com.google.devtools.build.lib.skyframe.ToplevelSkylarkAspectFunction.java Source code

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Here is the source code for com.google.devtools.build.lib.skyframe.ToplevelSkylarkAspectFunction.java

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// Copyright 2015 The Bazel Authors. All rights reserved.
//
// Licensed 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 com.google.devtools.build.lib.skyframe;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.packages.AspectDescriptor;
import com.google.devtools.build.lib.packages.AspectParameters;
import com.google.devtools.build.lib.packages.SkylarkAspect;
import com.google.devtools.build.lib.skyframe.AspectFunction.AspectCreationException;
import com.google.devtools.build.lib.skyframe.AspectValue.SkylarkAspectLoadingKey;
import com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.SkylarkImportFailedException;
import com.google.devtools.build.lib.syntax.SkylarkImport;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyFunctionException;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import javax.annotation.Nullable;

/**
 * SkyFunction to load aspects from Skylark extensions and calculate their values.
 *
 * Used for loading top-level aspects. At top level, in
 * {@link com.google.devtools.build.lib.analysis.BuildView}, we cannot invoke two SkyFunctions
 * one after another, so BuildView calls this function to do the work.
 */
public class ToplevelSkylarkAspectFunction implements SkyFunction {

    @Nullable
    @Override
    public SkyValue compute(SkyKey skyKey, Environment env)
            throws LoadSkylarkAspectFunctionException, InterruptedException {
        SkylarkAspectLoadingKey aspectLoadingKey = (SkylarkAspectLoadingKey) skyKey.argument();
        String skylarkValueName = aspectLoadingKey.getSkylarkValueName();
        SkylarkImport extensionFile = aspectLoadingKey.getSkylarkImport();

        // Find label corresponding to skylark file, if one exists.
        ImmutableMap<String, Label> labelLookupMap;
        try {
            labelLookupMap = SkylarkImportLookupFunction.findLabelsForLoadStatements(
                    ImmutableList.of(extensionFile), Label.parseAbsoluteUnchecked("//:empty"), env);
        } catch (SkylarkImportFailedException e) {
            env.getListener().handle(Event.error(e.getMessage()));
            throw new LoadSkylarkAspectFunctionException(new AspectCreationException(e.getMessage()));
        }
        if (labelLookupMap == null) {
            return null;
        }

        SkylarkAspect skylarkAspect;
        Label extensionFileLabel = Iterables.getOnlyElement(labelLookupMap.values());
        try {
            skylarkAspect = AspectFunction.loadSkylarkAspect(env, extensionFileLabel, skylarkValueName);
            if (skylarkAspect == null) {
                return null;
            }
            if (!skylarkAspect.getParamAttributes().isEmpty()) {
                throw new AspectCreationException(
                        "Cannot instantiate parameterized aspect " + skylarkAspect.getName() + " at the top level.",
                        extensionFileLabel);
            }
        } catch (AspectCreationException e) {
            throw new LoadSkylarkAspectFunctionException(e);
        }
        SkyKey aspectKey = ActionLookupValue.key(AspectValue.createAspectKey(aspectLoadingKey.getTargetLabel(),
                aspectLoadingKey.getTargetConfiguration(),
                new AspectDescriptor(skylarkAspect.getAspectClass(), AspectParameters.EMPTY),
                aspectLoadingKey.getAspectConfiguration()));

        return env.getValue(aspectKey);
    }

    @Nullable
    @Override
    public String extractTag(SkyKey skyKey) {
        return null;
    }

    /**
     * Exceptions thrown from ToplevelSkylarkAspectFunction.
     */
    public class LoadSkylarkAspectFunctionException extends SkyFunctionException {
        public LoadSkylarkAspectFunctionException(AspectCreationException cause) {
            super(cause, Transience.PERSISTENT);
        }
    }
}