Internal changes/optimizations

PiperOrigin-RevId: 632294209

12 files changed, 228 insertions, 188 deletions

diff --git a/java/core/BUILD.bazel b/java/core/BUILD.bazel
index 683b0654a..6127b4c5c 100644
--- a/java/core/BUILD.bazel
+++ b/java/core/BUILD.bazel
@@ -60,6 +60,8 @@ LITE_SRCS = [
     "src/main/java/com/google/protobuf/LazyStringArrayList.java",
     "src/main/java/com/google/protobuf/LazyStringList.java",
     "src/main/java/com/google/protobuf/ListFieldSchema.java",
+    "src/main/java/com/google/protobuf/ListFieldSchemaLite.java",
+    "src/main/java/com/google/protobuf/ListFieldSchemas.java",
     "src/main/java/com/google/protobuf/LongArrayList.java",
     "src/main/java/com/google/protobuf/ManifestSchemaFactory.java",
     "src/main/java/com/google/protobuf/MapEntryLite.java",
diff --git a/java/core/src/main/java/com/google/protobuf/ExtensionSchemas.java b/java/core/src/main/java/com/google/protobuf/ExtensionSchemas.java
index cd8c852e9..5f0ce0668 100644
--- a/java/core/src/main/java/com/google/protobuf/ExtensionSchemas.java
+++ b/java/core/src/main/java/com/google/protobuf/ExtensionSchemas.java
@@ -31,4 +31,6 @@ final class ExtensionSchemas {
     }
     return FULL_SCHEMA;
   }
+
+  private ExtensionSchemas() {}
 }
diff --git a/java/core/src/main/java/com/google/protobuf/ListFieldSchema.java b/java/core/src/main/java/com/google/protobuf/ListFieldSchema.java
index bc55eb23c..eaab68b8d 100644
--- a/java/core/src/main/java/com/google/protobuf/ListFieldSchema.java
+++ b/java/core/src/main/java/com/google/protobuf/ListFieldSchema.java
@@ -7,162 +7,17 @@
 
 package com.google.protobuf;
 
-import com.google.protobuf.Internal.ProtobufList;
-import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 /**
  * Utility class that aids in properly manipulating list fields for either the lite or full runtime.
  */
 @CheckReturnValue
-abstract class ListFieldSchema {
-  // Disallow construction.
-  private ListFieldSchema() {}
+interface ListFieldSchema {
 
-  private static final ListFieldSchema FULL_INSTANCE = new ListFieldSchemaFull();
-  private static final ListFieldSchema LITE_INSTANCE = new ListFieldSchemaLite();
+  <L> List<L> mutableListAt(Object msg, long offset);
 
-  abstract <L> List<L> mutableListAt(Object msg, long offset);
+  void makeImmutableListAt(Object msg, long offset);
 
-  abstract void makeImmutableListAt(Object msg, long offset);
-
-  abstract <L> void mergeListsAt(Object msg, Object otherMsg, long offset);
-
-  static ListFieldSchema full() {
-    return FULL_INSTANCE;
-  }
-
-  static ListFieldSchema lite() {
-    return LITE_INSTANCE;
-  }
-
-  /** Implementation for the full runtime. */
-  private static final class ListFieldSchemaFull extends ListFieldSchema {
-
-    private static final Class<?> UNMODIFIABLE_LIST_CLASS =
-        Collections.unmodifiableList(Collections.emptyList()).getClass();
-
-    @Override
-    <L> List<L> mutableListAt(Object message, long offset) {
-      return mutableListAt(message, offset, AbstractProtobufList.DEFAULT_CAPACITY);
-    }
-
-    @Override
-    void makeImmutableListAt(Object message, long offset) {
-      List<?> list = (List<?>) UnsafeUtil.getObject(message, offset);
-      Object immutable = null;
-      if (list instanceof LazyStringList) {
-        immutable = ((LazyStringList) list).getUnmodifiableView();
-      } else if (UNMODIFIABLE_LIST_CLASS.isAssignableFrom(list.getClass())) {
-        // already immutable
-        return;
-      } else if (list instanceof PrimitiveNonBoxingCollection && list instanceof ProtobufList) {
-        if (((ProtobufList<?>) list).isModifiable()) {
-          ((ProtobufList<?>) list).makeImmutable();
-        }
-        return;
-      } else {
-        immutable = Collections.unmodifiableList((List<?>) list);
-      }
-      UnsafeUtil.putObject(message, offset, immutable);
-    }
-
-    @SuppressWarnings("unchecked")
-    private static <L> List<L> mutableListAt(Object message, long offset, int additionalCapacity) {
-      List<L> list = getList(message, offset);
-      if (list.isEmpty()) {
-        if (list instanceof LazyStringList) {
-          list = (List<L>) new LazyStringArrayList(additionalCapacity);
-        } else if (list instanceof PrimitiveNonBoxingCollection && list instanceof ProtobufList) {
-          list = ((ProtobufList<L>) list).mutableCopyWithCapacity(additionalCapacity);
-        } else {
-          list = new ArrayList<L>(additionalCapacity);
-        }
-        UnsafeUtil.putObject(message, offset, list);
-      } else if (UNMODIFIABLE_LIST_CLASS.isAssignableFrom(list.getClass())) {
-        ArrayList<L> newList = new ArrayList<L>(list.size() + additionalCapacity);
-        newList.addAll(list);
-        list = newList;
-        UnsafeUtil.putObject(message, offset, list);
-      } else if (list instanceof UnmodifiableLazyStringList) {
-        LazyStringArrayList newList = new LazyStringArrayList(list.size() + additionalCapacity);
-        newList.addAll((UnmodifiableLazyStringList) list);
-        list = (List<L>) newList;
-        UnsafeUtil.putObject(message, offset, list);
-      } else if (list instanceof PrimitiveNonBoxingCollection
-          && list instanceof ProtobufList
-          && !((ProtobufList<L>) list).isModifiable()) {
-        list = ((ProtobufList<L>) list).mutableCopyWithCapacity(list.size() + additionalCapacity);
-        UnsafeUtil.putObject(message, offset, list);
-      }
-      return list;
-    }
-
-    @Override
-    <E> void mergeListsAt(Object msg, Object otherMsg, long offset) {
-      List<E> other = getList(otherMsg, offset);
-      List<E> mine = mutableListAt(msg, offset, other.size());
-
-      int size = mine.size();
-      int otherSize = other.size();
-      if (size > 0 && otherSize > 0) {
-        mine.addAll(other);
-      }
-
-      List<E> merged = size > 0 ? mine : other;
-      UnsafeUtil.putObject(msg, offset, merged);
-    }
-
-    @SuppressWarnings("unchecked")
-    static <E> List<E> getList(Object message, long offset) {
-      return (List<E>) UnsafeUtil.getObject(message, offset);
-    }
-  }
-
-  /** Implementation for the lite runtime. */
-  private static final class ListFieldSchemaLite extends ListFieldSchema {
-
-    @Override
-    <L> List<L> mutableListAt(Object message, long offset) {
-      ProtobufList<L> list = getProtobufList(message, offset);
-      if (!list.isModifiable()) {
-        int size = list.size();
-        list =
-            list.mutableCopyWithCapacity(
-                size == 0 ? AbstractProtobufList.DEFAULT_CAPACITY : size * 2);
-        UnsafeUtil.putObject(message, offset, list);
-      }
-      return list;
-    }
-
-    @Override
-    void makeImmutableListAt(Object message, long offset) {
-      ProtobufList<?> list = getProtobufList(message, offset);
-      list.makeImmutable();
-    }
-
-    @Override
-    <E> void mergeListsAt(Object msg, Object otherMsg, long offset) {
-      ProtobufList<E> mine = getProtobufList(msg, offset);
-      ProtobufList<E> other = getProtobufList(otherMsg, offset);
-
-      int size = mine.size();
-      int otherSize = other.size();
-      if (size > 0 && otherSize > 0) {
-        if (!mine.isModifiable()) {
-          mine = mine.mutableCopyWithCapacity(size + otherSize);
-        }
-        mine.addAll(other);
-      }
-
-      ProtobufList<E> merged = size > 0 ? mine : other;
-      UnsafeUtil.putObject(msg, offset, merged);
-    }
-
-    @SuppressWarnings("unchecked")
-    static <E> ProtobufList<E> getProtobufList(Object message, long offset) {
-      return (ProtobufList<E>) UnsafeUtil.getObject(message, offset);
-    }
-  }
+  <L> void mergeListsAt(Object msg, Object otherMsg, long offset);
 }
diff --git a/java/core/src/main/java/com/google/protobuf/ListFieldSchemaFull.java b/java/core/src/main/java/com/google/protobuf/ListFieldSchemaFull.java
new file mode 100644
index 000000000..8f0308ab6
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/ListFieldSchemaFull.java
@@ -0,0 +1,99 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+package com.google.protobuf;
+
+import com.google.protobuf.Internal.ProtobufList;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Utility class that aids in properly manipulating list fields for either the lite or full runtime.
+ */
+@CheckReturnValue
+final class ListFieldSchemaFull implements ListFieldSchema {
+
+  private static final Class<?> UNMODIFIABLE_LIST_CLASS =
+      Collections.unmodifiableList(Collections.emptyList()).getClass();
+
+  @Override
+  public <L> List<L> mutableListAt(Object message, long offset) {
+    return mutableListAt(message, offset, AbstractProtobufList.DEFAULT_CAPACITY);
+  }
+
+  @SuppressWarnings("unchecked")
+  private static <L> List<L> mutableListAt(Object message, long offset, int additionalCapacity) {
+    List<L> list = getList(message, offset);
+    if (list.isEmpty()) {
+      if (list instanceof LazyStringList) {
+        list = (List<L>) new LazyStringArrayList(additionalCapacity);
+      } else if (list instanceof PrimitiveNonBoxingCollection && list instanceof ProtobufList) {
+        list = ((ProtobufList<L>) list).mutableCopyWithCapacity(additionalCapacity);
+      } else {
+        list = new ArrayList<L>(additionalCapacity);
+      }
+      UnsafeUtil.putObject(message, offset, list);
+    } else if (UNMODIFIABLE_LIST_CLASS.isAssignableFrom(list.getClass())) {
+      ArrayList<L> newList = new ArrayList<L>(list.size() + additionalCapacity);
+      newList.addAll(list);
+      list = newList;
+      UnsafeUtil.putObject(message, offset, list);
+    } else if (list instanceof UnmodifiableLazyStringList) {
+      LazyStringArrayList newList = new LazyStringArrayList(list.size() + additionalCapacity);
+      newList.addAll((UnmodifiableLazyStringList) list);
+      list = (List<L>) newList;
+      UnsafeUtil.putObject(message, offset, list);
+    } else if (list instanceof PrimitiveNonBoxingCollection
+        && list instanceof ProtobufList
+        && !((ProtobufList<L>) list).isModifiable()) {
+      list = ((ProtobufList<L>) list).mutableCopyWithCapacity(list.size() + additionalCapacity);
+      UnsafeUtil.putObject(message, offset, list);
+    }
+    return list;
+  }
+
+  @Override
+  public void makeImmutableListAt(Object message, long offset) {
+    List<?> list = (List<?>) UnsafeUtil.getObject(message, offset);
+    Object immutable = null;
+    if (list instanceof LazyStringList) {
+      immutable = ((LazyStringList) list).getUnmodifiableView();
+    } else if (UNMODIFIABLE_LIST_CLASS.isAssignableFrom(list.getClass())) {
+      // already immutable
+      return;
+    } else if (list instanceof PrimitiveNonBoxingCollection && list instanceof ProtobufList) {
+      if (((ProtobufList<?>) list).isModifiable()) {
+        ((ProtobufList<?>) list).makeImmutable();
+      }
+      return;
+    } else {
+      immutable = Collections.unmodifiableList((List<?>) list);
+    }
+    UnsafeUtil.putObject(message, offset, immutable);
+  }
+
+  @Override
+  public <E> void mergeListsAt(Object msg, Object otherMsg, long offset) {
+    List<E> other = getList(otherMsg, offset);
+    List<E> mine = mutableListAt(msg, offset, other.size());
+
+    int size = mine.size();
+    int otherSize = other.size();
+    if (size > 0 && otherSize > 0) {
+      mine.addAll(other);
+    }
+
+    List<E> merged = size > 0 ? mine : other;
+    UnsafeUtil.putObject(msg, offset, merged);
+  }
+
+  @SuppressWarnings("unchecked")
+  static <E> List<E> getList(Object message, long offset) {
+    return (List<E>) UnsafeUtil.getObject(message, offset);
+  }
+}
diff --git a/java/core/src/main/java/com/google/protobuf/ListFieldSchemaLite.java b/java/core/src/main/java/com/google/protobuf/ListFieldSchemaLite.java
new file mode 100644
index 000000000..f0cf71ecc
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/ListFieldSchemaLite.java
@@ -0,0 +1,59 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+package com.google.protobuf;
+
+import com.google.protobuf.Internal.ProtobufList;
+import java.util.List;
+
+/**
+ * Utility class that aids in properly manipulating list fields for either the lite or full runtime.
+ */
+final class ListFieldSchemaLite implements ListFieldSchema {
+
+  @Override
+  public <L> List<L> mutableListAt(Object message, long offset) {
+    ProtobufList<L> list = getProtobufList(message, offset);
+    if (!list.isModifiable()) {
+      int size = list.size();
+      list =
+          list.mutableCopyWithCapacity(
+              size == 0 ? AbstractProtobufList.DEFAULT_CAPACITY : size * 2);
+      UnsafeUtil.putObject(message, offset, list);
+    }
+    return list;
+  }
+
+  @Override
+  public void makeImmutableListAt(Object message, long offset) {
+    ProtobufList<?> list = getProtobufList(message, offset);
+    list.makeImmutable();
+  }
+
+  @Override
+  public <E> void mergeListsAt(Object msg, Object otherMsg, long offset) {
+    ProtobufList<E> mine = getProtobufList(msg, offset);
+    ProtobufList<E> other = getProtobufList(otherMsg, offset);
+
+    int size = mine.size();
+    int otherSize = other.size();
+    if (size > 0 && otherSize > 0) {
+      if (!mine.isModifiable()) {
+        mine = mine.mutableCopyWithCapacity(size + otherSize);
+      }
+      mine.addAll(other);
+    }
+
+    ProtobufList<E> merged = size > 0 ? mine : other;
+    UnsafeUtil.putObject(msg, offset, merged);
+  }
+
+  @SuppressWarnings("unchecked")
+  static <E> ProtobufList<E> getProtobufList(Object message, long offset) {
+    return (ProtobufList<E>) UnsafeUtil.getObject(message, offset);
+  }
+}
diff --git a/java/core/src/main/java/com/google/protobuf/ListFieldSchemas.java b/java/core/src/main/java/com/google/protobuf/ListFieldSchemas.java
new file mode 100644
index 000000000..6250b7a2d
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/ListFieldSchemas.java
@@ -0,0 +1,33 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+package com.google.protobuf;
+
+@CheckReturnValue
+final class ListFieldSchemas {
+  private static final ListFieldSchema FULL_SCHEMA = loadSchemaForFullRuntime();
+  private static final ListFieldSchema LITE_SCHEMA = new ListFieldSchemaLite();
+
+  static ListFieldSchema full() {
+    return FULL_SCHEMA;
+  }
+
+  static ListFieldSchema lite() {
+    return LITE_SCHEMA;
+  }
+
+  private static ListFieldSchema loadSchemaForFullRuntime() {
+    try {
+      Class<?> clazz = Class.forName("com.google.protobuf.ListFieldSchemaFull");
+      return (ListFieldSchema) clazz.getDeclaredConstructor().newInstance();
+    } catch (Exception e) {
+      return null;
+    }
+  }
+
+  private ListFieldSchemas() {}
+}
diff --git a/java/core/src/main/java/com/google/protobuf/ManifestSchemaFactory.java b/java/core/src/main/java/com/google/protobuf/ManifestSchemaFactory.java
index c923b129d..9b4fd82d4 100644
--- a/java/core/src/main/java/com/google/protobuf/ManifestSchemaFactory.java
+++ b/java/core/src/main/java/com/google/protobuf/ManifestSchemaFactory.java
@@ -34,57 +34,37 @@ final class ManifestSchemaFactory implements SchemaFactory {
 
     // MessageSet has a special schema.
     if (messageInfo.isMessageSetWireFormat()) {
-      if (GeneratedMessageLite.class.isAssignableFrom(messageType)) {
-        return MessageSetSchema.newSchema(
-            SchemaUtil.unknownFieldSetLiteSchema(),
-            ExtensionSchemas.lite(),
-            messageInfo.getDefaultInstance());
-      }
-      return MessageSetSchema.newSchema(
-          SchemaUtil.unknownFieldSetFullSchema(),
-          ExtensionSchemas.full(),
-          messageInfo.getDefaultInstance());
+      return useLiteRuntime(messageType)
+          ? MessageSetSchema.newSchema(
+              SchemaUtil.unknownFieldSetLiteSchema(),
+              ExtensionSchemas.lite(),
+              messageInfo.getDefaultInstance())
+          : MessageSetSchema.newSchema(
+              SchemaUtil.unknownFieldSetFullSchema(),
+              ExtensionSchemas.full(),
+              messageInfo.getDefaultInstance());
     }
 
     return newSchema(messageType, messageInfo);
   }
 
   private static <T> Schema<T> newSchema(Class<T> messageType, MessageInfo messageInfo) {
-    if (GeneratedMessageLite.class.isAssignableFrom(messageType)) {
-      return allowExtensions(messageInfo)
-          ? MessageSchema.newSchema(
-              messageType,
-              messageInfo,
-              NewInstanceSchemas.lite(),
-              ListFieldSchema.lite(),
-              SchemaUtil.unknownFieldSetLiteSchema(),
-              ExtensionSchemas.lite(),
-              MapFieldSchemas.lite())
-          : MessageSchema.newSchema(
-              messageType,
-              messageInfo,
-              NewInstanceSchemas.lite(),
-              ListFieldSchema.lite(),
-              SchemaUtil.unknownFieldSetLiteSchema(),
-              /* extensionSchema= */ null,
-              MapFieldSchemas.lite());
-    }
-    return allowExtensions(messageInfo)
+    return useLiteRuntime(messageType)
         ? MessageSchema.newSchema(
             messageType,
             messageInfo,
-            NewInstanceSchemas.full(),
-            ListFieldSchema.full(),
-            SchemaUtil.unknownFieldSetFullSchema(),
-            ExtensionSchemas.full(),
-            MapFieldSchemas.full())
+            NewInstanceSchemas.lite(),
+            ListFieldSchemas.lite(),
+            SchemaUtil.unknownFieldSetLiteSchema(),
+            allowExtensions(messageInfo) ? ExtensionSchemas.lite() : null,
+            MapFieldSchemas.lite())
         : MessageSchema.newSchema(
             messageType,
             messageInfo,
             NewInstanceSchemas.full(),
-            ListFieldSchema.full(),
+            ListFieldSchemas.full(),
             SchemaUtil.unknownFieldSetFullSchema(),
-            /* extensionSchema= */ null,
+            allowExtensions(messageInfo) ? ExtensionSchemas.full() : null,
             MapFieldSchemas.full());
   }
 
@@ -152,4 +132,8 @@ final class ManifestSchemaFactory implements SchemaFactory {
       return EMPTY_FACTORY;
     }
   }
+
+  private static boolean useLiteRuntime(Class<?> messageType) {
+    return GeneratedMessageLite.class.isAssignableFrom(messageType);
+  }
 }
diff --git a/java/core/src/main/java/com/google/protobuf/MapFieldSchemaFull.java b/java/core/src/main/java/com/google/protobuf/MapFieldSchemaFull.java
index d41144917..624c258d4 100644
--- a/java/core/src/main/java/com/google/protobuf/MapFieldSchemaFull.java
+++ b/java/core/src/main/java/com/google/protobuf/MapFieldSchemaFull.java
@@ -10,7 +10,7 @@ package com.google.protobuf;
 import com.google.protobuf.MapEntryLite.Metadata;
 import java.util.Map;
 
-class MapFieldSchemaFull implements MapFieldSchema {
+final class MapFieldSchemaFull implements MapFieldSchema {
   @Override
   public Map<?, ?> forMutableMapData(Object mapField) {
     return ((MapField<?, ?>) mapField).getMutableMap();
diff --git a/java/core/src/main/java/com/google/protobuf/MapFieldSchemaLite.java b/java/core/src/main/java/com/google/protobuf/MapFieldSchemaLite.java
index f7c5d85f3..c21678d28 100644
--- a/java/core/src/main/java/com/google/protobuf/MapFieldSchemaLite.java
+++ b/java/core/src/main/java/com/google/protobuf/MapFieldSchemaLite.java
@@ -11,7 +11,7 @@ import com.google.protobuf.MapEntryLite.Metadata;
 import java.util.Map;
 
 @CheckReturnValue
-class MapFieldSchemaLite implements MapFieldSchema {
+final class MapFieldSchemaLite implements MapFieldSchema {
 
   @Override
   public Map<?, ?> forMutableMapData(Object mapField) {
diff --git a/java/core/src/main/java/com/google/protobuf/MapFieldSchemas.java b/java/core/src/main/java/com/google/protobuf/MapFieldSchemas.java
index d7eeccd8c..ea419a56c 100644
--- a/java/core/src/main/java/com/google/protobuf/MapFieldSchemas.java
+++ b/java/core/src/main/java/com/google/protobuf/MapFieldSchemas.java
@@ -28,4 +28,6 @@ final class MapFieldSchemas {
       return null;
     }
   }
+
+  private MapFieldSchemas() {}
 }
diff --git a/java/core/src/main/java/com/google/protobuf/NewInstanceSchemas.java b/java/core/src/main/java/com/google/protobuf/NewInstanceSchemas.java
index 800f44891..6fbdd47a3 100644
--- a/java/core/src/main/java/com/google/protobuf/NewInstanceSchemas.java
+++ b/java/core/src/main/java/com/google/protobuf/NewInstanceSchemas.java
@@ -28,4 +28,6 @@ final class NewInstanceSchemas {
       return null;
     }
   }
+
+  private NewInstanceSchemas() {}
 }
diff --git a/java/lite/pom.xml b/java/lite/pom.xml
index 64a69085f..d2da13084 100644
--- a/java/lite/pom.xml
+++ b/java/lite/pom.xml
@@ -139,6 +139,8 @@
                     <include>LazyStringArrayList.java</include>
                     <include>LazyStringList.java</include>
                     <include>ListFieldSchema.java</include>
+                    <include>ListFieldSchemaLite.java</include>
+                    <include>ListFieldSchemas.java</include>
                     <include>LongArrayList.java</include>
                     <include>ManifestSchemaFactory.java</include>
                     <include>MapEntryLite.java</include>