base.hpp

#pragma once
 
/// @file userver/ugrpc/server/middlewares/middleware_base.hpp
/// @brief @copybrief ugrpc::server::MiddlewareBase
 
#include <memory>
#include <vector>
 
#include <userver/components/component_base.hpp>
#include <userver/utils/function_ref.hpp>
 
#include <userver/ugrpc/server/middlewares/fwd.hpp>
#include <userver/ugrpc/server/rpc.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace ugrpc::server {
 
/// @brief Context for middleware-specific data during gRPC call
class MiddlewareCallContext final {
 public:
  /// @cond
  MiddlewareCallContext(const Middlewares& middlewares, CallAnyBase& call,
                        utils::function_ref<void()> user_call,
                        const dynamic_config::Snapshot& config,
                        ::google::protobuf::Message* request);
  /// @endcond
 
  /// @brief Call next plugin, or gRPC handler if none
  void Next();
 
  /// @brief Get original gRPC Call
  CallAnyBase& GetCall() const;
 
  /// @brief Get values extracted from dynamic_config. Snapshot will be
  /// deleted when the last middleware completes
  const dynamic_config::Snapshot& GetInitialDynamicConfig() const;
 
 private:
  void ClearMiddlewaresResources();
 
  Middlewares::const_iterator middleware_;
  Middlewares::const_iterator middleware_end_;
  utils::function_ref<void()> user_call_;
 
  CallAnyBase& call_;
 
  std::optional<dynamic_config::Snapshot> config_;
  ::google::protobuf::Message* request_;
  bool is_called_from_handle_{false};
};
 
/// @ingroup userver_base_classes
///
/// @brief Base class for server gRPC middleware
class MiddlewareBase {
 public:
  MiddlewareBase();
  MiddlewareBase(const MiddlewareBase&) = delete;
  MiddlewareBase& operator=(const MiddlewareBase&) = delete;
  MiddlewareBase& operator=(MiddlewareBase&&) = delete;
 
  virtual ~MiddlewareBase();
 
  /// @brief Handles the gRPC request
  /// @note You should call context.Next() inside, otherwise the call will be
  /// dropped
  virtual void Handle(MiddlewareCallContext& context) const = 0;
 
  /// @brief Request hook. The function is invoked on each request
  virtual void CallRequestHook(const MiddlewareCallContext& context,
                               google::protobuf::Message& request);
 
  /// @brief Response hook. The function is invoked on each response
  virtual void CallResponseHook(const MiddlewareCallContext& context,
                                google::protobuf::Message& response);
};
 
/// @ingroup userver_base_classes
///
/// @brief Base class for middleware component
class MiddlewareComponentBase : public components::ComponentBase {
  using components::ComponentBase::ComponentBase;
 
 public:
  /// @brief Returns a middleware according to the component's settings
  virtual std::shared_ptr<MiddlewareBase> GetMiddleware() = 0;
};
 
}  // namespace ugrpc::server
 
USERVER_NAMESPACE_END