table of contents
| CLSETEVENTCALLBACK(3clc) | OpenCL Manual | CLSETEVENTCALLBACK(3clc) |
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¶
eventA 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:
user_data
•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.
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 GroupCOPYRIGHT¶
Copyright © 2007-2011 The Khronos Group Inc.NOTES¶
- 1.
- OpenCL Specification
page 183, section 5.9 - Event Objects
| 06/18/2014 | The Khronos Group |