vlc | branch: master | Romain Vimont <ro...@videolabs.io> | Wed Jan 6 12:03:48 2021 +0100| [e00cf4e8c997bed4873a65d7795fd05c2e32770b] | committer: Hugo Beauzée-Luyssen
medialib: fix initialization The medialib initialization should be called exactly once. This was implemented by two mechanisms. Firstly, m_ml->isInitialized() was checked to avoid any work if the initialization already occurred. But since the medialib mutex was hold only during the call to isInitialized(), as soon as it returns, another thread may have set m_initialized. To handle this case harmlessly, Init() checks if m_ml->initialize() returns AlreadyInitialized. However, between the call to isInitialized() and initialize(), several medialibrary methods must be called (registerDeviceLister() and addFileSystemFactory()). These methods assert that m_initialized is false, which was not guaranteed. To fix this race condition, use our own flag protected by a local mutex, hold during the whole Init() execution. This also avoids a lot of unnecessary blocking calls: many medialibrary controls (including the asynchronous ones) need to call Init() just to make sure that the medialib was initialized. But since isInitialized() is protected by the medialibray mutex, all these calls had to wait for the mutex (hold during the execution of SQL queries) to be released. With a separate mutex, this problem disappears. Signed-off-by: Hugo Beauzée-Luyssen <h...@beauzee.fr> > http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=e00cf4e8c997bed4873a65d7795fd05c2e32770b --- modules/misc/medialibrary/medialibrary.cpp | 6 +++++- modules/misc/medialibrary/medialibrary.h | 3 +++ 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/modules/misc/medialibrary/medialibrary.cpp b/modules/misc/medialibrary/medialibrary.cpp index a58032668d..ff675cf865 100644 --- a/modules/misc/medialibrary/medialibrary.cpp +++ b/modules/misc/medialibrary/medialibrary.cpp @@ -388,8 +388,10 @@ MediaLibrary::MediaLibrary( vlc_medialibrary_module_t* ml ) bool MediaLibrary::Init() { - if ( m_ml->isInitialized() == true ) + vlc::threads::mutex_locker lock( m_mutex ); + if( m_initialized ) return true; + auto userDir = vlc::wrap_cptr( config_GetUserDir( VLC_USERDATA_DIR ) ); std::string mlDir = std::string{ userDir.get() } + "/ml/"; @@ -403,6 +405,7 @@ bool MediaLibrary::Init() switch ( initStatus ) { case medialibrary::InitializeResult::AlreadyInitialized: + assert(!"initialize() should not have been called if already initialized"); return true; case medialibrary::InitializeResult::Failed: msg_Err( m_vlc_ml, "Medialibrary failed to initialize" ); @@ -450,6 +453,7 @@ bool MediaLibrary::Init() m_ml->setDiscoverNetworkEnabled( true ); + m_initialized = true; return true; } diff --git a/modules/misc/medialibrary/medialibrary.h b/modules/misc/medialibrary/medialibrary.h index 5fc0e28d99..09c773bf59 100644 --- a/modules/misc/medialibrary/medialibrary.h +++ b/modules/misc/medialibrary/medialibrary.h @@ -167,6 +167,9 @@ private: std::unique_ptr<Logger> m_logger; std::unique_ptr<medialibrary::IMediaLibrary> m_ml; + vlc::threads::mutex m_mutex; + bool m_initialized = false; /* protected by m_mutex */ + // IMediaLibraryCb interface public: virtual void onMediaAdded(std::vector<medialibrary::MediaPtr> media) override; _______________________________________________ vlc-commits mailing list vlc-commits@videolan.org https://mailman.videolan.org/listinfo/vlc-commits
