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// Copyright 2018 Mimecast Ltd.
//
// 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.
#ifndef RBUFFER_H
#define RBUFFER_H
#include "signal.h"
#include "../defaults.h"
/**
* @brief An atomic ring buffer data type definition
*
* This data structure can be used for the common producer/consumer problem.
* As long as there is only max one producer thread and max one consumer thread
* it can be used without any mutex locking. All the operations are atomic.
*/
typedef struct rbuffer_s_ {
/**
* The positions are atomic, means the ring buffer can be accessed from
* multiple threads concurrently (one producer and one consumer thread).
* This is the current read position.
*/
sig_atomic_t read_pos;
/**
* This is the current write position.
*/
sig_atomic_t write_pos;
/**
* Holds the pointers to the actual ring data stored in the ring buffer
*/
void **ring;
/**
* Determines how many elements the ring buffer can hold. The capacity
* will be size-1 though, as we need one empty slot.
*/
int size;
} rbuffer_s;
/**
* @brief Creates a new ring buffer
*
* @param size The size of the ring buffer
* @return The new ring buffer object
*/
rbuffer_s* rbuffer_new(const int size);
/**
* @brief Destroys a ring buffer
*
* @param r The ring buffer object
*/
void rbuffer_destroy(rbuffer_s* r);
/**
* @brief Inserts data pointer to the ring buffer
*
* @param r The ring buffer object
* @param data The data pointer
*/
bool rbuffer_insert(rbuffer_s* r, void *data);
/**
* @brief Determines whether there is any data in the ring buffer
*
* @param r The ring buffer object
* @return True if there is any data, false otherwise
*/
bool rbuffer_has_next(rbuffer_s* r);
/**
* @brief Returns and removes the next element from the ring buffer
*
* @param r The ring buffer object
* @return The data pointer
*/
void* rbuffer_get_next(rbuffer_s* r);
/**
* @brief Prints a ring buffer
*
* @param r The ring buffer object
*/
void rbuffer_print(rbuffer_s* r);
/**
* @brief Unit tests the ring buffer
*/
void rbuffer_test(void);
#endif // RBUFFER_H
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