service_component_base.hpp

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#pragma once
 
/// @file userver/ugrpc/server/service_component_base.hpp
/// @brief @copybrief ugrpc::server::ServiceComponentBase
 
#include <atomic>
 
#include <userver/components/loggable_component_base.hpp>
#include <userver/engine/task/task_processor_fwd.hpp>
 
#include <userver/ugrpc/server/middlewares/fwd.hpp>
#include <userver/ugrpc/server/service_base.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace ugrpc::server {
 
class ServerComponent;
 
// clang-format off
 
/// @ingroup userver_components userver_base_classes
///
/// @brief Base class for all the gRPC service components.
///
/// ## Static options:
/// Name | Description | Default value
/// ---- | ----------- | -------------
/// task-processor | the task processor to use for responses | taken from grpc-server.service-defaults
/// middlewares | middleware component names to use for each RPC call, can be empty array ([]) | taken from grpc-server.service-defaults
 
// clang-format on
 
class ServiceComponentBase : public components::LoggableComponentBase {
 public:
  ServiceComponentBase(const components::ComponentConfig& config,
                       const components::ComponentContext& context);
 
  static yaml_config::Schema GetStaticConfigSchema();
 
 protected:
  /// Derived classes must store the actual service class in a field and call
  /// RegisterService with it
  void RegisterService(ServiceBase& service);
 
 private:
  ServerComponent& server_;
  ServiceConfig config_;
  std::atomic<bool> registered_{false};
};
 
namespace impl {
 
template <typename ServiceInterface>
// NOLINTNEXTLINE(fuchsia-multiple-inheritance)
class ServiceComponentBase : public server::ServiceComponentBase,
                             public ServiceInterface {
  static_assert(std::is_base_of_v<ServiceBase, ServiceInterface>);
 
 public:
  ServiceComponentBase(const components::ComponentConfig& config,
                       const components::ComponentContext& context)
      : server::ServiceComponentBase(config, context), ServiceInterface() {
    // At this point the derived class that implements ServiceInterface is not
    // constructed yet. We rely on the implementation detail that the methods of
    // ServiceInterface are never called right after RegisterService. Unless
    // Server starts during the construction of this component (which is an
    // error anyway), we should be fine.
    RegisterService(*this);
  }
 
 private:
  using server::ServiceComponentBase::RegisterService;
};
 
}  // namespace impl
 
}  // namespace ugrpc::server
 
USERVER_NAMESPACE_END