3 files changed, 34 insertions, 9 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/actions/cache/DigestUtils.java b/src/main/java/com/google/devtools/build/lib/actions/cache/DigestUtils.java
index aaf8b1d459..cae2a547af 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/cache/DigestUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/cache/DigestUtils.java
@@ -313,13 +313,12 @@ public class DigestUtils {
 
     if (md == null) {
       // Move along, nothing to see here.
-    } else if (md.digest == null) {
-      // Use the timestamp if the digest is not present, but not both.
-      // Modifying a timestamp while keeping the contents of a file the
-      // same should not cause rebuilds.
-      fp.addLong(md.mtime);
+    } else if (md.isFile()) {
+      fp.addBytes(md.getDigest());
     } else {
-      fp.addBytes(md.digest);
+      // Use the timestamp if the digest is not present, but not both. Modifying a timestamp while
+      // keeping the contents of a file the same should not cause rebuilds.
+      fp.addLong(md.getModifiedTime());
     }
     return fp.digestAndReset();
   }
diff --git a/src/main/java/com/google/devtools/build/lib/actions/cache/Metadata.java b/src/main/java/com/google/devtools/build/lib/actions/cache/Metadata.java
index 316fd234e5..0f5a037ac9 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/cache/Metadata.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/cache/Metadata.java
@@ -33,23 +33,49 @@ import java.util.Date;
  */
 @Immutable @ThreadSafe
 public final class Metadata {
-  public final long mtime;
-  public final byte[] digest;
+  private final long mtime;
+  private final byte[] digest;
 
   // Convenience object for use with volatile files that we do not want checked
   // (e.g. the build-changelist.txt)
   public static final Metadata CONSTANT_METADATA = new Metadata(-1);
 
+  /**
+   * Construct an instance for a directory with the specified mtime. The {@link #isFile} method
+   * returns true if and only if a digest is set.
+   */
   public Metadata(long mtime) {
     this.mtime = mtime;
     this.digest = null;
   }
 
+  /**
+   * Construct an instance for a file with the specified digest. The {@link #isFile} method returns
+   * true if and only if a digest is set.
+   */
   public Metadata(byte[] digest) {
     this.mtime = 0L;
     this.digest = Preconditions.checkNotNull(digest);
   }
 
+  public boolean isFile() {
+    return digest != null;
+  }
+
+  /**
+   * Returns the digest for the underlying file system object.
+   *
+   * <p>The return value is owned by the cache and must not be modified.
+   */
+  public byte[] getDigest() {
+    Preconditions.checkState(digest != null);
+    return digest;
+  }
+
+  public long getModifiedTime() {
+    return mtime;
+  }
+
   @Override
   public int hashCode() {
     int hash = 0;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/ApkManifestAction.java b/src/main/java/com/google/devtools/build/lib/rules/android/ApkManifestAction.java
index 4ab7f74dcd..e153a60c41 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/ApkManifestAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/ApkManifestAction.java
@@ -113,7 +113,7 @@ public final class ApkManifestAction extends AbstractFileWriteAction {
     ApkManifestCreator manifestCreator = new ApkManifestCreator(new ArtifactDigester() {
         @Override
         public byte[] getDigest(Artifact artifact) throws IOException {
-          return ctx.getMetadataHandler().getMetadata(artifact).digest;
+          return ctx.getMetadataHandler().getMetadata(artifact).getDigest();
         }
     });