Pass channel args to ChannelData ctor and ChannelData to CallData ctor.

include/grpc++/channel_filter.h

@@ -53,6 +53,20 @@
 
 namespace grpc {
 
+// Represents channel data.
+// Note: Must be copyable.
+class ChannelData {
+ public:
+  virtual ~ChannelData() {}
+
+  virtual void StartTransportOp(
+      grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
+      grpc_transport_op *op);
+
+ protected:
+  explicit ChannelData(const grpc_channel_args&) {}
+};
+
 // Represents call data.
 // Note: Must be copyable.
 class CallData {
@@ -70,21 +84,7 @@ class CallData {
   virtual char* GetPeer(grpc_exec_ctx *exec_ctx, grpc_call_element *elem);
 
  protected:
-  CallData() {}
+  explicit CallData(const ChannelData&) {}
-};
-
-// Represents channel data.
-// Note: Must be copyable.
-class ChannelData {
- public:
-  virtual ~ChannelData() {}
-
-  virtual void StartTransportOp(
-      grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
-      grpc_transport_op *op);
-
- protected:
-  ChannelData() {}
 };
 
 namespace internal {
@@ -93,13 +93,35 @@ namespace internal {
 template<typename ChannelDataType, typename CallDataType>
 class ChannelFilter {
  public:
+  static const size_t channel_data_size = sizeof(ChannelDataType);
+
+  static void InitChannelElement(
+      grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
+      grpc_channel_element_args *args) {
+    // Construct the object in the already-allocated memory.
+    new (elem->channel_data) ChannelDataType(*args->channel_args);
+  }
+
+  static void DestroyChannelElement(
+      grpc_exec_ctx *exec_ctx, grpc_channel_element *elem) {
+    reinterpret_cast<ChannelDataType*>(elem->channel_data)->~ChannelDataType();
+  }
+
+  static void StartTransportOp(
+      grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
+      grpc_transport_op *op) {
+    ChannelDataType* channel_data = (ChannelDataType*)elem->channel_data;
+    channel_data->StartTransportOp(exec_ctx, elem, op);
+  }
+
   static const size_t call_data_size = sizeof(CallDataType);
 
   static void InitCallElement(
       grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
       grpc_call_element_args *args) {
+    const ChannelDataType& channel_data = *(ChannelDataType*)elem->channel_data;
     // Construct the object in the already-allocated memory.
-    new (elem->call_data) CallDataType();
+    new (elem->call_data) CallDataType(channel_data);
   }
 
   static void DestroyCallElement(
@@ -127,33 +149,12 @@ class ChannelFilter {
     CallDataType* call_data = (CallDataType*)elem->call_data;
     return call_data->GetPeer(exec_ctx, elem);
   }
-
-  static const size_t channel_data_size = sizeof(ChannelDataType);
-
-  static void InitChannelElement(
-      grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
-      grpc_channel_element_args *args) {
-    // Construct the object in the already-allocated memory.
-    new (elem->channel_data) ChannelDataType();
-  }
-
-  static void DestroyChannelElement(
-      grpc_exec_ctx *exec_ctx, grpc_channel_element *elem) {
-    reinterpret_cast<ChannelDataType*>(elem->channel_data)->~ChannelDataType();
-  }
-
-  static void StartTransportOp(
-      grpc_exec_ctx *exec_ctx, grpc_channel_element *elem,
-      grpc_transport_op *op) {
-    ChannelDataType* channel_data = (ChannelDataType*)elem->channel_data;
-    channel_data->StartTransportOp(exec_ctx, elem, op);
-  }
 };
 
 struct FilterRecord {
   grpc_channel_stack_type stack_type;
   int priority;
-  std::function<bool(const grpc_channel_args*)> include_filter;
+  std::function<bool(const grpc_channel_args&)> include_filter;
   grpc_channel_filter filter;
 };
 extern std::vector<FilterRecord>* channel_filters;
@@ -171,7 +172,7 @@ void ChannelFilterPluginShutdown();
 template<typename ChannelDataType, typename CallDataType>
 void RegisterChannelFilter(
     const char* name, grpc_channel_stack_type stack_type, int priority,
-    std::function<bool(const grpc_channel_args*)> include_filter) {
+    std::function<bool(const grpc_channel_args&)> include_filter) {
   // If we haven't been called before, initialize channel_filters and
   // call grpc_register_plugin().
   if (internal::channel_filters == nullptr) {

src/cpp/common/channel_filter.cc

@@ -83,7 +83,7 @@ bool MaybeAddFilter(grpc_channel_stack_builder* builder, void* arg) {
   if (filter.include_filter != nullptr) {
     const grpc_channel_args *args =
         grpc_channel_stack_builder_get_channel_arguments(builder);
-    if (!filter.include_filter(args))
+    if (!filter.include_filter(*args))
       return true;
   }
   return grpc_channel_stack_builder_prepend_filter(

test/cpp/end2end/filter_end2end_test.cc

@@ -95,9 +95,16 @@ int GetCounterValue() {
 
 }  // namespace
 
+class ChannelDataImpl : public ChannelData {
+ public:
+  explicit ChannelDataImpl(const grpc_channel_args& args) : ChannelData(args) {}
+  virtual ~ChannelDataImpl() {}
+};
+
 class CallDataImpl : public CallData {
  public:
-  CallDataImpl() {}
+  explicit CallDataImpl(const ChannelDataImpl& channel_data)
+      : CallData(channel_data) {}
   virtual ~CallDataImpl() {}
 
   void StartTransportStreamOp(
@@ -109,12 +116,6 @@ class CallDataImpl : public CallData {
   }
 };
 
-class ChannelDataImpl : public ChannelData {
- public:
-  ChannelDataImpl() {}
-  virtual ~ChannelDataImpl() {}
-};
-
 class FilterEnd2endTest : public ::testing::Test {
  protected:
   FilterEnd2endTest() : server_host_("localhost") {}