LIBJXL

Functions
resizable_parallel_runner.h File Reference

implementation using std::thread of a resizeable JxlParallelRunner. More...

`#include <stddef.h>`
`#include <stdint.h>`
`#include <stdio.h>`
`#include <stdlib.h>`
`#include "jxl/jxl_threads_export.h"`
`#include "jxl/memory_manager.h"`
`#include "jxl/parallel_runner.h"`
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## Functions
JXL_THREADS_EXPORT JxlParallelRetCode | JxlResizableParallelRunner (void *runner_opaque, void *jpegxl_opaque, JxlParallelRunInit init, JxlParallelRunFunction func, uint32_t start_range, uint32_t end_range)
JXL_THREADS_EXPORT void * | JxlResizableParallelRunnerCreate (const JxlMemoryManager *memory_manager)
JXL_THREADS_EXPORT void | JxlResizableParallelRunnerSetThreads (void *runner_opaque, size_t num_threads)
JXL_THREADS_EXPORT uint32_t | JxlResizableParallelRunnerSuggestThreads (uint64_t xsize, uint64_t ysize)
JXL_THREADS_EXPORT void | JxlResizableParallelRunnerDestroy (void *runner_opaque)

## Detailed Description

implementation using std::thread of a resizeable JxlParallelRunner.

## Function Documentation

## ◆ JxlResizableParallelRunner()

JXL_THREADS_EXPORT JxlParallelRetCode JxlResizableParallelRunner | ( | void * | runner_opaque,
|  | void * | jpegxl_opaque,
|  | JxlParallelRunInit | init,
|  | JxlParallelRunFunction | func,
|  | uint32_t | start_range,
|  | uint32_t | end_range
| ) |  |

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 can be changed after creation of the thread pool; the threads (including the main thread) are re-used for every ResizableParallelRunner::Runner call. Only one concurrent JxlResizableParallelRunner 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.

Compared to the implementation in thread_parallel_runner.h, this implementation is tuned for execution on lower-powered systems, including for example ARM CPUs with big.LITTLE computation models. Parallel runner internally using std::thread. Use as JxlParallelRunner.

## ◆ JxlResizableParallelRunnerCreate()

JXL_THREADS_EXPORT void * JxlResizableParallelRunnerCreate | ( | const JxlMemoryManager * | memory_manager | ) |

Creates the runner for JxlResizableParallelRunner. Use as the opaque runner. The runner will execute tasks on the calling thread until JxlResizableParallelRunnerSetThreads is called.

## ◆ JxlResizableParallelRunnerDestroy()

JXL_THREADS_EXPORT void JxlResizableParallelRunnerDestroy | ( | void * | runner_opaque | ) |

Destroys the runner created by JxlResizableParallelRunnerCreate.

## ◆ JxlResizableParallelRunnerSetThreads()

JXL_THREADS_EXPORT void JxlResizableParallelRunnerSetThreads | ( | void * | runner_opaque,
|  | size_t | num_threads
| ) |  |

Changes the number of threads for JxlResizableParallelRunner.

## ◆ JxlResizableParallelRunnerSuggestThreads()

JXL_THREADS_EXPORT uint32_t JxlResizableParallelRunnerSuggestThreads | ( | uint64_t | xsize,
|  | uint64_t | ysize
| ) |  |

Suggests a number of threads to use for an image of given size.