org.elasticsearch.common.rounding.Rounding Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of elasticsearch Show documentation
Show all versions of elasticsearch Show documentation
Elasticsearch subproject :core
/*
* 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 org.elasticsearch.common.unit.TimeValue;
import org.joda.time.DateTimeField;
import org.joda.time.DateTimeZone;
import org.joda.time.IllegalInstantException;
import java.io.IOException;
import java.util.Objects;
/**
* A strategy for rounding long values.
*/
public abstract class Rounding implements Streamable {
public abstract byte id();
/**
* Rounds the given value.
*/
public abstract long round(long 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);
@Override
public abstract boolean equals(Object obj);
@Override
public abstract int hashCode();
public static Builder builder(DateTimeUnit unit) {
return new Builder(unit);
}
public static Builder builder(TimeValue interval) {
return new Builder(interval);
}
public static class Builder {
private final DateTimeUnit unit;
private final long interval;
private DateTimeZone timeZone = DateTimeZone.UTC;
public Builder(DateTimeUnit unit) {
this.unit = unit;
this.interval = -1;
}
public Builder(TimeValue interval) {
this.unit = null;
if (interval.millis() < 1)
throw new IllegalArgumentException("Zero or negative time interval not supported");
this.interval = interval.millis();
}
public Builder timeZone(DateTimeZone timeZone) {
if (timeZone == null) {
throw new IllegalArgumentException("Setting null as timezone is not supported");
}
this.timeZone = timeZone;
return this;
}
public Rounding build() {
Rounding timeZoneRounding;
if (unit != null) {
timeZoneRounding = new TimeUnitRounding(unit, timeZone);
} else {
timeZoneRounding = new TimeIntervalRounding(interval, timeZone);
}
return timeZoneRounding;
}
}
static class TimeUnitRounding extends Rounding {
static final byte ID = 1;
private DateTimeUnit unit;
private DateTimeField field;
private DateTimeZone timeZone;
TimeUnitRounding() { // for serialization
}
TimeUnitRounding(DateTimeUnit unit, DateTimeZone timeZone) {
this.unit = unit;
this.field = unit.field(timeZone);
this.timeZone = timeZone;
}
@Override
public byte id() {
return ID;
}
@Override
public long round(long utcMillis) {
long rounded = field.roundFloor(utcMillis);
if (timeZone.isFixed() == false) {
// special cases for non-fixed time zones with dst transitions
if (timeZone.getOffset(utcMillis) != timeZone.getOffset(rounded)) {
/*
* the offset change indicates a dst transition. In some
* edge cases this will result in a value that is not a
* rounded value before the transition. We round again to
* make sure we really return a rounded value. This will
* have no effect in cases where we already had a valid
* rounded value
*/
rounded = field.roundFloor(rounded);
} else {
/*
* check if the current time instant is at a start of a DST
* overlap by comparing the offset of the instant and the
* previous millisecond. We want to detect negative offset
* changes that result in an overlap
*/
if (timeZone.getOffset(rounded) < timeZone.getOffset(rounded - 1)) {
/*
* we are rounding a date just after a DST overlap. if
* the overlap is smaller than the time unit we are
* rounding to, we want to add the overlapping part to
* the following rounding interval
*/
long previousRounded = field.roundFloor(rounded - 1);
if (rounded - previousRounded < field.getDurationField().getUnitMillis()) {
rounded = previousRounded;
}
}
}
}
assert rounded == field.roundFloor(rounded);
return rounded;
}
@Override
public long nextRoundingValue(long utcMillis) {
long floor = round(utcMillis);
// add one unit and round to get to next rounded value
long next = round(field.add(floor, 1));
if (next == floor) {
// in rare case we need to add more than one unit
next = round(field.add(floor, 2));
}
return next;
}
@Override
public void readFrom(StreamInput in) throws IOException {
unit = DateTimeUnit.resolve(in.readByte());
timeZone = DateTimeZone.forID(in.readString());
field = unit.field(timeZone);
}
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeByte(unit.id());
out.writeString(timeZone.getID());
}
@Override
public int hashCode() {
return Objects.hash(unit, timeZone);
}
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
TimeUnitRounding other = (TimeUnitRounding) obj;
return Objects.equals(unit, other.unit) && Objects.equals(timeZone, other.timeZone);
}
@Override
public String toString() {
return "[" + timeZone + "][" + unit + "]";
}
}
static class TimeIntervalRounding extends Rounding {
static final byte ID = 2;
private long interval;
private DateTimeZone timeZone;
TimeIntervalRounding() { // for serialization
}
TimeIntervalRounding(long interval, DateTimeZone timeZone) {
if (interval < 1)
throw new IllegalArgumentException("Zero or negative time interval not supported");
this.interval = interval;
this.timeZone = timeZone;
}
@Override
public byte id() {
return ID;
}
@Override
public long round(long utcMillis) {
long timeLocal = timeZone.convertUTCToLocal(utcMillis);
long rounded = roundKey(timeLocal, interval) * interval;
long roundedUTC;
if (isInDSTGap(rounded) == false) {
roundedUTC = timeZone.convertLocalToUTC(rounded, true, utcMillis);
// check if we crossed DST transition, in this case we want the
// last rounded value before the transition
long transition = timeZone.previousTransition(utcMillis);
if (transition != utcMillis && transition > roundedUTC) {
roundedUTC = round(transition - 1);
}
} else {
/*
* Edge case where the rounded local time is illegal and landed
* in a DST gap. In this case, we choose 1ms tick after the
* transition date. We don't want the transition date itself
* because those dates, when rounded themselves, fall into the
* previous interval. This would violate the invariant that the
* rounding operation should be idempotent.
*/
roundedUTC = timeZone.previousTransition(utcMillis) + 1;
}
return roundedUTC;
}
private static long roundKey(long value, long interval) {
if (value < 0) {
return (value - interval + 1) / interval;
} else {
return value / interval;
}
}
/**
* Determine whether the local instant is a valid instant in the given
* time zone. The logic for this is taken from
* {@link DateTimeZone#convertLocalToUTC(long, boolean)} for the
* `strict` mode case, but instead of throwing an
* {@link IllegalInstantException}, which is costly, we want to return a
* flag indicating that the value is illegal in that time zone.
*/
private boolean isInDSTGap(long instantLocal) {
if (timeZone.isFixed()) {
return false;
}
// get the offset at instantLocal (first estimate)
int offsetLocal = timeZone.getOffset(instantLocal);
// adjust instantLocal using the estimate and recalc the offset
int offset = timeZone.getOffset(instantLocal - offsetLocal);
// if the offsets differ, we must be near a DST boundary
if (offsetLocal != offset) {
// determine if we are in the DST gap
long nextLocal = timeZone.nextTransition(instantLocal - offsetLocal);
if (nextLocal == (instantLocal - offsetLocal)) {
nextLocal = Long.MAX_VALUE;
}
long nextAdjusted = timeZone.nextTransition(instantLocal - offset);
if (nextAdjusted == (instantLocal - offset)) {
nextAdjusted = Long.MAX_VALUE;
}
if (nextLocal != nextAdjusted) {
// we are in the DST gap
return true;
}
}
return false;
}
@Override
public long nextRoundingValue(long time) {
long timeLocal = time;
timeLocal = timeZone.convertUTCToLocal(time);
long next = timeLocal + interval;
return timeZone.convertLocalToUTC(next, false);
}
@Override
public void readFrom(StreamInput in) throws IOException {
interval = in.readVLong();
timeZone = DateTimeZone.forID(in.readString());
}
@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeVLong(interval);
out.writeString(timeZone.getID());
}
@Override
public int hashCode() {
return Objects.hash(interval, timeZone);
}
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
TimeIntervalRounding other = (TimeIntervalRounding) obj;
return Objects.equals(interval, other.interval) && Objects.equals(timeZone, other.timeZone);
}
}
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 TimeUnitRounding.ID: rounding = new TimeUnitRounding(); break;
case TimeIntervalRounding.ID: rounding = new TimeIntervalRounding(); break;
default: throw new ElasticsearchException("unknown rounding id [" + id + "]");
}
rounding.readFrom(in);
return rounding;
}
}
}