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6880b22b90
Previously the maximum waiting time was just over 24 days. In a DTN setup we may want to wait longer, e.g., for contacts to occur. This allows for waiting about 292 years. If the provided delay exceeds this threshold, an infinite delay is assumed. Signed-off-by: Felix Walter <felix.walter@d3tn.com>
100 lines
3.1 KiB
C
100 lines
3.1 KiB
C
// SPDX-License-Identifier: BSD-3-Clause OR Apache-2.0
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/*
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* simple_queue.h
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*
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* Description: simple and lightweight implementation of message-queues in C.
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*
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* Copyright (c) 2016, Robert Wiewel
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*
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* This file has been initially provided under the BSD 3-clause license and
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* is now provided in agreement with the original author as part of uD3TN
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* under the terms and conditions of either the Apache 2.0 or the BSD 3-clause
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* license. See the LICENSE file in the project root for details.
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*
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*/
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#ifndef SIMPLE_QUEUE_H_INCLUDED
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#define SIMPLE_QUEUE_H_INCLUDED
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#include <stdint.h>
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#include <stdbool.h>
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/**
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* @brief The Queue_t struct Data structure holding all queue-related info
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*/
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typedef struct {
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// absolut length of the queue (in items)
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int item_length;
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// size of one single item (in bytes)
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int item_size;
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// provides mutual exclusion for the given queue
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struct Semaphore *semaphore;
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// these semaphores circumvent busy waiting
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struct Semaphore *sem_pop;
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struct Semaphore *sem_push;
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// abs_start and abs_end are pointers to the first and last
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// byte of the reserved memory
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char *abs_start;
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char *abs_end;
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// current_start and current_end point to the first and last currently
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// used elements in the queue
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char *current_start;
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char *current_end;
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} Queue_t;
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/**
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* @brief queueCreate Creates a new queue structure, i.e. allocates the
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* necessary memory ressources
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* @param queue_length absolute length of the queue (in items)
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* @param item_size size of a single item (in bytes)
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* @return returns a pointer to the queue "object"
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*/
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Queue_t *queueCreate(unsigned int queue_length, unsigned int item_size);
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/**
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* @brief queueDelete Delete a queue structure, i.e. frees the memory
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* ressources
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* @param queue The pointer to the queue structure
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*/
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void queueDelete(Queue_t *queue);
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/**
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* @brief queueReset Reset a given queue, i.e. empty the data section
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* @param queue The pointer to the queue structure
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*/
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void queueReset(Queue_t *queue);
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/**
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* @brief queuePush Pushes an item to the end of the queue
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* @param queue The pointer to the queue structure
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* @param item A pointer to the item that should be queued
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* @param timeout Defines how long the queuing should be tried
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* (in milliseconds)
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* If this value is -1 or larger than 9223372036854, pushing
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* will block indefinitely (see hal_semaphore_try_take)
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* @param force Defines if the last element of the queue should be replaced
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* forcefully (only applied when queue is full)
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* @return Exitcode, if queueing was successfull
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*/
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uint8_t queuePush(Queue_t *queue, const void *item, int64_t timeout,
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bool force);
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/**
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* @brief queuePop Pops the upmost element of the queue
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* @param queue The pointer to the queue structure
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* @param targetBuffer The memory location where the queued item should be
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* copied to
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* @param timeout Defines how long the dequeuing should be tried
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* (in milliseconds)
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* If this value is -1 or larger than 9223372036854, popping
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* will block indefinitely (see hal_semaphore_try_take)
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* @return Exitcode, if dequeueing was successfull
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*/
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uint8_t queuePop(Queue_t *queue, void *targetBuffer, int64_t timeout);
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#endif /* SIMPLE_QUEUE_H_INCLUDED */
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