#include <userver/components/component_context.hpp>
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, libraries/easy/samples/4_custom_dependency/main.cpp, libraries/easy/samples/5_pg_service_template/src/main.cpp, 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/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/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/ydb_service/components/federated_topic_reader.cpp, samples/ydb_service/components/federated_topic_reader.hpp, samples/ydb_service/components/topic_reader.cpp, and samples/ydb_service/components/topic_reader.hpp.
Definition at line 80 of file component_context.hpp.
|
|
| 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.
|
| |
| void | RegisterScope (ScopePtr) const |
| | Registers a functor to register some resource that will be called after the component is succesfully created (including all class descendants). The functor must return a RAII-style handle object that unregisters the previously registered resource. The returned handle's destructor is called just before the component destructor is called.
|
| |
◆ 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, libraries/easy/samples/4_custom_dependency/main.cpp, libraries/easy/samples/5_pg_service_template/src/main.cpp, postgresql/functional_tests/basic_chaos/postgres_service.cpp, samples/digest_auth_service/auth_digest.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/testsuite-support/src/metrics.cpp, samples/ydb_service/components/federated_topic_reader.cpp, and samples/ydb_service/components/topic_reader.cpp.
Definition at line 97 of file component_context.hpp.
◆ FindComponent() [2/3]
template<typename T>
| T & components::ComponentContext::FindComponent |
( |
std::string_view | name | ) |
const |
|
inline |
◆ FindComponent() [3/3]
template<typename T>
| T & components::ComponentContext::FindComponent |
( |
std::string_view | = {} | ) |
|
|
inline |
◆ FindComponentOptional() [1/3]
template<typename T>
| T * components::ComponentContext::FindComponentOptional |
( |
| ) |
const |
|
inline |
◆ FindComponentOptional() [2/3]
template<typename T>
| T * components::ComponentContext::FindComponentOptional |
( |
std::string_view | name | ) |
const |
|
inline |
◆ FindComponentOptional() [3/3]
template<typename T>
| T & components::ComponentContext::FindComponentOptional |
( |
std::string_view | = {} | ) |
|
|
inline |
◆ 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 |
◆ RegisterScope()
| void components::ComponentContext::RegisterScope |
( |
ScopePtr | | ) |
const |
Registers a functor to register some resource that will be called after the component is succesfully created (including all class descendants). The functor must return a RAII-style handle object that unregisters the previously registered resource. The returned handle's destructor is called just before the component destructor is called.
- Note
- callback is not called if the component is not created OR any previously registered callback throws an exception.
-
if you don't have an existing RAII-ish class, but still want to do a cleanup, you might want to use utils::FastScopeGuard to wrap the cleanup function.
The documentation for this class was generated from the following file:
