logring.h

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/*
        Copyright 2006-2026 The QElectroTech Team
        This file is part of QElectroTech.
 
        QElectroTech is free software: you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation, either version 2 of the License, or
        (at your option) any later version.
 
        QElectroTech 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 General Public License for more details.
 
        You should have received a copy of the GNU General Public License
        along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef LOGRING_H
#define LOGRING_H
 
#include <QByteArray>
#include <QVector>
#include <atomic>
#include <vector>

class LogRing
{
        public:
                static constexpr int kCapacityEntries = 4096;
                static constexpr int kEntryBytes = 512; // 4096 * 512 = 2 MiB total
 
                LogRing();

                void append(const QByteArray &line) noexcept;

                QVector<QByteArray> snapshot() const;

                void dumpToFd(int fd) const noexcept;
 
                void clear();
 
        private:
                struct Entry {
                        char data[kEntryBytes];
                        std::atomic<int> length{0}; // 0 = not yet written this lap
                };
 
                std::vector<Entry> m_entries; // preallocated once, capacity fixed
                std::atomic<quint64> m_write_cursor{0}; // monotonically increasing
};
 
#endif // LOGRING_H