com.netflix.fenzo.plugins

Class ExclusiveHostConstraint

java.lang.Object

com.netflix.fenzo.plugins.ExclusiveHostConstraint

All Implemented Interfaces:

ConstraintEvaluator

public final class ExclusiveHostConstraint
extends java.lang.Object
implements ConstraintEvaluator

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 ExclusiveHostRestraint then the host on which the task has been assigned fails this exclusive host constraint check as well.

Nested Class Summary

Nested classes/interfaces inherited from interface com.netflix.fenzo.ConstraintEvaluator

ConstraintEvaluator.Result

Constructor Summary

Constructors

Constructor and Description
ExclusiveHostConstraint()

Method Summary

Modifier and Type	Method and Description
ConstraintEvaluator.Result	evaluate(TaskRequest taskRequest, VirtualMachineCurrentState targetVM, TaskTrackerState taskTrackerState) 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.
java.lang.String	getName() Returns the name of this class as a String.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExclusiveHostConstraint

public ExclusiveHostConstraint()

Method Detail

getName

public java.lang.String getName()

Returns the name of this class as a String.

Specified by:

getName in interface ConstraintEvaluator

Returns:

the name of this class

evaluate

public ConstraintEvaluator.Result evaluate(TaskRequest taskRequest,
                                           VirtualMachineCurrentState targetVM,
                                           TaskTrackerState taskTrackerState)

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.

Specified by:

evaluate in interface ConstraintEvaluator

Parameters:

taskRequest - describes the task to be considered for assignment to the host

targetVM - describes the host to be considered for accepting the task

taskTrackerState - describes the state of tasks assigned to or running on hosts throughout the system

Returns:

an unsuccessful Result if the target already has running tasks or assigned tasks, or a successful Result otherwise