Add value constants to ObjectCodecRegistry. Value constants are to be used when there may not be a canonical instance of the object we want (or the canonical instance isn't available at registry construction time), but we can reasonably cheaply do value equality comparisons. Strings are a good example.

PiperOrigin-RevId: 192354865

1 files changed, 17 insertions, 3 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/serialization/AutoRegistry.java b/src/main/java/com/google/devtools/build/lib/skyframe/serialization/AutoRegistry.java
index 7785493aa5..6c81ccfe92 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/serialization/AutoRegistry.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/serialization/AutoRegistry.java
@@ -21,7 +21,10 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Ordering;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 
 /**
  * A lazy, automatically populated registry.
@@ -46,7 +49,7 @@ public class AutoRegistry {
   private static final ImmutableList<String> EXTERNAL_CLASS_NAMES_TO_REGISTER =
       ImmutableList.of("java.io.FileNotFoundException", "java.io.IOException");
 
-  private static final ImmutableList<Object> CONSTANTS_TO_REGISTER =
+  private static final ImmutableList<Object> REFERENCE_CONSTANTS_TO_REGISTER =
       ImmutableList.of(
           Predicates.alwaysTrue(),
           Predicates.alwaysFalse(),
@@ -57,6 +60,14 @@ public class AutoRegistry {
           Comparator.naturalOrder(),
           Ordering.natural());
 
+  private static final ImmutableList<Object> VALUE_CONSTANTS_TO_REGISTER =
+      ImmutableList.of(
+          "",
+          Boolean.FALSE,
+          Boolean.TRUE,
+          Collections.unmodifiableMap(new HashMap<>()),
+          Collections.unmodifiableList(new ArrayList<>()));
+
   public static ObjectCodecRegistry get() {
     return SUPPLIER.get();
   }
@@ -68,8 +79,11 @@ public class AutoRegistry {
       for (String className : EXTERNAL_CLASS_NAMES_TO_REGISTER) {
         registry.addClassName(className);
       }
-      for (Object constant : CONSTANTS_TO_REGISTER) {
-        registry.addConstant(constant);
+      for (Object constant : REFERENCE_CONSTANTS_TO_REGISTER) {
+        registry.addReferenceConstant(constant);
+      }
+      for (Object constant : VALUE_CONSTANTS_TO_REGISTER) {
+        registry.addValueConstant(constant);
       }
       return registry.build();
     } catch (IOException | ReflectiveOperationException e) {