src/main/java/com/google/devtools/build/lib/skyframe/BuildDriverFunction.java

// Copyright 2021 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.Preconditions;
import com.google.common.base.Supplier;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.actions.ActionAnalysisMetadata;
import com.google.devtools.build.lib.actions.ActionLookupKey;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.AspectValue;
import com.google.devtools.build.lib.analysis.ConfiguredTarget;
import com.google.devtools.build.lib.analysis.ConfiguredTargetValue;
import com.google.devtools.build.lib.analysis.ExtraActionArtifactsProvider;
import com.google.devtools.build.lib.analysis.TopLevelArtifactContext;
import com.google.devtools.build.lib.profiler.Profiler;
import com.google.devtools.build.lib.profiler.SilentCloseable;
import com.google.devtools.build.lib.skyframe.ArtifactConflictFinder.ConflictException;
import com.google.devtools.build.lib.skyframe.AspectCompletionValue.AspectCompletionKey;
import com.google.devtools.build.lib.skyframe.SkyframeExecutor.AnalysisTraversalResult;
import com.google.devtools.build.lib.skyframe.ToplevelStarlarkAspectFunction.TopLevelAspectsValue;
import com.google.devtools.build.lib.util.RegexFilter;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyFunction.Environment.SkyKeyComputeState;
import com.google.devtools.build.skyframe.SkyFunctionException;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.annotation.Nullable;

/**
 * Drives the analysis & execution of an ActionLookupKey, which is wrapped inside a BuildDriverKey.
 */
public class BuildDriverFunction implements SkyFunction {
  private final SkyframeExecutor skyframeExecutor;
  private final Supplier<IncrementalArtifactConflictFinder> incrementalArtifactConflictFinder;

  BuildDriverFunction(
      SkyframeExecutor skyframeExecutor,
      Supplier<IncrementalArtifactConflictFinder> incrementalArtifactConflictFinder) {
    this.skyframeExecutor = skyframeExecutor;
    this.incrementalArtifactConflictFinder = incrementalArtifactConflictFinder;
  }

  private static class State implements SkyKeyComputeState {
    private ImmutableMap<ActionAnalysisMetadata, ConflictException> actionConflicts;
  }
  /**
   * From the ConfiguredTarget/Aspect keys, get the top-level artifacts. Then evaluate them together
   * with the appropriate CompletionFunctions. This is the bridge between the conceptual analysis &
   * execution phases.
   *
   * <p>TODO(b/199053098): implement build-info, build-changelist, coverage & exception handling.
   */
  @Nullable
  @Override
  public SkyValue compute(SkyKey skyKey, Environment env)
      throws SkyFunctionException, InterruptedException {
    BuildDriverKey buildDriverKey = (BuildDriverKey) skyKey;
    ActionLookupKey actionLookupKey = buildDriverKey.getActionLookupKey();
    TopLevelArtifactContext topLevelArtifactContext = buildDriverKey.getTopLevelArtifactContext();
    State state = env.getState(State::new);

    // Register a dependency on the BUILD_ID. We do this to make sure BuildDriverFunction is
    // reevaluated every build.
    PrecomputedValue.BUILD_ID.get(env);

    // Why SkyValue and not ActionLookupValue? The evaluation of some ActionLookupKey can result in
    // classes that don't implement ActionLookupValue
    // (e.g. ConfiguredTargetKey -> NonRuleConfiguredTargetValue).
    SkyValue topLevelSkyValue = env.getValue(actionLookupKey);

    if (env.valuesMissing()) {
      return null;
    }

    // Unconditionally check for action conflicts.
    // TODO(b/214371092): Only check when necessary.
    try (SilentCloseable c =
        Profiler.instance().profile("BuildDriverFunction.checkActionConflicts")) {
      if (state.actionConflicts == null) {
        state.actionConflicts =
            checkActionConflicts(actionLookupKey, buildDriverKey.strictActionConflictCheck());
      }
      if (!state.actionConflicts.isEmpty()) {
        throw new BuildDriverFunctionException(
            new TopLevelConflictException(
                "Action conflict(s) detected while analyzing top-level target "
                    + actionLookupKey.getLabel(),
                state.actionConflicts));
      }
    }
    ImmutableSet.Builder<Artifact> artifactsToBuild = ImmutableSet.builder();

    Preconditions.checkState(
        topLevelSkyValue instanceof ConfiguredTargetValue
            || topLevelSkyValue instanceof TopLevelAspectsValue);
    if (topLevelSkyValue instanceof ConfiguredTargetValue) {
      ConfiguredTarget configuredTarget =
          ((ConfiguredTargetValue) topLevelSkyValue).getConfiguredTarget();
      addExtraActionsIfRequested(
          configuredTarget.getProvider(ExtraActionArtifactsProvider.class), artifactsToBuild);
      env.getValues(
          Iterables.concat(
              artifactsToBuild.build(),
              Collections.singletonList(
                  TargetCompletionValue.key(
                      (ConfiguredTargetKey) actionLookupKey, topLevelArtifactContext, false))));
    } else {
      List<SkyKey> aspectCompletionKeys = new ArrayList<>();
      for (SkyValue aspectValue :
          ((TopLevelAspectsValue) topLevelSkyValue).getTopLevelAspectsValues()) {
        addExtraActionsIfRequested(
            ((AspectValue) aspectValue)
                .getConfiguredAspect()
                .getProvider(ExtraActionArtifactsProvider.class),
            artifactsToBuild);
        aspectCompletionKeys.add(
            AspectCompletionKey.create(
                ((AspectValue) aspectValue).getKey(), topLevelArtifactContext));
      }
      env.getValues(Iterables.concat(artifactsToBuild.build(), aspectCompletionKeys));
    }

    return env.valuesMissing() ? null : new BuildDriverValue(topLevelSkyValue);
  }

  private ImmutableMap<ActionAnalysisMetadata, ConflictException> checkActionConflicts(
      ActionLookupKey actionLookupKey, boolean strictConflictCheck) throws InterruptedException {
    AnalysisTraversalResult analysisTraversalResult =
        skyframeExecutor.collectTransitiveActionLookupKeys(actionLookupKey);
    ArtifactConflictFinder.ActionConflictsAndStats conflictsAndStats =
        incrementalArtifactConflictFinder
            .get()
            .findArtifactConflicts(analysisTraversalResult.getActionShards(), strictConflictCheck);
    return conflictsAndStats.getConflicts();
  }

  private void addExtraActionsIfRequested(
      ExtraActionArtifactsProvider provider, ImmutableSet.Builder<Artifact> artifactsToBuild) {
    if (provider != null) {
      addArtifactsToBuilder(
          provider.getTransitiveExtraActionArtifacts().toList(), artifactsToBuild, null);
    }
  }

  private static void addArtifactsToBuilder(
      List<? extends Artifact> artifacts,
      ImmutableSet.Builder<Artifact> builder,
      RegexFilter filter) {
    for (Artifact artifact : artifacts) {
      if (filter.isIncluded(artifact.getOwnerLabel().toString())) {
        builder.add(artifact);
      }
    }
  }

  /** A SkyFunctionException wrapper for the actual TopLevelConflictException. */
  private static final class BuildDriverFunctionException extends SkyFunctionException {
    // The exception is transient here since it could be caused by external factors (conflict with
    // another target).
    BuildDriverFunctionException(TopLevelConflictException cause) {
      super(cause, Transience.TRANSIENT);
    }
  }

  /**
   * Encapsulates a collection of action conflicts of the transitive closure of a top-level
   * ActionLookupKey.
   */
  static final class TopLevelConflictException extends Exception {

    private final ImmutableMap<ActionAnalysisMetadata, ConflictException> transitiveActionConflicts;

    private TopLevelConflictException(
        String message, ImmutableMap<ActionAnalysisMetadata, ConflictException> actionConflicts) {
      super(message);
      this.transitiveActionConflicts = actionConflicts;
    }

    ImmutableMap<ActionAnalysisMetadata, ConflictException> getTransitiveActionConflicts() {
      return transitiveActionConflicts;
    }

    /**
     * Simply returns the first found exception in the map. This is deterministic since the
     * underlying map is immutable.
     */
    public ConflictException getRepresentativeException() {
      return transitiveActionConflicts.values().asList().get(0);
    }
  }
}