Collaboration diagram for Mutual exclusion locks:

Data Structures
struct	vlc_mutex_t
	Mutex. More...

Macros
#define	VLC_STATIC_MUTEX
	Static initializer for (static) mutex.

#define	vlc_mutex_assert(m) assert(vlc_mutex_held(m))
	Asserts that a mutex is locked by the calling thread.

Functions
void	vlc_mutex_init (vlc_mutex_t *)
	Initializes a fast mutex.

void	vlc_mutex_init_recursive (vlc_mutex_t *)
	Initializes a recursive mutex.

void	vlc_mutex_lock (vlc_mutex_t *)
	Acquires a mutex.

int	vlc_mutex_trylock (vlc_mutex_t *)
	Tries to acquire a mutex.

void	vlc_mutex_unlock (vlc_mutex_t *)
	Releases a mutex.

bool	vlc_mutex_held (const vlc_mutex_t *)
	Checks if a mutex is locked.

Detailed Description

Macro Definition Documentation

◆ vlc_mutex_assert

#define vlc_mutex_assert ( m ) assert(vlc_mutex_held(m))

Asserts that a mutex is locked by the calling thread.

◆ VLC_STATIC_MUTEX

#define VLC_STATIC_MUTEX

Value:

    { \
    .value = 0, \
    .recursion = 0, \
    .owner = 0, \
}

Static initializer for (static) mutex.

Note: This only works in C code. In C++, consider using a global vlc::threads::mutex instance instead.

Function Documentation

◆ vlc_mutex_held()

bool vlc_mutex_held ( const vlc_mutex_t * mtx )

Checks if a mutex is locked.

This function checks if the calling thread holds a given mutual exclusion lock. It has no side effects and is essentially intended for run-time debugging.

Note: To assert that the calling thread holds a lock, the helper macro vlc_mutex_assert() should be used instead of this function.; While it is nominally possible to implement recursive lock semantics with this function, vlc_mutex_init_recursive() should be used instead to create a recursive mutex explicitly..

Return values

false	the mutex is not locked by the calling thread
true	the mutex is locked by the calling thread

References vlc_mutex_t::owner, and vlc_thread_id().

Referenced by vlc_fifo_Held(), vlc_mutex_trylock(), vlc_mutex_unlock(), vlc_player_Delete(), and vlc_player_Lock().

◆ vlc_mutex_init()

void vlc_mutex_init ( vlc_mutex_t * mtx )

Initializes a fast mutex.

Recursive locking of a fast mutex is undefined behaviour. (In debug builds, recursive locking will cause an assertion failure.)

References vlc_mutex_init_common().

Referenced by addon_entry_New(), aout_New(), CreateDecoder(), dialog_add_locked(), httpd_HostCreate(), httpd_StreamNew(), httpd_UrlNew(), input_Create(), input_EsOutNew(), input_fetcher_New(), input_item_NewExt(), input_rate_Init(), input_resource_New(), libvlc_InternalCreate(), libvlc_InternalDialogInit(), libvlc_MlCreate(), vlc::threads::mutex::mutex(), picture_fifo_New(), picture_pool_NewCommon(), sout_StreamNewEmpty(), spu_Create(), TsStart(), update_New(), vlc_aout_stream_New(), vlc_audio_meter_Init(), vlc_clock_main_New(), vlc_cond_init(), vlc_demux_chained_New(), vlc_executor_New(), vlc_ExitInit(), vlc_gl_surface_Create(), vlc_h2_conn_create(), vlc_h2_output_create(), vlc_http_cookies_new(), vlc_interrupt_init(), vlc_LogEarlyOpen(), vlc_media_source_provider_New(), vlc_media_tree_New(), vlc_object_init(), vlc_player_InitLocks(), vlc_player_InitTimer(), vlc_preparser_New(), vlc_queue_Init(), vlc_timer_create(), vlc_window_New(), vlm_New(), vout_control_Init(), vout_Create(), vout_display_window_New(), and vout_snapshot_New().

◆ vlc_mutex_init_recursive()

void vlc_mutex_init_recursive ( vlc_mutex_t * mtx )

Initializes a recursive mutex.

Warning: This is strongly discouraged. Please use normal mutexes.

References vlc_mutex_init_common().

Referenced by input_EsOutTimeshiftNew(), and vlc_player_InitLocks().

◆ vlc_mutex_lock()

void vlc_mutex_lock ( vlc_mutex_t * mtx )

Acquires a mutex.

If needed, this waits for any other thread to release it.

Warning: Beware of deadlocks when locking multiple mutexes at the same time, or when using mutexes from callbacks.

Note: This function is not a cancellation point.

References vlc_mutex_t::owner, vlc_mutex_t::value, vlc_atomic_wait(), vlc_mutex_trylock(), vlc_restorecancel(), vlc_savecancel(), and vlc_thread_id().

◆ vlc_mutex_trylock()

int vlc_mutex_trylock ( vlc_mutex_t * mtx )

Tries to acquire a mutex.

This function acquires the mutex if and only if it is not currently held by another thread. This function never sleeps and can be used in delay-critical code paths.

Note: This function is not a cancellation point.

Warning: If this function fails, then the mutex is held... by another thread. The calling thread must deal with the error appropriately. That typically implies postponing the operations that would have required the mutex. If the thread cannot defer those operations, then it must use vlc_mutex_lock(). If in doubt, use vlc_mutex_lock() instead.