Implement @AutoCodec.Interner code generation.

PiperOrigin-RevId: 587149949
Change-Id: Iaa2a1328ede8e97e4ec67a3a07b9f4961f9ec959

src/main/java/com/google/devtools/build/lib/skyframe/serialization/ArrayProcessor.java

@@ -353,6 +353,16 @@ public double[] deserializeArrayData(CodedInputStream codedIn, int length)
         }
       };
 
+  /**
+   * Handles possibly nested arrays of {@code Object} or any type derived from {@code Object}.
+   *
+   * <p>This processor observes the nesting level of the array by reflective operations on the
+   * {@code type} parameter passed into its methods. It similarly uses reflective calls to create
+   * nested arrays of appropriate type and nesting level.
+   *
+   * <p>Finally, at the leaf level, it uses the {@code (Ser|Deser)ializationContext} to apply codecs
+   * to the base array components.
+   */
   public static final ArrayProcessor OBJECT_ARRAY_PROCESSOR =
       new ArrayProcessor() {
         // Special case uses `Array.newInstance` to also create leaf-level arrays. Additionally,

src/main/java/com/google/devtools/build/lib/skyframe/serialization/InterningObjectCodec.java

@@ -0,0 +1,47 @@
+// Copyright 2023 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.skyframe.serialization;
+
+import com.google.protobuf.CodedInputStream;
+import java.io.IOException;
+
+/** Codec variant that interns the deserialization result. */
+public abstract class InterningObjectCodec<T> implements ObjectCodec<T> {
+
+  @Override
+  public final MemoizationStrategy getStrategy() {
+    // There is no fixed reference to an interned object until after it has been constructed and
+    // passes through the interner. Therefore this is always MEMOIZE_AFTER.
+    return MemoizationStrategy.MEMOIZE_AFTER;
+  }
+
+  /**
+   * Adapter for synchronous contexts.
+   *
+   * <p>Deserializes using {@link #deserializeInterned} then calls {@link #intern} on the result.
+   */
+  @Override
+  public final T deserialize(DeserializationContext context, CodedInputStream codedIn)
+      throws SerializationException, IOException {
+    return intern(deserializeInterned(context, codedIn));
+  }
+
+  /** Performs the (async) deserialization work. */
+  public abstract T deserializeInterned(
+      AsyncDeserializationContext context, CodedInputStream codedIn)
+      throws SerializationException, IOException;
+
+  /** Interns the result of {@link #deserializeInterned}. */
+  public abstract T intern(T value);
+}

src/main/java/com/google/devtools/build/lib/skyframe/serialization/autocodec/BUILD

@@ -68,6 +68,7 @@ java_library(
     deps = [
         ":serialization-processing-exception",
         "//third_party:guava",
+        "//third_party:jsr305",
         "//third_party/java/javapoet",
     ],
 )
@@ -110,6 +111,8 @@ java_library(
         "CodecGenerator.java",
         "FieldGenerator.java",
         "Initializers.java",
+        "InterningObjectCodecFieldGenerators.java",
+        "InterningObjectCodecGenerator.java",
         "Marshallers.java",
         "SerializationCodeGenerator.java",
     ],