Function rcudnn_sys::cudaStreamAddCallback

pub unsafe extern "C" fn cudaStreamAddCallback(
    stream: cudaStream_t, 
    callback: cudaStreamCallback_t, 
    userData: *mut c_void, 
    flags: c_uint
) -> cudaError_t

\brief Add a callback to a compute stream

\note This function is slated for eventual deprecation and removal. If you do not require the callback to execute in case of a device error, consider using ::cudaLaunchHostFunc. Additionally, this function is not supported with ::cudaStreamBeginCapture and ::cudaStreamEndCapture, unlike ::cudaLaunchHostFunc.

Adds a callback to be called on the host after all currently enqueued items in the stream have completed. For each cudaStreamAddCallback call, a callback will be executed exactly once. The callback will block later work in the stream until it is finished.

The callback may be passed ::cudaSuccess or an error code. In the event of a device error, all subsequently executed callbacks will receive an appropriate ::cudaError_t.

Callbacks must not make any CUDA API calls. Attempting to use CUDA APIs may result in ::cudaErrorNotPermitted. Callbacks must not perform any synchronization that may depend on outstanding device work or other callbacks that are not mandated to run earlier. Callbacks without a mandated order (in independent streams) execute in undefined order and may be serialized.

For the purposes of Unified Memory, callback execution makes a number of guarantees:

• The callback stream is considered idle for the duration of the callback. Thus, for example, a callback may always use memory attached to the callback stream.
• The start of execution of a callback has the same effect as synchronizing an event recorded in the same stream immediately prior to the callback. It thus synchronizes streams which have been "joined" prior to the callback.
• Adding device work to any stream does not have the effect of making the stream active until all preceding callbacks have executed. Thus, for example, a callback might use global attached memory even if work has been added to another stream, if it has been properly ordered with an event.
• Completion of a callback does not cause a stream to become active except as described above. The callback stream will remain idle if no device work follows the callback, and will remain idle across consecutive callbacks without device work in between. Thus, for example, stream synchronization can be done by signaling from a callback at the end of the stream.

\param stream - Stream to add callback to \param callback - The function to call once preceding stream operations are complete \param userData - User specified data to be passed to the callback function \param flags - Reserved for future use, must be 0

\return ::cudaSuccess, ::cudaErrorInvalidResourceHandle, ::cudaErrorInvalidValue, ::cudaErrorNotSupported \note_null_stream \notefnerr \note_init_rt \note_callback

\sa ::cudaStreamCreate, ::cudaStreamCreateWithFlags, ::cudaStreamQuery, ::cudaStreamSynchronize, ::cudaStreamWaitEvent, ::cudaStreamDestroy, ::cudaMallocManaged, ::cudaStreamAttachMemAsync, ::cudaLaunchHostFunc, ::cuStreamAddCallback