Nuria::TemporaryBufferDevice Class Reference

In-memory buffer device with fallback to a temporary file. More...

#include <temporarybufferdevice.hpp>

Inheritance diagram for Nuria::TemporaryBufferDevice:

Public Types
enum	{ DefaultMemorySize = 4096 * 1024 }
enum	StorageMode { NoDevice = 0, InMemory, TemporaryFile }

Signals
void	storageModeChanged (Nuria::TemporaryBufferDevice::StorageMode storageMode)

Public Member Functions
	TemporaryBufferDevice (int maximumMemorySize, QObject *parent=0)
	TemporaryBufferDevice (QObject *parent=0)
	~TemporaryBufferDevice () override
bool	atEnd () const
qint64	bytesAvailable () const
qint64	bytesToWrite () const
bool	canReadLine () const
void	close ()
void	discard ()
QIODevice *	internalDevice () const
bool	isSequential () const
int	maximumMemorySize () const
bool	open (OpenMode mode)
qint64	pos () const
bool	reset ()
bool	seek (qint64 pos)
void	setMaximumMemorySize (int maximumSize)
qint64	size () const
QIODevice *	stealInternalDevice ()
StorageMode	storageMode () const
bool	waitForBytesWritten (int msecs)
bool	waitForReadyRead (int msecs)

Protected Member Functions
qint64	readData (char *data, qint64 maxlen)
qint64	readLineData (char *data, qint64 maxlen)
qint64	writeData (const char *data, qint64 len)

Detailed Description

In-memory buffer device with fallback to a temporary file.

This buffer uses internally a QBuffer to store data, but will start using a temporary file as storage when the buffer gets bigger than a given amount of bytes.

See also

DefaultMemorySize

Behaviour

This class acts as usual random-access (i.e. non-sequential) QIODevice for easy and quick storage of temporary data. It will try to use a QBuffer to store the data directly in-memory first. When the data gets bigger than a certain value though, it'll copy the data into a temporary file and begin using it as back-end. This process is completely transparent to the user.

The device itself is usually opened for read and write access. You can change this using open(), though this has no effect on the internal device.

Member Enumeration Documentation

anonymous enum

Enumerator
DefaultMemorySize	Default maximum size of the in-memory buffer.

enum Nuria::TemporaryBufferDevice::StorageMode

Storage mode for the internal device.

Enumerator
NoDevice	The buffer device contains no data.
InMemory	In-memory buffer.
TemporaryFile	Temporary file as buffer.

Constructor & Destructor Documentation

Nuria::TemporaryBufferDevice::TemporaryBufferDevice ( int  maximumMemorySize, QObject *  parent = 0  )

explicit

Constructor. Initializes maximumMemorySize directly.

Nuria::TemporaryBufferDevice::TemporaryBufferDevice ( QObject *  parent = 0 )

explicit

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Nuria::TemporaryBufferDevice::~TemporaryBufferDevice ( )

override

Destructor.

Member Function Documentation

void Nuria::TemporaryBufferDevice::close

(

)

Closes the internal device, deleting all buffered data.

void Nuria::TemporaryBufferDevice::discard

(

)

Discards the internal buffer. Doing so will loose all buffered data.

QIODevice* Nuria::TemporaryBufferDevice::internalDevice

(

)

const

Returns the currently used internal storage device.

Note

Usually you don't need this.

int Nuria::TemporaryBufferDevice::maximumMemorySize

(

)

const

Returns the maximum size of the in-memory buffer. After the buffer grows beyond this barrier, a temporary file will be used instead.

void Nuria::TemporaryBufferDevice::setMaximumMemorySize

(

int

maximumSize

)

Sets the maximum size of the in-memory buffer. The new value is applied immediately, thus if the buffer is exceeding the limit, a temporary file will be used.

QIODevice* Nuria::TemporaryBufferDevice::stealInternalDevice

(

)

Steals the internal storage device from the instance. Ownership of the device is transferred to the caller. The TemporaryBufferDevice instance will act as if it was just created, thus contain no data.

StorageMode Nuria::TemporaryBufferDevice::storageMode

(

)

const

Returns the current storage mode.

void Nuria::TemporaryBufferDevice::storageModeChanged ( Nuria::TemporaryBufferDevice::StorageMode  storageMode )

signal

Triggered when the storage mode has been changed.

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The documentation for this class was generated from the following file:

• temporarybufferdevice.hpp