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* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.rounding;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.io.stream.Streamable;
import java.io.IOException;
/**
* A strategy for rounding long values.
*/
public abstract class Rounding implements Streamable {
public abstract byte id();
/**
* Given a value, compute a key that uniquely identifies the rounded value although it is not necessarily equal to the rounding value itself.
*/
public abstract long roundKey(long value);
/**
* Compute the rounded value given the key that identifies it.
*/
public abstract long valueForKey(long key);
/**
* Rounds the given value, equivalent to calling <code>roundValue(roundKey(value))</code>.
*
* @param value The value to round.
* @return The rounded value.
*/
public final long round(long value) {
return valueForKey(roundKey(value));
}
/**
* Given the rounded value (which was potentially generated by {@link #round(long)}, returns the next rounding value. For example, with
* interval based rounding, if the interval is 3, {@code nextRoundValue(6) = 9 }.
*
* @param value The current rounding value
* @return The next rounding value;
*/
public abstract long nextRoundingValue(long value);
/**
* Rounding strategy which is based on an interval
*
* {@code rounded = value - (value % interval) }
*/
public static class Interval extends Rounding {
final static byte ID = 0;
private long interval;
public Interval() { // for serialization
}
/**
* Creates a new interval rounding.
*
* @param interval The interval
*/
public Interval(long interval) {
this.interval = interval;
}
@Override
public byte id() {
return ID;
}
public static long roundKey(long value, long interval) {
if (value < 0) {
return (value - interval + 1) / interval;
} else {
return value / interval;
}
}
public static long roundValue(long key, long interval) {
return key * interval;
}
@Override
public long roundKey(long value) {
return roundKey(value, interval);
}
@Override
public long valueForKey(long key) {
return key * interval;
}
@Override
public long nextRoundingValue(long value) {
assert value == round(value);
return value + interval;
}
@Override
public void readFrom(StreamInput in) throws IOException {
interval = in.readVLong();
}
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeVLong(interval);
}
}
public static class FactorRounding extends Rounding {
final static byte ID = 7;
private Rounding rounding;
private float factor;
FactorRounding() { // for serialization
}
FactorRounding(Rounding rounding, float factor) {
this.rounding = rounding;
this.factor = factor;
}
@Override
public byte id() {
return ID;
}
@Override
public long roundKey(long utcMillis) {
return rounding.roundKey((long) (factor * utcMillis));
}
@Override
public long valueForKey(long key) {
return rounding.valueForKey(key);
}
@Override
public long nextRoundingValue(long value) {
return rounding.nextRoundingValue(value);
}
@Override
public void readFrom(StreamInput in) throws IOException {
rounding = (TimeZoneRounding) Rounding.Streams.read(in);
factor = in.readFloat();
}
@Override
public void writeTo(StreamOutput out) throws IOException {
Rounding.Streams.write(rounding, out);
out.writeFloat(factor);
}
}
public static class OffsetRounding extends Rounding {
final static byte ID = 8;
private Rounding rounding;
private long offset;
OffsetRounding() { // for serialization
}
public OffsetRounding(Rounding intervalRounding, long offset) {
this.rounding = intervalRounding;
this.offset = offset;
}
@Override
public byte id() {
return ID;
}
@Override
public long roundKey(long value) {
return rounding.roundKey(value - offset);
}
@Override
public long valueForKey(long key) {
return offset + rounding.valueForKey(key);
}
@Override
public long nextRoundingValue(long value) {
return rounding.nextRoundingValue(value - offset) + offset;
}
@Override
public void readFrom(StreamInput in) throws IOException {
rounding = Rounding.Streams.read(in);
offset = in.readLong();
}
@Override
public void writeTo(StreamOutput out) throws IOException {
Rounding.Streams.write(rounding, out);
out.writeLong(offset);
}
}
public static class Streams {
public static void write(Rounding rounding, StreamOutput out) throws IOException {
out.writeByte(rounding.id());
rounding.writeTo(out);
}
public static Rounding read(StreamInput in) throws IOException {
Rounding rounding = null;
byte id = in.readByte();
switch (id) {
case Interval.ID: rounding = new Interval(); break;
case TimeZoneRounding.TimeUnitRounding.ID: rounding = new TimeZoneRounding.TimeUnitRounding(); break;
case TimeZoneRounding.TimeIntervalRounding.ID: rounding = new TimeZoneRounding.TimeIntervalRounding(); break;
case TimeZoneRounding.FactorRounding.ID: rounding = new FactorRounding(); break;
case OffsetRounding.ID: rounding = new OffsetRounding(); break;
default: throw new ElasticsearchException("unknown rounding id [" + id + "]");
}
rounding.readFrom(in);
return rounding;
}
}
}