core/log: add custom log encoder for smaller log storage

Will be used to store more detailed logs in the future without using
as much disk space.

src/core/logging_p.hpp

@@ -0,0 +1,123 @@
+#pragma once
+#include <qbytearrayview.h>
+#include <qcontainerfwd.h>
+#include <qfile.h>
+#include <qlogging.h>
+#include <qtmetamacros.h>
+#include <qtypes.h>
+
+#include "logging.hpp"
+#include "ringbuf.hpp"
+
+namespace qs::log {
+
+enum EncodedLogOpcode : quint8 {
+	RegisterCategory = 0,
+	RecentMessageShort,
+	RecentMessageLong,
+	BeginCategories,
+};
+
+enum CompressedLogType : quint8 {
+	Debug = 0,
+	Info = 1,
+	Warn = 2,
+	Critical = 3,
+};
+
+CompressedLogType compressedTypeOf(QtMsgType type);
+QtMsgType typeOfCompressed(CompressedLogType type);
+
+class WriteBuffer {
+public:
+	void setDevice(QIODevice* device);
+	[[nodiscard]] bool hasDevice() const;
+	[[nodiscard]] bool flush();
+	void writeBytes(const char* data, qsizetype length);
+	void writeU8(quint8 data);
+	void writeU16(quint16 data);
+	void writeU32(quint32 data);
+	void writeU64(quint64 data);
+
+private:
+	QIODevice* device = nullptr;
+	QByteArray buffer;
+};
+
+class DeviceReader {
+public:
+	void setDevice(QIODevice* device);
+	[[nodiscard]] bool hasDevice() const;
+	[[nodiscard]] bool readBytes(char* data, qsizetype length);
+	// peek UP TO length
+	[[nodiscard]] qsizetype peekBytes(char* data, qsizetype length);
+	[[nodiscard]] bool skip(qsizetype length);
+	[[nodiscard]] bool readU8(quint8* data);
+	[[nodiscard]] bool readU16(quint16* data);
+	[[nodiscard]] bool readU32(quint32* data);
+	[[nodiscard]] bool readU64(quint64* data);
+
+private:
+	QIODevice* device = nullptr;
+};
+
+class EncodedLogWriter {
+public:
+	void setDevice(QIODevice* target);
+	[[nodiscard]] bool writeHeader();
+	[[nodiscard]] bool write(const LogMessage& message);
+
+private:
+	void writeOp(EncodedLogOpcode opcode);
+	void writeVarInt(quint32 n);
+	void writeString(QByteArrayView bytes);
+	quint16 getOrCreateCategory(QLatin1StringView category);
+
+	WriteBuffer buffer;
+
+	QHash<QLatin1StringView, quint16> categories;
+	quint16 nextCategory = EncodedLogOpcode::BeginCategories;
+
+	QDateTime lastMessageTime = QDateTime::fromSecsSinceEpoch(0);
+	HashBuffer<LogMessage> recentMessages {256};
+};
+
+class EncodedLogReader {
+public:
+	void setDevice(QIODevice* source);
+	[[nodiscard]] bool readHeader(bool* success, quint8* logVersion, quint8* readerVersion);
+	// WARNING: log messages written to the given slot are invalidated when the log reader is destroyed.
+	[[nodiscard]] bool read(LogMessage* slot);
+
+private:
+	[[nodiscard]] bool readVarInt(quint32* slot);
+	[[nodiscard]] bool readString(QByteArray* slot);
+	[[nodiscard]] bool registerCategory();
+
+	DeviceReader reader;
+	QVector<QByteArray> categories;
+	QDateTime lastMessageTime = QDateTime::fromSecsSinceEpoch(0);
+	RingBuffer<LogMessage> recentMessages {256};
+};
+
+class ThreadLogging: public QObject {
+	Q_OBJECT;
+
+public:
+	explicit ThreadLogging(QObject* parent): QObject(parent) {}
+
+	void init();
+	void initFs();
+	void setupFileLogging();
+
+private slots:
+	void onMessage(const LogMessage& msg);
+
+private:
+	QFile* file = nullptr;
+	QTextStream fileStream;
+	QFile* detailedFile = nullptr;
+	EncodedLogWriter detailedWriter;
+};
+
+} // namespace qs::log