/* * Copyright (c) 2020 * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef AVFILTER_DNN_SAFE_QUEUE_H#define AVFILTER_DNN_SAFE_QUEUE_H /** * Double-ended queue with mutex locks ensuring * data consistency while multithreading. */typedef struct SafeQueue SafeQueue; /** * @brief Create and initialize a SafeQueue instance. * * @return Pointer to the SafeQueue * @retval NULL if initialization fails */SafeQueue *ff_safe_queue_create(void); /** * @brief Destroy the SafeQueue instance. * It also frees all elements of the queue, * destroys the mutex and condition variable. */void ff_safe_queue_destroy(SafeQueue *sq); /** * @brief Return the length of the SafeQueue */size_t ff_safe_queue_size(SafeQueue *sq); /** * @brief Add data to the head of queue in the * SafeQueue after locking mutex. After adding * the data, it signals the condition variable * and unlocks the mutex. It increases the length * of queue in the SafeQueue by one. * * @param sq pointer to the SafeQueue * @param v data to be added * @return The length of the queue * @retval 0 if the queue is not initialized * @retval -1 if new entry cannot be created */int ff_safe_queue_push_front(SafeQueue *sq, void *v); /** * @brief Add data to the tail of queue in the * SafeQueue after locking mutex. After adding * the data, it signals the condition variable * and unlocks the mutex. It increases the length * of queue in the SafeQueue by one. * * @param sq pointer to the SafeQueue * @param v data to be added * @return The length of the queue * @retval 0 if the queue is not initialized * @retval -1 if new entry cannot be created */int ff_safe_queue_push_back(SafeQueue *sq, void *v); /** * @brief Remove and free first element from * the queue in SafeQueue. Before removing, it * waits for the condition variable to signal and * acquires the mutex. Finally, it signals the * condition and unlocks the mutex. * It shrinks the length of queue in the SafeQueue * by one. * * @param sq pointer to the SafeQueue. * @return The value of first element as void. * If a null pointer or empty queue is passed, * it returns NULL */void *ff_safe_queue_pop_front(SafeQueue *sq); #endif