blob: 812950a6db995c955f8b9665b36c29414677af41 [file] [log] [blame]
// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2023 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
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Authors: vitus@google.com (Michael Vitus),
// dmitriy.korchemkin@gmail.com (Dmitriy Korchemkin)
#ifndef CERES_INTERNAL_PARALLEL_VECTOR_OPS_H_
#define CERES_INTERNAL_PARALLEL_VECTOR_OPS_H_
#include <mutex>
#include <vector>
#include "ceres/context_impl.h"
#include "ceres/internal/eigen.h"
#include "ceres/internal/export.h"
#include "ceres/parallel_for.h"
namespace ceres::internal {
// Lower bound on block size for parallel vector operations.
// Operations with vectors of less than kMinBlockSizeParallelVectorOps elements
// will be executed in a single thread.
constexpr int kMinBlockSizeParallelVectorOps = 1 << 16;
// Evaluate vector expression in parallel
// Assuming LhsExpression and RhsExpression are some sort of column-vector
// expression, assignment lhs = rhs is eavluated over a set of contiguous blocks
// in parallel. This is expected to work well in the case of vector-based
// expressions (since they typically do not result into temporaries). This
// method expects lhs to be size-compatible with rhs
template <typename LhsExpression, typename RhsExpression>
void ParallelAssign(ContextImpl* context,
int num_threads,
LhsExpression& lhs,
const RhsExpression& rhs) {
static_assert(LhsExpression::ColsAtCompileTime == 1);
static_assert(RhsExpression::ColsAtCompileTime == 1);
CHECK_EQ(lhs.rows(), rhs.rows());
const int num_rows = lhs.rows();
ParallelFor(
context,
0,
num_rows,
num_threads,
[&lhs, &rhs](const std::tuple<int, int>& range) {
auto [start, end] = range;
lhs.segment(start, end - start) = rhs.segment(start, end - start);
},
kMinBlockSizeParallelVectorOps);
}
// Set vector to zero using num_threads
template <typename VectorType>
void ParallelSetZero(ContextImpl* context,
int num_threads,
VectorType& vector) {
ParallelSetZero(context, num_threads, vector.data(), vector.rows());
}
void ParallelSetZero(ContextImpl* context,
int num_threads,
double* values,
int num_values);
} // namespace ceres::internal
#endif // CERES_INTERNAL_PARALLEL_FOR_H_