fix: protect _transcode_apps with shared_mutex in Transcoder#2067
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fix: protect _transcode_apps with shared_mutex in Transcoder#2067
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OnCreateApplication/OnDeleteApplication are called from the MediaRouter thread while GetApplicationById can be called from the API server thread. Without synchronization this is a data race on std::map. - Add mutable std::shared_mutex _transcode_apps_mutex to Transcoder - unique_lock for writes (Create/Delete) - shared_lock for reads (GetApplicationById) - OnDeleteApplication now extracts the shared_ptr under the lock then unregisters from MediaRouter outside the lock to avoid lock inversion
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Problem
Transcoder::_transcode_apps(std::map) was accessed from multiple threads without synchronization:OnCreateApplication,OnDeleteApplication— called from the MediaRouter threadGetApplicationById— can be called from API server threads or other contextsThis is a data race on
std::map, which is undefined behavior and can cause crashes or corruption.Changes
mutable std::shared_mutex _transcode_apps_mutextoTranscoderunique_lockfor all write paths (OnCreateApplication,OnDeleteApplication)shared_lockfor read paths (GetApplicationById)OnDeleteApplicationnow extracts theshared_ptrunder the lock, then callsUnregisterObserverApp/UnregisterConnectorAppoutside the lock to avoid lock inversion with MediaRouterOnCreateApplicationrolls back the map insertion if MediaRouter registration fails