component.hpp

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#pragma once
 
/// @file userver/clients/dns/component.hpp
/// @brief @copybrief clients::dns::Component
 
#include <userver/clients/dns/resolver.hpp>
#include <userver/components/component_base.hpp>
#include <userver/utils/statistics/entry.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace clients::dns {
 
// clang-format off
 
/// @ingroup userver_components
///
/// @brief Caching DNS resolver component.
///
/// Returned references to clients::dns::Resolver live for a lifetime
/// of the component and are safe for concurrent use.
///
/// ## Static options:
/// Name | Description | Default value
/// ---- | ----------- | -------------
/// fs-task-processor | task processor for disk I/O operations | engine::current_task::GetBlockingTaskProcessor()
/// hosts-file-path | path to the `hosts` file | /etc/hosts
/// hosts-file-update-interval | `hosts` file cache reload interval | 5m
/// network-timeout | timeout for network requests | 1s
/// network-attempts | number of attempts for network requests | 1
/// network-custom-servers | list of name servers to use | from `/etc/resolv.conf`
/// cache-ways | number of ways for network cache | 16
/// cache-size-per-way | size of each way of network cache | 256
/// cache-max-reply-ttl | TTL limit for network replies caching | 5m
/// cache-failure-ttl | TTL for network failures caching | 5s
///
/// ## Static configuration example:
///
/// @snippet components/common_component_list_test.cpp  Sample dns client component config
 
// clang-format on
class Component final : public components::ComponentBase {
public:
    /// @ingroup userver_component_names
    /// @brief The default name of clients::dns::Component component
    static constexpr std::string_view kName = "dns-client";
 
    Component(const components::ComponentConfig&, const components::ComponentContext&);
 
    Resolver& GetResolver();
 
private:
    void Write(utils::statistics::Writer& writer);
 
    Resolver resolver_;
    utils::statistics::Entry statistics_holder_;
};
 
}  // namespace clients::dns
 
template <>
inline constexpr bool components::kForceNoValidation<clients::dns::Component> = true;
 
template <>
inline constexpr auto components::kConfigFileMode<clients::dns::Component> = ConfigFileMode::kNotRequired;
 
USERVER_NAMESPACE_END