/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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.apache.hadoop.yarn.server.resourcemanager.scheduler;
import java.util.HashMap;
/**
* Create a set of buckets that hold key-time pairs. When the values of the
* buckets is queried, the number of objects with time differences in the
* different buckets is returned.
*/
class TimeBucketMetrics<OBJ> {
private final HashMap<OBJ, Long> map = new HashMap<OBJ, Long>();
private final int[] counts;
private final long[] cuts;
/**
* Create a set of buckets based on a set of time points. The number of
* buckets is one more than the number of points.
*/
TimeBucketMetrics(long[] cuts) {
this.cuts = cuts;
counts = new int[cuts.length + 1];
}
/**
* Add an object to be counted
*/
synchronized void add(OBJ key, long time) {
map.put(key, time);
}
/**
* Remove an object to be counted
*/
synchronized void remove(OBJ key) {
map.remove(key);
}
/**
* Find the bucket based on the cut points.
*/
private int findBucket(long val) {
for(int i=0; i < cuts.length; ++i) {
if (val < cuts[i]) {
return i;
}
}
return cuts.length;
}
/**
* Get the counts of how many keys are in each bucket. The same array is
* returned by each call to this method.
*/
synchronized int[] getBucketCounts(long now) {
for(int i=0; i < counts.length; ++i) {
counts[i] = 0;
}
for(Long time: map.values()) {
counts[findBucket(now - time)] += 1;
}
return counts;
}
}