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/*******************************************************************************
* Copyright (c) 2013, 2016 Willink Transformations and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* E.D.Willink - Initial API and implementation
*******************************************************************************/
package org.eclipse.qvtd.runtime.internal.evaluation;
import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;
import org.eclipse.qvtd.runtime.evaluation.AbstractInvocationManager;
import org.eclipse.qvtd.runtime.evaluation.AbstractTransformer;
import org.eclipse.qvtd.runtime.evaluation.Invocation;
import org.eclipse.qvtd.runtime.evaluation.InvocationFailedException;
import org.eclipse.qvtd.runtime.evaluation.SlotState;
/**
* InvocationManager supervises and provides thread safety for the lists of blocked and waiting invocations.
*/
public class LazyInvocationManager extends AbstractInvocationManager
{
/**
* Head of doubly linked list of blocked invocations.
*/
private @Nullable AbstractInvocationInternal blockedInvocations = null;
/**
* Head of doubly linked list of unblocked invocations waiting for a re-execution attempt.
*/
private @Nullable AbstractInvocationInternal waitingInvocations = null;
private synchronized void block(@NonNull Invocation invocation, @NonNull SlotState slotState) {
AbstractInvocationInternal castInvocation = (AbstractInvocationInternal) invocation;
assert castInvocation.debug_blockedBy == null;
castInvocation.debug_blockedBy = slotState;
AbstractInvocationInternal blockedInvocations2 = blockedInvocations;
if (blockedInvocations2 == null) {
blockedInvocations = castInvocation;
}
else {
castInvocation.insertAfter(blockedInvocations2.prev);
}
slotState.block(invocation);
if (debugInvocations) {
AbstractTransformer.INVOCATIONS.println("block " + invocation + " for " + slotState);
}
}
@Override
public boolean flush() {
flushInternal();
AbstractInvocationInternal blockedInvocation = blockedInvocations;
if (blockedInvocation == null) {
return true;
}
do {
if (debugInvocations) {
AbstractTransformer.INVOCATIONS.println("still blocked " + blockedInvocation + " by " + blockedInvocation.debug_blockedBy);
}
blockedInvocation = blockedInvocation.next;
}
while (blockedInvocation != blockedInvocations);
return false;
}
private void flushInternal() {
while (waitingInvocations != null) {
AbstractInvocationInternal invocation = null;
synchronized (this) {
AbstractInvocationInternal waitingInvocations2 = waitingInvocations;
if (waitingInvocations2 != null) {
invocation = waitingInvocations2;
waitingInvocations = waitingInvocations2.next;
if (waitingInvocations == invocation) {
waitingInvocations = null;
}
invocation.remove();
}
}
if (invocation != null) {
if (debugInvocations) {
AbstractTransformer.INVOCATIONS.println("re-invoke " + invocation);
}
invoke(invocation, false);
}
}
}
@Override
public void invoke(@NonNull Invocation invocation, boolean doFlush) {
try {
invocation.execute();
if (debugInvocations) {
AbstractTransformer.INVOCATIONS.println("done " + invocation);
}
if (doFlush) {
flushInternal();
}
}
catch (InvocationFailedException e) {
block(invocation, e.slotState);
}
}
@Override
public synchronized void unblock(@NonNull Invocation invocation) {
if (debugInvocations) {
AbstractTransformer.INVOCATIONS.println("unblock " + invocation);
}
AbstractInvocationInternal castInvocation = (AbstractInvocationInternal) invocation;
assert castInvocation.debug_blockedBy != null;
castInvocation.debug_blockedBy = null;
if (blockedInvocations == castInvocation) {
blockedInvocations = castInvocation.next;
if (blockedInvocations == castInvocation) {
blockedInvocations = null;
}
}
castInvocation.remove();
AbstractInvocationInternal waitingInvocations2 = waitingInvocations;
if (waitingInvocations2 == null) {
waitingInvocations = castInvocation;
}
else {
castInvocation.insertAfter(waitingInvocations2.prev);
}
}
}
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