components::DynamicConfig::NoblockSubscriber Class Reference

#include <userver/dynamic_config/storage/component.hpp>

Detailed Description

Allows to subscribe to DynamicConfig updates without waiting for the first update to complete. Primarily intended for internal use.

Definition at line 94 of file component.hpp.

Public Member Functions
	NoblockSubscriber (DynamicConfig &config_component) noexcept
	NoblockSubscriber (NoblockSubscriber &&)=delete
NoblockSubscriber &	operator= (NoblockSubscriber &&)=delete
template<typename Class>
concurrent::AsyncEventSubscriberScope	UpdateIfHasConfigAndListen (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.

Member Function Documentation

UpdateIfHasConfigAndListen()

template<typename Class>

concurrent::AsyncEventSubscriberScope components::DynamicConfig::NoblockSubscriber::UpdateIfHasConfigAndListen ( Class * obj, std::string_view name, void(Class::* func )(const dynamic_config::Diff &diff) )

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. actual configs values are already loaded, 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 130 of file component.hpp.

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

• userver/dynamic_config/storage/component.hpp