mirror of
https://github.com/ceres-solver/ceres-solver.git
synced 2026-08-29 08:34:37 +08:00
Yury Prokazov
4ffec20a44
There are platforms where OpenMP is not available. This patch adds support for Intel Threading Building Blocks (TBB) as an alternative threading backend. Change-Id: I94497d7cba0c3cfaccfc992169236f17fe948ae9
113 lines
4.3 KiB
C++
113 lines
4.3 KiB
C++
// Ceres Solver - A fast non-linear least squares minimizer
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// Copyright 2017 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: yp@photonscore.de (Yury Prokazov)
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#ifndef CERES_INTERNAL_THREAD_TOKEN_PROVIDER_H_
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#define CERES_INTERNAL_THREAD_TOKEN_PROVIDER_H_
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#include "ceres/internal/config.h"
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#if defined(CERES_USE_OPENMP)
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# if defined(CERES_USE_TBB) || defined(CERES_NO_THREADS)
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# error CERES_USE_OPENMP is mutually exclusive to CERES_USE_TBB and CERES_NO_THREADS
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# endif
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#elif defined(CERES_USE_TBB)
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# if defined(CERES_USE_OPENMP) || defined(CERES_NO_THREADS)
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# error CERES_USE_TBB is mutually exclusive to CERES_USE_OPENMP and CERES_NO_THREADS
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# endif
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#elif defined(CERES_NO_THREADS)
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# if defined(CERES_USE_OPENMP) || defined(CERES_USE_TBB)
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# error CERES_NO_THREADS is mutually exclusive to CERES_USE_OPENMP and CERES_USE_TBB
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# endif
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#else
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# error One of CERES_USE_OPENMP, CERES_USE_TBB or CERES_NO_THREADS must be defined.
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#endif
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#ifdef CERES_USE_TBB
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#include <tbb/concurrent_queue.h>
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#endif
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namespace ceres {
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namespace internal {
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// Helper for TBB thread number identification that is similar to
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// omp_get_thread_num() behaviour. This is necessary to support TBB threading
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// with a sequential thread id. This is used to access preallocated resources in
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// the parallelized code parts. The sequence of tokens varies from 0 to
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// num_threads - 1 that can be acquired to identify the thread in a thread pool.
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//
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// If CERES_NO_THREADS is defined, Acquire() always returns 0 and Release()
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// takes no action.
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//
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// If CERES_USE_OPENMP, omp_get_thread_num() is used to Acquire() with no action
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// in Release()
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//
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//
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// Example usage pseudocode:
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//
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// ThreadTokenProvider ttp(N); // allocate N tokens
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// Spawn N threads {
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// int token = ttp.Acquire(); // get unique token
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// ...
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// ... use token to access resources bound to the thread
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// ...
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// ttp.Release(token); // return token to the pool
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// }
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//
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class ThreadTokenProvider {
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public:
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ThreadTokenProvider(int num_threads);
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// Returns the first token from the queue. The acquired value must be
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// given back by Release().
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//
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// With TBB this function will block if all the tokens are aquired by
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// concurent threads.
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int Acquire();
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// Makes previously acquired token available for other threads.
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void Release(int thread_id);
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private:
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#ifdef CERES_USE_TBB
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// This queue initially holds a sequence from 0..num_threads-1. Every
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// Acquire() call the first number is removed from here. When the token is not
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// needed anymore it shall be given back with corresponding Release() call.
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tbb::concurrent_bounded_queue<int> pool_;
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#endif
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ThreadTokenProvider(ThreadTokenProvider&);
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ThreadTokenProvider& operator=(ThreadTokenProvider&);
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};
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} // namespace internal
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} // namespace ceres
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#endif // CERES_INTERNAL_THREAD_TOKEN_PROVIDER_H_
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