clGetEventInfo
clGetEventInfo
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clGetEventInfo Returns information about the event object.

##

cl_int `clGetEventInfo` cl_event event cl_event_info param_name size_t param_value_size void*param_value size_t*param_value_size_ret

## Parameters

`event`

  Specifies the event object being queried.

`param_value`

  A pointer to memory where the appropriate result being queried is returned. If `param_value` is NULL, it is ignored.

`param_value_size`

  Specifies the size in bytes of memory pointed to by `param_value`. This size must be ≥ size of the return type as described in the table below.

`param_value_size_ret`

  Returns the actual size in bytes of data copied to `param_value`. If `param_value_size_ret` is NULL, it is ignored.

`param_name`

  Specifies the information to query. The list of supported `param_name` types and the information returned in `param_value` by `clGetEventInfo` is described in the table below:

  cl_event_info | Return Type | Information returned in `param_value`
  --- | --- | ---
  `CL_EVENT_COMMAND_QUEUE` | cl_command_queue | Return the command-queue associated with `event`. For user event objects, a NULL value is returned.
  `CL_EVENT_CONTEXT` | cl_context | Return the context associated with `event`.
  `CL_EVENT_COMMAND_TYPE` | cl_command_type | Return the command associated with `event`. Can be one of the following values:
      CL_COMMAND_NDRANGE_KERNEL
      CL_COMMAND_TASK
      CL_COMMAND_NATIVE_KERNEL
      CL_COMMAND_READ_BUFFER
      CL_COMMAND_WRITE_BUFFER
      CL_COMMAND_COPY_BUFFER
      CL_COMMAND_READ_IMAGE
      CL_COMMAND_WRITE_IMAGE
      CL_COMMAND_COPY_IMAGE
      CL_COMMAND_COPY_BUFFER_TO_IMAGE
      CL_COMMAND_COPY_IMAGE_TO_BUFFER
      CL_COMMAND_MAP_BUFFER
      CL_COMMAND_MAP_IMAGE
      CL_COMMAND_UNMAP_MEM_OBJECT
      CL_COMMAND_MARKER
      CL_COMMAND_ACQUIRE_GL_OBJECTS
      CL_COMMAND_RELEASE_GL_OBJECTS
      CL_COMMAND_READ_BUFFER_RECT
      CL_COMMAND_WRITE_BUFFER_RECT
      CL_COMMAND_COPY_BUFFER_RECT
      CL_COMMAND_USER
      CL_COMMAND_BARRIER
      CL_COMMAND_MIGRATE_MEM_OBJECTS
      CL_COMMAND_FILL_BUFFER
      CL_COMMAND_FILL_IMAGE
      CL_COMMAND_GL_FENCE_SYNC_OBJECT_KHR
        (if cl_khr_gl_event is enabled)
      CL_COMMAND_ACQUIRE_D3D10_OBJECTS_KHR
        (if cl_khr_d3d10_sharing is enabled)
      CL_COMMAND_RELEASE_D3D10_OBJECTS_KHR
        (if cl_khr_d3d10_sharing is enabled)
      CL_COMMAND_ACQUIRE_DX9_MEDIA_SURFACES_KHR
        (if cl_khr_dx9_media_sharing is enabled)
      CL_COMMAND_RELEASE_DX9_MEDIA_SURFACES_KHR
        (if cl_khr_dx9_media_sharing is enabled)
      CL_COMMAND_ACQUIRE_D3D11_OBJECTS_KHR
        (if  cl_khr_d3d11_sharing is enabled)
      CL_COMMAND_RELEASE_D3D11_OBJECTS_KHR
        (if  cl_khr_d3d11_sharing is enabled)
  `CL_EVENT_COMMAND_ EXECUTION_STATUS` | cl_int | Return the execution status of the command identified by `event`. The valid values are: `CL_QUEUED` (command has been enqueued in the command-queue), `CL_SUBMITTED` (enqueued command has been submitted by the host to the device associated with the command-queue), `CL_RUNNING` (device is currently executing this command), `CL_COMPLETE` (the command has completed), or Error code given by a negative integer value. (command was abnormally terminated – this may be caused by a bad memory access etc.) These error codes come from the same set of error codes that are returned from the platform or runtime API calls as return values or `errcode_ret` values. The error code values are negative, and event state values are positive. The event state values are ordered from the largest value (`CL_QUEUED`) for the first or initial state to the smallest value (`CL_COMPLETE` or negative integer value) for the last or complete state. The value of `CL_COMPLETE` and `CL_SUCCESS` are the same.
  `CL_EVENT_REFERENCE_COUNT` | cl_uint | Return the `event` reference count. The reference count returned should be considered immediately stale. It is unsuitable for general use in applications. This feature is provided for identifying memory leaks.

## Notes

Using `clGetEventInfo` to determine if a command identified by `event` has finished execution (i.e. `CL_EVENT_COMMAND_EXECUTION_STATUS` returns `CL_COMPLETE`) is not a synchronization point. There are no guarantees that the memory objects being modified by command associated with `event` will be visible to other enqueued commands.

## Errors

Returns CL_SUCCESS if the function executed successfully, or one of the errors below:

- CL_INVALID_VALUE if `param_name` is not valid, or if size in bytes specified by `param_value_size` is < size of return type as described in the table above and `param_value` is not NULL.
- CL_INVALID_VALUE if information to query given in `param_name` cannot be queried for event.
- CL_INVALID_EVENT if `event` is not a valid `event` object.
- 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

## Also see

clReleaseEvent, clRetainEvent, clWaitForEvents, cl_khr_gl_event

##