com.netflix.fenzo.plugins.ExclusiveHostConstraint Maven / Gradle / Ivy
/*
* Copyright 2015 Netflix, 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.netflix.fenzo.plugins;
import com.netflix.fenzo.ConstraintEvaluator;
import com.netflix.fenzo.TaskAssignmentResult;
import com.netflix.fenzo.TaskRequest;
import com.netflix.fenzo.TaskTrackerState;
import com.netflix.fenzo.VirtualMachineCurrentState;
import java.util.Collection;
/**
* This constraint ensures that the host is exclusively assigned to the given job. You may not extend this
* class.
*
* The task scheduler gives this constraint special treatment: While usually the scheduler only evaluates the
* constraints of a new task, if an already-assigned task has an {@code ExclusiveHostRestraint} then the host on
* which the task has been assigned fails this exclusive host constraint check as well.
*/
public final class ExclusiveHostConstraint implements ConstraintEvaluator {
/**
* Returns the name of this class as a String.
*
* @return the name of this class
*/
@Override
public String getName() {
return ExclusiveHostConstraint.class.getName();
}
/**
* Determines whether the prospective host already has tasks either running on it or assigned to be run on
* it, and returns a false Result if either of those things is the case.
*
* @param taskRequest describes the task to be considered for assignment to the host
* @param targetVM describes the host to be considered for accepting the task
* @param taskTrackerState describes the state of tasks assigned to or running on hosts throughout the
* system
* @return an unsuccessful Result if the target already has running tasks or assigned tasks, or a successful
* Result otherwise
*/
@Override
public Result evaluate(TaskRequest taskRequest, VirtualMachineCurrentState targetVM, TaskTrackerState taskTrackerState) {
Collection runningTasks = targetVM.getRunningTasks();
if(runningTasks!=null && !runningTasks.isEmpty())
return new Result(false, "Already has " + runningTasks.size() + " tasks running on it");
Collection tasksCurrentlyAssigned = targetVM.getTasksCurrentlyAssigned();
if(tasksCurrentlyAssigned!=null && !tasksCurrentlyAssigned.isEmpty())
return new Result(false, "Already has " + tasksCurrentlyAssigned.size() + " assigned on it");
return new Result(true, "");
}
}