8.16. Clara Pipeline Callbacks

The Clara Pipeline Driver is a event based workflow. The set and ordering of the workflow’s event is referred to as the operator life-cycle. The operator life-cycle consists of the following three event as ordered below.

For each event, application (operator) code is allowed to register a callback handler with the driver. Callback handler registration happens as part of the Nvidia.Clara.Pipeline.Driver constructor. Application code can ignore an event by passing a null pointer, instead of a delegate, to the constructor.

see also: driver

1. Prepare

   Called before stage inputs are ready.

   Application code should perform any pre-execute setup or preparation work possible.

   Payload inputs and outputs are not yet available.

2. Execute

   Called after prepare once stage inputs are ready.

   Application code should perform all core pipeline operator work during this event.

   Payload inputs and outputs are available during this event.

3. Cleanup

   Called after execute before the driver’s stage life-cycle terminates.

   Application code should perform any post-execute clean-up work.

   Payload inputs and outputs are no longer available.

Provided by application code to the driver when calling Nvidia.Clara.Pipeline.Driver constructor, and called by the driver once driver initialization has completed. Application code is expected to perform any preparation or setup steps necessary when this delegate is called.

Providing a preparation delegate to the driver is optional. When no delegate is provided, the driver will move directly from initialization to waiting for inputs for execution.

see also: Clara Pipeline Driver

Parameters

• driver

  type: Nvidia.Clara.Pipeline.IDriver

  Reference to the IDriver instance calling the delegate.

Return

Returns zero if successful; otherwise a non-zero value.

            

            
delegate bool DriverPrepareDelegate(IDriver driver);
        

Provided by application code to the driver when calling Nvidia.Clara.Pipeline.Driver constructor, and called by the driver once inputs are ready for consumption. Application code will be provided an Nvidia.Clara.Pipeline.IPayload reference which can be used to obtain information about the payload.

Providing an execution delegate to the driver is optional. When no delegate is provided, the driver will move directly from waiting for inputs to clean-up.

see also: Clara Pipeline Driver

Parameters

• driver

  type: Nvidia.Clara.Pipeline.IDriver

  Reference to the IDriver instance calling the delegate.

• payload

  type: Nvidia.Clara.Pipeline.IPayload

  Reference to the current stage’s payload.

Return

Returns zero if successful; otherwise a non-zero value.

            

            
delegate bool DriverExecuteDelegate(IDriver driver, IPayload payload);
        

Provided by application code to the driver when calling Nvidia.Clara.Pipeline.Driver constructor, and called by the driver after execution is complete and internal driver clean up has completed. The application is expected to perform any clean or finalization steps during this callback event.

Providing a clean-up delegate to the driver is optional. When no delegate is provided, the driver will move directly from clean-up to internal finalization.

see also: Clara Pipeline Driver

Parameters

• driver

  type: Nvidia.Clara.Pipeline.IDriver

  Reference to the IDriver instance calling the delegate.

Return

Returns zero if successful; otherwise a non-zero value.

            

            
delegate bool DriverCleanupDelegate(IDriver driver);
        

Provided by application code to the driver when calling Nvidia.Clara.Pipeline.Driver constructor, and called by the driver when any noteworthy event happens. This includes internal errors.

Providing a notification delegate to the driver is optional. When no delegate is provided, the driver will be unable to notify application code of any internal errors or critical state changes.

see also: Clara Pipeline Driver

Parameters

• driver

  type: Nvidia.Clara.Pipeline.IDriver

  Reference to the IDriver instance calling the delegate.

• result

  type: System.Int32

  The result, or return code, of the event which generated the notification.

• message

  type: System.String

  The detailed message of the event which generated the notification.

• isFatal

  type: System.Boolean

  Boolean indicating if the event which generated the notification is fatal to the current stage or not.

Return

            

            
delegate void DriverNotification(IDriver driver, int result, string message, bool isFatal);