component_base.hpp

#pragma once
 
USERVER_NAMESPACE_BEGIN
 
namespace yaml_config {
 
struct Schema;
 
}  // namespace yaml_config
 
namespace components {
 
/// State of the component
enum class ComponentHealth {
  /// component is alive and fine
  kOk,
  /// component in fallback state, but the service keeps working
  kFallback,
  /// component is sick, service can not work without it
  kFatal,
};
 
/// Whether the static config for the component must always be present, or can
/// be missing
enum class ConfigFileMode {
  /// component must be setup in config
  kRequired,
  /// component must be not setup in config
  kNotRequired
};
 
namespace impl {
 
/// Don't use it for application components, use LoggableComponentBase instead
class ComponentBase {
 public:
  ComponentBase() = default;
 
  ComponentBase(ComponentBase&&) = delete;
 
  ComponentBase(const ComponentBase&) = delete;
 
  virtual ~ComponentBase();
 
  virtual ComponentHealth GetComponentHealth() const {
    return ComponentHealth::kOk;
  }
 
  virtual void OnLoadingCancelled() {}
 
  virtual void OnAllComponentsLoaded() {}
 
  virtual void OnAllComponentsAreStopping() {}
 
  static yaml_config::Schema GetStaticConfigSchema();
};
 
}  // namespace impl
 
/// Specialize it for typename Component to validate static config against
/// schema from Component::GetStaticConfigSchema
///
/// @see @ref static-configs-validation "Static configs validation"
template <typename Component>
inline constexpr bool kHasValidate = false;
 
/// Specialize this to customize the loading of component settings
///
/// @see @ref select-config-file-mode "Setup config file mode"
template <typename Component>
inline constexpr auto kConfigFileMode = ConfigFileMode::kRequired;
 
}  // namespace components
 
USERVER_NAMESPACE_END