forked from mirrors/gecko-dev
71 lines
2.5 KiB
C++
71 lines
2.5 KiB
C++
/* Copyright (c) the JPEG XL Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style
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* license that can be found in the LICENSE file.
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*/
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/** @addtogroup libjxl_threads
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* @{
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* @file thread_parallel_runner.h
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* @brief implementation using std::thread of a ::JxlParallelRunner.
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*/
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/** Implementation of JxlParallelRunner than can be used to enable
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* multithreading when using the JPEG XL library. This uses std::thread
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* internally and related synchronization functions. The number of threads
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* created is fixed at construction time and the threads are re-used for every
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* ThreadParallelRunner::Runner call. Only one concurrent
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* JxlThreadParallelRunner call per instance is allowed at a time.
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*
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* This is a scalable, lower-overhead thread pool runner, especially suitable
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* for data-parallel computations in the fork-join model, where clients need to
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* know when all tasks have completed.
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*
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* This thread pool can efficiently load-balance millions of tasks using an
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* atomic counter, thus avoiding per-task virtual or system calls. With 48
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* hyperthreads and 1M tasks that add to an atomic counter, overall runtime is
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* 10-20x higher when using std::async, and ~200x for a queue-based thread
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*/
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#ifndef JXL_THREAD_PARALLEL_RUNNER_H_
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#define JXL_THREAD_PARALLEL_RUNNER_H_
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#include <jxl/jxl_threads_export.h>
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#include <jxl/memory_manager.h>
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#include <jxl/parallel_runner.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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/** Parallel runner internally using std::thread. Use as @ref JxlParallelRunner.
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*/
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JXL_THREADS_EXPORT JxlParallelRetCode JxlThreadParallelRunner(
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void* runner_opaque, void* jpegxl_opaque, JxlParallelRunInit init,
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JxlParallelRunFunction func, uint32_t start_range, uint32_t end_range);
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/** Creates the runner for @ref JxlThreadParallelRunner. Use as the opaque
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* runner.
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*/
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JXL_THREADS_EXPORT void* JxlThreadParallelRunnerCreate(
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const JxlMemoryManager* memory_manager, size_t num_worker_threads);
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/** Destroys the runner created by @ref JxlThreadParallelRunnerCreate.
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*/
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JXL_THREADS_EXPORT void JxlThreadParallelRunnerDestroy(void* runner_opaque);
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/** Returns a default num_worker_threads value for
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* @ref JxlThreadParallelRunnerCreate.
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*/
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JXL_THREADS_EXPORT size_t JxlThreadParallelRunnerDefaultNumWorkerThreads(void);
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#if defined(__cplusplus) || defined(c_plusplus)
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}
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#endif
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#endif /* JXL_THREAD_PARALLEL_RUNNER_H_ */
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/** @}*/
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