vips_thread_state_set ()

void *
vips_thread_state_set (VipsObject *object,
                       void *a,
                       void *b);

vips_thread_state_new ()

VipsThreadState *
vips_thread_state_new (VipsImage *im,
                       void *a);

VipsThreadStartFn ()

VipsThreadState *
(*VipsThreadStartFn) (VipsImage *im,
                      void *a);

VipsThreadpoolAllocateFn ()

int
(*VipsThreadpoolAllocateFn) (VipsThreadState *state,
                             void *a,
                             gboolean *stop);

This function is called to allocate a new work unit for the thread. It is always single-threaded, so it can modify per-pool state (such as a counter).

a , b , c are the values supplied to the call to vips_threadpool_run().

It should set stop to TRUE to indicate that no work could be allocated because the job is done.

See also: vips_threadpool_run().

VipsThreadpoolWorkFn ()

int
(*VipsThreadpoolWorkFn) (VipsThreadState *state,
                         void *a);

This function is called to process a work unit. Many copies of this can run at once, so it should not write to the per-pool state. It can write to per-thread state.

a , b , c are the values supplied to the call to vips_threadpool_run().

See also: vips_threadpool_run().

VipsThreadpoolProgressFn ()

int
(*VipsThreadpoolProgressFn) (void *a);

This function is called by the main thread once for every work unit processed. It can be used to give the user progress feedback.

See also: vips_threadpool_run().

vips_threadpool_run ()

int
vips_threadpool_run (VipsImage *im,
                     VipsThreadStartFn start,
                     VipsThreadpoolAllocateFn allocate,
                     VipsThreadpoolWorkFn work,
                     VipsThreadpoolProgressFn progress,
                     void *a);

This function runs a set of threads over an image. Each thread first calls start to create new per-thread state, then runs allocate to set up a new work unit (perhaps the next tile in an image, for example), then work to process that work unit. After each unit is processed, progress is called, so that the operation can give progress feedback. progress may be NULL.

The object returned by start must be an instance of a subclass of VipsThreadState. Use this to communicate between allocate and work .

allocate and start are always single-threaded (so they can write to the per-pool state), whereas work can be executed concurrently. progress is always called by the main thread (ie. the thread which called vips_threadpool_run()).

See also: vips_concurrency_set().

vips_get_tile_size ()

void
vips_get_tile_size (VipsImage *im,
                    int *tile_width,
                    int *tile_height,
                    int *n_lines);

Pick a tile size and a buffer height for this image and the current value of vips_concurrency_get(). The buffer height will always be a multiple of tile_height.

vips_concurrency_set ()

void
vips_concurrency_set (int concurrency);

Sets the number of worker threads that vips should use when running a VipsThreadPool.

The special value 0 means "default". In this case, the number of threads is set by the environmnt variable VIPS_CONCURRENCY, or if that is not set, the number of threads availble on the hist machine.

See also: vips_concurrency_get().

vips_concurrency_get ()

int
vips_concurrency_get (void);

Returns the number of worker threads that vips should use when running a VipsThreadPool.

vips gets this values from these sources in turn:

If vips_concurrency_set() has been called, this value is used. The special value 0 means "default". You can also use the command-line argument "--vips-concurrency" to set this value.

If vips_concurrency_set() has not been called and no command-line argument was used, vips uses the value of the environment variable VIPS_CONCURRENCY,

If VIPS_CONCURRENCY has not been set, vips find the number of hardware threads that the host machine can run in parallel and uses that value.

The final value is clipped to the range 1 - 1024.

See also: vips_concurrency_get().