/
TaskEvaluationQueue.java
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/
TaskEvaluationQueue.java
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package org.metaborg.runtime.task.evaluation;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
import org.metaborg.runtime.task.ITaskEngine;
import org.metaborg.runtime.task.Task;
import org.metaborg.runtime.task.collection.BidirectionalLinkedHashMultimap;
import org.metaborg.runtime.task.collection.BidirectionalSetMultimap;
import org.spoofax.interpreter.core.IContext;
import org.spoofax.interpreter.core.Tools;
import org.spoofax.interpreter.stratego.Strategy;
import org.spoofax.interpreter.terms.IStrategoAppl;
import org.spoofax.interpreter.terms.IStrategoConstructor;
import org.spoofax.interpreter.terms.IStrategoList;
import org.spoofax.interpreter.terms.IStrategoTerm;
import org.spoofax.interpreter.terms.IStrategoTuple;
import org.spoofax.interpreter.terms.ITermFactory;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.HashMultiset;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multiset;
import com.google.common.collect.Multisets;
import com.google.common.collect.Sets;
public class TaskEvaluationQueue implements ITaskEvaluationQueue, ITaskEvaluationFrontend {
private final ITaskEngine taskEngine;
private final ITermFactory factory;
/** Queue of task that are scheduled for evaluation. */
private final Queue<IStrategoTerm> evaluationQueue = Lists.newLinkedList();
/** Set of tasks in the queue. **/
private final Set<IStrategoTerm> queued = Sets.newHashSet();
/** Dependencies of tasks which are updated during evaluation. */
private BidirectionalSetMultimap<IStrategoTerm, IStrategoTerm> runtimeDependencies =
BidirectionalLinkedHashMultimap.create();
/** Maps the constructor of a task to the evaluator that can evaluate the task. */
private final Map<IStrategoConstructor, ITaskEvaluator> taskEvaluators = Maps.newLinkedHashMap();
/** The default task evaluator that is used to evaluate tasks for which there is no specific evaluator. */
private final ITaskEvaluator defaultTaskEvaluator;
private Set<IStrategoTerm> scheduled;
private final Set<IStrategoTerm> skipped = Sets.newHashSet();
private final Set<IStrategoTerm> evaluated = Sets.newHashSet();
public TaskEvaluationQueue(ITaskEngine taskEngine, ITermFactory factory, ITaskEvaluator defaultTaskEvaluator) {
this.taskEngine = taskEngine;
this.factory = factory;
this.defaultTaskEvaluator = defaultTaskEvaluator;
}
@Override
public void queue(IStrategoTerm taskID) {
if(!queued.contains(taskID)) {
evaluationQueue.add(taskID);
queued.add(taskID);
}
}
@Override
public void queueOrDefer(IStrategoTerm taskID) {
final Iterable<IStrategoTerm> dependencies = taskEngine.getDependencies(taskID);
final Set<IStrategoTerm> dependenciesSet = Sets.newHashSet(dependencies);
// TODO: this could be done in constant time if task engine keeps a set of solved tasks.
for(final IStrategoTerm dependency : dependencies) {
if(taskEngine.getTask(dependency).solved()) {
dependenciesSet.remove(dependency);
}
}
if(dependenciesSet.isEmpty()) {
// If the task has no unsolved dependencies, queue it for analysis.
queue(taskID);
} else {
// Fill toRuntimeDependency for scheduled tasks such that solving the task activates their dependent tasks.
runtimeDependencies.putAll(taskID, dependenciesSet);
}
}
@Override
public void taskSolved(IStrategoTerm taskID) {
// Retrieve dependent tasks of the solved task.
final Set<IStrategoTerm> dependents = Sets.newHashSet(taskEngine.getDependent(taskID, false));
dependents.addAll(runtimeDependencies.getInverse(taskID));
for(final IStrategoTerm dependentTaskID : dependents) {
// Remove the dependency to the solved task. If that was the last dependency, schedule the task.
final boolean removed = runtimeDependencies.remove(dependentTaskID, taskID);
if(removed && runtimeDependencies.get(dependentTaskID).size() == 0
&& !taskEngine.getTask(dependentTaskID).solved())
queue(dependentTaskID);
}
}
@Override
public void taskSkipped(IStrategoTerm taskID) {
scheduled.remove(taskID);
skipped.add(taskID);
}
@Override
public void taskDelayed(IStrategoTerm taskID, Iterable<IStrategoTerm> dependencies) {
TaskEvaluationDebugging.debugDelayedDependecy(taskEngine, taskID, dependencies);
// Sets the runtime dependencies for a task to the given dependency list.
runtimeDependencies.removeAll(taskID);
for(final IStrategoTerm dependency : dependencies)
runtimeDependencies.put(taskID, dependency);
taskEngine.setDynamicDependencies(taskID, dependencies);
scheduled.add(taskID);
}
@Override
public void addRuntimeDependency(IStrategoTerm taskID, IStrategoTerm dependencyTaskID) {
runtimeDependencies.put(taskID, dependencyTaskID);
}
@Override
public void removeRuntimeDependency(IStrategoTerm taskID, IStrategoTerm dependencyTaskID) {
runtimeDependencies.remove(taskID, dependencyTaskID);
}
@Override
public void addTaskEvaluator(IStrategoConstructor constructor, ITaskEvaluator taskEvaluator) {
if(taskEvaluators.put(constructor, taskEvaluator) != null) {
throw new RuntimeException("Task evaluator for " + constructor + " already exists.");
}
}
@Override
public IStrategoList adjustDependencies(IStrategoList dependencies, IStrategoTerm instruction) {
final ITaskEvaluator taskEvaluator = getTaskEvaluator(instruction);
return taskEvaluator.adjustDependencies(dependencies, factory);
}
@Override
public IStrategoTuple evaluate(Set<IStrategoTerm> scheduled, IContext context, Strategy collect, Strategy insert,
Strategy perform) {
try {
this.scheduled = scheduled;
// Queue tasks and evaluate them for each specific task evaluator.
for(ITaskEvaluator taskEvaluator : taskEvaluators.values()) {
taskEvaluator.queue(taskEngine, this, this.scheduled);
evaluateQueuedTasks(context, collect, insert, perform);
}
// Evaluate the remaining tasks with the default task evaluator.
defaultTaskEvaluator.queue(taskEngine, this, this.scheduled);
evaluateQueuedTasks(context, collect, insert, perform);
if(!this.scheduled.isEmpty()) {
// Debug unevaluated tasks if debugging is enabled.
TaskEvaluationDebugging.debugUnevaluated(taskEngine, this.scheduled, runtimeDependencies);
// Make a copy of the dynamic dependency graph for later use.
final BidirectionalSetMultimap<IStrategoTerm, IStrategoTerm> copiedRuntimeDependencies =
BidirectionalLinkedHashMultimap.create(runtimeDependencies);
final Set<IStrategoTerm> taskIDs = Sets.newHashSet(copiedRuntimeDependencies.keySet());
// Evaluate all tasks left in the dependency graph using a special strategy to break cycles.
for(final IStrategoTerm taskID : taskIDs) {
queue(taskID);
}
evaluateCyclicTasks(context, collect, insert, perform);
// Store values
final Multimap<IStrategoTerm, IStrategoTerm> values = ArrayListMultimap.create();
for(final IStrategoTerm taskID : taskIDs) {
final Task task = taskEngine.getTask(taskID);
if(!task.failed())
values.putAll(taskID, task.results());
}
// Do fixpoint evaluation until the results of tasks stop changing.
for(int i = 0; i < 25; ++i) {
System.out.println("Fixpoint cycle " + i);
runtimeDependencies = BidirectionalLinkedHashMultimap.create(copiedRuntimeDependencies);
for(final IStrategoTerm taskID : taskIDs) {
queue(taskID);
}
evaluateCyclicTasks(context, collect, insert, perform);
// Compare values
boolean done = true;
for(final IStrategoTerm taskID : taskIDs) {
final Task task = taskEngine.getTask(taskID);
// TODO: this assumes that no results and failure means the same, is that correct?
if(values.get(taskID).isEmpty()) {
if(task.failed() || !task.hasResults()) {
continue;
} else {
done = false;
break;
}
} else if(task.failed() || !task.hasResults()) {
done = false;
break;
}
// TODO: creating two sets and taking the symmetric difference is VERY expensive?
final Multiset<IStrategoTerm> oldValues = HashMultiset.create(values.get(taskID));
final Multiset<IStrategoTerm> newValues = HashMultiset.create(task.results());
final Multiset<IStrategoTerm> diff1 = Multisets.difference(newValues, oldValues);
final Multiset<IStrategoTerm> diff2 = Multisets.difference(oldValues, newValues);
if(!diff1.isEmpty() || !diff2.isEmpty()) {
done = false;
break;
}
}
if(done) {
System.out.println("Done with fixpoint evaluation!");
break;
}
values.clear();
for(final IStrategoTerm taskID : taskIDs) {
final Task task = taskEngine.getTask(taskID);
if(!task.failed())
values.putAll(taskID, task.results());
}
}
}
// Return evaluated, skipped and unevaluated task identifiers.
return factory.makeTuple(factory.makeList(evaluated), factory.makeList(skipped),
factory.makeList(this.scheduled));
} finally {
reset();
}
}
@Override
public void reset() {
evaluationQueue.clear();
queued.clear();
runtimeDependencies.clear();
scheduled = null;
skipped.clear();
evaluated.clear();
for(ITaskEvaluator evaluator : taskEvaluators.values())
evaluator.reset();
defaultTaskEvaluator.reset();
}
/**
* Evaluates queued tasks and updates the scheduled and evaluated sets.
*/
private void evaluateQueuedTasks(IContext context, Strategy collect, Strategy insert, Strategy perform) {
// Evaluate each task in the queue.
for(IStrategoTerm taskID; (taskID = evaluationQueue.poll()) != null;) {
final Task task = taskEngine.getTask(taskID);
evaluated.add(taskID);
scheduled.remove(taskID);
queued.remove(taskID);
// Clean up data for this task again, since a task may be scheduled multiple times. A re-schedule should
// overwrite previous data.
taskEngine.invalidate(taskID);
evaluateTask(taskID, task, context, collect, insert, perform);
}
}
/**
* Evaluates queued tasks and updates the scheduled and evaluated sets.
*/
private void evaluateCyclicTasks(IContext context, Strategy collect, Strategy insert, Strategy perform) {
// Evaluate each task in the queue.
for(IStrategoTerm taskID; (taskID = evaluationQueue.poll()) != null;) {
final Task task = taskEngine.getTask(taskID);
evaluated.add(taskID);
scheduled.remove(taskID);
queued.remove(taskID);
// Clean up data for this task again, since a task may be scheduled multiple times. A re-schedule should
// overwrite previous data.
taskEngine.invalidate(taskID);
evaluateCyclicTask(taskID, task, context, collect, insert, perform);
}
}
/**
* Returns a task evaluator for given instruction.
*/
private ITaskEvaluator getTaskEvaluator(IStrategoTerm instruction) {
ITaskEvaluator taskEvaluator;
if(!Tools.isTermAppl(instruction)) {
taskEvaluator = defaultTaskEvaluator;
} else {
taskEvaluator = taskEvaluators.get(((IStrategoAppl) instruction).getConstructor());
if(taskEvaluator == null)
taskEvaluator = defaultTaskEvaluator;
}
return taskEvaluator;
}
/**
* Evaluates given task using a specific or default task evaluator.
*/
private void evaluateTask(IStrategoTerm taskID, Task task, IContext context, Strategy collect, Strategy insert,
Strategy perform) {
final ITaskEvaluator taskEvaluator = getTaskEvaluator(task.instruction);
taskEvaluator.evaluate(taskID, task, taskEngine, this, context, collect, insert, perform);
}
/**
* Evaluates given task using a specific or default task evaluator.
*/
private void evaluateCyclicTask(IStrategoTerm taskID, Task task, IContext context, Strategy collect,
Strategy insert, Strategy perform) {
final ITaskEvaluator taskEvaluator = getTaskEvaluator(task.instruction);
taskEvaluator.evaluateCyclic(taskID, task, taskEngine, this, context, collect, insert, perform);
}
}