temporarybufferdevice.hpp

/* Copyright (c) 2014-2015, The Nuria Project
 * The NuriaProject Framework is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * The NuriaProject Framework 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with The NuriaProject Framework.
 * If not, see <http://www.gnu.org/licenses/>.
 */

#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