// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2018 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
// * Neither the name of Google Inc. nor the names of its contributors may be
//   used to endorse or promote products derived from this software without
//   specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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//
// Author: vitus@google.com (Michael Vitus)

#ifndef CERES_INTERNAL_PARALLEL_FOR_
#define CERES_INTERNAL_PARALLEL_FOR_

#include <functional>

#include "ceres/context_impl.h"

namespace ceres {
namespace internal {

// Returns the maximum number of threads supported by the threading backend
// Ceres was compiled with.
int MaxNumThreadsAvailable();

// Execute the function for every element in the range [start, end) with at most
// num_threads. It will execute all the work on the calling thread if
// num_threads is 1.
void ParallelFor(ContextImpl* context,
                 int start,
                 int end,
                 int num_threads,
                 const std::function<void(int)>& function);

// Execute the function for every element in the range [start, end) with at most
// num_threads. It will execute all the work on the calling thread if
// num_threads is 1.  Each invocation of function() will be passed a thread_id
// in [0, num_threads) that is guaranteed to be distinct from the value passed
// to any concurrent execution of function().
void ParallelFor(ContextImpl* context,
                 int start,
                 int end,
                 int num_threads,
                 const std::function<void(int thread_id, int i)>& function);
}  // namespace internal
}  // namespace ceres

#endif  // CERES_INTERNAL_PARALLEL_FOR_H_