableSet> buildBound(boolean isStart, boolean isInclusive)
{
built = true;
if (hasMissingElements)
return BTreeSet.empty(comparator);
CBuilder builder = CBuilder.create(comparator);
if (elementsList.isEmpty())
return BTreeSet.of(comparator, builder.buildBound(isStart, isInclusive));
// Use a TreeSet to sort and eliminate duplicates
BTreeSet.Builder> set = BTreeSet.builder(comparator);
for (int i = 0, m = elementsList.size(); i < m; i++)
{
List elements = elementsList.get(i);
set.add(builder.buildBoundWith(elements, isStart, isInclusive));
}
return set.build();
}
}
}