Slice.java
/*
* 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.io.IOException;
import java.nio.ByteBuffer;
import java.util.List;
import java.util.Objects;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.utils.Comparables;
/**
* A slice represents the selection of a range of rows.
* <p>
* A slice has a start and an end bound that are both (potentially full) clustering prefixes.
* A slice selects every row whose clustering is included within its start and end bounds.
* Both start and end can be either inclusive or exclusive.
*/
public class Slice
{
public static final Serializer serializer = new Serializer();
/**
* The slice selecting all rows (of a given partition)
*/
public static final Slice ALL = new Slice(BufferClusteringBound.BOTTOM, BufferClusteringBound.TOP)
{
@Override
public boolean includes(ClusteringComparator comparator, ClusteringPrefix<?> clustering)
{
return true;
}
@Override
public boolean intersects(ClusteringComparator comparator, Slice other)
{
return !other.isEmpty(comparator);
}
@Override
public String toString(ClusteringComparator comparator)
{
return "ALL";
}
};
private final ClusteringBound<?> start;
private final ClusteringBound<?> end;
private Slice(ClusteringBound<?> start, ClusteringBound<?> end)
{
assert start.isStart() && end.isEnd();
this.start = start;
this.end = end;
}
public static Slice make(ClusteringBound<?> start, ClusteringBound<?> end)
{
assert start != null && end != null;
if (start.isBottom() && end.isTop())
return ALL;
return new Slice(start, end);
}
public static Slice make(ClusteringComparator comparator, Object... values)
{
CBuilder builder = CBuilder.create(comparator);
for (Object val : values)
{
if (val instanceof ByteBuffer)
builder.add((ByteBuffer) val);
else
builder.add(val);
}
return new Slice(builder.buildBound(true, true), builder.buildBound(false, true));
}
/**
* Makes a slice covering a single clustering
*/
public static Slice make(Clustering<?> clustering)
{
// This doesn't give us what we want with the clustering prefix
assert clustering != Clustering.STATIC_CLUSTERING;
return new Slice(ClusteringBound.inclusiveStartOf(clustering), ClusteringBound.inclusiveEndOf(clustering));
}
/**
* Makes a slice covering a range from start to end clusterings, with both start and end included
*/
public static Slice make(Clustering<?> start, Clustering<?> end)
{
// This doesn't give us what we want with the clustering prefix
assert start != Clustering.STATIC_CLUSTERING && end != Clustering.STATIC_CLUSTERING;
return new Slice(ClusteringBound.inclusiveStartOf(start), ClusteringBound.inclusiveEndOf(end));
}
/**
* Makes a slice for the given bounds
*/
public static Slice make(ClusteringBoundOrBoundary<?> start, ClusteringBoundOrBoundary<?> end)
{
// This doesn't give us what we want with the clustering prefix
return make(start.asStartBound(), end.asEndBound());
}
public ClusteringBound<?> start()
{
return start;
}
public ClusteringBound<?> end()
{
return end;
}
public ClusteringBound<?> open(boolean reversed)
{
return reversed ? end : start;
}
public ClusteringBound<?> close(boolean reversed)
{
return reversed ? start : end;
}
/**
* Return whether the slice is empty.
*
* @param comparator the comparator to compare the bounds.
* @return whether the slice formed is empty or not.
*/
public boolean isEmpty(ClusteringComparator comparator)
{
return isEmpty(comparator, start(), end());
}
/**
* Return whether the slice formed by the two provided bound is empty or not.
*
* @param comparator the comparator to compare the bounds.
* @param start the start for the slice to consider. This must be a start bound.
* @param end the end for the slice to consider. This must be an end bound.
* @return whether the slice formed by {@code start} and {@code end} is
* empty or not.
*/
public static boolean isEmpty(ClusteringComparator comparator, ClusteringBound<?> start, ClusteringBound<?> end)
{
assert start.isStart() && end.isEnd();
// Note: the comparator orders inclusive starts and exclusive ends as equal, and inclusive ends as being greater than starts.
return comparator.compare(start, end) >= 0;
}
/**
* Returns whether a given clustering or bound is included in this slice.
*
* @param comparator the comparator for the table this is a slice of.
* @param bound the bound to test inclusion of.
* @return whether {@code bound} is within the bounds of this slice.
*/
public boolean includes(ClusteringComparator comparator, ClusteringPrefix<?> bound)
{
return comparator.compare(start, bound) <= 0 && comparator.compare(bound, end) <= 0;
}
/**
* Returns a slice for continuing paging from the last returned clustering prefix.
*
* @param comparator the comparator for the table this is a filter for.
* @param lastReturned the last clustering that was returned for the query we are paging for. The
* resulting slices will be such that only results coming stricly after {@code lastReturned} are returned
* (where coming after means "greater than" if {@code !reversed} and "lesser than" otherwise).
* @param inclusive whether we want to include the {@code lastReturned} in the newly returned page of results.
* @param reversed whether the query we're paging for is reversed or not.
* @return a new slice that selects results coming after {@code lastReturned}, or {@code null} if paging
* the resulting slice selects nothing (i.e. if it originally selects nothing coming after {@code lastReturned}).
*/
public Slice forPaging(ClusteringComparator comparator, Clustering<?> lastReturned, boolean inclusive, boolean reversed)
{
if (lastReturned == null)
return this;
if (reversed)
{
int cmp = comparator.compare(lastReturned, start);
assert cmp != 0;
// start is > than lastReturned; got nothing to return no more
if (cmp < 0)
return null;
cmp = comparator.compare(end, lastReturned);
assert cmp != 0;
if (cmp < 0)
return this;
Slice slice = new Slice(start, inclusive ? ClusteringBound.inclusiveEndOf(lastReturned) : ClusteringBound.exclusiveEndOf(lastReturned));
if (slice.isEmpty(comparator))
return null;
return slice;
}
else
{
int cmp = comparator.compare(end, lastReturned);
assert cmp != 0;
if (cmp < 0)
return null;
cmp = comparator.compare(lastReturned, start);
assert cmp != 0;
if (cmp < 0)
return this;
Slice slice = new Slice(inclusive ? ClusteringBound.inclusiveStartOf(lastReturned) : ClusteringBound.exclusiveStartOf(lastReturned), end);
if (slice.isEmpty(comparator))
return null;
return slice;
}
}
/**
* Whether this slice and the provided slice intersects.
*
* @param comparator the comparator for the table this is a slice of.
* @param other the other slice to check intersection with.
* @return whether this slice intersects {@code other}.
*/
public boolean intersects(ClusteringComparator comparator, Slice other)
{
// Construct the intersection of the two slices and check if it is non-empty.
// This also works correctly when one or more of the inputs are be empty (i.e. with end <= start).
return comparator.compare(Comparables.max(start, other.start, comparator),
Comparables.min(end, other.end, comparator)) < 0;
}
public String toString(ClusteringComparator comparator)
{
StringBuilder sb = new StringBuilder();
sb.append(start.isInclusive() ? "[" : "(");
for (int i = 0; i < start.size(); i++)
{
if (i > 0)
sb.append(':');
sb.append(start.stringAt(i, comparator));
}
sb.append(", ");
for (int i = 0; i < end.size(); i++)
{
if (i > 0)
sb.append(':');
sb.append(end.stringAt(i, comparator));
}
sb.append(end.isInclusive() ? "]" : ")");
return sb.toString();
}
@Override
public boolean equals(Object other)
{
if (!(other instanceof Slice))
return false;
Slice that = (Slice) other;
return this.start().equals(that.start())
&& this.end().equals(that.end());
}
@Override
public int hashCode()
{
return Objects.hash(start(), end());
}
public static class Serializer
{
public void serialize(Slice slice, DataOutputPlus out, int version, List<AbstractType<?>> types) throws IOException
{
ClusteringBound.serializer.serialize(slice.start, out, version, types);
ClusteringBound.serializer.serialize(slice.end, out, version, types);
}
public long serializedSize(Slice slice, int version, List<AbstractType<?>> types)
{
return ClusteringBound.serializer.serializedSize(slice.start, version, types)
+ ClusteringBound.serializer.serializedSize(slice.end, version, types);
}
public Slice deserialize(DataInputPlus in, int version, List<AbstractType<?>> types) throws IOException
{
ClusteringBound<byte[]> start = (ClusteringBound<byte[]>) ClusteringBound.serializer.deserialize(in, version, types);
ClusteringBound<byte[]> end = (ClusteringBound<byte[]>) ClusteringBound.serializer.deserialize(in, version, types);
return new Slice(start, end);
}
}
}