mirror of
https://github.com/ceres-solver/ceres-solver.git
synced 2026-08-30 00:50:37 +08:00
Sameer Agarwal
5a30cae583
1. Add a version history 2. Update copyright years across the code base 3. Run format_all.sh 4. Update version strings from 2.1.0 to 2.2.0 in the docs and elsewhere. Change-Id: I46d8d479d54bd6002d532785e67342106e73c9ac
105 lines
3.5 KiB
C++
105 lines
3.5 KiB
C++
// Ceres Solver - A fast non-linear least squares minimizer
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// Copyright 2023 Google Inc. All rights reserved.
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// http://ceres-solver.org/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of Google Inc. nor the names of its contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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// Author: vitus@google.com (Michael Vitus)
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#include "ceres/thread_pool.h"
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#include <cmath>
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#include <limits>
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#include "ceres/internal/config.h"
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namespace ceres::internal {
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namespace {
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// Constrain the total number of threads to the amount the hardware can support.
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int GetNumAllowedThreads(int requested_num_threads) {
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return std::min(requested_num_threads, ThreadPool::MaxNumThreadsAvailable());
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}
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} // namespace
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int ThreadPool::MaxNumThreadsAvailable() {
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const int num_hardware_threads = std::thread::hardware_concurrency();
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// hardware_concurrency() can return 0 if the value is not well defined or not
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// computable.
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return num_hardware_threads == 0 ? std::numeric_limits<int>::max()
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: num_hardware_threads;
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}
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ThreadPool::ThreadPool() = default;
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ThreadPool::ThreadPool(int num_threads) { Resize(num_threads); }
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ThreadPool::~ThreadPool() {
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std::lock_guard<std::mutex> lock(thread_pool_mutex_);
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// Signal the thread workers to stop and wait for them to finish all scheduled
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// tasks.
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Stop();
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for (std::thread& thread : thread_pool_) {
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thread.join();
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}
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}
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void ThreadPool::Resize(int num_threads) {
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std::lock_guard<std::mutex> lock(thread_pool_mutex_);
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const int num_current_threads = thread_pool_.size();
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if (num_current_threads >= num_threads) {
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return;
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}
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const int create_num_threads =
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GetNumAllowedThreads(num_threads) - num_current_threads;
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for (int i = 0; i < create_num_threads; ++i) {
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thread_pool_.emplace_back(&ThreadPool::ThreadMainLoop, this);
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}
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}
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void ThreadPool::AddTask(const std::function<void()>& func) {
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task_queue_.Push(func);
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}
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int ThreadPool::Size() {
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std::lock_guard<std::mutex> lock(thread_pool_mutex_);
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return thread_pool_.size();
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}
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void ThreadPool::ThreadMainLoop() {
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std::function<void()> task;
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while (task_queue_.Wait(&task)) {
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task();
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}
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}
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void ThreadPool::Stop() { task_queue_.StopWaiters(); }
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} // namespace ceres::internal
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