/*
* 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;
}
}
}