clients::dns::Component Class Reference

#include <userver/clients/dns/component.hpp>

Detailed Description

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	-
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:

# yaml
    dns-client:
      fs-task-processor: fs-task-processor
      hosts-file-path: /etc/hosts
      hosts-file-update-interval: 5m
      network-timeout: 1s
      network-attempts: 1
      network-custom-servers:
        - 127.0.0.1
        - 127.0.0.2
      cache-ways: 16
      cache-size-per-way: 256
      cache-max-reply-ttl: 5m
      cache-failure-ttl: 5s

Examples

samples/http_caching/http_caching.cpp, samples/mongo_service/mongo_service.cpp, samples/postgres_auth/postgres_service.cpp, samples/redis_service/redis_service.cpp, and samples/tcp_full_duplex_service/tcp_full_duplex_service.cpp.

Definition at line 42 of file component.hpp.

Inheritance diagram for clients::dns::Component:

Public Member Functions
	Component (const components::ComponentConfig &, const components::ComponentContext &)
Resolver &	GetResolver ()
ComponentHealth	GetComponentHealth () const override
void	OnLoadingCancelled () override
void	OnAllComponentsLoaded () override
void	OnAllComponentsAreStopping () override

Static Public Member Functions
static yaml_config::Schema	GetStaticConfigSchema ()

Static Public Attributes
static constexpr std::string_view	kName = "dns-client"
	The default name of clients::dns::Component component.

Protected Types
using	LoggableComponentBase = ComponentBase
	Legacy alias, use ComponentBase instead.

Member Typedef Documentation

LoggableComponentBase

using components::ComponentBase::LoggableComponentBase = ComponentBase

protectedinherited

Legacy alias, use ComponentBase instead.

Definition at line 69 of file component_base.hpp.

Member Function Documentation

GetComponentHealth()

ComponentHealth components::ComponentBase::GetComponentHealth ( ) const

inlineoverridevirtualinherited

Override this function to inform the world of the state of your component.

Warning

The function is called concurrently from multiple threads.

Reimplemented from components::RawComponentBase.

Definition at line 35 of file component_base.hpp.

OnAllComponentsAreStopping()

void components::ComponentBase::OnAllComponentsAreStopping ( )

inlineoverridevirtualinherited

Component may use this function to stop doing work before the stop of the components that depend on it.

Base components may override it and make final to do some work before the derived object constructor is called. Don't use it otherwise.

Reimplemented from components::RawComponentBase.

Reimplemented in urabbitmq::ConsumerComponentBase, and components::Server.

Definition at line 60 of file component_base.hpp.

OnAllComponentsLoaded()

void components::ComponentBase::OnAllComponentsLoaded ( )

inlineoverridevirtualinherited

Component may use this function to finalize registration of other components that depend on it (for example, handler components register in server component, and the latter uses OnAllComponentsLoaded() to start processing requests).

Base components may override it and make final to do some work after the derived object constructor is called. Don't use it otherwise.

Reimplemented from components::RawComponentBase.

Reimplemented in urabbitmq::ConsumerComponentBase, components::Server, and server::handlers::Ping.

Definition at line 53 of file component_base.hpp.

OnLoadingCancelled()

void components::ComponentBase::OnLoadingCancelled ( )

inlineoverridevirtualinherited

Called once if the creation of any other component failed. If the current component expects some other component to take any action with the current component, this call is a signal that such action may never happen due to components loading was cancelled. Application components might not want to override it.

Reimplemented from components::RawComponentBase.

Definition at line 44 of file component_base.hpp.

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The documentation for this class was generated from the following file:

• userver/clients/dns/component.hpp