Merge branch 'arena-counting' into arena-test

src/core/BUILD

@@ -1236,6 +1236,7 @@ grpc_cc_library(
     public_hdrs = ["lib/gprpp/dual_ref_counted.h"],
     deps = [
         "down_cast",
+        "ref_counted",
         "//:debug_location",
         "//:gpr",
         "//:orphanable",

src/core/lib/gprpp/dual_ref_counted.h

@@ -28,6 +28,7 @@
 #include "src/core/lib/gprpp/debug_location.h"
 #include "src/core/lib/gprpp/down_cast.h"
 #include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 
 namespace grpc_core {
@@ -46,15 +47,16 @@ namespace grpc_core {
 //
 // This will be used by CRTP (curiously-recurring template pattern), e.g.:
 //   class MyClass : public RefCounted<MyClass> { ... };
-template <typename Child>
+//
-class DualRefCounted {
+// Impl & UnrefBehavior are as per RefCounted.
+template <typename Child, typename Impl = PolymorphicRefCount,
+          typename UnrefBehavior = UnrefDelete>
+class DualRefCounted : public Impl {
  public:
   // Not copyable nor movable.
   DualRefCounted(const DualRefCounted&) = delete;
   DualRefCounted& operator=(const DualRefCounted&) = delete;
 
-  virtual ~DualRefCounted() = default;
-
   GRPC_MUST_USE_RESULT RefCountedPtr<Child> Ref() {
     IncrementRefCount();
     return RefCountedPtr<Child>(static_cast<Child*>(this));
@@ -215,7 +217,7 @@ class DualRefCounted {
     CHECK_GT(weak_refs, 0u);
 #endif
     if (GPR_UNLIKELY(prev_ref_pair == MakeRefPair(0, 1))) {
-      delete static_cast<Child*>(this);
+      unref_behavior_(static_cast<Child*>(this));
     }
   }
   void WeakUnref(const DebugLocation& location, const char* reason) {
@@ -242,7 +244,7 @@ class DualRefCounted {
     (void)reason;
 #endif
     if (GPR_UNLIKELY(prev_ref_pair == MakeRefPair(0, 1))) {
-      delete static_cast<Child*>(this);
+      unref_behavior_(static_cast<const Child*>(this));
     }
   }
 
@@ -266,6 +268,9 @@ class DualRefCounted {
   // Ref count has dropped to zero, so the object is now orphaned.
   virtual void Orphaned() = 0;
 
+  // Note: Depending on the Impl used, this dtor can be implicitly virtual.
+  ~DualRefCounted() = default;
+
  private:
   // Allow RefCountedPtr<> to access IncrementRefCount().
   template <typename T>
@@ -358,6 +363,7 @@ class DualRefCounted {
   const char* trace_;
 #endif
   std::atomic<uint64_t> refs_{0};
+  GPR_NO_UNIQUE_ADDRESS UnrefBehavior unref_behavior_;
 };
 
 }  // namespace grpc_core

test/core/gprpp/dual_ref_counted_test.cc

@@ -21,6 +21,8 @@
 #include "absl/log/check.h"
 #include "gtest/gtest.h"
 
+#include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/gprpp/ref_counted.h"
 #include "test/core/test_util/test_config.h"
 
 namespace grpc_core {
@@ -115,6 +117,42 @@ TEST(DualRefCountedWithTracing, Basic) {
   foo->Unref(DEBUG_LOCATION, "original_ref");
 }
 
+class FooWithNoDelete final
+    : public DualRefCounted<FooWithNoDelete, NonPolymorphicRefCount,
+                            UnrefCallDtor> {
+ public:
+  FooWithNoDelete(bool* orphaned_called, bool* destructor_called)
+      : DualRefCounted<FooWithNoDelete, NonPolymorphicRefCount, UnrefCallDtor>(
+            "FooWithNoDelete"),
+        orphaned_called_(orphaned_called),
+        destructor_called_(destructor_called) {}
+  ~FooWithNoDelete() { *destructor_called_ = true; }
+
+  void Orphaned() override { *orphaned_called_ = true; }
+
+ private:
+  bool* const orphaned_called_;
+  bool* const destructor_called_;
+};
+
+TEST(DualRefCountedWithNoDelete, Basic) {
+  ManualConstructor<FooWithNoDelete> foo;
+  bool destructor_called = false;
+  bool orphaned_called = false;
+  foo.Init(&orphaned_called, &destructor_called);
+  EXPECT_FALSE(orphaned_called);
+  EXPECT_FALSE(destructor_called);
+  foo->WeakRef().release();
+  EXPECT_FALSE(orphaned_called);
+  EXPECT_FALSE(destructor_called);
+  foo->Unref();
+  EXPECT_TRUE(orphaned_called);
+  EXPECT_FALSE(destructor_called);
+  foo->WeakUnref();
+  EXPECT_TRUE(orphaned_called);
+  EXPECT_TRUE(destructor_called);
+}
+
 }  // namespace
 }  // namespace testing
 }  // namespace grpc_core