Implement hashCode, equals for TransitiveTraversalValue and related SkyValues

--
MOS_MIGRATED_REVID=101233095

3 files changed, 47 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PrepareDepsOfPatternValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/PrepareDepsOfPatternValue.java
index fe7a0da76b..9ffac75455 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PrepareDepsOfPatternValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PrepareDepsOfPatternValue.java
@@ -32,7 +32,7 @@ import java.util.List;
  * invoked only for its side effect (i.e. ensuring the graph contains targets matching the
  * pattern and its transitive dependencies), this value carries no information.
  *
- * <p>Because the returned value is always the same object, this value and the
+ * <p>Because the returned value is always equal to objects that share its type, this value and the
  * {@link PrepareDepsOfPatternFunction} which computes it are incompatible with change pruning. It
  * should only be requested by consumers who do not require reevaluation when
  * {@link PrepareDepsOfPatternFunction} is reevaluated. Safe consumers include, e.g., top-level
@@ -40,11 +40,23 @@ import java.util.List;
  * side-effects.
  */
 public class PrepareDepsOfPatternValue implements SkyValue {
+  // Note that this value does not guarantee singleton-like reference equality because we use Java
+  // deserialization. Java deserialization can create other instances.
   public static final PrepareDepsOfPatternValue INSTANCE = new PrepareDepsOfPatternValue();
 
   private PrepareDepsOfPatternValue() {
   }
 
+  @Override
+  public boolean equals(Object o) {
+    return o instanceof PrepareDepsOfPatternValue;
+  }
+
+  @Override
+  public int hashCode() {
+    return 42;
+  }
+
   /**
    * Returns an iterable of {@link PrepareDepsOfPatternSkyKeyOrException}, with {@link
    * TargetPatternKey} arguments. Negative target patterns of type other than {@link
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/TargetMarkerValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/TargetMarkerValue.java
index eef70843fd..d325de5496 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/TargetMarkerValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/TargetMarkerValue.java
@@ -26,11 +26,23 @@ import com.google.devtools.build.skyframe.SkyValue;
 @ThreadSafe
 public final class TargetMarkerValue implements SkyValue {
 
+  // Note that this value does not guarantee singleton-like reference equality because we use Java
+  // deserialization. java deserialization can create other instances.
   static final TargetMarkerValue TARGET_MARKER_INSTANCE = new TargetMarkerValue();
 
   private TargetMarkerValue() {
   }
 
+  @Override
+  public boolean equals(Object o) {
+    return o instanceof TargetMarkerValue;
+  }
+
+  @Override
+  public int hashCode() {
+    return 42;
+  }
+
   @ThreadSafe
   public static SkyKey key(Label label) {
     return new SkyKey(SkyFunctions.TARGET_MARKER, label);
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTraversalValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTraversalValue.java
index 8216381994..829bc7d7f0 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTraversalValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTraversalValue.java
@@ -20,6 +20,8 @@ import com.google.devtools.build.lib.syntax.Label;
 import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
 
+import java.util.Objects;
+
 import javax.annotation.Nullable;
 
 /**
@@ -33,6 +35,9 @@ public class TransitiveTraversalValue implements SkyValue {
   @Nullable
   private final NoSuchTargetException errorLoadingTarget;
 
+  // Note that this value does not guarantee singleton-like reference equality for successful
+  // {@link TransitiveTraversalValue}s because we use Java deserialization. Java deserialization can
+  // create other instances.
   static final TransitiveTraversalValue SUCCESSFUL_TRANSITIVE_TRAVERSAL_VALUE =
       new TransitiveTraversalValue(null);
 
@@ -51,6 +56,23 @@ public class TransitiveTraversalValue implements SkyValue {
     return errorLoadingTarget;
   }
 
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (!(o instanceof TransitiveTraversalValue)) {
+      return false;
+    }
+    TransitiveTraversalValue that = (TransitiveTraversalValue) o;
+    return Objects.equals(this.errorLoadingTarget, that.errorLoadingTarget);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hashCode(errorLoadingTarget);
+  }
+
   @ThreadSafe
   public static SkyKey key(Label label) {
     return new SkyKey(SkyFunctions.TRANSITIVE_TRAVERSAL, label);