Merge pull request #13984 from markdroth/ref_counting

Fix existing ref counting classes and add new ones.
diff --git a/BUILD b/BUILD
index ddcb0cd..e645f83 100644
--- a/BUILD
+++ b/BUILD
@@ -559,6 +559,16 @@
 )
 
 grpc_cc_library(
+    name = "orphanable",
+    public_hdrs = ["src/core/lib/support/orphanable.h"],
+    language = "c++",
+    deps = [
+        "grpc_trace",
+        "debug_location",
+    ],
+)
+
+grpc_cc_library(
     name = "ref_counted",
     language = "c++",
     public_hdrs = ["src/core/lib/support/ref_counted.h"],
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 93954b4..38bb92a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -563,6 +563,7 @@
 add_dependencies(buildtests_cxx metrics_client)
 add_dependencies(buildtests_cxx mock_test)
 add_dependencies(buildtests_cxx noop-benchmark)
+add_dependencies(buildtests_cxx orphanable_test)
 add_dependencies(buildtests_cxx proto_server_reflection_test)
 add_dependencies(buildtests_cxx proto_utils_test)
 if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_MAC OR _gRPC_PLATFORM_POSIX)
@@ -10913,6 +10914,45 @@
 endif (gRPC_BUILD_TESTS)
 if (gRPC_BUILD_TESTS)
 
+add_executable(orphanable_test
+  test/core/support/orphanable_test.cc
+  third_party/googletest/googletest/src/gtest-all.cc
+  third_party/googletest/googlemock/src/gmock-all.cc
+)
+
+
+target_include_directories(orphanable_test
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
+  PRIVATE ${_gRPC_SSL_INCLUDE_DIR}
+  PRIVATE ${PROTOBUF_ROOT_DIR}/src
+  PRIVATE ${BENCHMARK_ROOT_DIR}/include
+  PRIVATE ${ZLIB_ROOT_DIR}
+  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/zlib
+  PRIVATE ${CARES_INCLUDE_DIR}
+  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/cares/cares
+  PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/third_party/gflags/include
+  PRIVATE third_party/googletest/googletest/include
+  PRIVATE third_party/googletest/googletest
+  PRIVATE third_party/googletest/googlemock/include
+  PRIVATE third_party/googletest/googlemock
+  PRIVATE ${_gRPC_PROTO_GENS_DIR}
+)
+
+target_link_libraries(orphanable_test
+  ${_gRPC_PROTOBUF_LIBRARIES}
+  ${_gRPC_ALLTARGETS_LIBRARIES}
+  grpc_test_util
+  grpc++
+  grpc
+  gpr_test_util
+  gpr
+  ${_gRPC_GFLAGS_LIBRARIES}
+)
+
+endif (gRPC_BUILD_TESTS)
+if (gRPC_BUILD_TESTS)
+
 add_executable(proto_server_reflection_test
   test/cpp/end2end/proto_server_reflection_test.cc
   third_party/googletest/googletest/src/gtest-all.cc
diff --git a/Makefile b/Makefile
index 8a38cc8..3265cea 100644
--- a/Makefile
+++ b/Makefile
@@ -1160,6 +1160,7 @@
 metrics_client: $(BINDIR)/$(CONFIG)/metrics_client
 mock_test: $(BINDIR)/$(CONFIG)/mock_test
 noop-benchmark: $(BINDIR)/$(CONFIG)/noop-benchmark
+orphanable_test: $(BINDIR)/$(CONFIG)/orphanable_test
 proto_server_reflection_test: $(BINDIR)/$(CONFIG)/proto_server_reflection_test
 proto_utils_test: $(BINDIR)/$(CONFIG)/proto_utils_test
 qps_interarrival_test: $(BINDIR)/$(CONFIG)/qps_interarrival_test
@@ -1602,6 +1603,7 @@
   $(BINDIR)/$(CONFIG)/metrics_client \
   $(BINDIR)/$(CONFIG)/mock_test \
   $(BINDIR)/$(CONFIG)/noop-benchmark \
+  $(BINDIR)/$(CONFIG)/orphanable_test \
   $(BINDIR)/$(CONFIG)/proto_server_reflection_test \
   $(BINDIR)/$(CONFIG)/proto_utils_test \
   $(BINDIR)/$(CONFIG)/qps_interarrival_test \
@@ -1733,6 +1735,7 @@
   $(BINDIR)/$(CONFIG)/metrics_client \
   $(BINDIR)/$(CONFIG)/mock_test \
   $(BINDIR)/$(CONFIG)/noop-benchmark \
+  $(BINDIR)/$(CONFIG)/orphanable_test \
   $(BINDIR)/$(CONFIG)/proto_server_reflection_test \
   $(BINDIR)/$(CONFIG)/proto_utils_test \
   $(BINDIR)/$(CONFIG)/qps_interarrival_test \
@@ -2142,6 +2145,8 @@
 	$(Q) $(BINDIR)/$(CONFIG)/mock_test || ( echo test mock_test failed ; exit 1 )
 	$(E) "[RUN]     Testing noop-benchmark"
 	$(Q) $(BINDIR)/$(CONFIG)/noop-benchmark || ( echo test noop-benchmark failed ; exit 1 )
+	$(E) "[RUN]     Testing orphanable_test"
+	$(Q) $(BINDIR)/$(CONFIG)/orphanable_test || ( echo test orphanable_test failed ; exit 1 )
 	$(E) "[RUN]     Testing proto_server_reflection_test"
 	$(Q) $(BINDIR)/$(CONFIG)/proto_server_reflection_test || ( echo test proto_server_reflection_test failed ; exit 1 )
 	$(E) "[RUN]     Testing proto_utils_test"
@@ -16141,6 +16146,49 @@
 endif
 
 
+ORPHANABLE_TEST_SRC = \
+    test/core/support/orphanable_test.cc \
+
+ORPHANABLE_TEST_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(ORPHANABLE_TEST_SRC))))
+ifeq ($(NO_SECURE),true)
+
+# You can't build secure targets if you don't have OpenSSL.
+
+$(BINDIR)/$(CONFIG)/orphanable_test: openssl_dep_error
+
+else
+
+
+
+
+ifeq ($(NO_PROTOBUF),true)
+
+# You can't build the protoc plugins or protobuf-enabled targets if you don't have protobuf 3.0.0+.
+
+$(BINDIR)/$(CONFIG)/orphanable_test: protobuf_dep_error
+
+else
+
+$(BINDIR)/$(CONFIG)/orphanable_test: $(PROTOBUF_DEP) $(ORPHANABLE_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+	$(E) "[LD]      Linking $@"
+	$(Q) mkdir -p `dirname $@`
+	$(Q) $(LDXX) $(LDFLAGS) $(ORPHANABLE_TEST_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) $(LDLIBS_SECURE) $(GTEST_LIB) -o $(BINDIR)/$(CONFIG)/orphanable_test
+
+endif
+
+endif
+
+$(OBJDIR)/$(CONFIG)/test/core/support/orphanable_test.o:  $(LIBDIR)/$(CONFIG)/libgrpc_test_util.a $(LIBDIR)/$(CONFIG)/libgrpc++.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr_test_util.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
+deps_orphanable_test: $(ORPHANABLE_TEST_OBJS:.o=.dep)
+
+ifneq ($(NO_SECURE),true)
+ifneq ($(NO_DEPS),true)
+-include $(ORPHANABLE_TEST_OBJS:.o=.dep)
+endif
+endif
+
+
 PROTO_SERVER_REFLECTION_TEST_SRC = \
     test/cpp/end2end/proto_server_reflection_test.cc \
 
diff --git a/build.yaml b/build.yaml
index c3d54f1..c9adc9b 100644
--- a/build.yaml
+++ b/build.yaml
@@ -397,6 +397,7 @@
   - src/core/lib/slice/slice_internal.h
   - src/core/lib/slice/slice_string_helpers.h
   - src/core/lib/support/debug_location.h
+  - src/core/lib/support/orphanable.h
   - src/core/lib/support/ref_counted.h
   - src/core/lib/support/ref_counted_ptr.h
   - src/core/lib/support/vector.h
@@ -4403,6 +4404,20 @@
   deps:
   - benchmark
   defaults: benchmark
+- name: orphanable_test
+  gtest: true
+  build: test
+  language: c++
+  src:
+  - test/core/support/orphanable_test.cc
+  deps:
+  - grpc_test_util
+  - grpc++
+  - grpc
+  - gpr_test_util
+  - gpr
+  uses:
+  - grpc++_test
 - name: proto_server_reflection_test
   gtest: true
   build: test
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index 358fad3..d064ac8 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -420,6 +420,7 @@
                       'src/core/lib/slice/slice_internal.h',
                       'src/core/lib/slice/slice_string_helpers.h',
                       'src/core/lib/support/debug_location.h',
+                      'src/core/lib/support/orphanable.h',
                       'src/core/lib/support/ref_counted.h',
                       'src/core/lib/support/ref_counted_ptr.h',
                       'src/core/lib/support/vector.h',
@@ -901,6 +902,7 @@
                               'src/core/lib/slice/slice_internal.h',
                               'src/core/lib/slice/slice_string_helpers.h',
                               'src/core/lib/support/debug_location.h',
+                              'src/core/lib/support/orphanable.h',
                               'src/core/lib/support/ref_counted.h',
                               'src/core/lib/support/ref_counted_ptr.h',
                               'src/core/lib/support/vector.h',
diff --git a/grpc.gemspec b/grpc.gemspec
index 7547bc8..f8afaa5 100644
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -346,6 +346,7 @@
   s.files += %w( src/core/lib/slice/slice_internal.h )
   s.files += %w( src/core/lib/slice/slice_string_helpers.h )
   s.files += %w( src/core/lib/support/debug_location.h )
+  s.files += %w( src/core/lib/support/orphanable.h )
   s.files += %w( src/core/lib/support/ref_counted.h )
   s.files += %w( src/core/lib/support/ref_counted_ptr.h )
   s.files += %w( src/core/lib/support/vector.h )
diff --git a/package.xml b/package.xml
index ff3d079..8c59034 100644
--- a/package.xml
+++ b/package.xml
@@ -358,6 +358,7 @@
     <file baseinstalldir="/" name="src/core/lib/slice/slice_internal.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/slice/slice_string_helpers.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/debug_location.h" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/support/orphanable.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/ref_counted.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/ref_counted_ptr.h" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/vector.h" role="src" />
diff --git a/src/core/lib/support/abstract.h b/src/core/lib/support/abstract.h
index 5498769..1dffa30 100644
--- a/src/core/lib/support/abstract.h
+++ b/src/core/lib/support/abstract.h
@@ -26,4 +26,9 @@
 #define GRPC_ABSTRACT_BASE_CLASS \
   static void operator delete(void* p) { abort(); }
 
+// gRPC currently can't depend on libstdc++, so we can't use "= 0" for
+// pure virtual methods.  Instead, we use this macro.
+#define GRPC_ABSTRACT \
+  { GPR_ASSERT(false); }
+
 #endif /* GRPC_CORE_LIB_SUPPORT_ABSTRACT_H */
diff --git a/src/core/lib/support/orphanable.h b/src/core/lib/support/orphanable.h
new file mode 100644
index 0000000..2f53757
--- /dev/null
+++ b/src/core/lib/support/orphanable.h
@@ -0,0 +1,171 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_SUPPORT_ORPHANABLE_H
+#define GRPC_CORE_LIB_SUPPORT_ORPHANABLE_H
+
+#include <grpc/support/log.h>
+#include <grpc/support/sync.h>
+
+#include <memory>
+
+#include "src/core/lib/debug/trace.h"
+#include "src/core/lib/support/abstract.h"
+#include "src/core/lib/support/debug_location.h"
+#include "src/core/lib/support/memory.h"
+
+namespace grpc_core {
+
+// A base class for orphanable objects, which have one external owner
+// but are not necessarily destroyed immediately when the external owner
+// gives up ownership.  Instead, the owner calls the object's Orphan()
+// method, and the object then takes responsibility for its own cleanup
+// and destruction.
+class Orphanable {
+ public:
+  // Gives up ownership of the object.  The implementation must arrange
+  // to eventually destroy the object without further interaction from the
+  // caller.
+  virtual void Orphan() GRPC_ABSTRACT;
+
+  // Not copyable or movable.
+  Orphanable(const Orphanable&) = delete;
+  Orphanable& operator=(const Orphanable&) = delete;
+
+  GRPC_ABSTRACT_BASE_CLASS
+
+ protected:
+  Orphanable() {}
+  virtual ~Orphanable() {}
+};
+
+template <typename T>
+class OrphanableDelete {
+ public:
+  void operator()(T* p) { p->Orphan(); }
+};
+
+template <typename T, typename Deleter = OrphanableDelete<T>>
+using OrphanablePtr = std::unique_ptr<T, Deleter>;
+
+template <typename T, typename... Args>
+inline OrphanablePtr<T> MakeOrphanable(Args&&... args) {
+  return OrphanablePtr<T>(New<T>(std::forward<Args>(args)...));
+}
+
+// A type of Orphanable with internal ref-counting.
+class InternallyRefCounted : public Orphanable {
+ public:
+  // Not copyable nor movable.
+  InternallyRefCounted(const InternallyRefCounted&) = delete;
+  InternallyRefCounted& operator=(const InternallyRefCounted&) = delete;
+
+  GRPC_ABSTRACT_BASE_CLASS
+
+ protected:
+  InternallyRefCounted() { gpr_ref_init(&refs_, 1); }
+  virtual ~InternallyRefCounted() {}
+
+  void Ref() { gpr_ref(&refs_); }
+
+  void Unref() {
+    if (gpr_unref(&refs_)) {
+      Delete(this);
+    }
+  }
+
+  // Allow Delete() to access destructor.
+  template <typename T>
+  friend void Delete(T*);
+
+ private:
+  gpr_refcount refs_;
+};
+
+// An alternative version of the InternallyRefCounted base class that
+// supports tracing.  This is intended to be used in cases where the
+// object will be handled both by idiomatic C++ code using smart
+// pointers and legacy code that is manually calling Ref() and Unref().
+// Once all of our code is converted to idiomatic C++, we may be able to
+// eliminate this class.
+class InternallyRefCountedWithTracing : public Orphanable {
+ public:
+  // Not copyable nor movable.
+  InternallyRefCountedWithTracing(const InternallyRefCountedWithTracing&) =
+      delete;
+  InternallyRefCountedWithTracing& operator=(
+      const InternallyRefCountedWithTracing&) = delete;
+
+  GRPC_ABSTRACT_BASE_CLASS
+
+ protected:
+  // Allow Delete() to access destructor.
+  template <typename T>
+  friend void Delete(T*);
+
+  InternallyRefCountedWithTracing()
+      : InternallyRefCountedWithTracing(static_cast<TraceFlag*>(nullptr)) {}
+
+  explicit InternallyRefCountedWithTracing(TraceFlag* trace_flag)
+      : trace_flag_(trace_flag) {
+    gpr_ref_init(&refs_, 1);
+  }
+
+#ifdef NDEBUG
+  explicit InternallyRefCountedWithTracing(DebugOnlyTraceFlag* trace_flag)
+      : InternallyRefCountedWithTracing() {}
+#endif
+
+  virtual ~InternallyRefCountedWithTracing() {}
+
+  void Ref() { gpr_ref(&refs_); }
+
+  void Ref(const DebugLocation& location, const char* reason) {
+    if (location.Log() && trace_flag_ != nullptr && trace_flag_->enabled()) {
+      gpr_atm old_refs = gpr_atm_no_barrier_load(&refs_.count);
+      gpr_log(GPR_DEBUG, "%s:%p %s:%d ref %" PRIdPTR " -> %" PRIdPTR " %s",
+              trace_flag_->name(), this, location.file(), location.line(),
+              old_refs, old_refs + 1, reason);
+    }
+    Ref();
+  }
+
+  void Unref() {
+    if (gpr_unref(&refs_)) {
+      Delete(this);
+    }
+  }
+
+  void Unref(const DebugLocation& location, const char* reason) {
+    if (location.Log() && trace_flag_ != nullptr && trace_flag_->enabled()) {
+      gpr_atm old_refs = gpr_atm_no_barrier_load(&refs_.count);
+      gpr_log(GPR_DEBUG, "%s:%p %s:%d unref %" PRIdPTR " -> %" PRIdPTR " %s",
+              trace_flag_->name(), this, location.file(), location.line(),
+              old_refs, old_refs - 1, reason);
+    }
+    Unref();
+  }
+
+ private:
+  TraceFlag* trace_flag_ = nullptr;
+  gpr_refcount refs_;
+};
+
+}  // namespace grpc_core
+
+#endif /* GRPC_CORE_LIB_SUPPORT_ORPHANABLE_H */
diff --git a/src/core/lib/support/ref_counted.h b/src/core/lib/support/ref_counted.h
index 4c662f9..48c11f7 100644
--- a/src/core/lib/support/ref_counted.h
+++ b/src/core/lib/support/ref_counted.h
@@ -23,6 +23,7 @@
 #include <grpc/support/sync.h>
 
 #include "src/core/lib/debug/trace.h"
+#include "src/core/lib/support/abstract.h"
 #include "src/core/lib/support/debug_location.h"
 #include "src/core/lib/support/memory.h"
 
@@ -45,6 +46,8 @@
   RefCounted(const RefCounted&) = delete;
   RefCounted& operator=(const RefCounted&) = delete;
 
+  GRPC_ABSTRACT_BASE_CLASS
+
  protected:
   // Allow Delete() to access destructor.
   template <typename T>
@@ -98,18 +101,26 @@
   RefCountedWithTracing(const RefCountedWithTracing&) = delete;
   RefCountedWithTracing& operator=(const RefCountedWithTracing&) = delete;
 
+  GRPC_ABSTRACT_BASE_CLASS
+
  protected:
   // Allow Delete() to access destructor.
   template <typename T>
   friend void Delete(T*);
 
-  RefCountedWithTracing() : RefCountedWithTracing(nullptr) {}
+  RefCountedWithTracing()
+      : RefCountedWithTracing(static_cast<TraceFlag*>(nullptr)) {}
 
   explicit RefCountedWithTracing(TraceFlag* trace_flag)
       : trace_flag_(trace_flag) {
     gpr_ref_init(&refs_, 1);
   }
 
+#ifdef NDEBUG
+  explicit RefCountedWithTracing(DebugOnlyTraceFlag* trace_flag)
+      : RefCountedWithTracing() {}
+#endif
+
   virtual ~RefCountedWithTracing() {}
 
  private:
diff --git a/src/core/lib/support/ref_counted_ptr.h b/src/core/lib/support/ref_counted_ptr.h
index dc2385e..76ff0bb 100644
--- a/src/core/lib/support/ref_counted_ptr.h
+++ b/src/core/lib/support/ref_counted_ptr.h
@@ -76,6 +76,15 @@
   T& operator*() const { return *value_; }
   T* operator->() const { return value_; }
 
+  bool operator==(const RefCountedPtr& other) const {
+    return value_ == other.value_;
+  }
+  bool operator==(const T* other) const { return value_ == other; }
+  bool operator!=(const RefCountedPtr& other) const {
+    return value_ != other.value_;
+  }
+  bool operator!=(const T* other) const { return value_ != other; }
+
  private:
   T* value_ = nullptr;
 };
diff --git a/test/core/support/BUILD b/test/core/support/BUILD
index 4372b49..c8fa046 100644
--- a/test/core/support/BUILD
+++ b/test/core/support/BUILD
@@ -215,6 +215,19 @@
 )
 
 grpc_cc_test(
+    name = "orphanable_test",
+    srcs = ["orphanable_test.cc"],
+    language = "C++",
+    deps = [
+        "//:orphanable",
+        "//test/core/util:gpr_test_util",
+    ],
+    external_deps = [
+        "gtest",
+    ],
+)
+
+grpc_cc_test(
     name = "ref_counted_test",
     srcs = ["ref_counted_test.cc"],
     language = "C++",
diff --git a/test/core/support/orphanable_test.cc b/test/core/support/orphanable_test.cc
new file mode 100644
index 0000000..e07017a
--- /dev/null
+++ b/test/core/support/orphanable_test.cc
@@ -0,0 +1,114 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/lib/support/orphanable.h"
+
+#include <gtest/gtest.h>
+
+#include "src/core/lib/support/memory.h"
+#include "test/core/util/test_config.h"
+
+namespace grpc_core {
+namespace testing {
+namespace {
+
+class Foo : public Orphanable {
+ public:
+  Foo() : Foo(0) {}
+  explicit Foo(int value) : value_(value) {}
+  void Orphan() override { Delete(this); }
+  int value() const { return value_; }
+
+ private:
+  int value_;
+};
+
+TEST(Orphanable, Basic) {
+  Foo* foo = New<Foo>();
+  foo->Orphan();
+}
+
+TEST(OrphanablePtr, Basic) {
+  OrphanablePtr<Foo> foo(New<Foo>());
+  EXPECT_EQ(0, foo->value());
+}
+
+TEST(MakeOrphanable, DefaultConstructor) {
+  auto foo = MakeOrphanable<Foo>();
+  EXPECT_EQ(0, foo->value());
+}
+
+TEST(MakeOrphanable, WithParameters) {
+  auto foo = MakeOrphanable<Foo>(5);
+  EXPECT_EQ(5, foo->value());
+}
+
+class Bar : public InternallyRefCounted {
+ public:
+  Bar() : Bar(0) {}
+  explicit Bar(int value) : value_(value) {}
+  void Orphan() override { Unref(); }
+  int value() const { return value_; }
+
+  void StartWork() { Ref(); }
+  void FinishWork() { Unref(); }
+
+ private:
+  int value_;
+};
+
+TEST(OrphanablePtr, InternallyRefCounted) {
+  auto bar = MakeOrphanable<Bar>();
+  bar->StartWork();
+  bar->FinishWork();
+}
+
+// Note: We use DebugOnlyTraceFlag instead of TraceFlag to ensure that
+// things build properly in both debug and non-debug cases.
+DebugOnlyTraceFlag baz_tracer(true, "baz");
+
+class Baz : public InternallyRefCountedWithTracing {
+ public:
+  Baz() : Baz(0) {}
+  explicit Baz(int value)
+      : InternallyRefCountedWithTracing(&baz_tracer), value_(value) {}
+  void Orphan() override { Unref(); }
+  int value() const { return value_; }
+
+  void StartWork() { Ref(DEBUG_LOCATION, "work"); }
+  void FinishWork() { Unref(DEBUG_LOCATION, "work"); }
+
+ private:
+  int value_;
+};
+
+TEST(OrphanablePtr, InternallyRefCountedWithTracing) {
+  auto baz = MakeOrphanable<Baz>();
+  baz->StartWork();
+  baz->FinishWork();
+}
+
+}  // namespace
+}  // namespace testing
+}  // namespace grpc_core
+
+int main(int argc, char** argv) {
+  grpc_test_init(argc, argv);
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
diff --git a/test/core/support/ref_counted_ptr_test.cc b/test/core/support/ref_counted_ptr_test.cc
index 1830edc..ce4975d 100644
--- a/test/core/support/ref_counted_ptr_test.cc
+++ b/test/core/support/ref_counted_ptr_test.cc
@@ -138,6 +138,19 @@
   foo_ref.value();
 }
 
+TEST(RefCountedPtr, EqualityOperators) {
+  RefCountedPtr<Foo> foo(New<Foo>());
+  RefCountedPtr<Foo> bar = foo;
+  RefCountedPtr<Foo> empty;
+  // Test equality between RefCountedPtrs.
+  EXPECT_EQ(foo, bar);
+  EXPECT_NE(foo, empty);
+  // Test equality with bare pointers.
+  EXPECT_EQ(foo, foo.get());
+  EXPECT_EQ(empty, nullptr);
+  EXPECT_NE(foo, nullptr);
+}
+
 TEST(MakeRefCounted, NoArgs) {
   RefCountedPtr<Foo> foo = MakeRefCounted<Foo>();
   EXPECT_EQ(0, foo->value());
diff --git a/test/core/support/ref_counted_test.cc b/test/core/support/ref_counted_test.cc
index be9b6ff..0629e3f 100644
--- a/test/core/support/ref_counted_test.cc
+++ b/test/core/support/ref_counted_test.cc
@@ -44,7 +44,9 @@
   foo->Unref();
 }
 
-TraceFlag foo_tracer(true, "foo");
+// Note: We use DebugOnlyTraceFlag instead of TraceFlag to ensure that
+// things build properly in both debug and non-debug cases.
+DebugOnlyTraceFlag foo_tracer(true, "foo");
 
 class FooWithTracing : public RefCountedWithTracing {
  public:
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index d9184f4..85bbeed 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -1038,6 +1038,7 @@
 src/core/lib/support/memory.h \
 src/core/lib/support/mpscq.h \
 src/core/lib/support/murmur_hash.h \
+src/core/lib/support/orphanable.h \
 src/core/lib/support/ref_counted.h \
 src/core/lib/support/ref_counted_ptr.h \
 src/core/lib/support/spinlock.h \
diff --git a/tools/doxygen/Doxyfile.core.internal b/tools/doxygen/Doxyfile.core.internal
index 3d3c671..4bf0fc7 100644
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@@ -1304,6 +1304,7 @@
 src/core/lib/support/mpscq.h \
 src/core/lib/support/murmur_hash.cc \
 src/core/lib/support/murmur_hash.h \
+src/core/lib/support/orphanable.h \
 src/core/lib/support/ref_counted.h \
 src/core/lib/support/ref_counted_ptr.h \
 src/core/lib/support/spinlock.h \
diff --git a/tools/run_tests/generated/sources_and_headers.json b/tools/run_tests/generated/sources_and_headers.json
index c934155..df45489 100644
--- a/tools/run_tests/generated/sources_and_headers.json
+++ b/tools/run_tests/generated/sources_and_headers.json
@@ -3713,6 +3713,25 @@
       "gpr_test_util", 
       "grpc", 
       "grpc++", 
+      "grpc++_test", 
+      "grpc_test_util"
+    ], 
+    "headers": [], 
+    "is_filegroup": false, 
+    "language": "c++", 
+    "name": "orphanable_test", 
+    "src": [
+      "test/core/support/orphanable_test.cc"
+    ], 
+    "third_party": false, 
+    "type": "target"
+  }, 
+  {
+    "deps": [
+      "gpr", 
+      "gpr_test_util", 
+      "grpc", 
+      "grpc++", 
       "grpc++_proto_reflection_desc_db", 
       "grpc++_reflection", 
       "grpc++_test_util", 
@@ -8286,6 +8305,7 @@
       "src/core/lib/slice/slice_internal.h", 
       "src/core/lib/slice/slice_string_helpers.h", 
       "src/core/lib/support/debug_location.h", 
+      "src/core/lib/support/orphanable.h", 
       "src/core/lib/support/ref_counted.h", 
       "src/core/lib/support/ref_counted_ptr.h", 
       "src/core/lib/support/vector.h", 
@@ -8426,6 +8446,7 @@
       "src/core/lib/slice/slice_internal.h", 
       "src/core/lib/slice/slice_string_helpers.h", 
       "src/core/lib/support/debug_location.h", 
+      "src/core/lib/support/orphanable.h", 
       "src/core/lib/support/ref_counted.h", 
       "src/core/lib/support/ref_counted_ptr.h", 
       "src/core/lib/support/vector.h", 
diff --git a/tools/run_tests/generated/tests.json b/tools/run_tests/generated/tests.json
index 6f36dff..dc2b39e 100644
--- a/tools/run_tests/generated/tests.json
+++ b/tools/run_tests/generated/tests.json
@@ -4092,6 +4092,30 @@
     "flaky": false, 
     "gtest": true, 
     "language": "c++", 
+    "name": "orphanable_test", 
+    "platforms": [
+      "linux", 
+      "mac", 
+      "posix", 
+      "windows"
+    ], 
+    "uses_polling": true
+  }, 
+  {
+    "args": [], 
+    "benchmark": false, 
+    "ci_platforms": [
+      "linux", 
+      "mac", 
+      "posix", 
+      "windows"
+    ], 
+    "cpu_cost": 1.0, 
+    "exclude_configs": [], 
+    "exclude_iomgrs": [], 
+    "flaky": false, 
+    "gtest": true, 
+    "language": "c++", 
     "name": "proto_server_reflection_test", 
     "platforms": [
       "linux",