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/*
* Copyright (C) 2016+ AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license: https://github.com/azerothcore/azerothcore-wotlk/blob/master/LICENSE
*
* This file was based on
* https://embeddedartistry.com/blog/2017/05/17/creating-a-circular-buffer-in-c-and-c/
* https://github.com/embeddedartistry/embedded-resources/blob/master/examples/cpp/circular_buffer.cpp
*/
#ifndef AZEROTHCORE_CIRCULAR_BUFFER_H
#define AZEROTHCORE_CIRCULAR_BUFFER_H
#include <memory>
#include <mutex>
#include <vector>
template <typename T>
class CircularBuffer
{
public:
explicit CircularBuffer(size_t size) :
buf_(std::unique_ptr<T[]>(new T[size])),
max_size_(size)
{
}
void put(T item)
{
std::lock_guard<std::mutex> lock(mutex_);
buf_[head_] = item;
if (full_)
{
tail_ = (tail_ + 1) % max_size_;
}
head_ = (head_ + 1) % max_size_;
full_ = head_ == tail_;
}
[[nodiscard]] bool empty() const
{
//if head and tail are equal, we are empty
return (!full_ && (head_ == tail_));
}
[[nodiscard]] bool full() const
{
//If tail is ahead the head by 1, we are full
return full_;
}
[[nodiscard]] size_t capacity() const
{
return max_size_;
}
[[nodiscard]] size_t size() const
{
size_t size = max_size_;
if (!full_)
{
if (head_ >= tail_)
{
size = head_ - tail_;
}
else
{
size += head_ - tail_;
}
}
return size;
}
// the implementation of this function is simplified by the fact that head_ will never be lower than tail_
// when compared to the original implementation of this class
std::vector<T> content()
{
std::lock_guard<std::mutex> lock(mutex_);
return std::vector<T>(buf_.get(), buf_.get() + size());
}
T peak_back()
{
std::lock_guard<std::mutex> lock(mutex_);
return empty() ? T() : buf_[tail_];
}
private:
std::mutex mutex_;
std::unique_ptr<T[]> buf_;
size_t head_ = 0;
size_t tail_ = 0;
const size_t max_size_;
bool full_ = false;
};
#endif
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