/*
* Copyright 2016 Red Hat, Inc. and/or its affiliates.
*
* Licensed 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.optaplanner.core.impl.solver.termination;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import org.optaplanner.core.impl.phase.scope.AbstractPhaseScope;
import org.optaplanner.core.impl.solver.ChildThreadType;
import org.optaplanner.core.impl.solver.ProblemFactChange;
import org.optaplanner.core.impl.solver.scope.DefaultSolverScope;
/**
* Concurrency notes:
* Condition predicate on ({@link #problemFactChangeQueue} is not empty or {@link #terminatedEarly} is true).
*/
public class BasicPlumbingTermination extends AbstractTermination {
protected final boolean daemon;
protected boolean terminatedEarly = false;
protected BlockingQueue<ProblemFactChange> problemFactChangeQueue = new LinkedBlockingQueue<>();
protected boolean problemFactChangesBeingProcessed = false;
public BasicPlumbingTermination(boolean daemon) {
this.daemon = daemon;
}
// ************************************************************************
// Plumbing worker methods
// ************************************************************************
/**
* This method is thread-safe.
*/
public synchronized void resetTerminateEarly() {
terminatedEarly = false;
}
/**
* This method is thread-safe.
* <p>
* Concurrency note: unblocks {@link #waitForRestartSolverDecision()}.
* @return true if successful
*/
public synchronized boolean terminateEarly() {
boolean terminationEarlySuccessful = !terminatedEarly;
terminatedEarly = true;
notifyAll();
return terminationEarlySuccessful;
}
/**
* This method is thread-safe.
*/
public synchronized boolean isTerminateEarly() {
return terminatedEarly;
}
/**
* If this returns true, then the problemFactChangeQueue is definitely not empty.
* <p>
* Concurrency note: Blocks until {@link #problemFactChangeQueue} is not empty or {@link #terminatedEarly} is true.
* @return true if the solver needs to be restarted
*/
public synchronized boolean waitForRestartSolverDecision() {
if (!daemon) {
return !problemFactChangeQueue.isEmpty() && !terminatedEarly;
} else {
while (problemFactChangeQueue.isEmpty() && !terminatedEarly) {
try {
wait();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new IllegalStateException("Solver thread was interrupted during Object.wait().", e);
}
}
return !terminatedEarly;
}
}
/**
* Concurrency note: unblocks {@link #waitForRestartSolverDecision()}.
* @param problemFactChange never null
* @return as specified by {@link Collection#add}
*/
public synchronized <Solution_> boolean addProblemFactChange(ProblemFactChange<Solution_> problemFactChange) {
boolean added = problemFactChangeQueue.add(problemFactChange);
notifyAll();
return added;
}
/**
* Concurrency note: unblocks {@link #waitForRestartSolverDecision()}.
* @param problemFactChangeList never null
* @return as specified by {@link Collection#add}
*/
public synchronized <Solution_> boolean addProblemFactChanges(List<ProblemFactChange<Solution_>> problemFactChangeList) {
boolean added = problemFactChangeQueue.addAll(problemFactChangeList);
notifyAll();
return added;
}
public synchronized BlockingQueue<ProblemFactChange> startProblemFactChangesProcessing() {
problemFactChangesBeingProcessed = true;
return problemFactChangeQueue;
}
public synchronized void endProblemFactChangesProcessing() {
problemFactChangesBeingProcessed = false;
}
public synchronized boolean isEveryProblemFactChangeProcessed() {
return problemFactChangeQueue.isEmpty() && !problemFactChangesBeingProcessed;
}
// ************************************************************************
// Termination worker methods
// ************************************************************************
@Override
public synchronized boolean isSolverTerminated(DefaultSolverScope solverScope) {
// Destroying a thread pool with solver threads will only cause it to interrupt those solver threads
if (Thread.currentThread().isInterrupted()) { // Does not clear the interrupted flag
logger.info("The solver thread got interrupted, so this solver is terminating early.");
terminatedEarly = true;
}
return terminatedEarly || !problemFactChangeQueue.isEmpty();
}
@Override
public boolean isPhaseTerminated(AbstractPhaseScope phaseScope) {
throw new IllegalStateException(BasicPlumbingTermination.class.getSimpleName()
+ " configured only as solver termination."
+ " It is always bridged to phase termination.");
}
@Override
public double calculateSolverTimeGradient(DefaultSolverScope solverScope) {
return -1.0; // Not supported
}
@Override
public double calculatePhaseTimeGradient(AbstractPhaseScope phaseScope) {
throw new IllegalStateException(BasicPlumbingTermination.class.getSimpleName()
+ " configured only as solver termination."
+ " It is always bridged to phase termination.");
}
// ************************************************************************
// Other methods
// ************************************************************************
@Override
public Termination createChildThreadTermination(DefaultSolverScope solverScope, ChildThreadType childThreadType) {
return this;
}
@Override
public String toString() {
return "BasicPlumbing()";
}
}