src/cpp/server/rpc_service_method.h

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#ifndef __GRPCPP_INTERNAL_SERVER_RPC_SERVICE_METHOD_H__
#define __GRPCPP_INTERNAL_SERVER_RPC_SERVICE_METHOD_H__

#include <functional>
#include <map>
#include <memory>
#include <vector>

#include "src/cpp/rpc_method.h"
#include <google/protobuf/message.h>
#include <grpc++/status.h>

namespace grpc {

// TODO(rocking): we might need to split this file into multiple ones.

// Base class for running an RPC handler.
class MethodHandler {
 public:
  virtual ~MethodHandler() {}
  struct HandlerParameter {
    HandlerParameter(const google::protobuf::Message* req, google::protobuf::Message* resp)
        : request(req), response(resp) {}
    const google::protobuf::Message* request;
    google::protobuf::Message* response;
  };
  virtual ::grpc::Status RunHandler(const HandlerParameter& param) = 0;
};

// A wrapper class of an application provided rpc method handler.
template <class ServiceType, class RequestType, class ResponseType>
class RpcMethodHandler : public MethodHandler {
 public:
  RpcMethodHandler(std::function<::grpc::Status(
                       ServiceType*, const RequestType*, ResponseType*)> func,
                   ServiceType* service)
      : func_(func), service_(service) {}

  ::grpc::Status RunHandler(const HandlerParameter& param) final {
    // Invoke application function, cast proto messages to their actual types.
    return func_(service_, dynamic_cast<const RequestType*>(param.request),
                 dynamic_cast<ResponseType*>(param.response));
  }

 private:
  // Application provided rpc handler function.
  std::function<::grpc::Status(ServiceType*, const RequestType*, ResponseType*)>
      func_;
  // The class the above handler function lives in.
  ServiceType* service_;
};

// Server side rpc method class
class RpcServiceMethod : public RpcMethod {
 public:
  // Takes ownership of the handler and two prototype objects.
  RpcServiceMethod(const char* name, MethodHandler* handler,
                   google::protobuf::Message* request_prototype,
                   google::protobuf::Message* response_prototype)
      : RpcMethod(name),
        handler_(handler),
        request_prototype_(request_prototype),
        response_prototype_(response_prototype) {}

  MethodHandler* handler() { return handler_.get(); }

  google::protobuf::Message* AllocateRequestProto() { return request_prototype_->New(); }
  google::protobuf::Message* AllocateResponseProto() {
    return response_prototype_->New();
  }

 private:
  std::unique_ptr<MethodHandler> handler_;
  std::unique_ptr<google::protobuf::Message> request_prototype_;
  std::unique_ptr<google::protobuf::Message> response_prototype_;
};

// This class contains all the method information for an rpc service. It is
// used for registering a service on a grpc server.
class RpcService {
 public:
  // Takes ownership.
  void AddMethod(RpcServiceMethod* method) {
    methods_.push_back(std::unique_ptr<RpcServiceMethod>(method));
  }

  RpcServiceMethod* GetMethod(int i) {
    return methods_[i].get();
  }
  int GetMethodCount() const { return methods_.size(); }

 private:
  std::vector<std::unique_ptr<RpcServiceMethod>> methods_;
};

}  // namespace grpc

#endif  // __GRPCPP_INTERNAL_SERVER_RPC_SERVICE_METHOD_H__