Add CommandLineItem interface.

This interface makes it clearer in the type system exactly how items that go into a CustomCommandLine are turned into strings.

It is a preparatory change to allow command line fingerprints to be more cheaply calculated, but it is valuable in itself from a code quality standpoint.

PiperOrigin-RevId: 183274022

3 files changed, 17 insertions, 13 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java b/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java
index 6ba29a7655..6378675147 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java
@@ -20,22 +20,15 @@ import com.google.devtools.build.lib.util.Fingerprint;
 
 /** Contains state that aids in action key computation via {@link AbstractAction#computeKey}. */
 public class ActionKeyContext {
-  private static final class ArtifactNestedSetFingerprintCache
-      extends NestedSetFingerprintCache<Artifact> {
-    @Override
-    protected void addItemFingerprint(Fingerprint fingerprint, Artifact item) {
-      fingerprint.addPath(item.getExecPath());
-    }
-  }
 
-  private final ArtifactNestedSetFingerprintCache artifactNestedSetFingerprintCache =
-      new ArtifactNestedSetFingerprintCache();
+  private final NestedSetFingerprintCache nestedSetFingerprintCache =
+      new NestedSetFingerprintCache();
 
-  public void addArtifactsToFingerprint(Fingerprint fingerprint, NestedSet<Artifact> artifacts) {
-    artifactNestedSetFingerprintCache.addNestedSetToFingerprint(fingerprint, artifacts);
+  public <T> void addNestedSetToFingerprint(Fingerprint fingerprint, NestedSet<T> nestedSet) {
+    nestedSetFingerprintCache.addNestedSetToFingerprint(fingerprint, nestedSet);
   }
 
   public void clear() {
-    artifactNestedSetFingerprintCache.clear();
+    nestedSetFingerprintCache.clear();
   }
 }
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 e371ec1670..d45d16d587 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
@@ -27,6 +27,7 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Streams;
 import com.google.devtools.build.lib.actions.ActionAnalysisMetadata.MiddlemanType;
+import com.google.devtools.build.lib.analysis.actions.CommandLineItem;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.shell.ShellUtils;
@@ -115,7 +116,11 @@ import javax.annotation.Nullable;
           + "<a href='ctx.html#outputs'>ctx.outputs</a>."
 )
 public class Artifact
-    implements FileType.HasFileType, ActionInput, SkylarkValue, Comparable<Object> {
+    implements FileType.HasFileType,
+        ActionInput,
+        SkylarkValue,
+        Comparable<Object>,
+        CommandLineItem {
 
   /** Compares artifact according to their exec paths. Sorts null values first. */
   @SuppressWarnings("ReferenceEquality")  // "a == b" is an optimization
@@ -328,6 +333,11 @@ public class Artifact
     return getExecPath().filePathForFileTypeMatcher();
   }
 
+  @Override
+  public String expandToCommandLine() {
+    return getExecPathString();
+  }
+
   /**
    * Returns the artifact owner. May be null.
    */
diff --git a/src/main/java/com/google/devtools/build/lib/actions/BUILD b/src/main/java/com/google/devtools/build/lib/actions/BUILD
index 2c3f3abb0e..f936712ffb 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/actions/BUILD
@@ -17,6 +17,7 @@ java_library(
         "cache/*.java",
     ]),
     deps = [
+        "//src/main/java/com/google/devtools/build/lib:commandline_item",
         "//src/main/java/com/google/devtools/build/lib:events",
         "//src/main/java/com/google/devtools/build/lib:io",
         "//src/main/java/com/google/devtools/build/lib:packages-internal",