Don't symlink into the execroot if possible in SymlinkAction: instead, symlink directly to the target artifact. Also offer the option to not provide the package roots to create the execroot: we would like to avoid the execroot if possible.

PiperOrigin-RevId: 170515263

11 files changed, 232 insertions, 63 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/actions/ArtifactFactory.java b/src/main/java/com/google/devtools/build/lib/actions/ArtifactFactory.java
index 2a1f6634cc..dd7211e666 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ArtifactFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ArtifactFactory.java
@@ -15,7 +15,6 @@ package com.google.devtools.build.lib.actions;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact.SpecialArtifactType;
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
@@ -45,10 +44,10 @@ public class ArtifactFactory implements ArtifactResolver, ArtifactSerializer, Ar
   private final SourceArtifactCache sourceArtifactCache = new SourceArtifactCache();
 
   /**
-   * Map of package names to source root paths so that we can create source
-   * artifact paths given execPaths in the symlink forest.
+   * Map of package names to source root paths so that we can create source artifact paths given
+   * execPaths in the symlink forest.
    */
-  private ImmutableMap<PackageIdentifier, Root> packageRoots;
+  private PackageRoots.PackageRootLookup packageRoots;
 
   private ArtifactIdRegistry artifactIdRegistry = new ArtifactIdRegistry();
 
@@ -140,14 +139,13 @@ public class ArtifactFactory implements ArtifactResolver, ArtifactSerializer, Ar
   }
 
   /**
-   * Set the set of known packages and their corresponding source artifact
-   * roots. Must be called exactly once after construction or clear().
+   * Set the set of known packages and their corresponding source artifact roots. Must be called
+   * exactly once after construction or clear().
    *
-   * @param packageRoots the map of package names to source artifact roots to
-   *        use.
+   * @param packageRoots provider of a source root given a package identifier.
    */
-  public synchronized void setPackageRoots(Map<PackageIdentifier, Root> packageRoots) {
-    this.packageRoots = ImmutableMap.copyOf(packageRoots);
+  public synchronized void setPackageRoots(PackageRoots.PackageRootLookup packageRoots) {
+    this.packageRoots = packageRoots;
     sourceArtifactCache.newBuild();
   }
 
@@ -312,7 +310,13 @@ public class ArtifactFactory implements ArtifactResolver, ArtifactSerializer, Ar
     Root sourceRoot = findSourceRoot(execPath, baseExecPath, baseRoot, repositoryName);
     Artifact artifact = sourceArtifactCache.getArtifactIfValid(execPath);
     if (artifact != null) {
-      Preconditions.checkState(sourceRoot == null || sourceRoot.equals(artifact.getRoot()));
+      Root artifactRoot = artifact.getRoot();
+      Preconditions.checkState(
+          sourceRoot == null || sourceRoot.equals(artifactRoot),
+          "roots mismatch: %s %s %s",
+          sourceRoot,
+          artifactRoot,
+          artifact);
       return artifact;
     }
     return createArtifactIfNotValid(sourceRoot, execPath);
@@ -338,7 +342,8 @@ public class ArtifactFactory implements ArtifactResolver, ArtifactSerializer, Ar
     }
 
     while (dir != null && !dir.equals(baseExecPath)) {
-      Root sourceRoot = packageRoots.get(PackageIdentifier.create(repositoryName, dir));
+      Root sourceRoot =
+          packageRoots.getRootForPackage(PackageIdentifier.create(repositoryName, dir));
       if (sourceRoot != null) {
         return sourceRoot;
       }
diff --git a/src/main/java/com/google/devtools/build/lib/actions/PackageRoots.java b/src/main/java/com/google/devtools/build/lib/actions/PackageRoots.java
new file mode 100644
index 0000000000..35f7f3fb6d
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/actions/PackageRoots.java
@@ -0,0 +1,50 @@
+// Copyright 2017 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.actions;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.vfs.Path;
+import java.util.Optional;
+import javax.annotation.Nullable;
+
+/**
+ * An interface that provides information about package's source roots, that is, the paths on disk
+ * that their BUILD files can be found at. Usually this information is not needed except for when
+ * planting the symlink forest in the exec root, and when resolving source exec paths to artifacts
+ * in an {@link ArtifactResolver}.
+ */
+public interface PackageRoots {
+  /**
+   * Gets a map from {@link PackageIdentifier} to {@link Path}. If present, all known packages for
+   * this build are present in the map. Should only be needed for planting the symlink forest. If it
+   * is absent, planting the symlink forest is not necessary.
+   */
+  Optional<ImmutableMap<PackageIdentifier, Path>> getPackageRootsMap();
+
+  PackageRootLookup getPackageRootLookup();
+
+  /** Interface for getting the source root of a package, given its {@link PackageIdentifier}. */
+  interface PackageRootLookup {
+    /**
+     * Returns the {@link Root} of a package, given its {@link PackageIdentifier}. May be null if
+     * the given {@code packageIdentifier} does not correspond to a package in this build. However,
+     * if there is a unique source root for all packages, this may return that root even if the
+     * {@code packageIdentifier} given does not correspond to any packages.
+     */
+    @Nullable
+    Root getRootForPackage(PackageIdentifier packageIdentifier);
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java b/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
index 07688e6474..61dd9f199c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
@@ -35,7 +35,7 @@ import com.google.devtools.build.lib.actions.ActionLookupValue;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.ArtifactFactory;
 import com.google.devtools.build.lib.actions.ArtifactOwner;
-import com.google.devtools.build.lib.actions.Root;
+import com.google.devtools.build.lib.actions.PackageRoots;
 import com.google.devtools.build.lib.analysis.DependencyResolver.InconsistentAspectOrderException;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildConfigurationCollection;
@@ -50,7 +50,6 @@ import com.google.devtools.build.lib.analysis.test.CoverageReportActionFactory;
 import com.google.devtools.build.lib.analysis.test.CoverageReportActionFactory.CoverageReportActionsWrapper;
 import com.google.devtools.build.lib.analysis.test.InstrumentedFilesProvider;
 import com.google.devtools.build.lib.cmdline.Label;
-import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.collect.nestedset.Order;
@@ -95,7 +94,6 @@ import com.google.devtools.build.lib.util.OrderedSetMultimap;
 import com.google.devtools.build.lib.util.Pair;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.util.RegexFilter;
-import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.WalkableGraph;
@@ -107,7 +105,6 @@ import com.google.devtools.common.options.OptionsBase;
 import com.google.devtools.common.options.OptionsParsingException;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
@@ -348,7 +345,7 @@ public class BuildView {
     private final ImmutableSet<ConfiguredTarget> exclusiveTests;
     @Nullable private final TopLevelArtifactContext topLevelContext;
     private final ImmutableList<AspectValue> aspects;
-    private final ImmutableMap<PackageIdentifier, Path> packageRoots;
+    private final PackageRoots packageRoots;
     private final String workspaceName;
 
     private AnalysisResult(
@@ -362,7 +359,7 @@ public class BuildView {
         Collection<ConfiguredTarget> parallelTests,
         Collection<ConfiguredTarget> exclusiveTests,
         TopLevelArtifactContext topLevelContext,
-        ImmutableMap<PackageIdentifier, Path> packageRoots,
+        PackageRoots packageRoots,
         String workspaceName) {
       this.targetsToBuild = ImmutableSet.copyOf(targetsToBuild);
       this.aspects = ImmutableList.copyOf(aspects);
@@ -385,11 +382,8 @@ public class BuildView {
       return targetsToBuild;
     }
 
-    /**
-     * The map from package names to the package root where each package was found; this is used to
-     * set up the symlink tree.
-     */
-    public ImmutableMap<PackageIdentifier, Path> getPackageRoots() {
+    /** @see PackageRoots */
+    public PackageRoots getPackageRoots() {
       return packageRoots;
     }
 
@@ -1023,19 +1017,8 @@ public class BuildView {
    * paths with unknown roots to artifacts.
    */
   @VisibleForTesting // for BuildViewTestCase
-  public void setArtifactRoots(ImmutableMap<PackageIdentifier, Path> packageRoots) {
-    Map<Path, Root> rootMap = new HashMap<>();
-    Map<PackageIdentifier, Root> realPackageRoots = new HashMap<>();
-    for (Map.Entry<PackageIdentifier, Path> entry : packageRoots.entrySet()) {
-      Root root = rootMap.get(entry.getValue());
-      if (root == null) {
-        root = Root.asSourceRoot(entry.getValue(), entry.getKey().getRepository().isMain());
-        rootMap.put(entry.getValue(), root);
-      }
-      realPackageRoots.put(entry.getKey(), root);
-    }
-    // Source Artifact roots:
-    getArtifactFactory().setPackageRoots(realPackageRoots);
+  public void setArtifactRoots(PackageRoots packageRoots) {
+    getArtifactFactory().setPackageRoots(packageRoots.getPackageRootLookup());
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/actions/ExecutableSymlinkAction.java b/src/main/java/com/google/devtools/build/lib/analysis/actions/ExecutableSymlinkAction.java
index 4070e5a73a..4cdf2f1e12 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/actions/ExecutableSymlinkAction.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/actions/ExecutableSymlinkAction.java
@@ -35,7 +35,7 @@ public final class ExecutableSymlinkAction extends SymlinkAction {
   @Override
   public void execute(ActionExecutionContext actionExecutionContext)
       throws ActionExecutionException {
-    Path inputPath = actionExecutionContext.getExecRoot().getRelative(getInputPath());
+    Path inputPath = getPrimaryInput().getPath();
     try {
       // Validate that input path is a file with the executable bit is set.
       if (!inputPath.isFile()) {
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/actions/SymlinkAction.java b/src/main/java/com/google/devtools/build/lib/analysis/actions/SymlinkAction.java
index b79f152fb7..df3b56f829 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/actions/SymlinkAction.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/actions/SymlinkAction.java
@@ -26,6 +26,7 @@ import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.io.IOException;
+import javax.annotation.Nullable;
 
 /**
  * Action to create a symbolic link.
@@ -34,7 +35,9 @@ public class SymlinkAction extends AbstractAction {
 
   private static final String GUID = "349675b5-437c-4da8-891a-7fb98fba6ab5";
 
-  private final PathFragment inputPath;
+  /** Null when {@link #getPrimaryInput} is the target of the symlink. */
+  @Nullable private final PathFragment inputPath;
+
   private final Artifact output;
   private final String progressMessage;
 
@@ -50,7 +53,10 @@ public class SymlinkAction extends AbstractAction {
       String progressMessage) {
     // These actions typically have only one input and one output, which
     // become the sole and primary in their respective lists.
-    this(owner, input.getExecPath(), input, output, progressMessage);
+    super(owner, ImmutableList.of(input), ImmutableList.of(output));
+    this.inputPath = null;
+    this.output = Preconditions.checkNotNull(output);
+    this.progressMessage = progressMessage;
   }
 
   /**
@@ -93,7 +99,7 @@ public class SymlinkAction extends AbstractAction {
   }
 
   public PathFragment getInputPath() {
-    return inputPath;
+    return inputPath == null ? getPrimaryInput().getExecPath() : inputPath;
   }
 
   public Path getOutputPath() {
@@ -103,9 +109,14 @@ public class SymlinkAction extends AbstractAction {
   @Override
   public void execute(ActionExecutionContext actionExecutionContext)
       throws ActionExecutionException {
+    Path srcPath;
+    if (inputPath == null) {
+      srcPath = getPrimaryInput().getPath();
+    } else {
+      srcPath = actionExecutionContext.getExecRoot().getRelative(inputPath);
+    }
     try {
-      getOutputPath()
-          .createSymbolicLink(actionExecutionContext.getExecRoot().getRelative(inputPath));
+      getOutputPath().createSymbolicLink(srcPath);
     } catch (IOException e) {
       throw new ActionExecutionException("failed to create symbolic link '"
           + Iterables.getOnlyElement(getOutputs()).prettyPrint()
@@ -120,7 +131,9 @@ public class SymlinkAction extends AbstractAction {
     f.addString(GUID);
     // We don't normally need to add inputs to the key. In this case, however, the inputPath can be
     // different from the actual input artifact.
-    f.addPath(inputPath);
+    if (inputPath != null) {
+      f.addPath(inputPath);
+    }
     return f.hexDigestAndReset();
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java b/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
index af7659b8b8..241084782e 100644
--- a/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
+++ b/src/main/java/com/google/devtools/build/lib/buildtool/ExecutionTool.java
@@ -44,6 +44,7 @@ import com.google.devtools.build.lib.actions.ExecutionStrategy;
 import com.google.devtools.build.lib.actions.Executor;
 import com.google.devtools.build.lib.actions.ExecutorInitException;
 import com.google.devtools.build.lib.actions.LocalHostCapacity;
+import com.google.devtools.build.lib.actions.PackageRoots;
 import com.google.devtools.build.lib.actions.ResourceManager;
 import com.google.devtools.build.lib.actions.ResourceSet;
 import com.google.devtools.build.lib.actions.SpawnActionContext;
@@ -107,6 +108,7 @@ import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.TreeMap;
 import java.util.UUID;
@@ -321,19 +323,23 @@ public class ExecutionTool {
   }
 
   /**
-   * Performs the execution phase (phase 3) of the build, in which the Builder
-   * is applied to the action graph to bring the targets up to date. (This
-   * function will return prior to execution-proper if --nobuild was specified.)
+   * Performs the execution phase (phase 3) of the build, in which the Builder is applied to the
+   * action graph to bring the targets up to date. (This function will return prior to
+   * execution-proper if --nobuild was specified.)
+   *
    * @param buildId UUID of the build id
    * @param analysisResult the analysis phase output
    * @param buildResult the mutable build result
    * @param packageRoots package roots collected from loading phase and BuildConfigurationCollection
-   * creation
+   *     creation. May be empty if {@link
+   *     SkyframeExecutor#getForcedSingleSourceRootIfNoExecrootSymlinkCreation} is false.
    */
-  void executeBuild(UUID buildId, AnalysisResult analysisResult,
+  void executeBuild(
+      UUID buildId,
+      AnalysisResult analysisResult,
       BuildResult buildResult,
       BuildConfigurationCollection configurations,
-      ImmutableMap<PackageIdentifier, Path> packageRoots,
+      PackageRoots packageRoots,
       TopLevelArtifactContext topLevelArtifactContext)
       throws BuildFailedException, InterruptedException, TestExecException, AbruptExitException {
     Stopwatch timer = Stopwatch.createStarted();
@@ -516,15 +522,19 @@ public class ExecutionTool {
     }
   }
 
-  private void prepare(ImmutableMap<PackageIdentifier, Path> packageRoots)
-      throws ExecutorInitException {
+  private void prepare(PackageRoots packageRoots) throws ExecutorInitException {
+    Optional<ImmutableMap<PackageIdentifier, Path>> packageRootMap =
+        packageRoots.getPackageRootsMap();
+    if (!packageRootMap.isPresent()) {
+      return;
+    }
     // Prepare for build.
     Profiler.instance().markPhase(ProfilePhase.PREPARE);
 
     // Plant the symlink forest.
     try {
       new SymlinkForest(
-          packageRoots, getExecRoot(), runtime.getProductName(), env.getWorkspaceName())
+              packageRootMap.get(), getExecRoot(), runtime.getProductName(), env.getWorkspaceName())
           .plantSymlinkForest();
     } catch (IOException e) {
       throw new ExecutorInitException("Source forest creation failed", e);
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/MapAsPackageRoots.java b/src/main/java/com/google/devtools/build/lib/skyframe/MapAsPackageRoots.java
new file mode 100644
index 0000000000..baca2e02a1
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/MapAsPackageRoots.java
@@ -0,0 +1,56 @@
+// Copyright 2017 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.ImmutableMap;
+import com.google.devtools.build.lib.actions.PackageRoots;
+import com.google.devtools.build.lib.actions.Root;
+import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.vfs.Path;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * A {@link PackageRoots} backed by a map of package identifiers to paths. A symlink forest must be
+ * planted for execution.
+ */
+public class MapAsPackageRoots implements PackageRoots {
+  private final ImmutableMap<PackageIdentifier, Path> packageRootsMap;
+
+  MapAsPackageRoots(ImmutableMap<PackageIdentifier, Path> packageRootsMap) {
+    this.packageRootsMap = packageRootsMap;
+  }
+
+  @Override
+  public Optional<ImmutableMap<PackageIdentifier, Path>> getPackageRootsMap() {
+    return Optional.of(packageRootsMap);
+  }
+
+  @Override
+  public PackageRootLookup getPackageRootLookup() {
+    Map<Path, Root> rootMap = new HashMap<>();
+    Map<PackageIdentifier, Root> realPackageRoots = new HashMap<>();
+    for (Map.Entry<PackageIdentifier, Path> entry : packageRootsMap.entrySet()) {
+      Root root = rootMap.get(entry.getValue());
+      if (root == null) {
+        root = Root.asSourceRoot(entry.getValue(), entry.getKey().getRepository().isMain());
+        rootMap.put(entry.getValue(), root);
+      }
+      realPackageRoots.put(entry.getKey(), root);
+    }
+    return realPackageRoots::get;
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageRootsNoSymlinkCreation.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageRootsNoSymlinkCreation.java
new file mode 100644
index 0000000000..499e7413ae
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageRootsNoSymlinkCreation.java
@@ -0,0 +1,46 @@
+// Copyright 2017 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.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.actions.PackageRoots;
+import com.google.devtools.build.lib.actions.Root;
+import com.google.devtools.build.lib.cmdline.PackageIdentifier;
+import com.google.devtools.build.lib.vfs.Path;
+import java.util.Optional;
+
+/**
+ * {@link PackageRoots} with a single source root that does not want symlink forest creation, and
+ * whose {@link PackageRootLookup} returns the unique source root for any given package identifier.
+ */
+public class PackageRootsNoSymlinkCreation implements PackageRoots {
+  private final Root sourceRoot;
+
+  @VisibleForTesting
+  public PackageRootsNoSymlinkCreation(Path sourcePath) {
+    this.sourceRoot = Root.asSourceRoot(sourcePath, true);
+  }
+
+  @Override
+  public Optional<ImmutableMap<PackageIdentifier, Path>> getPackageRootsMap() {
+    return Optional.empty();
+  }
+
+  @Override
+  public PackageRootLookup getPackageRootLookup() {
+    return packageIdentifier -> sourceRoot;
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeAnalysisResult.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeAnalysisResult.java
index 7db70f3e62..0314debba0 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeAnalysisResult.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeAnalysisResult.java
@@ -14,12 +14,9 @@
 package com.google.devtools.build.lib.skyframe;
 
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.actions.PackageRoots;
 import com.google.devtools.build.lib.analysis.ConfiguredTarget;
-import com.google.devtools.build.lib.cmdline.PackageIdentifier;
-import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.skyframe.WalkableGraph;
-
 import java.util.Collection;
 
 /**
@@ -31,15 +28,15 @@ public class SkyframeAnalysisResult {
   private final ImmutableList<ConfiguredTarget> configuredTargets;
   private final WalkableGraph walkableGraph;
   private final ImmutableList<AspectValue> aspects;
-  private final ImmutableMap<PackageIdentifier, Path> packageRoots;
+  private final PackageRoots packageRoots;
 
-  public SkyframeAnalysisResult(
+  SkyframeAnalysisResult(
       boolean hasLoadingError,
       boolean hasAnalysisError,
       ImmutableList<ConfiguredTarget> configuredTargets,
       WalkableGraph walkableGraph,
       ImmutableList<AspectValue> aspects,
-      ImmutableMap<PackageIdentifier, Path> packageRoots) {
+      PackageRoots packageRoots) {
     this.hasLoadingError = hasLoadingError;
     this.hasAnalysisError = hasAnalysisError;
     this.configuredTargets = configuredTargets;
@@ -73,7 +70,7 @@ public class SkyframeAnalysisResult {
     return aspects;
   }
 
-  public ImmutableMap<PackageIdentifier, Path> getPackageRoots() {
+  public PackageRoots getPackageRoots() {
     return packageRoots;
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
index 56477bdbcd..20f1035990 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
@@ -30,6 +30,7 @@ import com.google.devtools.build.lib.actions.ArtifactOwner;
 import com.google.devtools.build.lib.actions.ArtifactPrefixConflictException;
 import com.google.devtools.build.lib.actions.MutableActionGraph;
 import com.google.devtools.build.lib.actions.MutableActionGraph.ActionConflictException;
+import com.google.devtools.build.lib.actions.PackageRoots;
 import com.google.devtools.build.lib.analysis.AnalysisFailureEvent;
 import com.google.devtools.build.lib.analysis.BlazeDirectories;
 import com.google.devtools.build.lib.analysis.BuildView;
@@ -46,7 +47,6 @@ import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildConfigurationCollection;
 import com.google.devtools.build.lib.analysis.config.ConfigMatchingProvider;
 import com.google.devtools.build.lib.cmdline.Label;
-import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.ExtendedEventHandler;
@@ -241,8 +241,12 @@ public final class SkyframeBuildView {
       goodCts.add(ctValue.getConfiguredTarget());
       packages.addTransitive(ctValue.getTransitivePackages());
     }
-    ImmutableMap<PackageIdentifier, Path> packageRoots =
-        LoadingPhaseRunner.collectPackageRoots(packages.build().toCollection());
+    Path singleSourceRoot = skyframeExecutor.getForcedSingleSourceRootIfNoExecrootSymlinkCreation();
+    PackageRoots packageRoots =
+        singleSourceRoot == null
+            ? new MapAsPackageRoots(
+                LoadingPhaseRunner.collectPackageRoots(packages.build().toCollection()))
+            : new PackageRootsNoSymlinkCreation(singleSourceRoot);
 
     if (!result.hasError() && badActions.isEmpty()) {
       return new SkyframeAnalysisResult(
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
index 97a10780fc..b3159c9134 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
@@ -653,6 +653,11 @@ public abstract class SkyframeExecutor implements WalkableGraphFactory {
     return true;
   }
 
+  @Nullable
+  protected Path getForcedSingleSourceRootIfNoExecrootSymlinkCreation() {
+    return null;
+  }
+
   @VisibleForTesting
   protected abstract Injectable injectable();