org.apache.cassandra.db.commitlog.IntervalSet Maven / Gradle / Ivy
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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.commitlog;
import java.io.IOException;
import java.util.*;
import com.google.common.collect.ImmutableSortedMap;
import org.apache.cassandra.db.TypeSizes;
import org.apache.cassandra.io.ISerializer;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
/**
* An immutable set of closed intervals, stored in normalized form (i.e. where overlapping intervals are converted
* to a single interval covering both).
*
* The set is stored as a sorted map from interval starts to the corresponding end. The map satisfies
* {@code curr().getKey() <= curr().getValue() < next().getKey()}
*/
public class IntervalSet>
{
@SuppressWarnings({ "rawtypes", "unchecked" })
private static final IntervalSet EMPTY = new IntervalSet(ImmutableSortedMap.of());
final private NavigableMap ranges;
private IntervalSet(ImmutableSortedMap ranges)
{
this.ranges = ranges;
}
/**
* Construct new set containing the interval with the given start and end position.
*/
public IntervalSet(T start, T end)
{
this(ImmutableSortedMap.of(start, end));
}
@SuppressWarnings("unchecked")
public static > IntervalSet empty()
{
return EMPTY;
}
public boolean contains(T position)
{
// closed (i.e. inclusive) intervals
Map.Entry range = ranges.floorEntry(position);
return range != null && position.compareTo(range.getValue()) <= 0;
}
public boolean isEmpty()
{
return ranges.isEmpty();
}
public Optional lowerBound()
{
return isEmpty() ? Optional.empty() : Optional.of(ranges.firstKey());
}
public Optional upperBound()
{
return isEmpty() ? Optional.empty() : Optional.of(ranges.lastEntry().getValue());
}
public Collection starts()
{
return ranges.keySet();
}
public Collection ends()
{
return ranges.values();
}
public String toString()
{
return ranges.toString();
}
@Override
public int hashCode()
{
return ranges.hashCode();
}
@Override
public boolean equals(Object obj)
{
return obj instanceof IntervalSet && ranges.equals(((IntervalSet) obj).ranges);
}
public static final > ISerializer> serializer(ISerializer pointSerializer)
{
return new ISerializer>()
{
public void serialize(IntervalSet intervals, DataOutputPlus out) throws IOException
{
out.writeInt(intervals.ranges.size());
for (Map.Entry en : intervals.ranges.entrySet())
{
pointSerializer.serialize(en.getKey(), out);
pointSerializer.serialize(en.getValue(), out);
}
}
public IntervalSet deserialize(DataInputPlus in) throws IOException
{
int count = in.readInt();
NavigableMap ranges = new TreeMap<>();
for (int i = 0; i < count; ++i)
ranges.put(pointSerializer.deserialize(in), pointSerializer.deserialize(in));
return new IntervalSet(ImmutableSortedMap.copyOfSorted(ranges));
}
public long serializedSize(IntervalSet intervals)
{
long size = TypeSizes.sizeof(intervals.ranges.size());
for (Map.Entry en : intervals.ranges.entrySet())
{
size += pointSerializer.serializedSize(en.getKey());
size += pointSerializer.serializedSize(en.getValue());
}
return size;
}
};
};
/**
* Builder of interval sets, applying the necessary normalization while adding ranges.
*
* Data is stored as above, as a sorted map from interval starts to the corresponding end, which satisfies
* {@code curr().getKey() <= curr().getValue() < next().getKey()}
*/
static public class Builder>
{
final NavigableMap ranges;
public Builder()
{
this.ranges = new TreeMap<>();
}
public Builder(T start, T end)
{
this();
assert start.compareTo(end) <= 0;
ranges.put(start, end);
}
/**
* Add an interval to the set and perform normalization.
*/
public void add(T start, T end)
{
assert start.compareTo(end) <= 0;
// extend ourselves to cover any ranges we overlap
// record directly preceding our end may extend past us, so take the max of our end and its
Map.Entry extend = ranges.floorEntry(end);
if (extend != null && extend.getValue().compareTo(end) > 0)
end = extend.getValue();
// record directly preceding our start may extend into us; if it does, we take it as our start
extend = ranges.lowerEntry(start);
if (extend != null && extend.getValue().compareTo(start) >= 0)
start = extend.getKey();
// remove all covered intervals
// since we have adjusted start and end to cover the ones that would be only partially covered, we
// are certain that anything whose start falls within the span is completely covered
ranges.subMap(start, end).clear();
// add the new interval
ranges.put(start, end);
}
public void addAll(IntervalSet otherSet)
{
for (Map.Entry en : otherSet.ranges.entrySet())
{
add(en.getKey(), en.getValue());
}
}
public IntervalSet build()
{
return new IntervalSet(ImmutableSortedMap.copyOfSorted(ranges));
}
}
}