src/main/java/com/google/devtools/build/lib/remote/ToplevelArtifactsDownloader.java

// Copyright 2022 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.remote;

import static com.google.common.util.concurrent.Futures.addCallback;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.eventbus.AllowConcurrentEvents;
import com.google.common.eventbus.Subscribe;
import com.google.common.flogger.GoogleLogger;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.actions.CompletionContext;
import com.google.devtools.build.lib.analysis.AspectCompleteEvent;
import com.google.devtools.build.lib.analysis.TargetCompleteEvent;
import com.google.devtools.build.lib.analysis.TopLevelArtifactHelper.ArtifactsInOutputGroup;
import com.google.devtools.build.lib.remote.AbstractActionInputPrefetcher.Priority;

/**
 * Class that uses {@link AbstractActionInputPrefetcher} to download artifacts of toplevel targets
 * in the background.
 */
public class ToplevelArtifactsDownloader {
  private static final GoogleLogger logger = GoogleLogger.forEnclosingClass();

  private final AbstractActionInputPrefetcher actionInputPrefetcher;

  public ToplevelArtifactsDownloader(AbstractActionInputPrefetcher actionInputPrefetcher) {
    this.actionInputPrefetcher = actionInputPrefetcher;
  }

  @Subscribe
  @AllowConcurrentEvents
  public void onAspectComplete(AspectCompleteEvent event) {
    if (event.failed()) {
      return;
    }

    downloadTargetOutputs(event.getCompletionContext(), event.getOutputGroups());
  }

  @Subscribe
  @AllowConcurrentEvents
  public void onTargetComplete(TargetCompleteEvent event) {
    if (event.failed()) {
      return;
    }

    downloadTargetOutputs(event.getCompletionContext(), event.getOutputs());
  }

  private void downloadTargetOutputs(
      CompletionContext completionContext,
      ImmutableMap<String, ArtifactsInOutputGroup> outputGroups) {

    ImmutableSet.Builder<Artifact> builder = ImmutableSet.builder();
    for (ArtifactsInOutputGroup outputs : outputGroups.values()) {
      if (!outputs.areImportant()) {
        continue;
      }
      for (Artifact output : outputs.getArtifacts().toList()) {
        if (completionContext.getFileArtifactValue(output) == null) {
          continue;
        }
        builder.add(output);
      }
    }

    ListenableFuture<Void> future =
        actionInputPrefetcher.prefetchFiles(
            builder.build(), completionContext.getImportantInputMap(), Priority.LOW);

    addCallback(
        future,
        new FutureCallback<Void>() {
          @Override
          public void onSuccess(Void unused) {}

          @Override
          public void onFailure(Throwable throwable) {
            logger.atWarning().withCause(throwable).log("Failed to download toplevel artifacts.");
          }
        },
        directExecutor());
  }
}