com.netflix.fenzo

Interface ConstraintEvaluator

All Known Implementing Classes:

BalancedHostAttrConstraint, ExclusiveHostConstraint, HostAttrValueConstraint, UniqueHostAttrConstraint

public interface ConstraintEvaluator

A constraint evaluator inspects a target to decide whether or not its attributes are satisfactory according to some standard given the current state of task assignments in the system at large. Different constraint evaluators look at different attributes and have different standards for how they make this decision.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ConstraintEvaluator.Result The result of the evaluation of a ConstraintEvaluator.

Method Summary

Modifier and Type	Method and Description
ConstraintEvaluator.Result	evaluate(TaskRequest taskRequest, VirtualMachineCurrentState targetVM, TaskTrackerState taskTrackerState) Inspects a target to decide whether or not it meets the constraints appropriate to a particular task.
java.lang.String	getName() Returns the name of the constraint evaluator.

Method Detail

getName

java.lang.String getName()

Returns the name of the constraint evaluator.

Returns:

the name of the constraint evaluator

evaluate

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

Inspects a target to decide whether or not it meets the constraints appropriate to a particular task.

Parameters:

taskRequest - a description of the task to be assigned

targetVM - a description of the host that is a potential match for the task

taskTrackerState - the current status of tasks and task assignments in the system at large

Returns:

a successful Result if the target meets the constraints enforced by this constraint evaluator, or an unsuccessful Result otherwise