/*
* 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.flink.runtime.jobmanager.scheduler;
import org.apache.flink.runtime.clusterframework.types.ResourceID;
import org.apache.flink.runtime.taskmanager.TaskManagerLocation;
import org.apache.flink.util.AbstractID;
import org.apache.flink.runtime.instance.Instance;
import org.apache.flink.util.Preconditions;
import org.apache.flink.runtime.instance.SharedSlot;
import static org.apache.flink.util.Preconditions.checkState;
import static org.apache.flink.util.Preconditions.checkNotNull;
/**
* 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 {@link Instance}.
* This is realized by creating a special shared slot that holds these tasks.
*
* <p>This class tracks the location and the shared slot for this set of tasks.
*/
public class CoLocationConstraint {
private final CoLocationGroup group;
private volatile SharedSlot sharedSlot;
private volatile ResourceID lockedLocation;
CoLocationConstraint(CoLocationGroup group) {
Preconditions.checkNotNull(group);
this.group = group;
}
// ------------------------------------------------------------------------
// Status & Properties
// ------------------------------------------------------------------------
/**
* Gets the shared slot into which this constraint's tasks are places.
*
* @return The shared slot into which this constraint's tasks are places.
*/
public SharedSlot getSharedSlot() {
return sharedSlot;
}
/**
* Gets the ID that identifies the co-location group.
*
* @return The ID that identifies the co-location group.
*/
public AbstractID getGroupId() {
return this.group.getId();
}
/**
* Checks whether the location of this constraint has been assigned.
* The location is assigned once a slot has been set, via the
* {@link #setSharedSlot(org.apache.flink.runtime.instance.SharedSlot)} method,
* and the location is locked via the {@link #lockLocation()} method.
*
* @return True if the location has been assigned, false otherwise.
*/
public boolean isAssigned() {
return lockedLocation != null;
}
/**
* Checks whether the location of this constraint has been assigned
* (as defined in the {@link #isAssigned()} method, and the current
* shared slot is alive.
*
* @return True if the location has been assigned and the shared slot is alive,
* false otherwise.
*/
public boolean isAssignedAndAlive() {
return lockedLocation != null && sharedSlot.isAlive();
}
/**
* Gets the location assigned to this slot. This method only succeeds after
* the location has been locked via the {@link #lockLocation()} method and
* {@link #isAssigned()} returns true.
*
* @return The instance describing the location for the tasks of this constraint.
* @throws IllegalStateException Thrown if the location has not been assigned, yet.
*/
public TaskManagerLocation getLocation() {
if (lockedLocation != null) {
return sharedSlot.getTaskManagerLocation();
} else {
throw new IllegalStateException("Location not yet locked");
}
}
// ------------------------------------------------------------------------
// Assigning resources and location
// ------------------------------------------------------------------------
/**
* 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.
*
* <p>If the constraint already has a slot, the current one will be released.</p>
*
* @param 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.
*/
public void setSharedSlot(SharedSlot newSlot) {
checkNotNull(newSlot);
if (this.sharedSlot == null) {
this.sharedSlot = newSlot;
}
else if (newSlot != this.sharedSlot){
if (lockedLocation != null && lockedLocation != newSlot.getTaskManagerID()) {
throw new IllegalArgumentException(
"Cannot assign different location to a constraint whose location is locked.");
}
if (this.sharedSlot.isAlive()) {
this.sharedSlot.releaseSlot();
}
this.sharedSlot = newSlot;
}
}
/**
* 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.
*/
public void lockLocation() throws IllegalStateException {
checkState(lockedLocation == null, "Location is already locked");
checkState(sharedSlot != null, "Cannot lock location without a slot.");
lockedLocation = sharedSlot.getTaskManagerID();
}
// ------------------------------------------------------------------------
// Utilities
// ------------------------------------------------------------------------
@Override
public String toString() {
return "CoLocation constraint id " + getGroupId() + " shared slot " + sharedSlot;
}
}