#include <userver/dynamic_config/source.hpp>

Detailed Description

A client for easy dynamic config fetching in components.

After construction, dynamic_config::Source can be copied around and passed to clients or child helper classes.

Usually retrieved from components::DynamicConfig component.

Typical usage:

namespace myservice::smth {
 
inline const dynamic_config::Key kMyConfig{"SAMPLE_INTEGER_FROM_RUNTIME_CONFIG",
                                           42};
 
int Component::DoSomething() const {
  // Getting a snapshot of dynamic config.
  const auto runtime_config = config_.GetSnapshot();
  return runtime_config[kMyConfig];
}
 
}  // namespace myservice::smth

Examples: components/component_sample_test.hpp.

Definition at line 77 of file source.hpp.

Public Types
using	SnapshotEventSource = concurrent::AsyncEventSource<const Snapshot&>

using	DiffEventSource = concurrent::AsyncEventSource<const Diff&>

Public Member Functions
	Source (impl::StorageData &storage)

	Source (const Source &)=default

	Source (Source &&)=default

Source &	operator= (const Source &)=default

Source &	operator= (Source &&)=default

Snapshot	GetSnapshot () const

template<typename VariableType >
VariableSnapshotPtr< VariableType >	GetSnapshot (const Key< VariableType > &key) const

template<typename VariableType >
VariableType	GetCopy (const Key< VariableType > &key) const

template<typename Class >
concurrent::AsyncEventSubscriberScope	UpdateAndListen (Class obj, std::string_view name, void(Class::func)(const dynamic_config::Snapshot &config))

template<typename Class >
concurrent::AsyncEventSubscriberScope	UpdateAndListen (Class obj, std::string_view name, void(Class::func)(const dynamic_config::Diff &diff))
	Subscribes to dynamic-config updates with information about the current and previous states.

template<typename Class , typename... Keys>
concurrent::AsyncEventSubscriberScope	UpdateAndListen (Class obj, std::string_view name, void(Class::func)(const dynamic_config::Snapshot &config), const Keys &... keys)
	Subscribes to updates of a subset of all configs.

SnapshotEventSource &	GetEventChannel ()

Member Typedef Documentation

◆ DiffEventSource

using dynamic_config::Source::DiffEventSource = concurrent::AsyncEventSource<const Diff&>

Definition at line 80 of file source.hpp.

◆ SnapshotEventSource

using dynamic_config::Source::SnapshotEventSource = concurrent::AsyncEventSource<const Snapshot&>

Definition at line 79 of file source.hpp.

Constructor & Destructor Documentation

◆ Source()

dynamic_config::Source::Source ( impl::StorageData & storage )

explicit

For internal use only. Obtain using components::DynamicConfig or dynamic_config::StorageMock instead.

Member Function Documentation

◆ GetCopy()

template<typename VariableType >

VariableType dynamic_config::Source::GetCopy ( const Key< VariableType > & key ) const

inline

Definition at line 101 of file source.hpp.

◆ GetSnapshot()

template<typename VariableType >

VariableSnapshotPtr< VariableType > dynamic_config::Source::GetSnapshot ( const Key< VariableType > & key ) const

inline

Definition at line 95 of file source.hpp.

◆ UpdateAndListen() [1/3]

template<typename Class >

concurrent::AsyncEventSubscriberScope dynamic_config::Source::UpdateAndListen	(	Class *	obj,
		std::string_view	name,
		void(Class::*)(const dynamic_config::Diff &diff)	func )

inline

Subscribes to dynamic-config updates with information about the current and previous states.

Subscribes to dynamic-config updates using a member function, named OnConfigUpdate by convention. Also constructs dynamic_config::Diff object using std::nullopt and current config snapshot, then immediately invokes the function with it (this invocation will be executed synchronously).

Note: Callbacks occur in full accordance with components::DynamicConfigClientUpdater options.

Warning: In debug mode the last notification for any subscriber will be called with std::nullopt and current config snapshot.

Example usage:

  void OnConfigUpdate(const dynamic_config::Diff& diff_data) {
    if (!diff_data.previous) return;
 
    const auto& previous = *diff_data.previous;
    const auto& current = diff_data.current;
    if (previous[kBoolConfig] != current[kBoolConfig]) {
      OnBoolConfigChanged();
    }
    if (previous[kDummyConfig].foo != current[kDummyConfig].foo) {
      OnFooChanged();
    }
  }
  void OnBoolConfigChanged() { bool_config_change_counter_++; }
  void OnFooChanged() { foo_interesting_event_counter_++; }

Parameters

obj	the subscriber, which is the owner of the listener method, and is also used as the unique identifier of the subscription
name	the name of the subscriber, for diagnostic purposes
func	the listener method, named `OnConfigUpdate` by convention.

Returns: a concurrent::AsyncEventSubscriberScope controlling the subscription, which should be stored as a member in the subscriber; Unsubscribe should be called explicitly

See also: based on concurrent::AsyncEventSource engine; dynamic_config::Diff

Definition at line 167 of file source.hpp.

◆ UpdateAndListen() [2/3]

template<typename Class >

concurrent::AsyncEventSubscriberScope dynamic_config::Source::UpdateAndListen	(	Class *	obj,
		std::string_view	name,
		void(Class::*)(const dynamic_config::Snapshot &config)	func )

inline

Subscribes to dynamic-config updates using a member function. Also immediately invokes the function with the current config snapshot (this invocation will be executed synchronously).

Note: Callbacks occur in full accordance with components::DynamicConfigClientUpdater options.

Parameters

obj	the subscriber, which is the owner of the listener method, and is also used as the unique identifier of the subscription
name	the name of the subscriber, for diagnostic purposes
func	the listener method, named `OnConfigUpdate` by convention.

Returns: a concurrent::AsyncEventSubscriberScope controlling the subscription, which should be stored as a member in the subscriber; Unsubscribe should be called explicitly

See also: based on concurrent::AsyncEventSource engine

Definition at line 123 of file source.hpp.

◆ UpdateAndListen() [3/3]

template<typename Class , typename... Keys>

concurrent::AsyncEventSubscriberScope dynamic_config::Source::UpdateAndListen	(	Class *	obj,
		std::string_view	name,
		void(Class::*)(const dynamic_config::Snapshot &config)	func,
		const Keys &...	keys )

inline

Subscribes to updates of a subset of all configs.

Subscribes to dynamic-config updates using a member function, named OnConfigUpdate by convention. The function will be invoked if at least one of the configs has been changed since the previous invocation. So at the first time immediately invokes the function with the current config snapshot (this invocation will be executed synchronously).

Note: Сallbacks occur only if one of the passed config is changed. This is true under any components::DynamicConfigClientUpdater options.

Warning: To use this function, configs must have the operator==.

Parameters

obj	the subscriber, which is the owner of the listener method, and is also used as the unique identifier of the subscription
name	the name of the subscriber, for diagnostic purposes
func	the listener method, named `OnConfigUpdate` by convention.
keys	config objects, specializations of `dynamic_config::Key`.

Returns: a concurrent::AsyncEventSubscriberScope controlling the subscription, which should be stored as a member in the subscriber; Unsubscribe should be called explicitly

See also: based on concurrent::AsyncEventSource engine

Definition at line 199 of file source.hpp.

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

userver/dynamic_config/source.hpp

Detailed Description

Public Types

Public Member Functions

Member Typedef Documentation

◆ DiffEventSource

◆ SnapshotEventSource

Constructor & Destructor Documentation

◆ Source()

Member Function Documentation

◆ GetCopy()

◆ GetSnapshot()

◆ UpdateAndListen() [1/3]

◆ UpdateAndListen() [2/3]

◆ UpdateAndListen() [3/3]