Rename MiddlemanExpander to ArtifactExpander, and refactor it to yield ArtifactFiles.

--
MOS_MIGRATED_REVID=114166208

12 files changed, 114 insertions, 87 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContext.java b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContext.java
index 66b6c4861a..dce5819ed3 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContext.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContext.java
@@ -14,7 +14,7 @@
 
 package com.google.devtools.build.lib.actions;
 
-import com.google.devtools.build.lib.actions.Artifact.MiddlemanExpander;
+import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander;
 import com.google.devtools.build.lib.actions.cache.MetadataHandler;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.util.io.FileOutErr;
@@ -32,32 +32,32 @@ public class ActionExecutionContext {
   private final ActionInputFileCache actionInputFileCache;
   private final MetadataHandler metadataHandler;
   private final FileOutErr fileOutErr;
-  private final MiddlemanExpander middlemanExpander;
+  private final ArtifactExpander artifactExpander;
   @Nullable
   private final Environment env;
 
   private ActionExecutionContext(Executor executor, ActionInputFileCache actionInputFileCache,
       MetadataHandler metadataHandler, FileOutErr fileOutErr,
-      @Nullable MiddlemanExpander middlemanExpander,
+      @Nullable ArtifactExpander artifactExpander,
       @Nullable SkyFunction.Environment env) {
     this.actionInputFileCache = actionInputFileCache;
     this.metadataHandler = metadataHandler;
     this.fileOutErr = fileOutErr;
     this.executor = executor;
-    this.middlemanExpander = middlemanExpander;
+    this.artifactExpander = artifactExpander;
     this.env = env;
   }
 
   public ActionExecutionContext(Executor executor, ActionInputFileCache actionInputFileCache,
-      MetadataHandler metadataHandler, FileOutErr fileOutErr, MiddlemanExpander middlemanExpander) {
-    this(executor, actionInputFileCache, metadataHandler, fileOutErr, middlemanExpander, null);
+      MetadataHandler metadataHandler, FileOutErr fileOutErr, ArtifactExpander artifactExpander) {
+    this(executor, actionInputFileCache, metadataHandler, fileOutErr, artifactExpander, null);
   }
 
   public static ActionExecutionContext normal(Executor executor,
       ActionInputFileCache actionInputFileCache, MetadataHandler metadataHandler,
-      FileOutErr fileOutErr, MiddlemanExpander middlemanExpander) {
+      FileOutErr fileOutErr, ArtifactExpander artifactExpander) {
     return new ActionExecutionContext(executor, actionInputFileCache, metadataHandler, fileOutErr,
-        middlemanExpander, null);
+        artifactExpander, null);
   }
 
   public static ActionExecutionContext forInputDiscovery(Executor executor,
@@ -79,8 +79,8 @@ public class ActionExecutionContext {
     return executor;
   }
 
-  public MiddlemanExpander getMiddlemanExpander() {
-    return middlemanExpander;
+  public ArtifactExpander getArtifactExpander() {
+    return artifactExpander;
   }
 
   /**
@@ -104,6 +104,6 @@ public class ActionExecutionContext {
    */
   public ActionExecutionContext withFileOutErr(FileOutErr fileOutErr) {
     return new ActionExecutionContext(executor, actionInputFileCache, metadataHandler, fileOutErr,
-        middlemanExpander, env);
+        artifactExpander, env);
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContextFactory.java b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContextFactory.java
index ed45880125..e87d72e2ee 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContextFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContextFactory.java
@@ -25,5 +25,5 @@ import java.util.Map;
  */
 public interface ActionExecutionContextFactory {
   ActionExecutionContext getContext(ActionInputFileCache graphFileCache,
-      MetadataHandler metadataHandler, Map<Artifact, Collection<Artifact>> expandedInputMiddlemen);
+      MetadataHandler metadataHandler, Map<Artifact, Collection<ArtifactFile>> expandedInputs);
 }
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionInputHelper.java b/src/main/java/com/google/devtools/build/lib/actions/ActionInputHelper.java
index 723c9fbd37..8bceb9acd3 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionInputHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionInputHelper.java
@@ -19,6 +19,7 @@ import com.google.common.base.Function;
 import com.google.common.base.Functions;
 import com.google.common.collect.Collections2;
 import com.google.common.collect.Iterables;
+import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.vfs.PathFragment;
 
@@ -34,11 +35,11 @@ public final class ActionInputHelper {
   }
 
   @VisibleForTesting
-  public static Artifact.MiddlemanExpander actionGraphMiddlemanExpander(
+  public static ArtifactExpander actionGraphArtifactExpander(
       final ActionGraph actionGraph) {
-    return new Artifact.MiddlemanExpander() {
+    return new ArtifactExpander() {
       @Override
-      public void expand(Artifact mm, Collection<? super Artifact> output) {
+      public void expand(Artifact mm, Collection<? super ArtifactFile> output) {
         // Skyframe is stricter in that it checks that "mm" is a input of the action, because
         // it cannot expand arbitrary middlemen without access to a global action graph.
         // We could check this constraint here too, but it seems unnecessary. This code is
@@ -157,13 +158,27 @@ public final class ActionInputHelper {
         });
   }
 
+  /** Returns an Collection of ArtifactFiles with the given parent and parent relative paths. */
+  public static Collection<ArtifactFile> asArtifactFiles(
+      final Artifact parent, Collection<? extends PathFragment> parentRelativePaths) {
+    Preconditions.checkState(parent.isTreeArtifact(),
+        "Given parent %s must be a TreeArtifact", parent);
+    return Collections2.transform(parentRelativePaths,
+        new Function<PathFragment, ArtifactFile>() {
+          @Override
+          public ArtifactFile apply(PathFragment pathFragment) {
+            return artifactFile(parent, pathFragment);
+          }
+        });
+  }
+
   /**
    * Expands middleman artifacts in a sequence of {@link ActionInput}s.
    *
    * <p>Non-middleman artifacts are returned untouched.
    */
-  public static List<ActionInput> expandMiddlemen(Iterable<? extends ActionInput> inputs,
-      Artifact.MiddlemanExpander middlemanExpander) {
+  public static List<ActionInput> expandArtifacts(Iterable<? extends ActionInput> inputs,
+      ArtifactExpander artifactExpander) {
 
     List<ActionInput> result = new ArrayList<>();
     List<Artifact> containedArtifacts = new ArrayList<>();
@@ -174,7 +189,7 @@ public final class ActionInputHelper {
       }
       containedArtifacts.add((Artifact) input);
     }
-    Artifact.addExpandedArtifacts(containedArtifacts, result, middlemanExpander);
+    Artifact.addExpandedArtifacts(containedArtifacts, result, artifactExpander);
     return result;
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
index 23e2a4cb46..2a700023ce 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
@@ -76,7 +76,7 @@ import javax.annotation.Nullable;
  * This is a legacy facility and should not be used by any new rule implementations.
  * In particular, the file system cache integrity checks fail for directories.
  * <li>An 'aggregating middleman' special Artifact, which may be expanded using a
- * {@link MiddlemanExpander} at Action execution time. This is used by a handful of rules to save
+ * {@link ArtifactExpander} at Action execution time. This is used by a handful of rules to save
  * memory.
  * <li>A 'constant metadata' special Artifact. These represent real files, changes to which are
  * ignored by the build system. They are useful for files which change frequently but do not affect
@@ -116,14 +116,15 @@ public class Artifact implements FileType.HasFilename, ArtifactFile, SkylarkValu
   };
 
   /** An object that can expand middleman artifacts. */
-  public interface MiddlemanExpander {
+  public interface ArtifactExpander {
 
     /**
-     * Expands the middleman artifact "mm", and populates "output" with the result.
+     * Expands the given artifact, and populates "output" with the result.
      *
-     * <p>{@code mm.isMiddlemanArtifact()} must be true. Only aggregating middlemen are expanded.
+     * <p>{@code artifact.isMiddlemanArtifact() || artifact.isTreeArtifact()} must be true.
+     * Only aggregating middlemen and tree artifacts are expanded.
      */
-    void expand(Artifact mm, Collection<? super Artifact> output);
+    void expand(Artifact artifact, Collection<? super ArtifactFile> output);
   }
 
   public static final ImmutableList<Artifact> NO_ARTIFACTS = ImmutableList.of();
@@ -639,8 +640,8 @@ public class Artifact implements FileType.HasFilename, ArtifactFile, SkylarkValu
    * {@link MiddlemanType#AGGREGATING_MIDDLEMAN} middleman actions expanded once.
    */
   public static void addExpandedArtifacts(Iterable<Artifact> artifacts,
-      Collection<? super Artifact> output, MiddlemanExpander middlemanExpander) {
-    addExpandedArtifacts(artifacts, output, Functions.<Artifact>identity(), middlemanExpander);
+      Collection<? super ArtifactFile> output, ArtifactExpander artifactExpander) {
+    addExpandedArtifacts(artifacts, output, Functions.<ArtifactFile>identity(), artifactExpander);
   }
 
   /**
@@ -652,9 +653,9 @@ public class Artifact implements FileType.HasFilename, ArtifactFile, SkylarkValu
   @VisibleForTesting
   public static void addExpandedExecPathStrings(Iterable<Artifact> artifacts,
                                                  Collection<String> output,
-                                                 MiddlemanExpander middlemanExpander) {
+                                                 ArtifactExpander artifactExpander) {
     addExpandedArtifacts(artifacts, output, ActionInputHelper.EXEC_PATH_STRING_FORMATTER,
-        middlemanExpander);
+        artifactExpander);
   }
 
   /**
@@ -664,8 +665,8 @@ public class Artifact implements FileType.HasFilename, ArtifactFile, SkylarkValu
    * once.
    */
   public static void addExpandedExecPaths(Iterable<Artifact> artifacts,
-      Collection<PathFragment> output, MiddlemanExpander middlemanExpander) {
-    addExpandedArtifacts(artifacts, output, EXEC_PATH_FORMATTER, middlemanExpander);
+      Collection<PathFragment> output, ArtifactExpander artifactExpander) {
+    addExpandedArtifacts(artifacts, output, EXEC_PATH_FORMATTER, artifactExpander);
   }
 
   /**
@@ -673,27 +674,29 @@ public class Artifact implements FileType.HasFilename, ArtifactFile, SkylarkValu
    * outputFormatter and adds them to a given collection. Middleman artifacts
    * are expanded once.
    */
-  private static <E> void addExpandedArtifacts(Iterable<Artifact> artifacts,
+  private static <E> void addExpandedArtifacts(Iterable<? extends Artifact> artifacts,
                                                Collection<? super E> output,
-                                               Function<? super Artifact, E> outputFormatter,
-                                               MiddlemanExpander middlemanExpander) {
+                                               Function<? super ArtifactFile, E> outputFormatter,
+                                               ArtifactExpander artifactExpander) {
     for (Artifact artifact : artifacts) {
-      if (artifact.isMiddlemanArtifact()) {
-        expandMiddlemanArtifact(artifact, output, outputFormatter, middlemanExpander);
+      if (artifact.isMiddlemanArtifact() || artifact.isTreeArtifact()) {
+        expandArtifact(artifact, output, outputFormatter, artifactExpander);
       } else {
         output.add(outputFormatter.apply(artifact));
       }
     }
   }
 
-  private static <E> void expandMiddlemanArtifact(Artifact middleman,
-                                                  Collection<? super E> output,
-                                                  Function<? super Artifact, E> outputFormatter,
-                                                  MiddlemanExpander middlemanExpander) {
-    Preconditions.checkArgument(middleman.isMiddlemanArtifact());
-    List<Artifact> artifacts = new ArrayList<>();
-    middlemanExpander.expand(middleman, artifacts);
-    addExpandedArtifacts(artifacts, output, outputFormatter, middlemanExpander);
+  private static <E> void expandArtifact(Artifact middleman,
+      Collection<? super E> output,
+      Function<? super ArtifactFile, E> outputFormatter,
+      ArtifactExpander artifactExpander) {
+    Preconditions.checkArgument(middleman.isMiddlemanArtifact() || middleman.isTreeArtifact());
+    List<ArtifactFile> artifacts = new ArrayList<>();
+    artifactExpander.expand(middleman, artifacts);
+    for (ArtifactFile artifact : artifacts) {
+      output.add(outputFormatter.apply(artifact));
+    }
   }
 
   /**
@@ -702,9 +705,9 @@ public class Artifact implements FileType.HasFilename, ArtifactFile, SkylarkValu
    * returned list is mutable.
    */
   public static List<String> asExpandedExecPathStrings(Iterable<Artifact> artifacts,
-                                                       MiddlemanExpander middlemanExpander) {
+                                                       ArtifactExpander artifactExpander) {
     List<String> result = new ArrayList<>();
-    addExpandedExecPathStrings(artifacts, result, middlemanExpander);
+    addExpandedExecPathStrings(artifacts, result, artifactExpander);
     return result;
   }
 
@@ -714,9 +717,9 @@ public class Artifact implements FileType.HasFilename, ArtifactFile, SkylarkValu
    * returned list is mutable.
    */
   public static List<PathFragment> asExpandedExecPaths(Iterable<Artifact> artifacts,
-                                                       MiddlemanExpander middlemanExpander) {
+                                                       ArtifactExpander artifactExpander) {
     List<PathFragment> result = new ArrayList<>();
-    addExpandedExecPaths(artifacts, result, middlemanExpander);
+    addExpandedExecPaths(artifacts, result, artifactExpander);
     return result;
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
index 32cfeb4aee..7f3120c66c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
@@ -27,7 +27,8 @@ import com.google.devtools.build.lib.actions.ActionExecutionException;
 import com.google.devtools.build.lib.actions.ActionInput;
 import com.google.devtools.build.lib.actions.ActionOwner;
 import com.google.devtools.build.lib.actions.Artifact;
-import com.google.devtools.build.lib.actions.Artifact.MiddlemanExpander;
+import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander;
+import com.google.devtools.build.lib.actions.ArtifactFile;
 import com.google.devtools.build.lib.actions.ArtifactResolver;
 import com.google.devtools.build.lib.actions.ExecException;
 import com.google.devtools.build.lib.actions.Executor;
@@ -686,15 +687,15 @@ public class CppCompileAction extends AbstractAction implements IncludeScannable
   @VisibleForTesting
   public void validateInclusions(
       Iterable<Artifact> inputsForValidation,
-      MiddlemanExpander middlemanExpander,
+      ArtifactExpander artifactExpander,
       EventHandler eventHandler)
       throws ActionExecutionException {
     IncludeProblems errors = new IncludeProblems();
     IncludeProblems warnings = new IncludeProblems();
-    Set<Artifact> allowedIncludes = new HashSet<>();
+    Set<ArtifactFile> allowedIncludes = new HashSet<>();
     for (Artifact input : mandatoryInputs) {
-      if (input.isMiddlemanArtifact()) {
-        middlemanExpander.expand(input, allowedIncludes);
+      if (input.isMiddlemanArtifact() || input.isTreeArtifact()) {
+        artifactExpander.expand(input, allowedIncludes);
       }
       allowedIncludes.add(input);
     }
@@ -1138,7 +1139,7 @@ public class CppCompileAction extends AbstractAction implements IncludeScannable
     // hdrs_check: This cannot be switched off, because doing so would allow for incorrect builds.
     validateInclusions(
         discoveredInputs,
-        actionExecutionContext.getMiddlemanExpander(),
+        actionExecutionContext.getArtifactExpander(),
         executor.getEventHandler());
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/FakeCppCompileAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/FakeCppCompileAction.java
index b92e61496d..d445dc24ce 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/FakeCppCompileAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/FakeCppCompileAction.java
@@ -151,7 +151,7 @@ public class FakeCppCompileAction extends CppCompileAction {
     try {
       validateInclusions(
           discoveredInputs,
-          actionExecutionContext.getMiddlemanExpander(),
+          actionExecutionContext.getArtifactExpander(),
           executor.getEventHandler());
     } catch (ActionExecutionException e) {
       // TODO(bazel-team): (2009) make this into an error, once most of the current warnings
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java b/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java
index 9148014a5e..a6f73854a8 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/LinuxSandboxedStrategy.java
@@ -442,8 +442,8 @@ public class LinuxSandboxedStrategy implements SpawnActionContext {
     MountMap mounts = new MountMap();
 
     List<ActionInput> inputs =
-        ActionInputHelper.expandMiddlemen(
-            spawn.getInputFiles(), actionExecutionContext.getMiddlemanExpander());
+        ActionInputHelper.expandArtifacts(
+            spawn.getInputFiles(), actionExecutionContext.getArtifactExpander());
 
     if (spawn.getResourceOwner() instanceof CppCompileAction) {
       CppCompileAction action = (CppCompileAction) spawn.getResourceOwner();
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ActionExecutionFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ActionExecutionFunction.java
index 228d8f1b09..c79fd134d1 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ActionExecutionFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ActionExecutionFunction.java
@@ -26,6 +26,7 @@ import com.google.devtools.build.lib.actions.ActionExecutionContext;
 import com.google.devtools.build.lib.actions.ActionExecutionException;
 import com.google.devtools.build.lib.actions.AlreadyReportedActionExecutionException;
 import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.actions.ArtifactFile;
 import com.google.devtools.build.lib.actions.MissingInputFileException;
 import com.google.devtools.build.lib.actions.NotifyOnActionCacheHit;
 import com.google.devtools.build.lib.actions.PackageRootResolutionException;
@@ -124,7 +125,7 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
       env.getValues(state.allInputs.keysRequested);
       Preconditions.checkState(!env.valuesMissing(), "%s %s", action, state);
     }
-    Pair<Map<Artifact, FileArtifactValue>, Map<Artifact, Collection<Artifact>>> checkedInputs =
+    Pair<Map<Artifact, FileArtifactValue>, Map<Artifact, Collection<ArtifactFile>>> checkedInputs =
         null;
     try {
       // Declare deps on known inputs to action. We do this unconditionally to maintain our
@@ -163,7 +164,7 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
     if (checkedInputs != null) {
       Preconditions.checkState(!state.hasArtifactData(), "%s %s", state, action);
       state.inputArtifactData = checkedInputs.first;
-      state.expandedMiddlemen = checkedInputs.second;
+      state.expandedArtifacts = checkedInputs.second;
     }
 
     ActionExecutionValue result;
@@ -369,7 +370,7 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
       }
       actionExecutionContext =
           skyframeActionExecutor.getContext(perActionFileCache,
-              metadataHandler, state.expandedMiddlemen);
+              metadataHandler, state.expandedArtifacts);
       if (!state.hasExecutedAction()) {
         state.value = skyframeActionExecutor.executeAction(action,
             metadataHandler, actionStartTime, actionExecutionContext);
@@ -515,8 +516,8 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
    * Declare dependency on all known inputs of action. Throws exception if any are known to be
    * missing. Some inputs may not yet be in the graph, in which case the builder should abort.
    */
-  private Pair<Map<Artifact, FileArtifactValue>, Map<Artifact, Collection<Artifact>>> checkInputs(
-      Environment env, Action action,
+  private Pair<Map<Artifact, FileArtifactValue>, Map<Artifact, Collection<ArtifactFile>>>
+  checkInputs(Environment env, Action action,
       Map<SkyKey, ValueOrException2<MissingInputFileException, ActionExecutionException>> inputDeps)
       throws ActionExecutionException {
     int missingCount = 0;
@@ -530,7 +531,7 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
     NestedSetBuilder<Label> rootCauses = NestedSetBuilder.stableOrder();
     Map<Artifact, FileArtifactValue> inputArtifactData =
         new HashMap<>(populateInputData ? inputDeps.size() : 0);
-    Map<Artifact, Collection<Artifact>> expandedMiddlemen =
+    Map<Artifact, Collection<ArtifactFile>> expandedArtifacts =
         new HashMap<>(populateInputData ? 128 : 0);
 
     ActionExecutionException firstActionExecutionException = null;
@@ -547,9 +548,14 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
           // We have to cache the "digest" of the aggregating value itself, because the action cache
           // checker may want it.
           inputArtifactData.put(input, aggregatingValue.getSelfData());
-          expandedMiddlemen.put(input,
+          expandedArtifacts.put(input,
               Collections2.transform(aggregatingValue.getInputs(),
-                  Pair.<Artifact, FileArtifactValue>firstFunction()));
+                  new Function<Pair<Artifact, FileArtifactValue>, ArtifactFile>() {
+                    @Override
+                    public ArtifactFile apply(Pair<Artifact, FileArtifactValue> pair) {
+                      return pair.first;
+                    }
+                  }));
         } else if (populateInputData && value instanceof FileArtifactValue) {
           // TODO(bazel-team): Make sure middleman "virtual" artifact data is properly processed.
           inputArtifactData.put(input, (FileArtifactValue) value);
@@ -590,7 +596,7 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
     }
     return Pair.of(
         Collections.unmodifiableMap(inputArtifactData),
-        Collections.unmodifiableMap(expandedMiddlemen));
+        Collections.unmodifiableMap(expandedArtifacts));
   }
 
   /**
@@ -668,7 +674,7 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
   private static class ContinuationState {
     AllInputs allInputs;
     Map<Artifact, FileArtifactValue> inputArtifactData = null;
-    Map<Artifact, Collection<Artifact>> expandedMiddlemen = null;
+    Map<Artifact, Collection<ArtifactFile>> expandedArtifacts = null;
     Token token = null;
     Collection<Artifact> discoveredInputs = null;
     ActionExecutionValue value = null;
@@ -679,7 +685,7 @@ public class ActionExecutionFunction implements SkyFunction, CompletionReceiver
 
     boolean hasArtifactData() {
       boolean result = inputArtifactData != null;
-      Preconditions.checkState(result == (expandedMiddlemen != null), this);
+      Preconditions.checkState(result == (expandedArtifacts != null), this);
       return result;
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java
index cf8556d2b6..5e2ba5d73b 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeActionExecutor.java
@@ -38,7 +38,8 @@ import com.google.devtools.build.lib.actions.ActionStartedEvent;
 import com.google.devtools.build.lib.actions.Actions;
 import com.google.devtools.build.lib.actions.AlreadyReportedActionExecutionException;
 import com.google.devtools.build.lib.actions.Artifact;
-import com.google.devtools.build.lib.actions.Artifact.MiddlemanExpander;
+import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander;
+import com.google.devtools.build.lib.actions.ArtifactFile;
 import com.google.devtools.build.lib.actions.ArtifactPrefixConflictException;
 import com.google.devtools.build.lib.actions.CachedActionEvent;
 import com.google.devtools.build.lib.actions.EnvironmentalExecException;
@@ -428,17 +429,17 @@ public final class SkyframeActionExecutor implements ActionExecutionContextFacto
     }
   }
 
-  private static class MiddlemanExpanderImpl implements MiddlemanExpander {
-    private final Map<Artifact, Collection<Artifact>> expandedInputMiddlemen;
+  private static class ArtifactExpanderImpl implements ArtifactExpander {
+    private final Map<Artifact, Collection<ArtifactFile>> expandedInputs;
 
-    private MiddlemanExpanderImpl(Map<Artifact, Collection<Artifact>> expandedInputMiddlemen) {
-      this.expandedInputMiddlemen = expandedInputMiddlemen;
+    private ArtifactExpanderImpl(Map<Artifact, Collection<ArtifactFile>> expandedInputMiddlemen) {
+      this.expandedInputs = expandedInputMiddlemen;
     }
 
     @Override
-    public void expand(Artifact middlemanArtifact, Collection<? super Artifact> output) {
-      Preconditions.checkState(middlemanArtifact.isMiddlemanArtifact(), middlemanArtifact);
-      Collection<Artifact> result = expandedInputMiddlemen.get(middlemanArtifact);
+    public void expand(Artifact artifact, Collection<? super ArtifactFile> output) {
+      Preconditions.checkState(artifact.isMiddlemanArtifact(), artifact);
+      Collection<ArtifactFile> result = expandedInputs.get(artifact);
       // Note that result may be null for non-aggregating middlemen.
       if (result != null) {
         output.addAll(result);
@@ -454,14 +455,14 @@ public final class SkyframeActionExecutor implements ActionExecutionContextFacto
   @Override
   public ActionExecutionContext getContext(
       ActionInputFileCache graphFileCache, MetadataHandler metadataHandler,
-      Map<Artifact, Collection<Artifact>> expandedInputMiddlemen) {
+      Map<Artifact, Collection<ArtifactFile>> expandedInputs) {
     FileOutErr fileOutErr = actionLogBufferPathGenerator.generate();
     return new ActionExecutionContext(
         executorEngine,
         new DelegatingPairFileCache(graphFileCache, perBuildFileCache),
         metadataHandler,
         fileOutErr,
-        new MiddlemanExpanderImpl(expandedInputMiddlemen));
+        new ArtifactExpanderImpl(expandedInputs));
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/worker/WorkerSpawnStrategy.java b/src/main/java/com/google/devtools/build/lib/worker/WorkerSpawnStrategy.java
index 20e0755be0..edee914438 100644
--- a/src/main/java/com/google/devtools/build/lib/worker/WorkerSpawnStrategy.java
+++ b/src/main/java/com/google/devtools/build/lib/worker/WorkerSpawnStrategy.java
@@ -161,8 +161,8 @@ final class WorkerSpawnStrategy implements SpawnActionContext {
       expandArgument(requestBuilder, Iterables.getLast(spawn.getArguments()));
 
       List<ActionInput> inputs =
-          ActionInputHelper.expandMiddlemen(
-              spawn.getInputFiles(), actionExecutionContext.getMiddlemanExpander());
+          ActionInputHelper.expandArtifacts(
+              spawn.getInputFiles(), actionExecutionContext.getArtifactExpander());
 
       for (ActionInput input : inputs) {
         ByteString digest = inputFileCache.getDigest(input);
diff --git a/src/test/java/com/google/devtools/build/lib/actions/ArtifactTest.java b/src/test/java/com/google/devtools/build/lib/actions/ArtifactTest.java
index cd978217d0..c0c992f2b5 100644
--- a/src/test/java/com/google/devtools/build/lib/actions/ArtifactTest.java
+++ b/src/test/java/com/google/devtools/build/lib/actions/ArtifactTest.java
@@ -176,7 +176,7 @@ public class ArtifactTest {
     List<String> paths = new ArrayList<>();
     MutableActionGraph actionGraph = new MapBasedActionGraph();
     Artifact.addExpandedExecPathStrings(getFooBarArtifacts(actionGraph, true), paths,
-        ActionInputHelper.actionGraphMiddlemanExpander(actionGraph));
+        ActionInputHelper.actionGraphArtifactExpander(actionGraph));
     assertThat(paths).containsExactly("bar1.h", "bar1.h", "bar2.h", "bar3.h");
   }
 
@@ -185,7 +185,7 @@ public class ArtifactTest {
     List<PathFragment> paths = new ArrayList<>();
     MutableActionGraph actionGraph = new MapBasedActionGraph();
     Artifact.addExpandedExecPaths(getFooBarArtifacts(actionGraph, true), paths,
-        ActionInputHelper.actionGraphMiddlemanExpander(actionGraph));
+        ActionInputHelper.actionGraphArtifactExpander(actionGraph));
     assertThat(paths).containsExactly(
         new PathFragment("bar1.h"),
         new PathFragment("bar1.h"),
@@ -195,11 +195,11 @@ public class ArtifactTest {
 
   @Test
   public void testAddExpandedArtifacts() throws Exception {
-    List<Artifact> expanded = new ArrayList<>();
+    List<ArtifactFile> expanded = new ArrayList<>();
     MutableActionGraph actionGraph = new MapBasedActionGraph();
     List<Artifact> original = getFooBarArtifacts(actionGraph, true);
     Artifact.addExpandedArtifacts(original, expanded,
-        ActionInputHelper.actionGraphMiddlemanExpander(actionGraph));
+        ActionInputHelper.actionGraphArtifactExpander(actionGraph));
 
     List<Artifact> manuallyExpanded = new ArrayList<>();
     for (Artifact artifact : original) {
@@ -226,7 +226,7 @@ public class ArtifactTest {
     List<String> paths = new ArrayList<>();
     MutableActionGraph actionGraph = new MapBasedActionGraph();
     Artifact.addExpandedExecPathStrings(getFooBarArtifacts(actionGraph, true), paths,
-        ActionInputHelper.actionGraphMiddlemanExpander(actionGraph));
+        ActionInputHelper.actionGraphArtifactExpander(actionGraph));
     assertThat(paths).containsExactly("bar1.h", "bar1.h", "bar2.h", "bar3.h");
   }
 
@@ -235,7 +235,7 @@ public class ArtifactTest {
     List<PathFragment> paths = new ArrayList<>();
     MutableActionGraph actionGraph = new MapBasedActionGraph();
     Artifact.addExpandedExecPaths(getFooBarArtifacts(actionGraph, true), paths,
-        ActionInputHelper.actionGraphMiddlemanExpander(actionGraph));
+        ActionInputHelper.actionGraphArtifactExpander(actionGraph));
     assertThat(paths).containsExactly(
         new PathFragment("bar1.h"),
         new PathFragment("bar1.h"),
@@ -243,13 +243,14 @@ public class ArtifactTest {
         new PathFragment("bar3.h"));
   }
 
+  // TODO consider tests for the future
   @Test
   public void testAddExpandedArtifactsNewActionGraph() throws Exception {
-    List<Artifact> expanded = new ArrayList<>();
+    List<ArtifactFile> expanded = new ArrayList<>();
     MutableActionGraph actionGraph = new MapBasedActionGraph();
     List<Artifact> original = getFooBarArtifacts(actionGraph, true);
     Artifact.addExpandedArtifacts(original, expanded,
-        ActionInputHelper.actionGraphMiddlemanExpander(actionGraph));
+        ActionInputHelper.actionGraphArtifactExpander(actionGraph));
 
     List<Artifact> manuallyExpanded = new ArrayList<>();
     for (Artifact artifact : original) {
diff --git a/src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java b/src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java
index 305188e693..38aad5ce28 100644
--- a/src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java
+++ b/src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java
@@ -90,7 +90,7 @@ public final class ActionsTestUtil {
         metadataHandler, fileOutErr,
         actionGraph == null
             ? null
-            : ActionInputHelper.actionGraphMiddlemanExpander(actionGraph));
+            : ActionInputHelper.actionGraphArtifactExpander(actionGraph));
   }
 
   public static ActionExecutionContext createContextForInputDiscovery(Executor executor,