resizable_parallel_runner.h (2731B)
1 /* Copyright (c) the JPEG XL Project Authors. All rights reserved. 2 * 3 * Use of this source code is governed by a BSD-style 4 * license that can be found in the LICENSE file. 5 */ 6 7 /** @addtogroup libjxl_threads 8 * @{ 9 * @file resizable_parallel_runner.h 10 * @brief implementation using std::thread of a resizeable ::JxlParallelRunner. 11 */ 12 13 /** Implementation of JxlParallelRunner than can be used to enable 14 * multithreading when using the JPEG XL library. This uses std::thread 15 * internally and related synchronization functions. The number of threads 16 * created can be changed after creation of the thread pool; the threads 17 * (including the main thread) are re-used for every 18 * ResizableParallelRunner::Runner call. Only one concurrent 19 * @ref JxlResizableParallelRunner call per instance is allowed at a time. 20 * 21 * This is a scalable, lower-overhead thread pool runner, especially suitable 22 * for data-parallel computations in the fork-join model, where clients need to 23 * know when all tasks have completed. 24 * 25 * Compared to the implementation in @ref thread_parallel_runner.h, this 26 * implementation is tuned for execution on lower-powered systems, including 27 * for example ARM CPUs with big.LITTLE computation models. 28 */ 29 30 #ifndef JXL_RESIZABLE_PARALLEL_RUNNER_H_ 31 #define JXL_RESIZABLE_PARALLEL_RUNNER_H_ 32 33 #include <jxl/jxl_threads_export.h> 34 #include <jxl/memory_manager.h> 35 #include <jxl/parallel_runner.h> 36 #include <stddef.h> 37 #include <stdint.h> 38 #include <stdlib.h> 39 40 #ifdef __cplusplus 41 extern "C" { 42 #endif 43 44 /** Parallel runner internally using std::thread. Use as @ref JxlParallelRunner. 45 */ 46 JXL_THREADS_EXPORT JxlParallelRetCode JxlResizableParallelRunner( 47 void* runner_opaque, void* jpegxl_opaque, JxlParallelRunInit init, 48 JxlParallelRunFunction func, uint32_t start_range, uint32_t end_range); 49 50 /** Creates the runner for @ref JxlResizableParallelRunner. Use as the opaque 51 * runner. The runner will execute tasks on the calling thread until 52 * @ref JxlResizableParallelRunnerSetThreads is called. 53 */ 54 JXL_THREADS_EXPORT void* JxlResizableParallelRunnerCreate( 55 const JxlMemoryManager* memory_manager); 56 57 /** Changes the number of threads for @ref JxlResizableParallelRunner. 58 */ 59 JXL_THREADS_EXPORT void JxlResizableParallelRunnerSetThreads( 60 void* runner_opaque, size_t num_threads); 61 62 /** Suggests a number of threads to use for an image of given size. 63 */ 64 JXL_THREADS_EXPORT uint32_t 65 JxlResizableParallelRunnerSuggestThreads(uint64_t xsize, uint64_t ysize); 66 67 /** Destroys the runner created by @ref JxlResizableParallelRunnerCreate. 68 */ 69 JXL_THREADS_EXPORT void JxlResizableParallelRunnerDestroy(void* runner_opaque); 70 71 #ifdef __cplusplus 72 } 73 #endif 74 75 #endif /* JXL_RESIZABLE_PARALLEL_RUNNER_H_ */ 76 77 /** @}*/