/**
* 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.fair;
import java.io.Serializable;
import java.util.Comparator;
import org.apache.hadoop.classification.InterfaceAudience.Private;
import org.apache.hadoop.classification.InterfaceStability.Unstable;
/**
* Order {@link AppSchedulable} objects by priority and then by submit time, as
* in the default scheduler in Hadoop.
*/
@Private
@Unstable
public class FifoAppComparator implements Comparator<AppSchedulable>, Serializable {
private static final long serialVersionUID = 3428835083489547918L;
public int compare(AppSchedulable a1, AppSchedulable a2) {
int res = a1.getPriority().compareTo(a2.getPriority());
if (res == 0) {
if (a1.getStartTime() < a2.getStartTime()) {
res = -1;
} else {
res = (a1.getStartTime() == a2.getStartTime() ? 0 : 1);
}
}
if (res == 0) {
// If there is a tie, break it by app ID to get a deterministic order
res = a1.getApp().getApplicationId().compareTo(a2.getApp().getApplicationId());
}
return res;
}
}