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Diffstat (limited to 'third_party/jpeg-xl/lib/include/jxl/thread_parallel_runner.h')
-rw-r--r-- | third_party/jpeg-xl/lib/include/jxl/thread_parallel_runner.h | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/third_party/jpeg-xl/lib/include/jxl/thread_parallel_runner.h b/third_party/jpeg-xl/lib/include/jxl/thread_parallel_runner.h new file mode 100644 index 0000000000..715648b256 --- /dev/null +++ b/third_party/jpeg-xl/lib/include/jxl/thread_parallel_runner.h @@ -0,0 +1,72 @@ +/* Copyright (c) the JPEG XL Project Authors. All rights reserved. + * + * Use of this source code is governed by a BSD-style + * license that can be found in the LICENSE file. + */ + +/** @addtogroup libjxl_threads + * @{ + * @file thread_parallel_runner.h + * @brief implementation using std::thread of a ::JxlParallelRunner. + */ + +/** Implementation of JxlParallelRunner than can be used to enable + * multithreading when using the JPEG XL library. This uses std::thread + * internally and related synchronization functions. The number of threads + * created is fixed at construction time and the threads are re-used for every + * ThreadParallelRunner::Runner call. Only one concurrent + * JxlThreadParallelRunner call per instance is allowed at a time. + * + * This is a scalable, lower-overhead thread pool runner, especially suitable + * for data-parallel computations in the fork-join model, where clients need to + * know when all tasks have completed. + * + * This thread pool can efficiently load-balance millions of tasks using an + * atomic counter, thus avoiding per-task virtual or system calls. With 48 + * hyperthreads and 1M tasks that add to an atomic counter, overall runtime is + * 10-20x higher when using std::async, and ~200x for a queue-based thread + */ + +#ifndef JXL_THREAD_PARALLEL_RUNNER_H_ +#define JXL_THREAD_PARALLEL_RUNNER_H_ + +#include <jxl/jxl_threads_export.h> +#include <jxl/memory_manager.h> +#include <jxl/parallel_runner.h> +#include <stddef.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> + +#if defined(__cplusplus) || defined(c_plusplus) +extern "C" { +#endif + +/** Parallel runner internally using std::thread. Use as JxlParallelRunner. + */ +JXL_THREADS_EXPORT JxlParallelRetCode JxlThreadParallelRunner( + void* runner_opaque, void* jpegxl_opaque, JxlParallelRunInit init, + JxlParallelRunFunction func, uint32_t start_range, uint32_t end_range); + +/** Creates the runner for JxlThreadParallelRunner. Use as the opaque + * runner. + */ +JXL_THREADS_EXPORT void* JxlThreadParallelRunnerCreate( + const JxlMemoryManager* memory_manager, size_t num_worker_threads); + +/** Destroys the runner created by JxlThreadParallelRunnerCreate. + */ +JXL_THREADS_EXPORT void JxlThreadParallelRunnerDestroy(void* runner_opaque); + +/** Returns a default num_worker_threads value for + * JxlThreadParallelRunnerCreate. + */ +JXL_THREADS_EXPORT size_t JxlThreadParallelRunnerDefaultNumWorkerThreads(); + +#if defined(__cplusplus) || defined(c_plusplus) +} +#endif + +#endif /* JXL_THREAD_PARALLEL_RUNNER_H_ */ + +/** @}*/ |