parallel_for.h

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// Copyright (c) 2025 libmv authors.
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// TBB-compatible implementation of parallel_for() functions.
//
// The parallel_for() function applies given functor for every index within the
// given range. The range might be provided in multiple ways.
//
// Supports multiple underlying threading implementations (in the order of
// preference):
// - TBB, requires LIBMV_USE_TBB_THREADS to be defined.
// - OpenMP, requires compiler to use -fopenmp, used when _OPENMP is defined.
// - Single-threaded fall-back.
//
// The function occupies all threads of the default theading pool.
 
#ifndef LIBMV_THREADING_PARALLEL_FOR_H_
#define LIBMV_THREADING_PARALLEL_FOR_H_
 
#if defined(LIBMV_USE_TBB_THREADS)
#  include <tbb/parallel_for.h>
#endif
 
namespace libmv {
 
// Run the function f() for all indices within [first, last).
template <typename Index, typename Function>
void parallel_for(const Index first, const Index last, const Function& f) {
#if defined(LIBMV_USE_TBB_THREADS)
  tbb::parallel_for(first, last, f);
#else
#  if defined(_OPENMP)
#    pragma omp parallel for schedule(static)
#  endif
  for (Index i = first; i < last; ++i) {
    f(i);
  }
#endif
}
 
}  // namespace libmv
 
#endif  // LIBMV_THREADING_PARALLEL_FOR_H_