bionic (3) clSetMemObjectDestructorCallback.3clc.gz

NAME

       clSetMemObjectDestructorCallback - Registers a user callback function with a memory object.

       cl_int clSetMemObjectDestructorCallback(cl_mem memobj, void (CL_CALLBACK *pfn_notify) (cl_mem memobj,
                                               void *user_data), void *user_data);

PARAMETERS

       memobj
           A valid memory object.

       pfn_notify
           The 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:

           •   memobj: the memory object being deleted.  When the user callback is called by the implementation,
               this memory object is no longer valid.  memobj is only provided for reference purposes.

           •   user_data: a pointer to user supplied data.

       user_data
           Data which will be passed as the user_data argument when pfn_notify is called.  user_data can be
           NULL.

NOTES

       Each call to clSetMemObjectDestructorCallback registers the specified user callback function on a
       callback stack associated with memobj. The registered user callback functions are called in the reverse
       order in which they were registered. The user callback functions are called and then the memory object's
       resources are freed and the memory object is deleted. This provides a mechanism for the application (and
       libraries) using memobj to be notified when the memory referenced by host_ptr, specified when the memory
       object is created and used as the storage bits for the memory object, can be reused or freed.

       When the user callback function is called by the implementation, the contents of the memory region
       pointed to by host_ptr (if the memory object is created with CL_MEM_USE_HOST_PTR) are undefined. The
       callback function is typically used by the application to either free or reuse the memory region pointed
       to by host_ptr.

       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), 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).RE

                               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.

                               The user callback function may not call OpenCL APIs with the memory object for
                               which the callback function is invoked and for such cases the behavior of OpenCL
                               APIs is considered to be undefined.

ERRORS

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

       •   CL_INVALID_MEM_OBJECT if memobj is not a valid memory object.

       •   CL_INVALID_VALUE if pfn_notify is NULL.

       •   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]

SEE ALSO

       clCreateCommandQueue(3clc), clGetCommandQueueInfo(3clc), clReleaseCommandQueue(3clc),
       clRetainCommandQueue(3clc)

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 119, section 5.4.1 - Retaining and Releasing Memory Objects