/*
* 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.tinkerpop.gremlin.process.computer.traversal.step.map;
import org.apache.tinkerpop.gremlin.process.computer.Computer;
import org.apache.tinkerpop.gremlin.process.computer.ComputerResult;
import org.apache.tinkerpop.gremlin.process.computer.GraphComputer;
import org.apache.tinkerpop.gremlin.process.computer.Memory;
import org.apache.tinkerpop.gremlin.process.computer.traversal.TraversalVertexProgram;
import org.apache.tinkerpop.gremlin.process.computer.traversal.step.VertexComputing;
import org.apache.tinkerpop.gremlin.process.computer.util.EmptyMemory;
import org.apache.tinkerpop.gremlin.process.traversal.Step;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalSideEffects;
import org.apache.tinkerpop.gremlin.process.traversal.Traverser;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.EmptyStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.ProfileStep;
import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalInterruptedException;
import org.apache.tinkerpop.gremlin.structure.Graph;
import java.util.NoSuchElementException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
/**
* @author Marko A. Rodriguez (http://markorodriguez.com)
* @author Stephen Mallette (http://stephen.genoprime.com)
*/
public abstract class VertexProgramStep extends AbstractStep<ComputerResult, ComputerResult> implements VertexComputing {
public static final String ROOT_TRAVERSAL = "gremlin.vertexProgramStep.rootTraversal";
public static final String STEP_ID = "gremlin.vertexProgramStep.stepId";
protected Computer computer = Computer.compute();
protected boolean first = true;
public VertexProgramStep(final Traversal.Admin traversal) {
super(traversal);
}
@Override
protected Traverser.Admin<ComputerResult> processNextStart() throws NoSuchElementException {
Future<ComputerResult> future = null;
try {
if (this.first && this.getPreviousStep() instanceof EmptyStep) {
this.first = false;
final Graph graph = this.getTraversal().getGraph().get();
future = this.getComputer().apply(graph).program(this.generateProgram(graph, EmptyMemory.instance())).submit();
final ComputerResult result = future.get();
this.processMemorySideEffects(result.memory());
return this.getTraversal().getTraverserGenerator().generate(result, this, 1l);
} else {
final Traverser.Admin<ComputerResult> traverser = this.starts.next();
final Graph graph = traverser.get().graph();
final Memory memory = traverser.get().memory();
future = this.generateComputer(graph).program(this.generateProgram(graph, memory)).submit();
final ComputerResult result = future.get();
this.processMemorySideEffects(result.memory());
return traverser.split(result, this);
}
} catch (final InterruptedException ie) {
// the thread running the traversal took an interruption while waiting on the call the future.get().
// the future should then be cancelled with interruption so that the GraphComputer that created
// the future knows we don't care about it anymore. The GraphComputer should attempt to respect this
// cancellation request.
if (future != null) future.cancel(true);
throw new TraversalInterruptedException();
} catch (ExecutionException e) {
throw new IllegalStateException(e.getMessage(), e);
}
}
@Override
public Computer getComputer() {
Computer tempComputer = this.computer;
if (!this.isEndStep()) {
if (null == tempComputer.getPersist())
tempComputer = tempComputer.persist(GraphComputer.Persist.EDGES);
if (null == tempComputer.getResultGraph())
tempComputer = tempComputer.result(GraphComputer.ResultGraph.NEW);
}
return tempComputer;
}
@Override
public void setComputer(final Computer computer) {
this.computer = computer;
}
protected boolean previousTraversalVertexProgram() {
Step<?, ?> currentStep = this;
while (!(currentStep instanceof EmptyStep)) {
if (currentStep instanceof TraversalVertexProgramStep)
return true;
currentStep = currentStep.getPreviousStep();
}
return false;
}
private void processMemorySideEffects(final Memory memory) {
// update the traversal side-effects with the state of the memory after the OLAP job execution
final TraversalSideEffects sideEffects = this.getTraversal().getSideEffects();
for (final String key : memory.keys()) {
if (sideEffects.exists(key)) {
// halted traversers should never be propagated through sideEffects
assert !key.equals(TraversalVertexProgram.HALTED_TRAVERSERS);
sideEffects.set(key, memory.get(key));
}
}
}
protected boolean isEndStep() {
return this.getNextStep() instanceof ComputerResultStep || (this.getNextStep() instanceof ProfileStep && this.getNextStep().getNextStep() instanceof ComputerResultStep);
}
}