logmeow/arb.h

#pragma once

#include <atomic>

#define ARB_MAX_SIZE 255

template<typename T>
class AtomicRingBuffer {
public:
    T* get();
    void increment_read();
    bool try_put_and_increment_write(T item);

private:
    size_t _read = 0;
    size_t _write = 0;
    std::atomic<unsigned char> _used = 0;
    T _items[ARB_MAX_SIZE];
};

// function bodies must be in the header because https://stackoverflow.com/a/999383

template<typename T>
T* AtomicRingBuffer<T>::get() {
    if (this->_used.load() == 0) {
        return nullptr;
    }
    return &this->_items[this->_read];
}

template<typename T>
void AtomicRingBuffer<T>::increment_read() {
    if (this->_used.load() == 0) {
        return;
    }
    --this->_used;
    this->_read = (this->_read + 1) % ARB_MAX_SIZE;
}

template<typename T>
bool AtomicRingBuffer<T>::try_put_and_increment_write(T item) {
    if (this->_used.load() == ARB_MAX_SIZE) {
        return false;
    }
    this->_items[this->_write] = std::move(item);
    ++this->_used;
    this->_write = (this->_write + 1) % ARB_MAX_SIZE;
    return true;
}