/*
* 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.instance;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import org.apache.flink.runtime.executiongraph.Execution;
import org.apache.flink.runtime.jobgraph.JobID;
import org.apache.flink.runtime.jobmanager.scheduler.Locality;
/**
* An allocated slot is the unit in which resources are allocated on instances.
*/
public class AllocatedSlot {
private static final AtomicIntegerFieldUpdater<AllocatedSlot> STATUS_UPDATER =
AtomicIntegerFieldUpdater.newUpdater(AllocatedSlot.class, "status");
private static final AtomicReferenceFieldUpdater<AllocatedSlot, Execution> VERTEX_UPDATER =
AtomicReferenceFieldUpdater.newUpdater(AllocatedSlot.class, Execution.class, "executedTask");
private static final int ALLOCATED_AND_ALIVE = 0; // tasks may be added and might be running
private static final int CANCELLED = 1; // no more tasks may run
private static final int RELEASED = 2; // has been given back to the instance
/** The ID of the job this slice belongs to. */
private final JobID jobID;
/** The instance on which the slot is allocated */
private final Instance instance;
/** The number of the slot on which the task is deployed */
private final int slotNumber;
/** Task being executed in the slot. Volatile to force a memory barrier and allow for correct double-checking */
private volatile Execution executedTask;
/** The state of the vertex, only atomically updated */
private volatile int status = ALLOCATED_AND_ALIVE;
private Locality locality = Locality.UNCONSTRAINED;
public AllocatedSlot(JobID jobID, Instance instance, int slotNumber) {
if (jobID == null || instance == null || slotNumber < 0) {
throw new IllegalArgumentException();
}
this.jobID = jobID;
this.instance = instance;
this.slotNumber = slotNumber;
}
// --------------------------------------------------------------------------------------------
/**
* Returns the ID of the job this allocated slot belongs to.
*
* @return the ID of the job this allocated slot belongs to
*/
public JobID getJobID() {
return this.jobID;
}
public Instance getInstance() {
return instance;
}
public int getSlotNumber() {
return slotNumber;
}
public Execution getExecutedVertex() {
return executedTask;
}
public Locality getLocality() {
return locality;
}
public void setLocality(Locality locality) {
this.locality = locality;
}
public boolean setExecutedVertex(Execution executedVertex) {
if (executedVertex == null) {
throw new NullPointerException();
}
// check that we can actually run in this slot
if (status != ALLOCATED_AND_ALIVE) {
return false;
}
// atomically assign the vertex
if (!VERTEX_UPDATER.compareAndSet(this, null, executedVertex)) {
return false;
}
// we need to do a double check that we were not cancelled in the meantime
if (status != ALLOCATED_AND_ALIVE) {
this.executedTask = null;
return false;
}
return true;
}
// --------------------------------------------------------------------------------------------
// Status and life cycle
// --------------------------------------------------------------------------------------------
public boolean isAlive() {
return status == ALLOCATED_AND_ALIVE;
}
public boolean isCanceled() {
return status != ALLOCATED_AND_ALIVE;
}
public boolean isReleased() {
return status == RELEASED;
}
public void cancel() {
if (STATUS_UPDATER.compareAndSet(this, ALLOCATED_AND_ALIVE, CANCELLED)) {
// kill all tasks currently running in this slot
Execution exec = this.executedTask;
if (exec != null && !exec.isFinished()) {
exec.fail(new Exception("The slot in which the task was scheduled has been killed (probably loss of TaskManager)."));
}
}
}
public void releaseSlot() {
// cancel everything, if there is something. since this is atomically status based,
// it will not happen twice if another attempt happened before or concurrently
try {
cancel();
} finally {
this.instance.returnAllocatedSlot(this);
}
}
protected boolean markReleased() {
return STATUS_UPDATER.compareAndSet(this, CANCELLED, RELEASED);
}
// --------------------------------------------------------------------------------------------
// Utilities
// --------------------------------------------------------------------------------------------
@Override
public String toString() {
return instance.getId() + " (" + slotNumber + ") - " + getStateName(status);
}
private static final String getStateName(int state) {
switch (state) {
case ALLOCATED_AND_ALIVE:
return "ALLOCATED/ALIVE";
case CANCELLED:
return "CANCELLED";
case RELEASED:
return "RELEASED";
default:
return "(unknown)";
}
}
}