test_common/harness/ThreadPool.h

//
// Copyright (c) 2017 The Khronos Group Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef THREAD_POOL_H
#define THREAD_POOL_H

#if defined(__APPLE__)
#include <OpenCL/opencl.h>
#else
#include <CL/cl.h>
#endif

//
// An atomic add operator
cl_int ThreadPool_AtomicAdd(volatile cl_int *a, cl_int b); // returns old value

// Your function prototype
//
// A function pointer to the function you want to execute in a multithreaded
// context.  No synchronization primitives are provided, other than the atomic
// add above. You may not call ThreadPool_Do from your function.
// ThreadPool_AtomicAdd() and GetThreadCount() should work, however.
//
// job ids and thread ids are 0 based.  If number of jobs or threads was 8, they
// will numbered be 0 through 7. Note that while every job will be run, it is
// not guaranteed that every thread will wake up before the work is done.
typedef cl_int (*TPFuncPtr)(cl_uint /*job_id*/, cl_uint /* thread_id */,
                            void *userInfo);

// returns first non-zero result from func_ptr, or CL_SUCCESS if all are zero.
// Some workitems may not run if a non-zero result is returned from func_ptr().
// This function may not be called from a TPFuncPtr.
cl_int ThreadPool_Do(TPFuncPtr func_ptr, cl_uint count, void *userInfo);

// Returns the number of worker threads that underlie the threadpool.  The value
// passed as the TPFuncPtrs thread_id will be between 0 and this value less one,
// inclusive. This is safe to call from a TPFuncPtr.
cl_uint GetThreadCount(void);

// SetThreadCount() may be used to artifically set the number of worker threads
// If the value is 0 (the default) the number of threads will be determined
// based on the number of CPU cores.  If it is a unicore machine, then 2 will be
// used, so that we still get some testing for thread safety.
//
// If count < 2 or the CL_TEST_SINGLE_THREADED environment variable is set then
// the code will run single threaded, but will report an error to indicate that
// the test is invalid.  This option is intended for debugging purposes only. It
// is suggested as a convention that test apps set the thread count to 1 in
// response to the -m flag.
//
// SetThreadCount() must be called before the first call to GetThreadCount() or
// ThreadPool_Do(), otherwise the behavior is indefined. It may not be called
// from a TPFuncPtr.
void SetThreadCount(int count);


#endif /* THREAD_POOL_H  */