/*
* Copyright (C) 2012 Facebook, Inc.
*
* Licensed 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 com.facebook.stats;
import org.joda.time.Duration;
import org.joda.time.ReadableDateTime;
import java.util.concurrent.atomic.AtomicLong;
public class AssociativeAggregationCounter implements EventCounter {
private final ReadableDateTime start;
private final ReadableDateTime end;
private final long initialValue;
private final AssociativeAggregation associativeAggregation;
protected final AtomicLong value;
public AssociativeAggregationCounter(
ReadableDateTime start,
ReadableDateTime end,
AssociativeAggregation associativeAggregation,
long initialValue
) {
if (start.isAfter(end)) {
this.start = end;
this.end = start;
} else {
this.start = start;
this.end = end;
}
this.initialValue = initialValue;
this.associativeAggregation = associativeAggregation;
this.value = new AtomicLong(initialValue);
}
public void add(long delta) {
long val = value.get();
while (
!value.compareAndSet(val, associativeAggregation.combine(val, delta))
) {
val = value.get();
}
}
public long getValue() {
return value.get();
}
public ReadableDateTime getStart() {
return start;
}
public ReadableDateTime getEnd() {
return end;
}
@Override
public Duration getLength() {
return new Duration(start, end);
}
@Override
public EventCounter merge(EventCounter counter) {
ReadableDateTime mergedStart = start;
ReadableDateTime mergedEnd = end;
if (counter.getStart().isBefore(mergedStart)) {
mergedStart = counter.getStart();
}
if (counter.getEnd().isAfter(mergedEnd)) {
mergedEnd = counter.getEnd();
}
AssociativeAggregationCounter mergedCounter = new AssociativeAggregationCounter(
mergedStart, mergedEnd, associativeAggregation, initialValue
);
mergedCounter.add(associativeAggregation.combine(value.get(), counter.getValue()));
return mergedCounter;
}
}