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Diffstat (limited to 'thirdparty/astcenc/astcenc_internal_entry.h')
| -rw-r--r-- | thirdparty/astcenc/astcenc_internal_entry.h | 273 |
1 files changed, 273 insertions, 0 deletions
diff --git a/thirdparty/astcenc/astcenc_internal_entry.h b/thirdparty/astcenc/astcenc_internal_entry.h new file mode 100644 index 0000000000..4e8794547a --- /dev/null +++ b/thirdparty/astcenc/astcenc_internal_entry.h @@ -0,0 +1,273 @@ +// SPDX-License-Identifier: Apache-2.0 +// ---------------------------------------------------------------------------- +// Copyright 2011-2022 Arm Limited +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may not +// use this file except in compliance with the License. You may obtain a copy +// of the License at: +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT +// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the +// License for the specific language governing permissions and limitations +// under the License. +// ---------------------------------------------------------------------------- + +/** + * @brief Functions and data declarations for the outer context. + * + * The outer context includes thread-pool management, which is slower to + * compile due to increased use of C++ stdlib. The inner context used in the + * majority of the codec library does not include this. + */ + +#ifndef ASTCENC_INTERNAL_ENTRY_INCLUDED +#define ASTCENC_INTERNAL_ENTRY_INCLUDED + +#include <atomic> +#include <condition_variable> +#include <functional> +#include <mutex> + +#include "astcenc_internal.h" + +/* ============================================================================ + Parallel execution control +============================================================================ */ + +/** + * @brief A simple counter-based manager for parallel task execution. + * + * The task processing execution consists of: + * + * * A single-threaded init stage. + * * A multi-threaded processing stage. + * * A condition variable so threads can wait for processing completion. + * + * The init stage will be executed by the first thread to arrive in the critical section, there is + * no main thread in the thread pool. + * + * The processing stage uses dynamic dispatch to assign task tickets to threads on an on-demand + * basis. Threads may each therefore executed different numbers of tasks, depending on their + * processing complexity. The task queue and the task tickets are just counters; the caller must map + * these integers to an actual processing partition in a specific problem domain. + * + * The exit wait condition is needed to ensure processing has finished before a worker thread can + * progress to the next stage of the pipeline. Specifically a worker may exit the processing stage + * because there are no new tasks to assign to it while other worker threads are still processing. + * Calling @c wait() will ensure that all other worker have finished before the thread can proceed. + * + * The basic usage model: + * + * // --------- From single-threaded code --------- + * + * // Reset the tracker state + * manager->reset() + * + * // --------- From multi-threaded code --------- + * + * // Run the stage init; only first thread actually runs the lambda + * manager->init(<lambda>) + * + * do + * { + * // Request a task assignment + * uint task_count; + * uint base_index = manager->get_tasks(<granule>, task_count); + * + * // Process any tasks we were given (task_count <= granule size) + * if (task_count) + * { + * // Run the user task processing code for N tasks here + * ... + * + * // Flag these tasks as complete + * manager->complete_tasks(task_count); + * } + * } while (task_count); + * + * // Wait for all threads to complete tasks before progressing + * manager->wait() + * + * // Run the stage term; only first thread actually runs the lambda + * manager->term(<lambda>) + */ +class ParallelManager +{ +private: + /** @brief Lock used for critical section and condition synchronization. */ + std::mutex m_lock; + + /** @brief True if the stage init() step has been executed. */ + bool m_init_done; + + /** @brief True if the stage term() step has been executed. */ + bool m_term_done; + + /** @brief Condition variable for tracking stage processing completion. */ + std::condition_variable m_complete; + + /** @brief Number of tasks started, but not necessarily finished. */ + std::atomic<unsigned int> m_start_count; + + /** @brief Number of tasks finished. */ + unsigned int m_done_count; + + /** @brief Number of tasks that need to be processed. */ + unsigned int m_task_count; + +public: + /** @brief Create a new ParallelManager. */ + ParallelManager() + { + reset(); + } + + /** + * @brief Reset the tracker for a new processing batch. + * + * This must be called from single-threaded code before starting the multi-threaded processing + * operations. + */ + void reset() + { + m_init_done = false; + m_term_done = false; + m_start_count = 0; + m_done_count = 0; + m_task_count = 0; + } + + /** + * @brief Trigger the pipeline stage init step. + * + * This can be called from multi-threaded code. The first thread to hit this will process the + * initialization. Other threads will block and wait for it to complete. + * + * @param init_func Callable which executes the stage initialization. It must return the + * total number of tasks in the stage. + */ + void init(std::function<unsigned int(void)> init_func) + { + std::lock_guard<std::mutex> lck(m_lock); + if (!m_init_done) + { + m_task_count = init_func(); + m_init_done = true; + } + } + + /** + * @brief Trigger the pipeline stage init step. + * + * This can be called from multi-threaded code. The first thread to hit this will process the + * initialization. Other threads will block and wait for it to complete. + * + * @param task_count Total number of tasks needing processing. + */ + void init(unsigned int task_count) + { + std::lock_guard<std::mutex> lck(m_lock); + if (!m_init_done) + { + m_task_count = task_count; + m_init_done = true; + } + } + + /** + * @brief Request a task assignment. + * + * Assign up to @c granule tasks to the caller for processing. + * + * @param granule Maximum number of tasks that can be assigned. + * @param[out] count Actual number of tasks assigned, or zero if no tasks were assigned. + * + * @return Task index of the first assigned task; assigned tasks increment from this. + */ + unsigned int get_task_assignment(unsigned int granule, unsigned int& count) + { + unsigned int base = m_start_count.fetch_add(granule, std::memory_order_relaxed); + if (base >= m_task_count) + { + count = 0; + return 0; + } + + count = astc::min(m_task_count - base, granule); + return base; + } + + /** + * @brief Complete a task assignment. + * + * Mark @c count tasks as complete. This will notify all threads blocked on @c wait() if this + * completes the processing of the stage. + * + * @param count The number of completed tasks. + */ + void complete_task_assignment(unsigned int count) + { + // Note: m_done_count cannot use an atomic without the mutex; this has a race between the + // update here and the wait() for other threads + std::unique_lock<std::mutex> lck(m_lock); + this->m_done_count += count; + if (m_done_count == m_task_count) + { + lck.unlock(); + m_complete.notify_all(); + } + } + + /** + * @brief Wait for stage processing to complete. + */ + void wait() + { + std::unique_lock<std::mutex> lck(m_lock); + m_complete.wait(lck, [this]{ return m_done_count == m_task_count; }); + } + + /** + * @brief Trigger the pipeline stage term step. + * + * This can be called from multi-threaded code. The first thread to hit this will process the + * work pool termination. Caller must have called @c wait() prior to calling this function to + * ensure that processing is complete. + * + * @param term_func Callable which executes the stage termination. + */ + void term(std::function<void(void)> term_func) + { + std::lock_guard<std::mutex> lck(m_lock); + if (!m_term_done) + { + term_func(); + m_term_done = true; + } + } +}; + +/** + * @brief The astcenc compression context. + */ +struct astcenc_context +{ + /** @brief The context internal state. */ + astcenc_contexti context; + +#if !defined(ASTCENC_DECOMPRESS_ONLY) + /** @brief The parallel manager for averages computation. */ + ParallelManager manage_avg; + + /** @brief The parallel manager for compression. */ + ParallelManager manage_compress; +#endif + + /** @brief The parallel manager for decompression. */ + ParallelManager manage_decompress; +}; + +#endif |