flag_updater.hpp

#pragma once
 
#include <memory>
#include <mutex>
#include <string>
#include <unordered_map>
 
#include "../data_sources/data_source_update_sink.hpp"
#include "flag_store.hpp"
 
#include <launchdarkly/client_side/flag_change_event.hpp>
#include <launchdarkly/client_side/flag_notifier.hpp>
 
#include <boost/signals2.hpp>
 
namespace launchdarkly::client_side::flag_manager {
 
class FlagUpdater : public IDataSourceUpdateSink, public IFlagNotifier {
   public:
    FlagUpdater(FlagStore& flag_store);
    void Init(Context const& context,
              std::unordered_map<std::string, ItemDescriptor> data) override;
    void Upsert(Context const& context,
                std::string key,
                ItemDescriptor item) override;
 
    std::unique_ptr<IConnection> OnFlagChange(
        std::string const& key,
        std::function<void(std::shared_ptr<FlagValueChangeEvent>)> handler)
        override;
 
   private:
    bool HasListeners() const;
 
    FlagStore& flag_store_;
    std::unordered_map<
        std::string,
        boost::signals2::signal<void(std::shared_ptr<FlagValueChangeEvent>)>>
        signals_;
 
    // Recursive mutex so that has_listeners can non-conditionally lock
    // the mutex. Otherwise a pre-condition for the call would be holding
    // the mutex, which is more difficult to keep consistent over the code
    // lifetime.
    mutable std::recursive_mutex signal_mutex_;
 
    void DispatchEvent(FlagValueChangeEvent event);
};
 
}  // namespace launchdarkly::client_side::flag_manager