Merge pull request #17630 from yashykt/nocopyinterception

Modifying semantics for GetSendMessage and GetSerializedSendMessage. Also adding ModifySendMessage

3 files changed, 70 insertions, 24 deletions

diff --git a/include/grpcpp/impl/codegen/call_op_set.h b/include/grpcpp/impl/codegen/call_op_set.h
index 1c75560c04..880c62344b 100644
--- a/include/grpcpp/impl/codegen/call_op_set.h
+++ b/include/grpcpp/impl/codegen/call_op_set.h
@@ -317,7 +317,15 @@ class CallOpSendMessage {
 
  protected:
   void AddOp(grpc_op* ops, size_t* nops) {
-    if (!send_buf_.Valid() || hijacked_) return;
+    if (msg_ == nullptr && !send_buf_.Valid()) return;
+    if (hijacked_) {
+      serializer_ = nullptr;
+      return;
+    }
+    if (msg_ != nullptr) {
+      GPR_CODEGEN_ASSERT(serializer_(msg_).ok());
+    }
+    serializer_ = nullptr;
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_SEND_MESSAGE;
     op->flags = write_options_.flags();
@@ -327,9 +335,7 @@ class CallOpSendMessage {
     write_options_.Clear();
   }
   void FinishOp(bool* status) {
-    if (!send_buf_.Valid()) {
-      return;
-    }
+    if (msg_ == nullptr && !send_buf_.Valid()) return;
     if (hijacked_ && failed_send_) {
       // Hijacking interceptor failed this Op
       *status = false;
@@ -341,22 +347,25 @@ class CallOpSendMessage {
 
   void SetInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {
-    if (!send_buf_.Valid()) return;
+    if (msg_ == nullptr && !send_buf_.Valid()) return;
     interceptor_methods->AddInterceptionHookPoint(
         experimental::InterceptionHookPoints::PRE_SEND_MESSAGE);
-    interceptor_methods->SetSendMessage(&send_buf_, msg_, &failed_send_);
+    interceptor_methods->SetSendMessage(&send_buf_, &msg_, &failed_send_,
+                                        serializer_);
   }
 
   void SetFinishInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {
-    if (send_buf_.Valid()) {
+    if (msg_ != nullptr || send_buf_.Valid()) {
       interceptor_methods->AddInterceptionHookPoint(
           experimental::InterceptionHookPoints::POST_SEND_MESSAGE);
     }
     send_buf_.Clear();
+    msg_ = nullptr;
     // The contents of the SendMessage value that was previously set
     // has had its references stolen by core's operations
-    interceptor_methods->SetSendMessage(nullptr, nullptr, &failed_send_);
+    interceptor_methods->SetSendMessage(nullptr, nullptr, &failed_send_,
+                                        nullptr);
   }
 
   void SetHijackingState(InterceptorBatchMethodsImpl* interceptor_methods) {
@@ -369,22 +378,32 @@ class CallOpSendMessage {
   bool failed_send_ = false;
   ByteBuffer send_buf_;
   WriteOptions write_options_;
+  std::function<Status(const void*)> serializer_;
 };
 
 template <class M>
 Status CallOpSendMessage::SendMessage(const M& message, WriteOptions options) {
   write_options_ = options;
-  bool own_buf;
-  // TODO(vjpai): Remove the void below when possible
-  // The void in the template parameter below should not be needed
-  // (since it should be implicit) but is needed due to an observed
-  // difference in behavior between clang and gcc for certain internal users
-  Status result = SerializationTraits<M, void>::Serialize(
-      message, send_buf_.bbuf_ptr(), &own_buf);
-  if (!own_buf) {
-    send_buf_.Duplicate();
-  }
-  return result;
+  serializer_ = [this](const void* message) {
+    bool own_buf;
+    send_buf_.Clear();
+    // TODO(vjpai): Remove the void below when possible
+    // The void in the template parameter below should not be needed
+    // (since it should be implicit) but is needed due to an observed
+    // difference in behavior between clang and gcc for certain internal users
+    Status result = SerializationTraits<M, void>::Serialize(
+        *static_cast<const M*>(message), send_buf_.bbuf_ptr(), &own_buf);
+    if (!own_buf) {
+      send_buf_.Duplicate();
+    }
+    return result;
+  };
+  // Serialize immediately only if we do not have access to the message pointer
+  if (msg_ == nullptr) {
+    return serializer_(&message);
+    serializer_ = nullptr;
+  }
+  return Status();
 }
 
 template <class M>
diff --git a/include/grpcpp/impl/codegen/interceptor.h b/include/grpcpp/impl/codegen/interceptor.h
index a57a3fccbb..d749d8578a 100644
--- a/include/grpcpp/impl/codegen/interceptor.h
+++ b/include/grpcpp/impl/codegen/interceptor.h
@@ -118,6 +118,8 @@ class InterceptorBatchMethods {
   /// only supported for sync and callback APIs at the present moment.
   virtual const void* GetSendMessage() = 0;
 
+  virtual void ModifySendMessage(const void* message) = 0;
+
   /// Checks whether the SEND MESSAGE op succeeded. Valid for POST_SEND_MESSAGE
   /// interceptions.
   virtual bool GetSendMessageStatus() = 0;
diff --git a/include/grpcpp/impl/codegen/interceptor_common.h b/include/grpcpp/impl/codegen/interceptor_common.h
index 345127c830..09721343ff 100644
--- a/include/grpcpp/impl/codegen/interceptor_common.h
+++ b/include/grpcpp/impl/codegen/interceptor_common.h
@@ -79,9 +79,24 @@ class InterceptorBatchMethodsImpl
     hooks_[static_cast<size_t>(type)] = true;
   }
 
-  ByteBuffer* GetSerializedSendMessage() override { return send_message_; }
+  ByteBuffer* GetSerializedSendMessage() override {
+    GPR_CODEGEN_ASSERT(orig_send_message_ != nullptr);
+    if (*orig_send_message_ != nullptr) {
+      GPR_CODEGEN_ASSERT(serializer_(*orig_send_message_).ok());
+      *orig_send_message_ = nullptr;
+    }
+    return send_message_;
+  }
+
+  const void* GetSendMessage() override {
+    GPR_CODEGEN_ASSERT(orig_send_message_ != nullptr);
+    return *orig_send_message_;
+  }
 
-  const void* GetSendMessage() override { return orig_send_message_; }
+  void ModifySendMessage(const void* message) override {
+    GPR_CODEGEN_ASSERT(orig_send_message_ != nullptr);
+    *orig_send_message_ = message;
+  }
 
   bool GetSendMessageStatus() override { return !*fail_send_message_; }
 
@@ -125,11 +140,13 @@ class InterceptorBatchMethodsImpl
     return recv_trailing_metadata_->map();
   }
 
-  void SetSendMessage(ByteBuffer* buf, const void* msg,
-                      bool* fail_send_message) {
+  void SetSendMessage(ByteBuffer* buf, const void** msg,
+                      bool* fail_send_message,
+                      std::function<Status(const void*)> serializer) {
     send_message_ = buf;
     orig_send_message_ = msg;
     fail_send_message_ = fail_send_message;
+    serializer_ = serializer;
   }
 
   void SetSendInitialMetadata(
@@ -359,7 +376,8 @@ class InterceptorBatchMethodsImpl
 
   ByteBuffer* send_message_ = nullptr;
   bool* fail_send_message_ = nullptr;
-  const void* orig_send_message_ = nullptr;
+  const void** orig_send_message_ = nullptr;
+  std::function<Status(const void*)> serializer_;
 
   std::multimap<grpc::string, grpc::string>* send_initial_metadata_;
 
@@ -429,6 +447,13 @@ class CancelInterceptorBatchMethods
     return nullptr;
   }
 
+  void ModifySendMessage(const void* message) override {
+    GPR_CODEGEN_ASSERT(
+        false &&
+        "It is illegal to call ModifySendMessage on a method which "
+        "has a Cancel notification");
+  }
+
   std::multimap<grpc::string, grpc::string>* GetSendInitialMetadata() override {
     GPR_CODEGEN_ASSERT(false &&
                        "It is illegal to call GetSendInitialMetadata on a "