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#pragma once
#include <algorithm>
#include <atomic>
#include <cstddef>
#include <exception>
#ifdef _OPENMP
#define INTRA_OP_PARALLEL
#include <omp.h>
#endif
#ifdef _OPENMP
namespace at::internal {
template <typename F>
inline void invoke_parallel(
int64_t begin,
int64_t end,
int64_t grain_size,
const F& f) {
std::atomic_flag err_flag = ATOMIC_FLAG_INIT;
std::exception_ptr eptr;
#pragma omp parallel
{
// choose number of tasks based on grain size and number of threads
// can't use num_threads clause due to bugs in GOMP's thread pool (See
// #32008)
int64_t num_threads = omp_get_num_threads();
if (grain_size > 0) {
num_threads = std::min(num_threads, divup((end - begin), grain_size));
}
int64_t tid = omp_get_thread_num();
int64_t chunk_size = divup((end - begin), num_threads);
int64_t begin_tid = begin + tid * chunk_size;
if (begin_tid < end) {
try {
internal::ThreadIdGuard tid_guard(tid);
f(begin_tid, std::min(end, chunk_size + begin_tid));
} catch (...) {
if (!err_flag.test_and_set()) {
eptr = std::current_exception();
}
}
}
}
if (eptr) {
std::rethrow_exception(eptr);
}
}
} // namespace at::internal
#endif // _OPENMP
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