grpc/include/grpc++/impl/codegen/proto_utils.h

/*
 *
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 *
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#ifndef GRPCXX_IMPL_CODEGEN_PROTO_UTILS_H
#define GRPCXX_IMPL_CODEGEN_PROTO_UTILS_H

#include <type_traits>

#include <grpc/impl/codegen/byte_buffer.h>
#include <grpc/impl/codegen/log.h>
#include <grpc++/impl/codegen/serialization_traits.h>
#include <grpc++/impl/codegen/config_protobuf.h>
#include <grpc++/impl/codegen/status.h>

namespace grpc {

class ProtoSerializerInterface {
 public:
  // Serialize the msg into a buffer created inside the function. The caller
  // should destroy the returned buffer when done with it. If serialization
  // fails,
  // false is returned and buffer is left unchanged.
  virtual Status SerializeProto(const grpc::protobuf::Message& msg,
                                grpc_byte_buffer** buffer) = 0;

  // The caller keeps ownership of buffer and msg.
  virtual Status DeserializeProto(grpc_byte_buffer* buffer,
                                  grpc::protobuf::Message* msg,
                                  int max_message_size) = 0;
};

// TODO(dgq): This is a temporary fix to work around codegen issues related to
// a certain sharp-sounding build system. Its purpose is to hold a polymorphic
// proto serializer/deserializer instance. It's initialized as part of
// src/cpp/proto/proto_serializer.cc.
//
// This global variable plus all related code (ProtoSerializerInteface,
// ProtoSerializer) will be removed in the future.
extern ProtoSerializerInterface* g_proto_serializer;

class ProtoSerializer : public ProtoSerializerInterface {
 public:
  // Serialize the msg into a buffer created inside the function. The caller
  // should destroy the returned buffer when done with it. If serialization
  // fails,
  // false is returned and buffer is left unchanged.
  Status SerializeProto(const grpc::protobuf::Message& msg,
                                grpc_byte_buffer** buffer) override;

  // The caller keeps ownership of buffer and msg.
  Status DeserializeProto(grpc_byte_buffer* buffer,
                                  grpc::protobuf::Message* msg,
                                  int max_message_size) override;
};


template <class T>
class SerializationTraits<T, typename std::enable_if<std::is_base_of<
                                 grpc::protobuf::Message, T>::value>::type> {
 public:
  static Status Serialize(const grpc::protobuf::Message& msg,
                          grpc_byte_buffer** buffer, bool* own_buffer) {
    *own_buffer = true;
    GPR_ASSERT(g_proto_serializer != nullptr &&
               "No ProtoSerializer instance registered. Make sure grpc++ is being initialized.");
    return g_proto_serializer->SerializeProto(msg, buffer);
  }
  static Status Deserialize(grpc_byte_buffer* buffer,
                            grpc::protobuf::Message* msg,
                            int max_message_size) {
    GPR_ASSERT(g_proto_serializer != nullptr &&
               "No ProtoSerializer instance registered. Make sure grpc++ is being initialized.");
    auto status =
        g_proto_serializer->DeserializeProto(buffer, msg, max_message_size);
    grpc_byte_buffer_destroy(buffer);
    return status;
  }
};

}  // namespace grpc

#endif  // GRPCXX_IMPL_CODEGEN_PROTO_UTILS_H