qrandomaccessasyncfile_p_p.h

qt/qtbase/src/corelib/io/qrandomaccessasyncfile_p_p.h

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// Copyright (C) 2025 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

// Qt-Security score:significant reason:default

#ifndef QRANDOMACCESSASYNCFILE_P_P_H

#define QRANDOMACCESSASYNCFILE_P_P_H

//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API.  It exists purely as an

// implementation detail.  This header file may change from version to

// version without notice, or even be removed.

//

// We mean it.

//

#include "qrandomaccessasyncfile_p.h"

#include <QtCore/private/qobject_p.h>

#include <QtCore/qstring.h>

#if QT_CONFIG(future) && QT_CONFIG(thread)

#include <QtCore/private/qfsfileengine_p.h>

#include <QtCore/qfuturewatcher.h>

#include <QtCore/qmutex.h>

#include <QtCore/qqueue.h>

#endif // future && thread

#ifdef Q_OS_DARWIN

#include <QtCore/qlist.h>

#include <QtCore/qmutex.h>

#include <QtCore/qset.h>

#include <QtCore/qwaitcondition.h>

#include <dispatch/dispatch.h>

#endif // Q_OS_DARWIN

#ifdef QT_RANDOMACCESSASYNCFILE_QIORING

#include <QtCore/private/qioring_p.h>

#include <QtCore/qlist.h>

#endif

QT_BEGIN_NAMESPACE

class QRandomAccessAsyncFileBackend

    Q_DISABLE_COPY_MOVE(QRandomAccessAsyncFileBackend)

public:

    explicit QRandomAccessAsyncFileBackend(QRandomAccessAsyncFile *owner);

    virtual ~QRandomAccessAsyncFileBackend();

    virtual bool init() = 0;

    virtual void cancelAndWait(QIOOperation *op) = 0;

    virtual void close() = 0;

    virtual qint64 size() const = 0;

    [[nodiscard]] virtual QIOOperation *open(const QString &path, QIODeviceBase::OpenMode mode) = 0;

    [[nodiscard]] virtual QIOOperation *flush() = 0;

    [[nodiscard]] virtual QIOReadOperation *read(qint64 offset, qint64 maxSize) = 0;

    [[nodiscard]] virtual QIOWriteOperation *write(qint64 offset, const QByteArray &data) = 0;

    [[nodiscard]] virtual QIOWriteOperation *write(qint64 offset, QByteArray &&data) = 0;

    [[nodiscard]] virtual QIOVectoredReadOperation *

    readInto(qint64 offset, QSpan<std::byte> buffer) = 0;

    [[nodiscard]] virtual QIOVectoredWriteOperation *

    writeFrom(qint64 offset, QSpan<const std::byte> buffer) = 0;

    [[nodiscard]] virtual QIOVectoredReadOperation *

    readInto(qint64 offset, QSpan<const QSpan<std::byte>> buffers) = 0;

    [[nodiscard]] virtual QIOVectoredWriteOperation *

    writeFrom(qint64 offset, QSpan<const QSpan<const std::byte>> buffers) = 0;

protected:

    // common for all backends

    enum class FileState : quint8

        Closed,

        OpenPending, // already got an open request

        Opened,

};

    QString m_filePath;

    QRandomAccessAsyncFile *m_owner = nullptr;

    QIODeviceBase::OpenMode m_openMode;

    FileState m_fileState = FileState::Closed;

};

class QRandomAccessAsyncFilePrivate : public QObjectPrivate

    Q_DECLARE_PUBLIC(QRandomAccessAsyncFile)

    Q_DISABLE_COPY_MOVE(QRandomAccessAsyncFilePrivate)

public:

    QRandomAccessAsyncFilePrivate();

    ~QRandomAccessAsyncFilePrivate() override;

    static QRandomAccessAsyncFilePrivate *get(QRandomAccessAsyncFile *file)

    { return file->d_func(); }

    void init();

    void cancelAndWait(QIOOperation *op)

        checkValid();

        m_backend->cancelAndWait(op);

    void close()

        checkValid();

        m_backend->close();

    qint64 size() const

        checkValid();

        return m_backend->size();

    [[nodiscard]] QIOOperation *open(const QString &path, QIODeviceBase::OpenMode mode)

        checkValid();

        return m_backend->open(path, mode);

    [[nodiscard]] QIOOperation *flush()

        checkValid();

        return m_backend->flush();

    [[nodiscard]] QIOReadOperation *read(qint64 offset, qint64 maxSize)

        checkValid();

        return m_backend->read(offset, maxSize);

    [[nodiscard]] QIOWriteOperation *write(qint64 offset, const QByteArray &data)

        checkValid();

        return m_backend->write(offset, data);

    [[nodiscard]] QIOWriteOperation *write(qint64 offset, QByteArray &&data)

        checkValid();

        return m_backend->write(offset, std::move(data));

    [[nodiscard]] QIOVectoredReadOperation *readInto(qint64 offset, QSpan<std::byte> buffer)

        checkValid();

        return m_backend->readInto(offset, buffer);

    [[nodiscard]] QIOVectoredWriteOperation *writeFrom(qint64 offset, QSpan<const std::byte> buffer)

        checkValid();

        return m_backend->writeFrom(offset, buffer);

    [[nodiscard]] QIOVectoredReadOperation *readInto(qint64 offset,

                                                     QSpan<const QSpan<std::byte>> buffers)

        checkValid();

        return m_backend->readInto(offset, buffers);

    [[nodiscard]] QIOVectoredWriteOperation *writeFrom(qint64 offset,

                                                       QSpan<const QSpan<const std::byte>> buffers)

        checkValid();

        return m_backend->writeFrom(offset, buffers);

private:

    void checkValid() const { Q_ASSERT(m_backend); }

    std::unique_ptr<QRandomAccessAsyncFileBackend> m_backend;

};

#if defined(QT_RANDOMACCESSASYNCFILE_QIORING) || defined(Q_OS_DARWIN)

class QRandomAccessAsyncFileNativeBackend final : public QRandomAccessAsyncFileBackend

    Q_DISABLE_COPY_MOVE(QRandomAccessAsyncFileNativeBackend)

public:

    explicit QRandomAccessAsyncFileNativeBackend(QRandomAccessAsyncFile *owner);

    ~QRandomAccessAsyncFileNativeBackend();

    bool init() override;

    void cancelAndWait(QIOOperation *op) override;

    void close() override;

    qint64 size() const override;

    [[nodiscard]] QIOOperation *open(const QString &path, QIODeviceBase::OpenMode mode) override;

    [[nodiscard]] QIOOperation *flush() override;

    [[nodiscard]] QIOReadOperation *read(qint64 offset, qint64 maxSize) override;

    [[nodiscard]] QIOWriteOperation *write(qint64 offset, const QByteArray &data) override;

    [[nodiscard]] QIOWriteOperation *write(qint64 offset, QByteArray &&data) override;

    [[nodiscard]] QIOVectoredReadOperation *

    readInto(qint64 offset, QSpan<std::byte> buffer) override;

    [[nodiscard]] QIOVectoredWriteOperation *

    writeFrom(qint64 offset, QSpan<const std::byte> buffer) override;

    [[nodiscard]] QIOVectoredReadOperation *

    readInto(qint64 offset, QSpan<const QSpan<std::byte>> buffers) override;

    [[nodiscard]] QIOVectoredWriteOperation *

    writeFrom(qint64 offset, QSpan<const QSpan<const std::byte>> buffers) override;

private:

#if defined(QT_RANDOMACCESSASYNCFILE_QIORING)

    void queueCompletion(QIOOperationPrivate *priv, QIOOperation::Error error);

    void startReadIntoSingle(QIOOperation *op, const QSpan<std::byte> &to);

    void startWriteFromSingle(QIOOperation *op, const QSpan<const std::byte> &from);

    QIORing::RequestHandle cancel(QIORing::RequestHandle handle);

    QIORing *m_ioring = nullptr;

    qintptr m_fd = -1;

    QList<QPointer<QIOOperation>> m_operations;

    QHash<QIOOperation *, QIORing::RequestHandle> m_opHandleMap;

#endif

#ifdef Q_OS_DARWIN

    using OperationId = quint64;

    static constexpr OperationId kInvalidOperationId = 0;

    static constexpr OperationId kAllOperationIds = std::numeric_limits<OperationId>::max();

    struct OperationResult

        OperationId opId;

        qint64 result; // num bytes processed or file descriptor

        int error;

};

    enum class OpState : quint8

        Pending,

        Running,

};

    struct OperationInfo

        OperationId opId;

        dispatch_io_t channel;

        QPointer<QIOOperation> operation;

        OpState state;

        OperationInfo(OperationId _id, QIOOperation *_op)

            : opId(_id),

              channel(nullptr),

              operation(_op),

              state(OpState::Pending)

{}

};

    // We need to maintain an actual queue of the operations, because

    // certain operations (i.e. flush) should act like barriers. The docs

    // for dispatch_io_barrier mention that it can synchronize between multiple

    // channels handling the same file descriptor, but that DOES NOT work in

    // practice. It works correctly only when there's a signle IO channel. But

    // with a signle IO channel we're not able to cancel individual operations.

    // As a result, we need to make sure that all previous operations are

    // completed before starting a barrier operation. Similarly, we cannot start

    // any other operation until a barrier operation is finished.

    QList<OperationInfo> m_operations;

    dispatch_io_t m_ioChannel = nullptr;

    int m_fd = -1;

    QMutex m_mutex;

    // the members below should only be accessed with the mutex

    OperationId m_opToCancel = kInvalidOperationId;

    QSet<OperationId> m_runningOps;

    qsizetype m_numChannelsToClose = 0;

    QWaitCondition m_cancellationCondition;

    static OperationId getNextId();

    template <typename Operation, typename ...Args>

    Operation *addOperation(QIOOperation::Type type, qint64 offset, Args &&...args);

    void notifyIfOperationsAreCompleted();

    dispatch_io_t createMainChannel(int fd);

    dispatch_io_t duplicateIoChannel(OperationId opId);

    void closeIoChannel(dispatch_io_t channel);

    void releaseIoChannel(dispatch_io_t channel);

    void handleOperationComplete(const OperationResult &opResult);

    void queueCompletion(OperationId opId, int error);

    void startOperationsUntilBarrier();

    void executeRead(OperationInfo &opInfo);

    void executeWrite(OperationInfo &opInfo);

    void executeFlush(OperationInfo &opInfo);

    void executeOpen(OperationInfo &opInfo);

    void readOneBuffer(OperationId opId, qsizetype bufferIdx, qint64 alreadyRead);

    void readOneBufferHelper(OperationId opId, dispatch_io_t channel, qint64 offset,

                             void *bytesPtr, qint64 maxSize, qsizetype currentBufferIdx,

                             qsizetype totalBuffers, qint64 alreadyRead);

    void writeHelper(OperationId opId, dispatch_io_t channel, qint64 offset,

                     dispatch_data_t dataToWrite, qint64 dataSize);

#endif

};

#endif // QIORing || macOS

#if QT_CONFIG(future) && QT_CONFIG(thread)

class QRandomAccessAsyncFileThreadPoolBackend : public QRandomAccessAsyncFileBackend

    Q_DISABLE_COPY_MOVE(QRandomAccessAsyncFileThreadPoolBackend)

public:

    explicit QRandomAccessAsyncFileThreadPoolBackend(QRandomAccessAsyncFile *owner);

    ~QRandomAccessAsyncFileThreadPoolBackend();

    bool init() override;

    void cancelAndWait(QIOOperation *op) override;

    void close() override;

    qint64 size() const override;

    [[nodiscard]] QIOOperation *open(const QString &path, QIODeviceBase::OpenMode mode) override;

    [[nodiscard]] QIOOperation *flush() override;

    [[nodiscard]] QIOReadOperation *read(qint64 offset, qint64 maxSize) override;

    [[nodiscard]] QIOWriteOperation *write(qint64 offset, const QByteArray &data) override;

    [[nodiscard]] QIOWriteOperation *write(qint64 offset, QByteArray &&data) override;

    [[nodiscard]] QIOVectoredReadOperation *

    readInto(qint64 offset, QSpan<std::byte> buffer) override;

    [[nodiscard]] QIOVectoredWriteOperation *

    writeFrom(qint64 offset, QSpan<const std::byte> buffer) override;

    [[nodiscard]] QIOVectoredReadOperation *

    readInto(qint64 offset, QSpan<const QSpan<std::byte>> buffers) override;

    [[nodiscard]] QIOVectoredWriteOperation *

    writeFrom(qint64 offset, QSpan<const QSpan<const std::byte>> buffers) override;

    struct OperationResult

        qint64 bytesProcessed; // either read or written

        QIOOperation::Error error;

};

private:

    mutable QBasicMutex m_engineMutex;

    std::unique_ptr<QFSFileEngine> m_engine;

    QFutureWatcher<OperationResult> m_watcher;

    QQueue<QPointer<QIOOperation>> m_operations;

    QPointer<QIOOperation> m_currentOperation;

    qsizetype numProcessedBuffers = 0;

    void executeNextOperation();

    void processBufferAt(qsizetype idx);

    void processFlush();

    void processOpen();

    void operationComplete();

};

#endif // future && thread

QT_END_NAMESPACE

#endif // QRANDOMACCESSASYNCFILE_P_P_H