raw_component_base.hpp

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#pragma once
 
/// @file userver/components/raw_component_base.hpp
/// @brief @copybrief components::RawComponentBase
 
#include <type_traits>
 
USERVER_NAMESPACE_BEGIN
 
namespace yaml_config {
 
struct Schema;
 
}  // namespace yaml_config
 
namespace engine {
 
class Deadline;
 
}  // namespace engine
 
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
};
 
/// @brief The base class for all components. Don't use it for application
/// components, use ComponentBase instead.
///
/// Only inherited directly by some of the built-in userver components.
class RawComponentBase {
public:
    RawComponentBase() = default;
 
    RawComponentBase(RawComponentBase&&) = delete;
 
    RawComponentBase(const RawComponentBase&) = delete;
 
    virtual ~RawComponentBase();
 
    virtual ComponentHealth GetComponentHealth() const { return ComponentHealth::kOk; }
 
    virtual void OnLoadingCancelled() {}
 
    virtual void OnAllComponentsLoaded() {}
 
    virtual void OnGracefulShutdown(engine::Deadline /*serving_shutdown_deadline*/);
 
    virtual void OnAllComponentsAreStopping() {}
 
    static yaml_config::Schema GetStaticConfigSchema();
};
 
/// 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 it for typename Component to skip validation of static config against
/// schema from Component::GetStaticConfigSchema
///
/// @see @ref static-configs-validation "Static configs validation"
template <typename Component>
inline constexpr bool kForceNoValidation = false;
 
namespace impl {
 
template <typename Component>
inline constexpr auto kDefaultConfigFileMode = ConfigFileMode::kRequired;
 
template <typename Component>
requires requires { Component::kConfigFileMode; }
inline constexpr auto kDefaultConfigFileMode<Component> = Component::kConfigFileMode;
}  // namespace impl
 
/// 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 = impl::kDefaultConfigFileMode<Component>;
 
}  // namespace components
 
USERVER_NAMESPACE_END