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

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

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// Copyright 2014 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.base.Function;
import com.google.common.base.Predicate;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.cmdline.PackageIdentifier;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.EventHandler;
import com.google.devtools.build.skyframe.CycleInfo;
import com.google.devtools.build.skyframe.CyclesReporter;
import com.google.devtools.build.skyframe.SkyKey;

/**
 * Reports cycles of recursive import of Skylark files.
 */
public class SkylarkModuleCycleReporter implements CyclesReporter.SingleCycleReporter {

    private static final Predicate<SkyKey> IS_SKYLARK_MODULE_SKY_KEY = SkyFunctions
            .isSkyFunction(SkyFunctions.SKYLARK_IMPORTS_LOOKUP);

    private static final Predicate<SkyKey> IS_PACKAGE_SKY_KEY = SkyFunctions.isSkyFunction(SkyFunctions.PACKAGE);

    private static final Predicate<SkyKey> IS_PACKAGE_LOOKUP = SkyFunctions
            .isSkyFunction(SkyFunctions.PACKAGE_LOOKUP);

    private static final Predicate<SkyKey> IS_WORKSPACE_FILE = SkyFunctions
            .isSkyFunction(SkyFunctions.WORKSPACE_FILE);

    private static final Predicate<SkyKey> IS_REPOSITORY_DIRECTORY = SkyFunctions
            .isSkyFunction(SkyFunctions.REPOSITORY_DIRECTORY);

    private static final Predicate<SkyKey> IS_AST_FILE_LOOKUP = SkyFunctions
            .isSkyFunction(SkyFunctions.AST_FILE_LOOKUP);

    private static final Predicate<SkyKey> IS_EXTERNAL_PACKAGE = SkyFunctions
            .isSkyFunction(SkyFunctions.EXTERNAL_PACKAGE);

    @Override
    public boolean maybeReportCycle(SkyKey topLevelKey, CycleInfo cycleInfo, boolean alreadyReported,
            EventHandler eventHandler) {
        ImmutableList<SkyKey> pathToCycle = cycleInfo.getPathToCycle();
        ImmutableList<SkyKey> cycle = cycleInfo.getCycle();
        if (pathToCycle.isEmpty()) {
            return false;
        }
        SkyKey lastPathElement = pathToCycle.get(pathToCycle.size() - 1);
        if (alreadyReported) {
            return true;
        } else if (Iterables.all(cycle, IS_SKYLARK_MODULE_SKY_KEY)
                // The last element before the cycle has to be a PackageFunction or SkylarkModule.
                && (IS_PACKAGE_SKY_KEY.apply(lastPathElement)
                        || IS_SKYLARK_MODULE_SKY_KEY.apply(lastPathElement))) {

            Function printer = new Function<SkyKey, String>() {
                @Override
                public String apply(SkyKey input) {
                    if (input.argument() instanceof SkylarkImportLookupValue.SkylarkImportLookupKey) {
                        return ((SkylarkImportLookupValue.SkylarkImportLookupKey) input.argument()).importLabel
                                .toString();
                    } else if (input.argument() instanceof PackageIdentifier) {
                        return ((PackageIdentifier) input.argument()) + "/BUILD";
                    } else {
                        throw new UnsupportedOperationException();
                    }
                }
            };

            StringBuilder cycleMessage = new StringBuilder().append("cycle detected in extension files: ")
                    .append("\n    ").append(printer.apply(lastPathElement));

            AbstractLabelCycleReporter.printCycle(cycleInfo.getCycle(), cycleMessage, printer);
            // TODO(bazel-team): it would be nice to pass the Location of the load Statement in the
            // BUILD file.
            eventHandler.handle(Event.error(null, cycleMessage.toString()));
            return true;
        } else if (Iterables.any(cycle, IS_PACKAGE_LOOKUP) && Iterables.any(cycle, IS_WORKSPACE_FILE)
                && (IS_REPOSITORY_DIRECTORY.apply(lastPathElement) || IS_PACKAGE_SKY_KEY.apply(lastPathElement)
                        || IS_EXTERNAL_PACKAGE.apply(lastPathElement))) {
            // We have a cycle in the workspace file, report as such.
            Label fileLabel = (Label) Iterables.getLast(Iterables.filter(cycle, IS_AST_FILE_LOOKUP)).argument();
            String repositoryName = fileLabel.getPackageIdentifier().getRepository().strippedName();
            eventHandler.handle(Event.error(null, "Failed to load Skylark extension '" + fileLabel.toString()
                    + "'.\n" + "It usually happens when the repository is not defined prior to being used.\n"
                    + "Maybe repository '" + repositoryName + "' was defined later in your WORKSPACE file?"));
            return true;
        }
        return false;
    }
}