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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.Writeable;
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.
*
* Use the java based Rounding class where applicable
*/
@Deprecated
public abstract class Rounding implements Writeable {
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 final DateTimeUnit unit;
private final DateTimeField field;
private final DateTimeZone timeZone;
private final boolean unitRoundsToMidnight;
TimeUnitRounding(DateTimeUnit unit, DateTimeZone timeZone) {
this.unit = unit;
this.field = unit.field(timeZone);
unitRoundsToMidnight = this.field.getDurationField().getUnitMillis() > 60L * 60L * 1000L;
this.timeZone = timeZone;
}
TimeUnitRounding(StreamInput in) throws IOException {
unit = DateTimeUnit.resolve(in.readByte());
timeZone = DateTimeZone.forID(in.readString());
field = unit.field(timeZone);
unitRoundsToMidnight = field.getDurationField().getUnitMillis() > 60L * 60L * 1000L;
}
@Override
public byte id() {
return ID;
}
/**
* @return The latest timestamp T which is strictly before utcMillis
* and such that timeZone.getOffset(T) != timeZone.getOffset(utcMillis).
* If there is no such T, returns Long.MAX_VALUE.
*/
private long previousTransition(long utcMillis) {
final int offsetAtInputTime = timeZone.getOffset(utcMillis);
do {
// Some timezones have transitions that do not change the offset, so we have to
// repeatedly call previousTransition until a nontrivial transition is found.
long previousTransition = timeZone.previousTransition(utcMillis);
if (previousTransition == utcMillis) {
// There are no earlier transitions
return Long.MAX_VALUE;
}
assert previousTransition < utcMillis; // Progress was made
utcMillis = previousTransition;
} while (timeZone.getOffset(utcMillis) == offsetAtInputTime);
return utcMillis;
}
@Override
public long round(long utcMillis) {
// field.roundFloor() works as long as the offset doesn't change. It is worth getting this case out of the way first, as
// the calculations for fixing things near to offset changes are a little expensive and are unnecessary in the common case
// of working in UTC.
if (timeZone.isFixed()) {
return field.roundFloor(utcMillis);
}
// When rounding to hours we consider any local time of the form 'xx:00:00' as rounded, even though this gives duplicate
// bucket names for the times when the clocks go back. Shorter units behave similarly. However, longer units round down to
// midnight, and on the days where there are two midnights we would rather pick the earlier one, so that buckets are
// uniquely identified by the date.
if (unitRoundsToMidnight) {
final long anyLocalStartOfDay = field.roundFloor(utcMillis);
// `anyLocalStartOfDay` is _supposed_ to be the Unix timestamp for the start of the day in question in the current time
// zone. Mostly this just means "midnight", which is fine, and on days with no local midnight it's the first time that
// does occur on that day which is also ok. However, on days with >1 local midnight this is _one_ of the midnights, but
// may not be the first. Check whether this is happening, and fix it if so.
final long previousTransition = previousTransition(anyLocalStartOfDay);
if (previousTransition == Long.MAX_VALUE) {
// No previous transitions, so there can't be another earlier local midnight.
return anyLocalStartOfDay;
}
final long currentOffset = timeZone.getOffset(anyLocalStartOfDay);
final long previousOffset = timeZone.getOffset(previousTransition);
assert currentOffset != previousOffset;
// NB we only assume interference from one previous transition. It's theoretically possible to have two transitions in
// quick succession, both of which have a midnight in them, but this doesn't appear to happen in the TZDB so (a) it's
// pointless to implement and (b) it won't be tested. I recognise that this comment is tempting fate and will likely
// cause this very situation to occur in the near future, and eagerly look forward to fixing this using a loop over
// previous transitions when it happens.
final long alsoLocalStartOfDay = anyLocalStartOfDay + currentOffset - previousOffset;
// `alsoLocalStartOfDay` is the Unix timestamp for the start of the day in question if the previous offset were in
// effect.
if (alsoLocalStartOfDay <= previousTransition) {
// Therefore the previous offset _is_ in effect at `alsoLocalStartOfDay`, and it's earlier than anyLocalStartOfDay,
// so this is the answer to use.
return alsoLocalStartOfDay;
}
else {
// The previous offset is not in effect at `alsoLocalStartOfDay`, so the current offset must be.
return anyLocalStartOfDay;
}
} else {
do {
long rounded = field.roundFloor(utcMillis);
// field.roundFloor() mostly works as long as the offset hasn't changed in [rounded, utcMillis], so look at where
// the offset most recently changed.
final long previousTransition = previousTransition(utcMillis);
if (previousTransition == Long.MAX_VALUE || previousTransition < rounded) {
// The offset did not change in [rounded, utcMillis], so roundFloor() worked as expected.
return rounded;
}
// The offset _did_ change in [rounded, utcMillis]. Put differently, this means that none of the times in
// [previousTransition+1, utcMillis] were rounded, so the rounded time must be <= previousTransition. This means
// it's sufficient to try and round previousTransition down.
assert previousTransition < utcMillis;
utcMillis = previousTransition;
} while (true);
}
}
@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 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 final long interval;
private final DateTimeZone timeZone;
TimeIntervalRounding(long interval, DateTimeZone timeZone) {
if (interval < 1)
throw new IllegalArgumentException("Zero or negative time interval not supported");
this.interval = interval;
this.timeZone = timeZone;
}
TimeIntervalRounding(StreamInput in) throws IOException {
interval = in.readVLong();
timeZone = DateTimeZone.forID(in.readString());
}
@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 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;
byte id = in.readByte();
switch (id) {
case TimeUnitRounding.ID:
rounding = new TimeUnitRounding(in);
break;
case TimeIntervalRounding.ID:
rounding = new TimeIntervalRounding(in);
break;
default:
throw new ElasticsearchException("unknown rounding id [" + id + "]");
}
return rounding;
}
}
}