org.apache.flink.runtime.jobmanager.scheduler

Class CoLocationConstraint

java.lang.Object

org.apache.flink.runtime.jobmanager.scheduler.CoLocationConstraint

public class CoLocationConstraint
extends Object

A CoLocationConstraint manages the location of a set of tasks (Execution Vertices). In co-location groups, the different subtasks of different JobVertices need to be executed on the same Instance. This is realized by creating a special shared slot that holds these tasks.

This class tracks the location and the shared slot for this set of tasks.

Method Summary

Modifier and Type	Method and Description
org.apache.flink.util.AbstractID	getGroupId() Gets the ID that identifies the co-location group.
Instance	getLocation() Gets the location assigned to this slot.
SharedSlot	getSharedSlot() Gets the shared slot into which this constraint's tasks are places.
boolean	isAssigned() Checks whether the location of this constraint has been assigned.
boolean	isAssignedAndAlive() Checks whether the location of this constraint has been assigned (as defined in the isAssigned() method, and the current shared slot is alive.
void	lockLocation() Locks the location of this slot.
void	setSharedSlot(SharedSlot newSlot) Assigns a new shared slot to this co-location constraint.
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

getSharedSlot

public SharedSlot getSharedSlot()

Gets the shared slot into which this constraint's tasks are places.

Returns:

The shared slot into which this constraint's tasks are places.

getGroupId

public org.apache.flink.util.AbstractID getGroupId()

Gets the ID that identifies the co-location group.

Returns:

The ID that identifies the co-location group.

isAssigned

public boolean isAssigned()

Checks whether the location of this constraint has been assigned. The location is assigned once a slot has been set, via the setSharedSlot(org.apache.flink.runtime.instance.SharedSlot) method, and the location is locked via the lockLocation() method.

Returns:

True if the location has been assigned, false otherwise.

isAssignedAndAlive

public boolean isAssignedAndAlive()

Checks whether the location of this constraint has been assigned (as defined in the isAssigned() method, and the current shared slot is alive.

Returns:

True if the location has been assigned and the shared slot is alive, false otherwise.

getLocation

public Instance getLocation()

Gets the location assigned to this slot. This method only succeeds after the location has been locked via the lockLocation() method and isAssigned() returns true.

Returns:

The instance describing the location for the tasks of this constraint.

Throws:

IllegalStateException - Thrown if the location has not been assigned, yet.

setSharedSlot

public void setSharedSlot(SharedSlot newSlot)

Assigns a new shared slot to this co-location constraint. The shared slot will hold the subtasks that are executed under this co-location constraint. If the constraint's location is assigned, then this slot needs to be from the same location (instance) as the one assigned to this constraint.

If the constraint already has a slot, the current one will be released.

Parameters:

newSlot - The new shared slot to assign to this constraint.

Throws:

IllegalArgumentException - If the constraint's location has been assigned and the new slot is from a different location.

lockLocation

public void lockLocation()
                  throws IllegalStateException

Locks the location of this slot. The location can be locked only once and only after a shared slot has been assigned.

Throws:

IllegalStateException - Thrown, if the location is already locked, or is no slot has been set, yet.

toString

public String toString()

Overrides:

toString in class Object