Remove MOA experiment flag.

PiperOrigin-RevId: 494865635

src/google/protobuf/arena.cc

@@ -603,7 +603,6 @@ void ThreadSafeArena::AddSerialArena(void* id, SerialArena* serial) {
 }
 
 void ThreadSafeArena::Init() {
-  // Message-owned arenas bypass thread cache and do not need life cycle ID.
   tag_and_id_ = GetNextLifeCycleId();
   arena_stats_ = Sample();
   head_.store(SentrySerialArenaChunk(), std::memory_order_relaxed);

src/google/protobuf/compiler/cpp/message.cc

@@ -3602,20 +3602,21 @@ void MessageGenerator::GenerateCopyFrom(io::Printer* p) {
     // It is also disabled if a message has neither message fields nor
     // extensions, as it's impossible to copy from its descendant.
     //
-    // Note that FailIfCopyFromDescendant is implemented by reflection and not
-    // available for lite runtime. In that case, check if the size of the source
-    // has changed after Clear.
-    format("#ifndef NDEBUG\n");
+    // Note that IsDescendant is implemented by reflection and not available for
+    // lite runtime. In that case, check if the size of the source has changed
+    // after Clear.
     if (HasDescriptorMethods(descriptor_->file(), options_)) {
-      format("FailIfCopyFromDescendant(*this, from);\n");
+      format(
+          "$DCHK$(!::_pbi::IsDescendant(*this, from))\n"
+          "    << \"Source of CopyFrom cannot be a descendant of the "
+          "target.\";\n"
+          "Clear();\n");
     } else {
-      format("::size_t from_size = from.ByteSizeLong();\n");
-    }
-    format(
-        "#endif\n"
-        "Clear();\n");
-    if (!HasDescriptorMethods(descriptor_->file(), options_)) {
       format(
+          "#ifndef NDEBUG\n"
+          "::size_t from_size = from.ByteSizeLong();\n"
+          "#endif\n"
+          "Clear();\n"
           "#ifndef NDEBUG\n"
           "$CHK$_EQ(from_size, from.ByteSizeLong())\n"
           "  << \"Source of CopyFrom changed when clearing target.  Either \"\n"

src/google/protobuf/extension_set_unittest.cc

@@ -829,8 +829,7 @@ TEST(ExtensionSetTest, SpaceUsedExcludingSelf) {
 
   // Repeated primitive extensions will increase space used by at least a
   // RepeatedField<T>, and will cause additional allocations when the array
-  // gets too big for the initial space.  Note, we explicitly allocate on the
-  // heap to avoid message-owned arenas.
+  // gets too big for the initial space.
   // This macro:
   //   - Adds a value to the repeated extension, then clears it, establishing
   //     the base size.

src/google/protobuf/generated_message_reflection_unittest.cc

@@ -614,10 +614,16 @@ TEST(GeneratedMessageReflectionTest, ReleaseLast) {
   (void)expected;  // unused in somce configurations
   std::unique_ptr<Message> released(message.GetReflection()->ReleaseLast(
       &message, descriptor->FindFieldByName("repeated_foreign_message")));
+#ifndef PROTOBUF_FORCE_COPY_IN_RELEASE
   EXPECT_EQ(expected, released.get());
+#endif  // !PROTOBUF_FORCE_COPY_IN_RELEASE
 }
 
 TEST(GeneratedMessageReflectionTest, ReleaseLastExtensions) {
+#ifdef PROTOBUF_FORCE_COPY_IN_RELEASE
+  GTEST_SKIP() << "Won't work with FORCE_COPY_IN_RELEASE.";
+#endif  // !PROTOBUF_FORCE_COPY_IN_RELEASE
+
   unittest::TestAllExtensions message;
   const Descriptor* descriptor = message.GetDescriptor();
   TestUtil::ReflectionTester reflection_tester(descriptor);
@@ -1041,7 +1047,9 @@ TEST(GeneratedMessageReflectionTest, SetAllocatedOneofMessageTest) {
   released = reflection->ReleaseMessage(
       &to_message, descriptor->FindFieldByName("foo_lazy_message"));
   EXPECT_TRUE(released != nullptr);
+#ifndef PROTOBUF_FORCE_COPY_IN_RELEASE
   EXPECT_EQ(&sub_message, released);
+#endif  // !PROTOBUF_FORCE_COPY_IN_RELEASE
   delete released;
 
   TestUtil::ReflectionTester::SetOneofViaReflection(&from_message2);
@@ -1059,7 +1067,9 @@ TEST(GeneratedMessageReflectionTest, SetAllocatedOneofMessageTest) {
   released = reflection->ReleaseMessage(
       &to_message, descriptor->FindFieldByName("foo_message"));
   EXPECT_TRUE(released != nullptr);
+#ifndef PROTOBUF_FORCE_COPY_IN_RELEASE
   EXPECT_EQ(&sub_message2, released);
+#endif  // !PROTOBUF_FORCE_COPY_IN_RELEASE
   delete released;
 }
 
@@ -1180,7 +1190,9 @@ TEST(GeneratedMessageReflectionTest, ReleaseOneofMessageTest) {
       &message, descriptor->FindFieldByName("foo_lazy_message"));
 
   EXPECT_TRUE(released != nullptr);
+#ifndef PROTOBUF_FORCE_COPY_IN_RELEASE
   EXPECT_EQ(&sub_message, released);
+#endif  // !PROTOBUF_FORCE_COPY_IN_RELEASE
   delete released;
 
   released = reflection->ReleaseMessage(

src/google/protobuf/map_test.inc

@@ -3170,7 +3170,9 @@ TEST(GeneratedMapFieldReflectionTest, ReleaseLast) {
   std::vector<const Message*> release_last =
       MapTestUtil::GetMapEntriesFromRelease(&message);
   MapTestUtil::ExpectMapsSize(message, 1);
+#ifndef PROTOBUF_FORCE_COPY_IN_RELEASE
   EXPECT_TRUE(expect_last == release_last);
+#endif  // !PROTOBUF_FORCE_COPY_IN_RELEASE
   for (std::vector<const Message*>::iterator it = release_last.begin();
        it != release_last.end(); ++it) {
     delete *it;

src/google/protobuf/message.cc

@@ -121,22 +121,14 @@ void Message::CopyFrom(const Message& from) {
 }
 
 void Message::CopyWithSourceCheck(Message& to, const Message& from) {
-#ifndef NDEBUG
-  FailIfCopyFromDescendant(to, from);
-#endif
+  // Fail if "from" is a descendant of "to" as such copy is not allowed.
+  GOOGLE_ABSL_DCHECK(!internal::IsDescendant(to, from))
+      << "Source of CopyFrom cannot be a descendant of the target.";
+
   to.Clear();
   to.GetClassData()->merge_to_from(to, from);
 }
 
-void Message::FailIfCopyFromDescendant(Message& to, const Message& from) {
-  auto* arena = to.GetArenaForAllocation();
-  bool same_message_owned_arena = to.GetOwningArena() == nullptr &&
-                                  arena != nullptr &&
-                                  arena == from.GetOwningArena();
-  GOOGLE_ABSL_CHECK(!same_message_owned_arena && !internal::IsDescendant(to, from))
-      << "Source of CopyFrom cannot be a descendant of the target.";
-}
-
 std::string Message::GetTypeName() const {
   return GetDescriptor()->full_name();
 }

src/google/protobuf/message.h

@@ -412,9 +412,6 @@ class PROTOBUF_EXPORT Message : public MessageLite {
   // type, and thus uses GetClassData().
   static void CopyWithSourceCheck(Message& to, const Message& from);
 
-  // Fail if "from" is a descendant of "to" as such copy is not allowed.
-  static void FailIfCopyFromDescendant(Message& to, const Message& from);
-
   inline explicit Message(Arena* arena) : MessageLite(arena) {}
   size_t ComputeUnknownFieldsSize(size_t total_size,
                                   internal::CachedSize* cached_size) const;

src/google/protobuf/message_lite.h

@@ -187,8 +187,7 @@ class PROTOBUF_EXPORT MessageLite {
   // if arena is a nullptr.
   virtual MessageLite* New(Arena* arena) const = 0;
 
-  // Returns user-owned arena; nullptr if it's message owned.
-  Arena* GetArena() const { return _internal_metadata_.user_arena(); }
+  Arena* GetArena() const { return _internal_metadata_.arena(); }
 
   // Clear all fields of the message and set them to their default values.
   // Clear() assumes that any memory allocated to hold parts of the message
@@ -436,7 +435,7 @@ class PROTOBUF_EXPORT MessageLite {
   // internal memory). This method is used in proto's implementation for
   // swapping, moving and setting allocated, for deciding whether the ownership
   // of this message or its internal memory could be changed.
-  Arena* GetOwningArena() const { return _internal_metadata_.owning_arena(); }
+  Arena* GetOwningArena() const { return _internal_metadata_.arena(); }
 
   // Returns the arena, used for allocating internal objects(e.g., child
   // messages, etc), or owning incoming objects (e.g., set allocated).

src/google/protobuf/metadata_lite.h

@@ -95,10 +95,6 @@ class PROTOBUF_EXPORT InternalMetadata {
     }
   }
 
-  PROTOBUF_NDEBUG_INLINE Arena* owning_arena() const { return arena(); }
-
-  PROTOBUF_NDEBUG_INLINE Arena* user_arena() const { return arena(); }
-
   PROTOBUF_NDEBUG_INLINE Arena* arena() const {
     if (PROTOBUF_PREDICT_FALSE(have_unknown_fields())) {
       return PtrValue<ContainerBase>()->arena;

src/google/protobuf/port_def.inc

@@ -655,18 +655,6 @@
 #error "endian detection failed for current compiler"
 #endif
 
-// For enabling message owned arena, one major blocker is semantic change from
-// moving to copying when there is ownership transfer (e.g., move ctor, swap,
-// set allocated, release). This change not only causes performance regression
-// but also breaks users code (e.g., dangling reference). For top-level
-// messages, since it owns the arena, we can mitigate the issue by transferring
-// ownership of arena. However, we cannot do that for nested messages. In order
-// to tell how many usages of nested messages affected by message owned arena,
-// we need to simulate the arena ownership.
-// This experiment is purely for the purpose of gathering data. All code guarded
-// by this flag is supposed to be removed after this experiment.
-#define PROTOBUF_MESSAGE_OWNED_ARENA_EXPERIMENT
-
 #ifdef PROTOBUF_CONSTINIT
 #error PROTOBUF_CONSTINIT was previously defined
 #endif

src/google/protobuf/port_undef.inc

@@ -90,7 +90,6 @@
 #undef PROTOBUF_THREAD_LOCAL
 #undef PROTOBUF_LITTLE_ENDIAN
 #undef PROTOBUF_BIG_ENDIAN
-#undef PROTOBUF_MESSAGE_OWNED_ARENA_EXPERIMENT
 #undef PROTOBUF_CONSTINIT
 #undef PROTOBUF_CONSTEXPR
 #undef PROTOBUF_ATTRIBUTE_WEAK

src/google/protobuf/repeated_ptr_field.h

@@ -516,7 +516,6 @@ class PROTOBUF_EXPORT RepeatedPtrFieldBase {
     GOOGLE_ABSL_DCHECK(GetOwningArena() == nullptr)
         << "ReleaseCleared() can only be used on a RepeatedPtrField not on "
         << "an arena.";
-    GOOGLE_ABSL_DCHECK(GetOwningArena() == nullptr);
     GOOGLE_ABSL_DCHECK(rep_ != nullptr);
     GOOGLE_ABSL_DCHECK_GT(rep_->allocated_size, current_size_);
     return cast<TypeHandler>(rep_->elements[--rep_->allocated_size]);