parallel_runner.h

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/* 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.
 */

#ifndef JXL_PARALLEL_RUNNER_H_
#define JXL_PARALLEL_RUNNER_H_

#include <stddef.h>
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

typedef int JxlParallelRetCode;

#define JXL_PARALLEL_RET_SUCCESS (0)

#define JXL_PARALLEL_RET_RUNNER_ERROR (-1)

typedef JxlParallelRetCode (*JxlParallelRunInit)(void* jpegxl_opaque,
                                                 size_t num_threads);

typedef void (*JxlParallelRunFunction)(void* jpegxl_opaque, uint32_t value,
                                       size_t thread_id);

typedef JxlParallelRetCode (*JxlParallelRunner)(
    void* runner_opaque, void* jpegxl_opaque, JxlParallelRunInit init,
    JxlParallelRunFunction func, uint32_t start_range, uint32_t end_range);

/* The following is an example of a @ref JxlParallelRunner that doesn't use any
 * multi-threading. Note that this implementation doesn't store any state
 * between multiple calls of the ExampleSequentialRunner function, so the
 * runner_opaque value is not used.

  JxlParallelRetCode ExampleSequentialRunner(void* runner_opaque,
                                                void* jpegxl_opaque,
                                                JxlParallelRunInit init,
                                                JxlParallelRunFunction func,
                                                uint32_t start_range,
                                                uint32_t end_range) {
    // We only use one thread (the currently running thread).
    JxlParallelRetCode init_ret = (*init)(jpegxl_opaque, 1);
    if (init_ret != 0) return init_ret;

    // In case of other initialization error (for example when initializing the
    // threads) one can return JXL_PARALLEL_RET_RUNNER_ERROR.

    for (uint32_t i = start_range; i < end_range; i++) {
      // Every call is in the thread number 0. These don't need to be in any
      // order.
      (*func)(jpegxl_opaque, i, 0);
    }
    return JXL_PARALLEL_RET_SUCCESS;
  }
 */

#ifdef __cplusplus
}
#endif

#endif /* JXL_PARALLEL_RUNNER_H_ */