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* 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.
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package org.apache.tinkerpop.gremlin.process.computer.traversal;
import org.apache.tinkerpop.gremlin.process.computer.Memory;
import org.apache.tinkerpop.gremlin.process.traversal.Path;
import org.apache.tinkerpop.gremlin.process.traversal.Step;
import org.apache.tinkerpop.gremlin.process.traversal.Traverser;
import org.apache.tinkerpop.gremlin.process.traversal.step.Barrier;
import org.apache.tinkerpop.gremlin.process.traversal.step.GraphComputing;
import org.apache.tinkerpop.gremlin.process.traversal.step.LocalBarrier;
import org.apache.tinkerpop.gremlin.process.traversal.step.filter.ConnectiveStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.filter.HasStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.filter.RangeGlobalStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.filter.TailGlobalStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.IdStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.LabelStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.PropertiesStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.PropertyKeyStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.PropertyMapStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.PropertyValueStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.SackStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.EmptyStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.ReducingBarrierStep;
import org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.HaltedTraverserStrategy;
import org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet;
import org.apache.tinkerpop.gremlin.process.traversal.util.PureTraversal;
import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalMatrix;
import org.apache.tinkerpop.gremlin.structure.util.Attachable;
import org.apache.tinkerpop.gremlin.structure.util.detached.DetachedFactory;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* @author Marko A. Rodriguez (http://markorodriguez.com)
*/
final class MasterExecutor {
private MasterExecutor() {
}
protected static void processMemory(final TraversalMatrix<?, ?> traversalMatrix, final Memory memory, final TraverserSet<Object> toProcessTraversers, final Set<String> completedBarriers) {
// handle traversers and data that were sent from the workers to the master traversal via memory
if (memory.exists(TraversalVertexProgram.MUTATED_MEMORY_KEYS)) {
for (final String key : memory.<Set<String>>get(TraversalVertexProgram.MUTATED_MEMORY_KEYS)) {
final Step<Object, Object> step = traversalMatrix.getStepById(key);
assert step instanceof Barrier;
completedBarriers.add(step.getId());
if (!(step instanceof LocalBarrier)) { // local barriers don't do any processing on the master traversal (they just lock on the workers)
final Barrier<Object> barrier = (Barrier<Object>) step;
barrier.addBarrier(memory.get(key));
step.forEachRemaining(toProcessTraversers::add);
// if it was a reducing barrier step, reset the barrier to its seed value
if (step instanceof ReducingBarrierStep)
memory.set(step.getId(), ((ReducingBarrierStep) step).getSeedSupplier().get());
}
}
}
memory.set(TraversalVertexProgram.MUTATED_MEMORY_KEYS, new HashSet<>());
}
protected static void processTraversers(final PureTraversal<?, ?> traversal,
final TraversalMatrix<?, ?> traversalMatrix,
TraverserSet<Object> toProcessTraversers,
final TraverserSet<Object> remoteActiveTraversers,
final TraverserSet<Object> haltedTraversers,
final HaltedTraverserStrategy haltedTraverserStrategy) {
while (!toProcessTraversers.isEmpty()) {
final TraverserSet<Object> localActiveTraversers = new TraverserSet<>();
Step<Object, Object> previousStep = EmptyStep.instance();
Step<Object, Object> currentStep = EmptyStep.instance();
// these are traversers that are at the master traversal and will either halt here or be distributed back to the workers as needed
final Iterator<Traverser.Admin<Object>> traversers = toProcessTraversers.iterator();
while (traversers.hasNext()) {
final Traverser.Admin<Object> traverser = traversers.next();
traversers.remove();
traverser.set(DetachedFactory.detach(traverser.get(), true)); // why?
traverser.setSideEffects(traversal.get().getSideEffects());
if (traverser.isHalted())
haltedTraversers.add(haltedTraverserStrategy.halt(traverser));
else if (isRemoteTraverser(traverser, traversalMatrix)) // this is so that patterns like order().name work as expected. try and stay local as long as possible
remoteActiveTraversers.add(traverser.detach());
else {
currentStep = traversalMatrix.getStepById(traverser.getStepId());
if (!currentStep.getId().equals(previousStep.getId()) && !(previousStep instanceof EmptyStep)) {
GraphComputing.atMaster(previousStep, true);
while (previousStep.hasNext()) {
final Traverser.Admin<Object> result = previousStep.next();
if (result.isHalted())
haltedTraversers.add(haltedTraverserStrategy.halt(result));
else if (isRemoteTraverser(result, traversalMatrix))
remoteActiveTraversers.add(result.detach());
else
localActiveTraversers.add(result);
}
}
currentStep.addStart(traverser);
previousStep = currentStep;
}
}
if (!(currentStep instanceof EmptyStep)) {
GraphComputing.atMaster(currentStep, true);
while (currentStep.hasNext()) {
final Traverser.Admin<Object> traverser = currentStep.next();
if (traverser.isHalted())
haltedTraversers.add(haltedTraverserStrategy.halt(traverser));
else if (isRemoteTraverser(traverser, traversalMatrix))
remoteActiveTraversers.add(traverser.detach());
else
localActiveTraversers.add(traverser);
}
}
assert toProcessTraversers.isEmpty();
toProcessTraversers = localActiveTraversers;
}
}
private static boolean isRemoteTraverser(final Traverser.Admin traverser, final TraversalMatrix<?, ?> traversalMatrix) {
return traverser.get() instanceof Attachable &&
!(traverser.get() instanceof Path) &&
!isLocalElement(traversalMatrix.getStepById(traverser.getStepId()));
}
// TODO: once this is complete (fully known), move to TraversalHelper
private static boolean isLocalElement(final Step<?, ?> step) {
return step instanceof PropertiesStep || step instanceof PropertyMapStep ||
step instanceof IdStep || step instanceof LabelStep || step instanceof SackStep ||
step instanceof PropertyKeyStep || step instanceof PropertyValueStep ||
step instanceof TailGlobalStep || step instanceof RangeGlobalStep || step instanceof HasStep ||
step instanceof ConnectiveStep;
}
}