Make Artifact#equals take the owner into account for derived artifacts.

Derived artifacts' owners are important because they are used to determine the artifact's generating action. Source artifacts' owners are not used in this way, so I left them alone.

This allows us to get rid of most uses of ArtifactSkyKey. We may be able to delete it entirely in a follow-up.

PiperOrigin-RevId: 199836436

1 files changed, 53 insertions, 22 deletions

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 f18e14f0d0..f91c5cde5a 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
@@ -15,7 +15,6 @@
 package com.google.devtools.build.lib.actions;
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
-import static java.util.Comparator.comparing;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Function;
@@ -45,6 +44,8 @@ import com.google.devtools.build.lib.util.FileType;
 import com.google.devtools.build.lib.util.FileTypeSet;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
+import com.google.devtools.build.skyframe.SkyFunctionName;
+import com.google.devtools.build.skyframe.SkyKey;
 import com.google.protobuf.CodedInputStream;
 import com.google.protobuf.CodedOutputStream;
 import java.io.IOException;
@@ -107,7 +108,8 @@ public class Artifact
         ActionInput,
         FileApi,
         Comparable<Object>,
-        CommandLineItem {
+        CommandLineItem,
+        SkyKey {
 
   /** Compares artifact according to their exec paths. Sorts null values first. */
   @SuppressWarnings("ReferenceEquality")  // "a == b" is an optimization
@@ -124,9 +126,7 @@ public class Artifact
         }
       };
 
-  /** Compares artifacts according to their root relative paths. */
-  public static final Comparator<Artifact> ROOT_RELATIVE_PATH_COMPARATOR =
-      comparing(Artifact::getRootRelativePath);
+  public static final SkyFunctionName ARTIFACT = SkyFunctionName.create("ARTIFACT");
 
   @Override
   public int compareTo(Object o) {
@@ -228,6 +228,9 @@ public class Artifact
       throw new IllegalArgumentException(
           "it is illegal to create an artifact with an empty execPath");
     }
+    // The ArtifactOwner is not part of this computation because it is very rare that two Artifacts
+    // have the same execPath and different owners, so a collision is fine there. If this is
+    // changed, OwnerlessArtifactWrapper must also be changed.
     this.hashCode = execPath.hashCode() + this.getClass().hashCode() * 13;
     this.root = root;
     this.execPath = execPath;
@@ -455,6 +458,15 @@ public class Artifact
     public SourceArtifact asSourceArtifact() {
       return this;
     }
+
+    /**
+     * SourceArtifacts are compared without their owners, since owners do not affect behavior,
+     * unlike with derived artifacts, whose owners determine their generating actions.
+     */
+    @Override
+    public boolean equals(Object other) {
+      return other instanceof SourceArtifact && equalsWithoutOwner((SourceArtifact) other);
+    }
   }
 
   /**
@@ -637,36 +649,26 @@ public class Artifact
   }
 
   @Override
-  public final boolean equals(Object other) {
+  public boolean equals(Object other) {
     if (!(other instanceof Artifact)) {
       return false;
     }
     if (!getClass().equals(other.getClass())) {
       return false;
     }
-    // We don't bother to check root in the equivalence relation, because we
-    // assume that no root is an ancestor of another one.
     Artifact that = (Artifact) other;
-    return Objects.equals(this.execPath, that.execPath) && Objects.equals(this.root, that.root);
+    return equalsWithoutOwner(that) && owner.equals(that.getArtifactOwner());
   }
 
-  /**
-   * Compare equality including Artifact owner equality, a notable difference compared to the
-   * {@link #equals(Object)} method of {@link Artifact}.
-   */
-  public static boolean equalWithOwner(@Nullable Artifact first, @Nullable Artifact second) {
-    if (first != null) {
-      return first.equals(second) && first.getArtifactOwner().equals(second.getArtifactOwner());
-    } else {
-      return second == null;
-    }
+  public boolean equalsWithoutOwner(Artifact other) {
+    return Objects.equals(this.execPath, other.execPath) && Objects.equals(this.root, other.root);
   }
 
   @Override
   public final int hashCode() {
-    // This is just path.hashCode().  We cache a copy in the Artifact object to reduce LLC misses
-    // during operations which build a HashSet out of many Artifacts.  This is a slight loss for
-    // memory but saves ~1% overall CPU in some real builds.
+    // This is just execPath.hashCode() (along with the class). We cache a copy in the Artifact
+    // object to reduce LLC misses during operations which build a HashSet out of many Artifacts.
+    // This is a slight loss for memory but saves ~1% overall CPU in some real builds.
     return hashCode;
   }
 
@@ -974,4 +976,33 @@ public class Artifact
       printer.append("<generated file " + rootRelativePath + ">");
     }
   }
+
+  /**
+   * A utility class that compares {@link Artifact}s without taking their owners into account.
+   * Should only be used for detecting action conflicts and merging shared action data.
+   */
+  public static class OwnerlessArtifactWrapper {
+    private final Artifact artifact;
+
+    public OwnerlessArtifactWrapper(Artifact artifact) {
+      this.artifact = artifact;
+    }
+
+    @Override
+    public int hashCode() {
+      // Depends on the fact that Artifact#hashCode does not use ArtifactOwner.
+      return artifact.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+      return obj instanceof OwnerlessArtifactWrapper
+          && this.artifact.equalsWithoutOwner(((OwnerlessArtifactWrapper) obj).artifact);
+    }
+  }
+
+  @Override
+  public SkyFunctionName functionName() {
+    return ARTIFACT;
+  }
 }