NAME

       clSetEventCallback - Registers a user callback function for a specific command execution
       status.

       cl_int clSetEventCallback(cl_event event, cl_int command_exec_callback_type,
                                 void (CL_CALLBACK *pfn_event_notify) (cl_event event, cl_int event_command_exec_status, void *user_data),
                                 void *user_data);

PARAMETERS

       event
           A valid event object.

       command_exec_callback_type
           The command execution status for which the callback is registered. The command
           execution callback value for which a callback can be registered is CL_SUBMITTED,
           CL_RUNNING, or CL_COMPLETE. There is no guarantee that the callback functions
           registered for various execution status values for an event will be called in the
           exact order that the execution status of a command changes. Furthermore, it should be
           noted that receiving a call back for an event with a status other than CL_COMPLETE, in
           no way implies that the memory model or execution model as defined by the OpenCL
           specification has changed. For example, it is not valid to assume that a corresponding
           memory transfer has completed unless the event is in a state CL_COMPLETE.

           The callback function registered for a command_exec_callback_type value of CL_COMPLETE
           will be called when the command has completed successfully or is abnormally
           terminated.

       pfn_event_notify
           The event callback function that can be registered by the application. This callback
           function may be called asynchronously by the OpenCL implementation. It is the
           application's responsibility to ensure that the callback function is thread-safe. The
           parameters to this callback function are:

           •   event is the event object for which the callback function is invoked.

           •   event_command_exec_status represents the execution status of command for which
               this callback function is invoked. See the table of values for param_value for
               clGetEventInfo(3clc) for the command execution status values. If the callback is
               called as the result of the command associated with event being abnormally
               terminated, an appropriate error code for the error that caused the termination
               will be passed to event_command_exec_status instead.

           •   user_data is a pointer to user supplied data.

       user_data
           Will be passed as the user_data argument when pfn_notify is called.  user_data can be
           NULL.

NOTES

       The registered callback function will be called when the execution status of command
       associated with event changes to an execution status equal to or past the status specified
       by command_exec_status.

       Each call to clSetEventCallback registers the specified user callback function on a
       callback stack associated with event. The order in which the registered user callback
       functions are called is undefined.

       All callbacks registered for an event object must be called. All enqueued callbacks shall
       be called before the event object is destroyed. Callbacks must return promptly. The
       behavior of calling expensive system routines, OpenCL API calls to create contexts or
       command-queues, or blocking OpenCL operations from the following list below, in a callback
       is undefined.

       •   clFinish(3clc).RE

           •   clWaitForEvents(3clc).RE

               •    blocking calls to clEnqueueReadBuffer(3clc), clEnqueueReadBufferRect(3clc),
                   clEnqueueWriteBuffer(3clc), and clEnqueueWriteBufferRect(3clc).RE

                   •    blocking calls to clEnqueueReadImage(3clc) and
                       clEnqueueWriteImage(3clc).RE

                       •    blocking calls to clEnqueueMapBuffer(3clc) and
                           clEnqueueMapImage(3clc).RE

                           •    blocking calls to clBuildProgram(3clc), clCompileProgram(3clc),
                               or clLinkProgram(3clc).

                           If an application needs to wait for completion of a routine from the
                           above list in a callback, please use the non-blocking form of the
                           function, and assign a completion callback to it to do the remainder
                           of your work. Note that when a callback (or other code) enqueues
                           commands to a command-queue, the commands are not required to begin
                           execution until the queue is flushed. In standard usage, blocking
                           enqueue calls serve this role by implicitly flushing the queue. Since
                           blocking calls are not permitted in callbacks, those callbacks that
                           enqueue commands on a command queue should either call clFlush(3clc)
                           on the queue before returning or arrange for clFlush(3clc) to be
                           called later on another thread.

ERRORS

       Returns CL_SUCCESS if the function is executed successfully. Otherwise, it returns one of
       the following errors:

       •   CL_INVALID_EVENT if event is not a valid event object.

       •   CL_INVALID_VALUE if pfn_event_notify is NULL or if command_exec_callback_type is not
           CL_COMPLETE.

       •   CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the OpenCL
           implementation on the device.

       •   CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the
           OpenCL implementation on the host.

SPECIFICATION

       OpenCL Specification[1]

AUTHORS

       The Khronos Group

COPYRIGHT

       Copyright © 2007-2011 The Khronos Group Inc.
       Permission is hereby granted, free of charge, to any person obtaining a copy of this
       software and/or associated documentation files (the "Materials"), to deal in the Materials
       without restriction, including without limitation the rights to use, copy, modify, merge,
       publish, distribute, sublicense, and/or sell copies of the Materials, and to permit
       persons to whom the Materials are furnished to do so, subject to the condition that this
       copyright notice and permission notice shall be included in all copies or substantial
       portions of the Materials.

NOTES

        1. OpenCL Specification
           page 183, section 5.9 - Event Objects