temporarybufferdevice.hpp

/* Copyright (c) 2014, The Nuria Project
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event will the authors be held liable for any damages
 * arising from the use of this software.
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *    1. The origin of this software must not be misrepresented; you must not
 *       claim that you wrote the original software. If you use this software
 *       in a product, an acknowledgment in the product documentation would be
 *       appreciated but is not required.
 *    2. Altered source versions must be plainly marked as such, and must not be
 *       misrepresented as being the original software.
 *    3. This notice may not be removed or altered from any source
 *       distribution.
 */

#ifndef NURIA_TEMPORARYBUFFERDEVICE_HPP
#define NURIA_TEMPORARYBUFFERDEVICE_HPP

#include "essentials.hpp"
#include <QIODevice>

namespace Nuria {

class TemporaryBufferDevicePrivate;

class NURIA_CORE_EXPORT TemporaryBufferDevice : public QIODevice {
    Q_OBJECT
public:
    enum {
        DefaultMemorySize = 4096 * 1024 // 4MiB
    };
    
    enum StorageMode {
        
        NoDevice = 0,
        
        InMemory,
        
        TemporaryFile
    };
    
    explicit TemporaryBufferDevice (int maximumMemorySize, QObject *parent = 0);
    
    explicit TemporaryBufferDevice (QObject *parent = 0);
    
    ~TemporaryBufferDevice () override;
    
    int maximumMemorySize () const;
    
    void setMaximumMemorySize (int maximumSize);
    
    StorageMode storageMode () const;
    
    QIODevice *internalDevice () const;
    
    QIODevice *stealInternalDevice ();
    
    void discard ();
    
    // 
    bool isSequential () const;
    bool open (OpenMode mode);
    
    void close ();
    qint64 pos () const;
    qint64 size () const;
    bool seek (qint64 pos);
    bool atEnd () const;
    bool reset ();
    qint64 bytesAvailable () const;
    qint64 bytesToWrite () const;
    bool canReadLine () const;
    bool waitForReadyRead (int msecs);
    bool waitForBytesWritten (int msecs);
    
signals:
    
    void storageModeChanged (Nuria::TemporaryBufferDevice::StorageMode storageMode);
    
protected:
    qint64 readData(char *data, qint64 maxlen);
    qint64 readLineData(char *data, qint64 maxlen);
    qint64 writeData(const char *data, qint64 len);
    
private:
    void decideStrategy (int newSize);
    void moveMemoryBufferToFileDevice (QIODevice *memory, QIODevice *file);
    QIODevice *openMemoryBuffer ();
    QIODevice *openFileBuffer ();
    
    TemporaryBufferDevicePrivate *d_ptr;
    
};

}

Q_DECLARE_METATYPE(Nuria::TemporaryBufferDevice::StorageMode)

#endif // NURIA_TEMPORARYBUFFERDEVICE_HPP