A subclass of QFile which writes to a temporary file while it is open, then renames the file when it is closed, so that it overwrites the target file as a single, atomic transaction. More...

#include <atomicfile.h>

Inheritance diagram for swift::misc::CAtomicFile:

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Public Member Functions
	CAtomicFile (const QString &filename)
	~CAtomicFile ()
bool	open (OpenMode mode)
void	close ()
bool	checkedClose ()
	Calls close() and returns false if there was an error at any stage.
void	abandon ()
	Closes the file without renaming it.
FileError	error () const
void	unsetError ()
Public Member Functions inherited from QFile
	QFile (QObject *parent)
	QFile (const QString &name)
	QFile (const QString &name, QObject *parent)
	QFile (const std::filesystem::path &name)
	QFile (const std::filesystem::path &name, QObject *parent)
bool	copy (const QString &newName)
bool	copy (const std::filesystem::path &newName)
bool	link (const QString &linkName)
bool	link (const std::filesystem::path &newName)
bool	moveToTrash ()
bool	open (FILE *fh, QIODeviceBase::OpenMode mode, QFileDevice::FileHandleFlags handleFlags)
virtual bool	open (QIODeviceBase::OpenMode mode) override
bool	open (QIODeviceBase::OpenMode mode, QFileDevice::Permissions permissions)
bool	open (int fd, QIODeviceBase::OpenMode mode, QFileDevice::FileHandleFlags handleFlags)
bool	remove ()
bool	rename (const QString &newName)
bool	rename (const std::filesystem::path &newName)
virtual bool	resize (qint64 sz) override
virtual bool	setPermissions (QFileDevice::Permissions permissions) override
void	setFileName (const QString &name)
void	setFileName (const std::filesystem::path &name)
virtual QFileDevice::Permissions	permissions () const const override
virtual QString	fileName () const const override
QString	symLinkTarget () const const
bool	exists () const const
virtual qint64	size () const const override
std::filesystem::path	filesystemFileName () const const
std::filesystem::path	filesystemSymLinkTarget () const const
Public Member Functions inherited from QFileDevice
	QT_NO_USE_NODISCARD_FILE_OPEN QT_NO_USE_NODISCARD_FILE_OPEN
	QT_USE_NODISCARD_FILE_OPEN QT_USE_NODISCARD_FILE_OPEN
bool	flush ()
virtual bool	seek (qint64 pos) override
bool	setFileTime (const QDateTime &newDate, QFileDevice::FileTime fileTime)
bool	unmap (uchar *address)
uchar *	map (qint64 offset, qint64 size, QFileDevice::MemoryMapFlags flags)
void	unsetError ()
QDateTime	fileTime (QFileDevice::FileTime time) const const
QFileDevice::FileError	error () const const
virtual bool	atEnd () const const override
virtual bool	isSequential () const const override
int	handle () const const
virtual qint64	pos () const const override
Public Member Functions inherited from QIODevice
QByteArray	peek (qint64 maxSize)
QByteArray	read (qint64 maxSize)
QByteArray	readAll ()
QByteArray	readLine (qint64 maxSize)
QByteArrayView	readLineInto (QSpan< char > buffer)
QByteArrayView	readLineInto (QSpan< std::byte > buffer)
QByteArrayView	readLineInto (QSpan< uchar > buffer)
	QIODevice (QObject *parent)
bool	getChar (char *c)
bool	putChar (char c)
bool	readLineInto (QByteArray *line, qint64 maxSize)
virtual bool	reset ()
virtual bool	waitForBytesWritten (int msecs)
virtual bool	waitForReadyRead (int msecs)
qint64	peek (char *data, qint64 maxSize)
qint64	read (char *data, qint64 maxSize)
qint64	readLine (char *data, qint64 maxSize)
qint64	skip (qint64 maxSize)
qint64	write (const QByteArray &data)
qint64	write (const char *data)
qint64	write (const char *data, qint64 maxSize)
void	aboutToClose ()
void	bytesWritten (qint64 bytes)
void	channelBytesWritten (int channel, qint64 bytes)
void	channelReadyRead (int channel)
void	commitTransaction ()
void	readChannelFinished ()
void	readyRead ()
void	rollbackTransaction ()
void	setCurrentReadChannel (int channel)
void	setCurrentWriteChannel (int channel)
void	setTextModeEnabled (bool enabled)
void	startTransaction ()
void	ungetChar (char c)
QIODeviceBase::OpenMode	openMode () const const
QString	errorString () const const
virtual bool	canReadLine () const const
bool	isOpen () const const
bool	isReadable () const const
bool	isTextModeEnabled () const const
bool	isTransactionStarted () const const
bool	isWritable () const const
int	currentReadChannel () const const
int	currentWriteChannel () const const
int	readChannelCount () const const
int	writeChannelCount () const const
virtual qint64	bytesAvailable () const const
virtual qint64	bytesToWrite () const const
Public Member Functions inherited from QObject
QBindable< QString >	bindableObjectName ()
	QObject (QObject *parent)
	QT_NO_CONTEXTLESS_CONNECT QT_NO_CONTEXTLESS_CONNECT
	QT_NO_NARROWING_CONVERSIONS_IN_CONNECT QT_NO_NARROWING_CONVERSIONS_IN_CONNECT
	Q_CLASSINFO (Name, Value)
	Q_EMIT Q_EMIT
	Q_ENUM (...)
	Q_ENUMS (...)
	Q_ENUM_NS (...)
	Q_FLAG (...)
	Q_FLAGS (...)
	Q_FLAG_NS (...)
	Q_GADGET Q_GADGET
	Q_GADGET_EXPORT (EXPORT_MACRO)
	Q_INTERFACES (...)
	Q_INVOKABLE Q_INVOKABLE
	Q_MOC_INCLUDE Q_MOC_INCLUDE
	Q_NAMESPACE Q_NAMESPACE
	Q_NAMESPACE_EXPORT (EXPORT_MACRO)
	Q_OBJECT Q_OBJECT
	Q_PROPERTY (...)
	Q_REVISION Q_REVISION
	Q_SET_OBJECT_NAME (Object)
	Q_SIGNAL Q_SIGNAL
	Q_SIGNALS Q_SIGNALS
	Q_SLOT Q_SLOT
	Q_SLOTS Q_SLOTS
T	qobject_cast (QObject *object)
T	qobject_cast (const QObject *object)
bool	blockSignals (bool block)
virtual bool	event (QEvent *e)
virtual bool	eventFilter (QObject watched, QEvent event)
bool	moveToThread (QThread *targetThread)
bool	setProperty (const char *name, QVariant &&value)
bool	setProperty (const char *name, const QVariant &value)
int	startTimer (int interval, Qt::TimerType timerType)
int	startTimer (std::chrono::nanoseconds interval, Qt::TimerType timerType)
void	deleteLater ()
void	destroyed (QObject *obj)
void	installEventFilter (QObject *filterObj)
void	killTimer (Qt::TimerId id)
void	killTimer (int id)
void	objectNameChanged (const QString &objectName)
void	removeEventFilter (QObject *obj)
void	setObjectName (QAnyStringView name)
void	setObjectName (const QString &name)
void	setParent (QObject *parent)
QList< QByteArray >	dynamicPropertyNames () const const
QList< T >	findChildren (QAnyStringView name, Qt::FindChildOptions options) const const
QList< T >	findChildren (Qt::FindChildOptions options) const const
QList< T >	findChildren (const QRegularExpression &re, Qt::FindChildOptions options) const const
QMetaObject::Connection	connect (const QObject sender, const char signal, const char *method, Qt::ConnectionType type) const const
QObject *	parent () const const
QString	objectName () const const
QThread *	thread () const const
QVariant	property (const char *name) const const
T	findChild (QAnyStringView name, Qt::FindChildOptions options) const const
T	findChild (Qt::FindChildOptions options) const const
bool	disconnect (const QObject receiver, const char method) const const
bool	disconnect (const char signal, const QObject receiver, const char *method) const const
bool	inherits (const char *className) const const
bool	isQmlExposed () const const
bool	isQuickItemType () const const
bool	isWidgetType () const const
bool	isWindowType () const const
bool	signalsBlocked () const const
virtual const QMetaObject *	metaObject () const const
const QObjectList &	children () const const
void	dumpObjectInfo () const const
void	dumpObjectTree () const const

Additional Inherited Members
Public Types inherited from QFileDevice
enum	FileError
enum	FileHandleFlag
enum	FileTime
enum	MemoryMapFlag
enum	Permission
Public Types inherited from QObject
enum	TimerId
Public Types inherited from QIODeviceBase
enum	OpenModeFlag
Static Public Member Functions inherited from QFile
QByteArray	encodeName (const QString &fileName)
QFileDevice::Permissions	permissions (const QString &fileName)
QFileDevice::Permissions	permissions (const std::filesystem::path &filename)
QString	decodeName (const QByteArray &localFileName)
QString	decodeName (const char *localFileName)
QString	symLinkTarget (const QString &fileName)
bool	copy (const QString &fileName, const QString &newName)
bool	exists (const QString &fileName)
bool	link (const QString &fileName, const QString &linkName)
bool	moveToTrash (const QString &fileName, QString *pathInTrash)
bool	remove (const QString &fileName)
bool	rename (const QString &oldName, const QString &newName)
bool	resize (const QString &fileName, qint64 sz)
bool	setPermissions (const QString &fileName, QFileDevice::Permissions permissions)
bool	setPermissions (const std::filesystem::path &filename, QFileDevice::Permissions permissionSpec)
bool	supportsMoveToTrash ()
std::filesystem::path	filesystemSymLinkTarget (const std::filesystem::path &fileName)
Static Public Member Functions inherited from QObject
QMetaObject::Connection	connect (const QObject *sender, PointerToMemberFunction signal, Functor functor)
QMetaObject::Connection	connect (const QObject sender, PointerToMemberFunction signal, const QObject context, Functor functor, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject sender, PointerToMemberFunction signal, const QObject receiver, PointerToMemberFunction method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type)
QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char method, Qt::ConnectionType type)
QString	tr (const char sourceText, const char disambiguation, int n)
bool	disconnect (const QMetaObject::Connection &connection)
bool	disconnect (const QObject sender, PointerToMemberFunction signal, const QObject receiver, PointerToMemberFunction method)
bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method)
bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char method)
Public Attributes inherited from QFileDevice
typedef	FileHandleFlags
typedef	MemoryMapFlags
typedef	Permissions
	NoError
	ReadError
	WriteError
	FatalError
	ResourceError
	OpenError
	AbortError
	TimeOutError
	UnspecifiedError
	RemoveError
	RenameError
	PositionError
	ResizeError
	PermissionsError
	CopyError
	AutoCloseHandle
	DontCloseHandle
	FileAccessTime
	FileBirthTime
	FileMetadataChangeTime
	FileModificationTime
	NoOptions
	MapPrivateOption
	ReadOwner
	WriteOwner
	ExeOwner
	ReadUser
	WriteUser
	ExeUser
	ReadGroup
	WriteGroup
	ExeGroup
	ReadOther
	WriteOther
	ExeOther
Public Attributes inherited from QObject
typedef	QObjectList
	Invalid
Public Attributes inherited from QIODeviceBase
typedef	OpenMode
	NotOpen
	ReadOnly
	WriteOnly
	ReadWrite
	Append
	Truncate
	Text
	Unbuffered
	NewOnly
	ExistingOnly
Protected Member Functions inherited from QFileDevice
virtual qint64	readData (char *data, qint64 len) override
virtual qint64	readLineData (char *data, qint64 maxlen) override
virtual qint64	writeData (const char *data, qint64 len) override
Protected Member Functions inherited from QIODevice
virtual qint64	skipData (qint64 maxSize)
void	setErrorString (const QString &str)
void	setOpenMode (QIODeviceBase::OpenMode openMode)
Protected Member Functions inherited from QObject
virtual void	childEvent (QChildEvent *event)
virtual void	connectNotify (const QMetaMethod &signal)
virtual void	customEvent (QEvent *event)
virtual void	disconnectNotify (const QMetaMethod &signal)
virtual void	timerEvent (QTimerEvent *event)
QObject *	sender () const const
bool	isSignalConnected (const QMetaMethod &signal) const const
int	receivers (const char *signal) const const
int	senderSignalIndex () const const
Properties inherited from QObject
	objectName

Detailed Description

A subclass of QFile which writes to a temporary file while it is open, then renames the file when it is closed, so that it overwrites the target file as a single, atomic transaction.

If the application crashes while data is still being written, the original file is unchanged.

Fixme: Consider using QSaveFile.

Definition at line 25 of file atomicfile.h.

Constructor & Destructor Documentation

◆ CAtomicFile()

swift::misc::CAtomicFile::CAtomicFile ( const QString & filename )

inline

Definition at line 31 of file atomicfile.h.

◆ ~CAtomicFile()

swift::misc::CAtomicFile::~CAtomicFile ( )

Definition at line 83 of file atomicfile.cpp.

Member Function Documentation

◆ abandon()

void swift::misc::CAtomicFile::abandon ( )

Closes the file without renaming it.

Definition at line 117 of file atomicfile.cpp.

◆ checkedClose()

bool swift::misc::CAtomicFile::checkedClose ( )

Calls close() and returns false if there was an error at any stage.

Definition at line 111 of file atomicfile.cpp.

◆ close()

void swift::misc::CAtomicFile::close ( )

virtual

After closing the file, it is renamed so that it overwrites the target file.

Reimplemented from QFileDevice.

Definition at line 91 of file atomicfile.cpp.

◆ error()

CAtomicFile::FileError swift::misc::CAtomicFile::error ( ) const

Definition at line 129 of file atomicfile.cpp.

◆ open()

bool swift::misc::CAtomicFile::open ( OpenMode mode )

Just before opening the file, the filename is changed so we actually write to a temporary file.

Definition at line 47 of file atomicfile.cpp.

◆ unsetError()

void swift::misc::CAtomicFile::unsetError ( )

Definition at line 142 of file atomicfile.cpp.

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

src/misc/atomicfile.h
src/misc/atomicfile.cpp

Public Member Functions

Additional Inherited Members