Merge pull request #17053 from yashykt/global_interceptor

Add global client interceptor factory

15 files changed, 197 insertions, 6 deletions

diff --git a/BUILD b/BUILD
index ff3dd0b1f5..9dc484550e 100644
--- a/BUILD
+++ b/BUILD
@@ -2111,6 +2111,7 @@ grpc_cc_library(
     name = "grpc++_codegen_base_src",
     srcs = [
         "src/cpp/codegen/codegen_init.cc",
+        "src/cpp/codegen/client_interceptor.cc",
     ],
     language = "c++",
     deps = [
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 49c31baecb..92db21cb24 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2896,6 +2896,7 @@ add_library(grpc++
   third_party/nanopb/pb_common.c
   third_party/nanopb/pb_decode.c
   third_party/nanopb/pb_encode.c
+  src/cpp/codegen/client_interceptor.cc
   src/cpp/codegen/codegen_init.cc
 )
 
@@ -3267,6 +3268,7 @@ add_library(grpc++_cronet
   third_party/nanopb/pb_common.c
   third_party/nanopb/pb_decode.c
   third_party/nanopb/pb_encode.c
+  src/cpp/codegen/client_interceptor.cc
   src/cpp/codegen/codegen_init.cc
   src/core/ext/transport/chttp2/client/insecure/channel_create.cc
   src/core/ext/transport/chttp2/client/insecure/channel_create_posix.cc
@@ -4020,6 +4022,7 @@ add_library(grpc++_test_util
   test/cpp/util/string_ref_helper.cc
   test/cpp/util/subprocess.cc
   test/cpp/util/test_credentials_provider.cc
+  src/cpp/codegen/client_interceptor.cc
   src/cpp/codegen/codegen_init.cc
 )
 
@@ -4210,6 +4213,7 @@ add_library(grpc++_test_util_unsecure
   test/cpp/util/byte_buffer_proto_helper.cc
   test/cpp/util/string_ref_helper.cc
   test/cpp/util/subprocess.cc
+  src/cpp/codegen/client_interceptor.cc
   src/cpp/codegen/codegen_init.cc
 )
 
@@ -4413,6 +4417,7 @@ add_library(grpc++_unsecure
   third_party/nanopb/pb_common.c
   third_party/nanopb/pb_decode.c
   third_party/nanopb/pb_encode.c
+  src/cpp/codegen/client_interceptor.cc
   src/cpp/codegen/codegen_init.cc
 )
 
@@ -12640,6 +12645,7 @@ add_executable(codegen_test_minimal
   ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/stats.pb.h
   ${_gRPC_PROTO_GENS_DIR}/src/proto/grpc/testing/stats.grpc.pb.h
   test/cpp/codegen/codegen_test_minimal.cc
+  src/cpp/codegen/client_interceptor.cc
   src/cpp/codegen/codegen_init.cc
   third_party/googletest/googletest/src/gtest-all.cc
   third_party/googletest/googlemock/src/gmock-all.cc
diff --git a/Makefile b/Makefile
index df171607c4..7404bbd5ca 100644
--- a/Makefile
+++ b/Makefile
@@ -5282,6 +5282,7 @@ LIBGRPC++_SRC = \
     third_party/nanopb/pb_common.c \
     third_party/nanopb/pb_decode.c \
     third_party/nanopb/pb_encode.c \
+    src/cpp/codegen/client_interceptor.cc \
     src/cpp/codegen/codegen_init.cc \
 
 PUBLIC_HEADERS_CXX += \
@@ -5663,6 +5664,7 @@ LIBGRPC++_CRONET_SRC = \
     third_party/nanopb/pb_common.c \
     third_party/nanopb/pb_decode.c \
     third_party/nanopb/pb_encode.c \
+    src/cpp/codegen/client_interceptor.cc \
     src/cpp/codegen/codegen_init.cc \
     src/core/ext/transport/chttp2/client/insecure/channel_create.cc \
     src/core/ext/transport/chttp2/client/insecure/channel_create_posix.cc \
@@ -6418,6 +6420,7 @@ LIBGRPC++_TEST_UTIL_SRC = \
     test/cpp/util/string_ref_helper.cc \
     test/cpp/util/subprocess.cc \
     test/cpp/util/test_credentials_provider.cc \
+    src/cpp/codegen/client_interceptor.cc \
     src/cpp/codegen/codegen_init.cc \
 
 PUBLIC_HEADERS_CXX += \
@@ -6570,6 +6573,7 @@ $(OBJDIR)/$(CONFIG)/test/cpp/util/create_test_channel.o: $(GENDIR)/src/proto/grp
 $(OBJDIR)/$(CONFIG)/test/cpp/util/string_ref_helper.o: $(GENDIR)/src/proto/grpc/channelz/channelz.pb.cc $(GENDIR)/src/proto/grpc/channelz/channelz.grpc.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
 $(OBJDIR)/$(CONFIG)/test/cpp/util/subprocess.o: $(GENDIR)/src/proto/grpc/channelz/channelz.pb.cc $(GENDIR)/src/proto/grpc/channelz/channelz.grpc.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
 $(OBJDIR)/$(CONFIG)/test/cpp/util/test_credentials_provider.o: $(GENDIR)/src/proto/grpc/channelz/channelz.pb.cc $(GENDIR)/src/proto/grpc/channelz/channelz.grpc.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
+$(OBJDIR)/$(CONFIG)/src/cpp/codegen/client_interceptor.o: $(GENDIR)/src/proto/grpc/channelz/channelz.pb.cc $(GENDIR)/src/proto/grpc/channelz/channelz.grpc.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
 $(OBJDIR)/$(CONFIG)/src/cpp/codegen/codegen_init.o: $(GENDIR)/src/proto/grpc/channelz/channelz.pb.cc $(GENDIR)/src/proto/grpc/channelz/channelz.grpc.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
 
 
@@ -6582,6 +6586,7 @@ LIBGRPC++_TEST_UTIL_UNSECURE_SRC = \
     test/cpp/util/byte_buffer_proto_helper.cc \
     test/cpp/util/string_ref_helper.cc \
     test/cpp/util/subprocess.cc \
+    src/cpp/codegen/client_interceptor.cc \
     src/cpp/codegen/codegen_init.cc \
 
 PUBLIC_HEADERS_CXX += \
@@ -6731,6 +6736,7 @@ $(OBJDIR)/$(CONFIG)/test/cpp/end2end/test_service_impl.o: $(GENDIR)/src/proto/gr
 $(OBJDIR)/$(CONFIG)/test/cpp/util/byte_buffer_proto_helper.o: $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
 $(OBJDIR)/$(CONFIG)/test/cpp/util/string_ref_helper.o: $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
 $(OBJDIR)/$(CONFIG)/test/cpp/util/subprocess.o: $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
+$(OBJDIR)/$(CONFIG)/src/cpp/codegen/client_interceptor.o: $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
 $(OBJDIR)/$(CONFIG)/src/cpp/codegen/codegen_init.o: $(GENDIR)/src/proto/grpc/health/v1/health.pb.cc $(GENDIR)/src/proto/grpc/health/v1/health.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.pb.cc $(GENDIR)/src/proto/grpc/testing/echo_messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.pb.cc $(GENDIR)/src/proto/grpc/testing/echo.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.pb.cc $(GENDIR)/src/proto/grpc/testing/duplicate/echo_duplicate.grpc.pb.cc
 
 
@@ -6774,6 +6780,7 @@ LIBGRPC++_UNSECURE_SRC = \
     third_party/nanopb/pb_common.c \
     third_party/nanopb/pb_decode.c \
     third_party/nanopb/pb_encode.c \
+    src/cpp/codegen/client_interceptor.cc \
     src/cpp/codegen/codegen_init.cc \
 
 PUBLIC_HEADERS_CXX += \
@@ -17482,6 +17489,7 @@ CODEGEN_TEST_MINIMAL_SRC = \
     $(GENDIR)/src/proto/grpc/testing/worker_service.pb.cc $(GENDIR)/src/proto/grpc/testing/worker_service.grpc.pb.cc \
     $(GENDIR)/src/proto/grpc/testing/stats.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.grpc.pb.cc \
     test/cpp/codegen/codegen_test_minimal.cc \
+    src/cpp/codegen/client_interceptor.cc \
     src/cpp/codegen/codegen_init.cc \
 
 CODEGEN_TEST_MINIMAL_OBJS = $(addprefix $(OBJDIR)/$(CONFIG)/, $(addsuffix .o, $(basename $(CODEGEN_TEST_MINIMAL_SRC))))
@@ -17529,6 +17537,8 @@ $(OBJDIR)/$(CONFIG)/src/proto/grpc/testing/stats.o:  $(LIBDIR)/$(CONFIG)/libgrpc
 
 $(OBJDIR)/$(CONFIG)/test/cpp/codegen/codegen_test_minimal.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_core_stats.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
+$(OBJDIR)/$(CONFIG)/src/cpp/codegen/client_interceptor.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_core_stats.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a
+
 $(OBJDIR)/$(CONFIG)/src/cpp/codegen/codegen_init.o:  $(LIBDIR)/$(CONFIG)/libgrpc++_core_stats.a $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a
 
 deps_codegen_test_minimal: $(CODEGEN_TEST_MINIMAL_OBJS:.o=.dep)
@@ -17539,6 +17549,7 @@ ifneq ($(NO_DEPS),true)
 endif
 endif
 $(OBJDIR)/$(CONFIG)/test/cpp/codegen/codegen_test_minimal.o: $(GENDIR)/src/proto/grpc/testing/control.pb.cc $(GENDIR)/src/proto/grpc/testing/control.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc $(GENDIR)/src/proto/grpc/testing/payloads.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/benchmark_service.pb.cc $(GENDIR)/src/proto/grpc/testing/benchmark_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/report_qps_scenario_service.pb.cc $(GENDIR)/src/proto/grpc/testing/report_qps_scenario_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/worker_service.pb.cc $(GENDIR)/src/proto/grpc/testing/worker_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.grpc.pb.cc
+$(OBJDIR)/$(CONFIG)/src/cpp/codegen/client_interceptor.o: $(GENDIR)/src/proto/grpc/testing/control.pb.cc $(GENDIR)/src/proto/grpc/testing/control.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc $(GENDIR)/src/proto/grpc/testing/payloads.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/benchmark_service.pb.cc $(GENDIR)/src/proto/grpc/testing/benchmark_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/report_qps_scenario_service.pb.cc $(GENDIR)/src/proto/grpc/testing/report_qps_scenario_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/worker_service.pb.cc $(GENDIR)/src/proto/grpc/testing/worker_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.grpc.pb.cc
 $(OBJDIR)/$(CONFIG)/src/cpp/codegen/codegen_init.o: $(GENDIR)/src/proto/grpc/testing/control.pb.cc $(GENDIR)/src/proto/grpc/testing/control.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.pb.cc $(GENDIR)/src/proto/grpc/testing/messages.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/payloads.pb.cc $(GENDIR)/src/proto/grpc/testing/payloads.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/benchmark_service.pb.cc $(GENDIR)/src/proto/grpc/testing/benchmark_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/report_qps_scenario_service.pb.cc $(GENDIR)/src/proto/grpc/testing/report_qps_scenario_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/worker_service.pb.cc $(GENDIR)/src/proto/grpc/testing/worker_service.grpc.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.pb.cc $(GENDIR)/src/proto/grpc/testing/stats.grpc.pb.cc
 
 
diff --git a/build.yaml b/build.yaml
index 748258da0c..a9e1098070 100644
--- a/build.yaml
+++ b/build.yaml
@@ -1262,6 +1262,7 @@ filegroups:
 - name: grpc++_codegen_base_src
   language: c++
   src:
+  - src/cpp/codegen/client_interceptor.cc
   - src/cpp/codegen/codegen_init.cc
   uses:
   - grpc++_codegen_base
diff --git a/gRPC-C++.podspec b/gRPC-C++.podspec
index f8a4a78e8d..e7ae154c02 100644
--- a/gRPC-C++.podspec
+++ b/gRPC-C++.podspec
@@ -225,6 +225,7 @@ Pod::Spec.new do |s|
                       'src/cpp/util/status.cc',
                       'src/cpp/util/string_ref.cc',
                       'src/cpp/util/time_cc.cc',
+                      'src/cpp/codegen/client_interceptor.cc',
                       'src/cpp/codegen/codegen_init.cc',
                       'src/core/lib/gpr/alloc.h',
                       'src/core/lib/gpr/arena.h',
diff --git a/grpc.gyp b/grpc.gyp
index 10c9b84bef..fdb61cc713 100644
--- a/grpc.gyp
+++ b/grpc.gyp
@@ -1420,6 +1420,7 @@
         'third_party/nanopb/pb_common.c',
         'third_party/nanopb/pb_decode.c',
         'third_party/nanopb/pb_encode.c',
+        'src/cpp/codegen/client_interceptor.cc',
         'src/cpp/codegen/codegen_init.cc',
       ],
     },
@@ -1500,6 +1501,7 @@
         'test/cpp/util/string_ref_helper.cc',
         'test/cpp/util/subprocess.cc',
         'test/cpp/util/test_credentials_provider.cc',
+        'src/cpp/codegen/client_interceptor.cc',
         'src/cpp/codegen/codegen_init.cc',
       ],
     },
@@ -1520,6 +1522,7 @@
         'test/cpp/util/byte_buffer_proto_helper.cc',
         'test/cpp/util/string_ref_helper.cc',
         'test/cpp/util/subprocess.cc',
+        'src/cpp/codegen/client_interceptor.cc',
         'src/cpp/codegen/codegen_init.cc',
       ],
     },
@@ -1570,6 +1573,7 @@
         'third_party/nanopb/pb_common.c',
         'third_party/nanopb/pb_decode.c',
         'third_party/nanopb/pb_encode.c',
+        'src/cpp/codegen/client_interceptor.cc',
         'src/cpp/codegen/codegen_init.cc',
       ],
     },
diff --git a/include/grpcpp/channel.h b/include/grpcpp/channel.h
index 14209b85ee..4502b94b17 100644
--- a/include/grpcpp/channel.h
+++ b/include/grpcpp/channel.h
@@ -91,7 +91,7 @@ class Channel final : public ChannelInterface,
 
   internal::Call CreateCallInternal(const internal::RpcMethod& method,
                                     ClientContext* context, CompletionQueue* cq,
-                                    int interceptor_pos) override;
+                                    size_t interceptor_pos) override;
 
   const grpc::string host_;
   grpc_channel* const c_channel_;  // owned
diff --git a/include/grpcpp/impl/codegen/channel_interface.h b/include/grpcpp/impl/codegen/channel_interface.h
index 39805a0ef5..6ec1ffb8c7 100644
--- a/include/grpcpp/impl/codegen/channel_interface.h
+++ b/include/grpcpp/impl/codegen/channel_interface.h
@@ -134,7 +134,7 @@ class ChannelInterface {
   virtual internal::Call CreateCallInternal(const internal::RpcMethod& method,
                                             ClientContext* context,
                                             CompletionQueue* cq,
-                                            int interceptor_pos) {
+                                            size_t interceptor_pos) {
     return internal::Call();
   }
 
diff --git a/include/grpcpp/impl/codegen/client_interceptor.h b/include/grpcpp/impl/codegen/client_interceptor.h
index 0e08a7ce01..f69c99ab22 100644
--- a/include/grpcpp/impl/codegen/client_interceptor.h
+++ b/include/grpcpp/impl/codegen/client_interceptor.h
@@ -19,6 +19,7 @@
 #ifndef GRPCPP_IMPL_CODEGEN_CLIENT_INTERCEPTOR_H
 #define GRPCPP_IMPL_CODEGEN_CLIENT_INTERCEPTOR_H
 
+#include <memory>
 #include <vector>
 
 #include <grpcpp/impl/codegen/interceptor.h>
@@ -41,7 +42,14 @@ class ClientInterceptorFactoryInterface {
   virtual ~ClientInterceptorFactoryInterface() {}
   virtual Interceptor* CreateClientInterceptor(ClientRpcInfo* info) = 0;
 };
+}  // namespace experimental
 
+namespace internal {
+extern experimental::ClientInterceptorFactoryInterface*
+    g_global_client_interceptor_factory;
+}
+
+namespace experimental {
 class ClientRpcInfo {
  public:
   ClientRpcInfo() {}
@@ -71,12 +79,21 @@ class ClientRpcInfo {
   void RegisterInterceptors(
       const std::vector<std::unique_ptr<
           experimental::ClientInterceptorFactoryInterface>>& creators,
-      int interceptor_pos) {
+      size_t interceptor_pos) {
+    if (interceptor_pos > creators.size()) {
+      // No interceptors to register
+      return;
+    }
     for (auto it = creators.begin() + interceptor_pos; it != creators.end();
          ++it) {
       interceptors_.push_back(std::unique_ptr<experimental::Interceptor>(
           (*it)->CreateClientInterceptor(this)));
     }
+    if (internal::g_global_client_interceptor_factory != nullptr) {
+      interceptors_.push_back(std::unique_ptr<experimental::Interceptor>(
+          internal::g_global_client_interceptor_factory
+              ->CreateClientInterceptor(this)));
+    }
   }
 
   grpc::ClientContext* ctx_ = nullptr;
@@ -90,6 +107,20 @@ class ClientRpcInfo {
   friend class grpc::ClientContext;
 };
 
+// PLEASE DO NOT USE THIS. ALWAYS PREFER PER CHANNEL INTERCEPTORS OVER A GLOBAL
+// INTERCEPTOR. IF USAGE IS ABSOLUTELY NECESSARY, PLEASE READ THE SAFETY NOTES.
+// Registers a global client interceptor factory object, which is used for all
+// RPCs made in this process.  If the argument is nullptr, the global
+// interceptor factory is deregistered. The application is responsible for
+// maintaining the life of the object while gRPC operations are in progress. It
+// is unsafe to try to register/deregister if any gRPC operation is in progress.
+// For safety, it is in the best interests of the developer to register the
+// global interceptor factory once at the start of the process before any gRPC
+// operations have begun. Deregistration is optional since gRPC does not
+// maintain any references to the object.
+void RegisterGlobalClientInterceptorFactory(
+    ClientInterceptorFactoryInterface* factory);
+
 }  // namespace experimental
 }  // namespace grpc
 
diff --git a/include/grpcpp/impl/codegen/intercepted_channel.h b/include/grpcpp/impl/codegen/intercepted_channel.h
index 612e56d862..5255a6d147 100644
--- a/include/grpcpp/impl/codegen/intercepted_channel.h
+++ b/include/grpcpp/impl/codegen/intercepted_channel.h
@@ -42,7 +42,7 @@ class InterceptedChannel : public ChannelInterface {
   }
 
  private:
-  InterceptedChannel(ChannelInterface* channel, int pos)
+  InterceptedChannel(ChannelInterface* channel, size_t pos)
       : channel_(channel), interceptor_pos_(pos) {}
 
   Call CreateCall(const RpcMethod& method, ClientContext* context,
@@ -70,7 +70,7 @@ class InterceptedChannel : public ChannelInterface {
   CompletionQueue* CallbackCQ() override { return channel_->CallbackCQ(); }
 
   ChannelInterface* channel_;
-  int interceptor_pos_;
+  size_t interceptor_pos_;
 
   friend class InterceptorBatchMethodsImpl;
 };
diff --git a/src/cpp/client/channel_cc.cc b/src/cpp/client/channel_cc.cc
index f5c1b4e2c5..6ef7df4ea0 100644
--- a/src/cpp/client/channel_cc.cc
+++ b/src/cpp/client/channel_cc.cc
@@ -115,7 +115,7 @@ void ChannelResetConnectionBackoff(Channel* channel) {
 internal::Call Channel::CreateCallInternal(const internal::RpcMethod& method,
                                            ClientContext* context,
                                            CompletionQueue* cq,
-                                           int interceptor_pos) {
+                                           size_t interceptor_pos) {
   const bool kRegistered = method.channel_tag() && context->authority().empty();
   grpc_call* c_call = nullptr;
   if (kRegistered) {
diff --git a/src/cpp/codegen/client_interceptor.cc b/src/cpp/codegen/client_interceptor.cc
new file mode 100644
index 0000000000..3a5cac9830
--- /dev/null
+++ b/src/cpp/codegen/client_interceptor.cc
@@ -0,0 +1,34 @@
+/*
+ *
+ * Copyright 2018 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 <grpcpp/impl/codegen/client_interceptor.h>
+
+namespace grpc {
+
+namespace internal {
+experimental::ClientInterceptorFactoryInterface*
+    g_global_client_interceptor_factory = nullptr;
+}
+
+namespace experimental {
+void RegisterGlobalClientInterceptorFactory(
+    ClientInterceptorFactoryInterface* factory) {
+  internal::g_global_client_interceptor_factory = factory;
+}
+}  // namespace experimental
+}  // namespace grpc
diff --git a/test/cpp/end2end/client_interceptors_end2end_test.cc b/test/cpp/end2end/client_interceptors_end2end_test.cc
index e8ffd46344..205f64c0f2 100644
--- a/test/cpp/end2end/client_interceptors_end2end_test.cc
+++ b/test/cpp/end2end/client_interceptors_end2end_test.cc
@@ -601,6 +601,106 @@ TEST_F(ClientInterceptorsStreamingEnd2endTest, BidiStreamingTest) {
   EXPECT_EQ(DummyInterceptor::GetNumTimesRun(), 20);
 }
 
+class ClientGlobalInterceptorEnd2endTest : public ::testing::Test {
+ protected:
+  ClientGlobalInterceptorEnd2endTest() {
+    int port = grpc_pick_unused_port_or_die();
+
+    ServerBuilder builder;
+    server_address_ = "localhost:" + std::to_string(port);
+    builder.AddListeningPort(server_address_, InsecureServerCredentials());
+    builder.RegisterService(&service_);
+    server_ = builder.BuildAndStart();
+  }
+
+  ~ClientGlobalInterceptorEnd2endTest() { server_->Shutdown(); }
+
+  std::string server_address_;
+  TestServiceImpl service_;
+  std::unique_ptr<Server> server_;
+};
+
+TEST_F(ClientGlobalInterceptorEnd2endTest, DummyGlobalInterceptor) {
+  // We should ideally be registering a global interceptor only once per
+  // process, but for the purposes of testing, it should be fine to modify the
+  // registered global interceptor when there are no ongoing gRPC operations
+  DummyInterceptorFactory global_factory;
+  experimental::RegisterGlobalClientInterceptorFactory(&global_factory);
+  ChannelArguments args;
+  DummyInterceptor::Reset();
+  auto creators = std::unique_ptr<std::vector<
+      std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>>(
+      new std::vector<
+          std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>());
+  // Add 20 dummy interceptors
+  for (auto i = 0; i < 20; i++) {
+    creators->push_back(std::unique_ptr<DummyInterceptorFactory>(
+        new DummyInterceptorFactory()));
+  }
+  auto channel = experimental::CreateCustomChannelWithInterceptors(
+      server_address_, InsecureChannelCredentials(), args, std::move(creators));
+  MakeCall(channel);
+  // Make sure all 20 dummy interceptors were run with the global interceptor
+  EXPECT_EQ(DummyInterceptor::GetNumTimesRun(), 21);
+  // Reset the global interceptor. This is again 'safe' because there are no
+  // other ongoing gRPC operations
+  experimental::RegisterGlobalClientInterceptorFactory(nullptr);
+}
+
+TEST_F(ClientGlobalInterceptorEnd2endTest, LoggingGlobalInterceptor) {
+  // We should ideally be registering a global interceptor only once per
+  // process, but for the purposes of testing, it should be fine to modify the
+  // registered global interceptor when there are no ongoing gRPC operations
+  LoggingInterceptorFactory global_factory;
+  experimental::RegisterGlobalClientInterceptorFactory(&global_factory);
+  ChannelArguments args;
+  DummyInterceptor::Reset();
+  auto creators = std::unique_ptr<std::vector<
+      std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>>(
+      new std::vector<
+          std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>());
+  // Add 20 dummy interceptors
+  for (auto i = 0; i < 20; i++) {
+    creators->push_back(std::unique_ptr<DummyInterceptorFactory>(
+        new DummyInterceptorFactory()));
+  }
+  auto channel = experimental::CreateCustomChannelWithInterceptors(
+      server_address_, InsecureChannelCredentials(), args, std::move(creators));
+  MakeCall(channel);
+  // Make sure all 20 dummy interceptors were run
+  EXPECT_EQ(DummyInterceptor::GetNumTimesRun(), 20);
+  // Reset the global interceptor. This is again 'safe' because there are no
+  // other ongoing gRPC operations
+  experimental::RegisterGlobalClientInterceptorFactory(nullptr);
+}
+
+TEST_F(ClientGlobalInterceptorEnd2endTest, HijackingGlobalInterceptor) {
+  // We should ideally be registering a global interceptor only once per
+  // process, but for the purposes of testing, it should be fine to modify the
+  // registered global interceptor when there are no ongoing gRPC operations
+  HijackingInterceptorFactory global_factory;
+  experimental::RegisterGlobalClientInterceptorFactory(&global_factory);
+  ChannelArguments args;
+  DummyInterceptor::Reset();
+  auto creators = std::unique_ptr<std::vector<
+      std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>>(
+      new std::vector<
+          std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>());
+  // Add 20 dummy interceptors
+  for (auto i = 0; i < 20; i++) {
+    creators->push_back(std::unique_ptr<DummyInterceptorFactory>(
+        new DummyInterceptorFactory()));
+  }
+  auto channel = experimental::CreateCustomChannelWithInterceptors(
+      server_address_, InsecureChannelCredentials(), args, std::move(creators));
+  MakeCall(channel);
+  // Make sure all 20 dummy interceptors were run
+  EXPECT_EQ(DummyInterceptor::GetNumTimesRun(), 20);
+  // Reset the global interceptor. This is again 'safe' because there are no
+  // other ongoing gRPC operations
+  experimental::RegisterGlobalClientInterceptorFactory(nullptr);
+}
+
 }  // namespace
 }  // namespace testing
 }  // namespace grpc
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index 7f5f9bc0db..dc27a6ae76 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -1196,6 +1196,7 @@ src/cpp/client/generic_stub.cc \
 src/cpp/client/insecure_credentials.cc \
 src/cpp/client/secure_credentials.cc \
 src/cpp/client/secure_credentials.h \
+src/cpp/codegen/client_interceptor.cc \
 src/cpp/codegen/codegen_init.cc \
 src/cpp/common/alarm.cc \
 src/cpp/common/auth_property_iterator.cc \
diff --git a/tools/run_tests/generated/sources_and_headers.json b/tools/run_tests/generated/sources_and_headers.json
index f79b391681..399e3ead33 100644
--- a/tools/run_tests/generated/sources_and_headers.json
+++ b/tools/run_tests/generated/sources_and_headers.json
@@ -11322,6 +11322,7 @@
     "language": "c++", 
     "name": "grpc++_codegen_base_src", 
     "src": [
+      "src/cpp/codegen/client_interceptor.cc", 
       "src/cpp/codegen/codegen_init.cc"
     ], 
     "third_party": false,