components::ComponentContext Class Reference

#include <userver/components/component_context.hpp>

Detailed Description

Class to retrieve other components.

Only the const member functions of this class are meant for usage in component constructor (because of that this class is always passed as a const reference to the constructors).

Warning

Don't store references to ComponentContext in your component! Lifetime of the passed ComponentContext ends as soon as the constructor ends.

For usage outside the component constructor see components::State.

See also

Components

Examples

components/component_sample_test.cpp, components/component_sample_test.hpp, grpc-generic-proxy/src/proxy_service.cpp, grpc-generic-proxy/src/proxy_service.hpp, postgresql/functional_tests/basic_chaos/postgres_service.cpp, samples/config_service/main.cpp, samples/digest_auth_service/auth_digest.cpp, samples/digest_auth_service/auth_digest.hpp, samples/easy/4_custom_dependency/main.cpp, samples/easy/5_pg_service_template/src/main.cpp, samples/flatbuf_service/main.cpp, samples/grpc_middleware_service/src/middlewares/server/meta_filter.cpp, samples/grpc_middleware_service/src/middlewares/server/meta_filter.hpp, samples/grpc_service/src/greeter_service.cpp, samples/grpc_service/src/greeter_service.hpp, samples/kafka_service/src/consumer_handler.cpp, samples/kafka_service/src/consumer_handler.hpp, samples/kafka_service/src/producer_handler.cpp, samples/kafka_service/src/producer_handler.hpp, samples/mongo_service/main.cpp, samples/postgres_auth/auth_bearer.cpp, samples/postgres_auth/auth_bearer.hpp, samples/postgres_service/main.cpp, samples/redis_service/main.cpp, samples/s3api/src/s3api_client.cpp, samples/s3api/src/s3api_client.hpp, samples/scylla_service/src/main.cpp, samples/tcp_full_duplex_service/main.cpp, samples/tcp_service/main.cpp, samples/testsuite-support/src/metrics.cpp, samples/testsuite-support/src/metrics.hpp, samples/testsuite-support/src/tasks.cpp, samples/websocket_client/main.cpp, samples/ydb_service/components/federated_topic_reader.cpp, samples/ydb_service/components/federated_topic_reader.hpp, samples/ydb_service/components/topic_reader.cpp, samples/ydb_service/components/topic_reader.hpp, samples/ydb_service/views/base_handler.hpp, samples/ydb_topic_writer_service/src/write_handler.cpp, and samples/ydb_topic_writer_service/src/write_handler.hpp.

Definition at line 79 of file component_context.hpp.

Public Member Functions
	ComponentContext (ComponentContext &&)=delete
ComponentContext &	operator= (ComponentContext &&)=delete
template<typename T>
T &	FindComponent () const
	Finds a component of type T with specified name (if any) and returns the component after it was initialized.
template<typename T>
T &	FindComponent (std::string_view name) const
template<typename T>
T &	FindComponent (std::string_view={})
template<typename T>
T *	FindComponentOptional () const
	If there's no component with specified type and name return nullptr; otherwise behaves as FindComponent().
template<typename T>
T *	FindComponentOptional (std::string_view name) const
template<typename T>
T &	FindComponentOptional (std::string_view={})
engine::TaskProcessor &	GetTaskProcessor (std::string_view name) const
	Returns an engine::TaskProcessor with the specified name.
template<typename T>
engine::TaskProcessor &	GetTaskProcessor (const T &)
std::string_view	GetComponentName () const
	Returns the current component name. This is helpful in cases where multiple instances of the component class may be created using component_list.Append<T>("custom-name") syntax.
utils::ResourceScopeStorage &	Scopes () const
	Returns utils::ResourceScopeStorage that can be used (by a component or any other class) to register user resources.

Member Function Documentation

FindComponent() [1/3]

template<typename T>

T & components::ComponentContext::FindComponent ( ) const

inline

Finds a component of type T with specified name (if any) and returns the component after it was initialized.

Can only be called from other component's constructor in a task where that constructor was called. May block and asynchronously wait for the creation of the requested component.

Exceptions

ComponentsLoadCancelledException	if components loading was cancelled due to errors in the creation of other component.
std::runtime_error	if component missing in component_list was requested.

Examples

components/component_sample_test.cpp, postgresql/functional_tests/basic_chaos/postgres_service.cpp, samples/digest_auth_service/auth_digest.cpp, samples/easy/4_custom_dependency/main.cpp, samples/easy/5_pg_service_template/src/main.cpp, samples/kafka_service/src/consumer_handler.cpp, samples/kafka_service/src/producer_handler.cpp, samples/mongo_service/main.cpp, samples/postgres_auth/auth_bearer.cpp, samples/s3api/src/s3api_client.cpp, samples/scylla_service/src/main.cpp, samples/testsuite-support/src/metrics.cpp, samples/websocket_client/main.cpp, samples/ydb_service/components/federated_topic_reader.cpp, samples/ydb_service/components/topic_reader.cpp, samples/ydb_service/views/base_handler.hpp, and samples/ydb_topic_writer_service/src/write_handler.cpp.

Definition at line 96 of file component_context.hpp.

FindComponent() [2/3]

template<typename T>

T & components::ComponentContext::FindComponent ( std::string_view name ) const

inline

Definition at line 102 of file component_context.hpp.

FindComponent() [3/3]

template<typename T>

T & components::ComponentContext::FindComponent ( std::string_view = {} )

inline

Definition at line 117 of file component_context.hpp.

FindComponentOptional() [1/3]

template<typename T>

T * components::ComponentContext::FindComponentOptional ( ) const

inline

If there's no component with specified type and name return nullptr; otherwise behaves as FindComponent().

Definition at line 124 of file component_context.hpp.

FindComponentOptional() [2/3]

template<typename T>

T * components::ComponentContext::FindComponentOptional ( std::string_view name ) const

inline

Definition at line 130 of file component_context.hpp.

FindComponentOptional() [3/3]

template<typename T>

T & components::ComponentContext::FindComponentOptional ( std::string_view = {} )

inline

Definition at line 138 of file component_context.hpp.

GetComponentName()

std::string_view components::ComponentContext::GetComponentName

(

)

const

Returns the current component name. This is helpful in cases where multiple instances of the component class may be created using component_list.Append<T>("custom-name") syntax.

Warning

The lifetime of the returned string ends as soon as the current component's constructor completes. Store it as an std::string if needed.

GetTaskProcessor()

template<typename T>

engine::TaskProcessor & components::ComponentContext::GetTaskProcessor ( const T & )

inline

Definition at line 146 of file component_context.hpp.

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

• userver/components/component_context.hpp