[GitHub] tinkerpop pull request #445: TINKERPOP-1470: InlineFilterStrategy should try...

[dkuppitz <gi...@git.apache.org>]

Github user dkuppitz commented on a diff in the pull request:

    https://github.com/apache/tinkerpop/pull/445#discussion_r81550568
  
    --- Diff: gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/optimization/InlineFilterStrategy.java ---
    @@ -72,97 +75,163 @@ public void apply(final Traversal.Admin<?, ?> traversal) {
             boolean changed = true; // recursively walk child traversals trying to inline them into the current traversal line.
             while (changed) {
                 changed = false;
    -            // filter(x.y) --> x.y
    -            for (final TraversalFilterStep<?> step : TraversalHelper.getStepsOfClass(TraversalFilterStep.class, traversal)) {
    -                final Traversal.Admin<?, ?> childTraversal = step.getLocalChildren().get(0);
    -                if (TraversalHelper.hasAllStepsOfClass(childTraversal, FilterStep.class) &&
    -                        !TraversalHelper.hasStepOfClass(childTraversal,
    -                                DropStep.class,
    -                                RangeGlobalStep.class,
    -                                DedupGlobalStep.class,
    -                                LambdaHolder.class)) {
    +            for (final FilterStep<?> step : TraversalHelper.getStepsOfAssignableClass(FilterStep.class, traversal)) {
    --- End diff --
    
    Complex traversal could waste a few CPU cycles in this method. Here's an optimized version:
    
    ```
        @Override
        public void apply(final Traversal.Admin<?, ?> traversal) {
            boolean changed = true; // recursively walk child traversals trying to inline them into the current traversal line.
            while (changed) {
                changed = false;
                final Iterator<FilterStep> filterStepIterator = TraversalHelper.getStepsOfAssignableClass(FilterStep.class, traversal).iterator();
                while (!changed && filterStepIterator.hasNext()) {
                    final FilterStep<?> step = filterStepIterator.next();
                    changed = step instanceof HasStep && InlineFilterStrategy.processHasStep((HasStep) step, traversal) ||
                            step instanceof TraversalFilterStep && InlineFilterStrategy.processTraversalFilterStep((TraversalFilterStep) step, traversal) ||
                            step instanceof OrStep && InlineFilterStrategy.processOrStep((OrStep) step, traversal) ||
                            step instanceof AndStep && InlineFilterStrategy.processAndStep((AndStep) step, traversal);
                }
                if (!changed && traversal.getParent() instanceof EmptyStep) {
                    final Iterator<MatchStep> matchStepIterator = TraversalHelper.getStepsOfClass(MatchStep.class, traversal).iterator();
                    while (!changed && matchStepIterator.hasNext()) {
                        if (InlineFilterStrategy.processMatchStep(matchStepIterator.next(), traversal))
                            changed = true;
                    }
                }
            }
        }
    ```


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