KAutoSaveFile

#include <KAutoSaveFile>

Inheritance diagram for KAutoSaveFile:

[legend]

Public Member Functions
	KAutoSaveFile (const QUrl &filename, QObject *parent=nullptr)

	KAutoSaveFile (QObject *parent=nullptr)

	~KAutoSaveFile () override

QUrl	managedFile () const

bool	open (OpenMode openmode) override

virtual void	releaseLock ()

void	setManagedFile (const QUrl &filename)

Public Member Functions inherited from QFile
	QFile (const QString &name)

	QFile (const QString &name, QObject *parent)

	QFile (const std::filesystem::path &name)

	QFile (const std::filesystem::path &name, QObject *parent)

	QFile (QObject *parent)

bool	copy (const QString &newName)

bool	copy (const std::filesystem::path &newName)

bool	exists () const const

virtual QString	fileName () const const override

std::filesystem::path	filesystemFileName () const const

std::filesystem::path	filesystemSymLinkTarget () const const

bool	link (const QString &linkName)

bool	link (const std::filesystem::path &newName)

bool	moveToTrash ()

bool	open (FILE *fh, OpenMode mode, FileHandleFlags handleFlags)

bool	open (int fd, OpenMode mode, FileHandleFlags handleFlags)

bool	open (OpenMode mode, Permissions permissions)

virtual Permissions	permissions () const const override

bool	remove ()

bool	rename (const QString &newName)

bool	rename (const std::filesystem::path &newName)

virtual bool	resize (qint64 sz) override

void	setFileName (const QString &name)

void	setFileName (const std::filesystem::path &name)

virtual bool	setPermissions (Permissions permissions) override

virtual qint64	size () const const override

QString	symLinkTarget () const const

Public Member Functions inherited from QFileDevice
virtual bool	atEnd () const const override

virtual void	close () override

FileError	error () const const

QDateTime	fileTime (QFileDevice::FileTime time) const const

bool	flush ()

int	handle () const const

virtual bool	isSequential () const const override

uchar *	map (qint64 offset, qint64 size, MemoryMapFlags flags)

virtual qint64	pos () const const override

virtual bool	seek (qint64 pos) override

bool	setFileTime (const QDateTime &newDate, QFileDevice::FileTime fileTime)

bool	unmap (uchar *address)

void	unsetError ()

Public Member Functions inherited from QIODevice
	QIODevice (QObject *parent)

void	aboutToClose ()

virtual qint64	bytesAvailable () const const

virtual qint64	bytesToWrite () const const

void	bytesWritten (qint64 bytes)

virtual bool	canReadLine () const const

void	channelBytesWritten (int channel, qint64 bytes)

void	channelReadyRead (int channel)

void	commitTransaction ()

int	currentReadChannel () const const

int	currentWriteChannel () const const

QString	errorString () const const

bool	getChar (char *c)

bool	isOpen () const const

bool	isReadable () const const

bool	isTextModeEnabled () const const

bool	isTransactionStarted () const const

bool	isWritable () const const

QIODeviceBase::OpenMode	openMode () const const

qint64	peek (char *data, qint64 maxSize)

QByteArray	peek (qint64 maxSize)

bool	putChar (char c)

qint64	read (char *data, qint64 maxSize)

QByteArray	read (qint64 maxSize)

QByteArray	readAll ()

int	readChannelCount () const const

void	readChannelFinished ()

qint64	readLine (char *data, qint64 maxSize)

QByteArray	readLine (qint64 maxSize)

void	readyRead ()

virtual bool	reset ()

void	rollbackTransaction ()

void	setCurrentReadChannel (int channel)

void	setCurrentWriteChannel (int channel)

void	setTextModeEnabled (bool enabled)

qint64	skip (qint64 maxSize)

void	startTransaction ()

void	ungetChar (char c)

virtual bool	waitForBytesWritten (int msecs)

virtual bool	waitForReadyRead (int msecs)

qint64	write (const char *data)

qint64	write (const char *data, qint64 maxSize)

qint64	write (const QByteArray &data)

int	writeChannelCount () const const

Public Member Functions inherited from QObject
	QObject (QObject *parent)

QBindable< QString >	bindableObjectName ()

bool	blockSignals (bool block)

const QObjectList &	children () const const

QMetaObject::Connection	connect (const QObject sender, const char signal, const char *method, Qt::ConnectionType type) const const

void	deleteLater ()

void	destroyed (QObject *obj)

bool	disconnect (const char signal, const QObject receiver, const char *method) const const

bool	disconnect (const QObject receiver, const char method) const const

void	dumpObjectInfo () const const

void	dumpObjectTree () const const

QList< QByteArray >	dynamicPropertyNames () const const

virtual bool	event (QEvent *e)

virtual bool	eventFilter (QObject watched, QEvent event)

T	findChild (const QString &name, Qt::FindChildOptions options) const const

QList< T >	findChildren (const QRegularExpression &re, Qt::FindChildOptions options) const const

QList< T >	findChildren (const QString &name, Qt::FindChildOptions options) const const

QList< T >	findChildren (Qt::FindChildOptions options) const const

bool	inherits (const char *className) const const

void	installEventFilter (QObject *filterObj)

bool	isQuickItemType () const const

bool	isWidgetType () const const

bool	isWindowType () const const

void	killTimer (int id)

virtual const QMetaObject *	metaObject () const const

void	moveToThread (QThread *targetThread)

QString	objectName () const const

void	objectNameChanged (const QString &objectName)

QObject *	parent () const const

QVariant	property (const char *name) const const

	Q_CLASSINFO (Name, Value)

	Q_EMIT Q_EMIT

	Q_ENUM (...)

	Q_ENUM_NS (...)

	Q_ENUMS (...)

	Q_FLAG (...)

	Q_FLAG_NS (...)

	Q_FLAGS (...)

	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 (const QObject *object)

T	qobject_cast (QObject *object)

	QT_NO_NARROWING_CONVERSIONS_IN_CONNECT QT_NO_NARROWING_CONVERSIONS_IN_CONNECT

void	removeEventFilter (QObject *obj)

void	setObjectName (const QString &name)

void	setObjectName (QAnyStringView name)

void	setParent (QObject *parent)

bool	setProperty (const char *name, const QVariant &value)

bool	setProperty (const char *name, QVariant &&value)

bool	signalsBlocked () const const

int	startTimer (int interval, Qt::TimerType timerType)

int	startTimer (std::chrono::milliseconds interval, Qt::TimerType timerType)

QThread *	thread () const const

Static Public Member Functions
static QList< KAutoSaveFile * >	allStaleFiles (const QString &applicationName=QString())

static QList< KAutoSaveFile * >	staleFiles (const QUrl &url, const QString &applicationName=QString())

Static Public Member Functions inherited from QFile
bool	copy (const QString &fileName, const QString &newName)

QString	decodeName (const char *localFileName)

QString	decodeName (const QByteArray &localFileName)

QByteArray	encodeName (const QString &fileName)

bool	exists (const QString &fileName)

std::filesystem::path	filesystemSymLinkTarget (const std::filesystem::path &fileName)

bool	link (const QString &fileName, const QString &linkName)

bool	moveToTrash (const QString &fileName, QString *pathInTrash)

Permissions	permissions (const QString &fileName)

Permissions	permissions (const std::filesystem::path &filename)

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, Permissions permissions)

bool	setPermissions (const std::filesystem::path &filename, Permissions permissionSpec)

QString	symLinkTarget (const QString &fileName)

Static Public Member Functions inherited from QObject
QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char 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, 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, PointerToMemberFunction signal, Functor functor)

bool	disconnect (const QMetaObject::Connection &connection)

bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char method)

bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method)

bool	disconnect (const QObject sender, PointerToMemberFunction signal, const QObject receiver, PointerToMemberFunction method)

QString	tr (const char sourceText, const char disambiguation, int n)

Additional Inherited Members
Public Types inherited from QFileDevice
enum	FileError

enum	FileHandleFlag

typedef	FileHandleFlags

enum	FileTime

enum	MemoryMapFlag

typedef	MemoryMapFlags

enum	Permission

typedef	Permissions

Public Types inherited from QObject
typedef	QObjectList

Public Types inherited from QIODeviceBase
typedef	OpenMode

enum	OpenModeFlag

Properties inherited from QObject
	objectName

Public Attributes inherited from QFileDevice
	AbortError

	AutoCloseHandle

	CopyError

	DontCloseHandle

	ExeGroup

	ExeOther

	ExeOwner

	ExeUser

	FatalError

	FileAccessTime

	FileBirthTime

	FileMetadataChangeTime

	FileModificationTime

	MapPrivateOption

	NoError

	NoOptions

	OpenError

	PermissionsError

	PositionError

	ReadError

	ReadGroup

	ReadOther

	ReadOwner

	ReadUser

	RemoveError

	RenameError

	ResizeError

	ResourceError

	TimeOutError

	UnspecifiedError

	WriteError

	WriteGroup

	WriteOther

	WriteOwner

	WriteUser

Public Attributes inherited from QIODeviceBase
	Append

	ExistingOnly

	NewOnly

	NotOpen

	ReadOnly

	ReadWrite

	Text

	Truncate

	Unbuffered

	WriteOnly

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
void	setErrorString (const QString &str)

void	setOpenMode (QIODeviceBase::OpenMode openMode)

virtual qint64	skipData (qint64 maxSize)

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)

bool	isSignalConnected (const QMetaMethod &signal) const const

int	receivers (const char *signal) const const

QObject *	sender () const const

int	senderSignalIndex () const const

virtual void	timerEvent (QTimerEvent *event)

Detailed Description

Creates and manages a temporary "auto-save" file.

Autosave files are temporary files that applications use to store the unsaved data in a file they have open for editing. KAutoSaveFile allows you to easily create and manage such files, as well as to recover the unsaved data left over by a crashed or otherwise gone process.

Each KAutoSaveFile object is associated with one specific file that the application holds open. KAutoSaveFile is also a QObject, so it can be reparented to the actual opened file object, so as to manage the lifetime of the temporary file.

Typical use consists of:

verifying whether stale autosave files exist for the opened file
deciding whether to recover the old, autosaved data
if not recovering, creating a KAutoSaveFile object for the opened file
during normal execution of the program, periodically save unsaved data into the KAutoSaveFile file.

KAutoSaveFile holds a lock on the autosave file, so it's safe to delete the file and recreate it later. Because of that, disposing of stale autosave files should be done with releaseLock(). No lock is held on the managed file.

Examples: Opening a new file:

void Document::open(const QUrl &url)
{
    // check whether autosave files exist:
    const QList<KAutoSaveFile *> staleFiles = KAutoSaveFile::staleFiles(url);
    if (!staleFiles.isEmpty()) {
        if (KMessageBox::questionTwoActions(parent,
                                            "Auto-saved files exist. Do you want to recover them now?",
                                            "File Recovery",
                                            KGuiItem("Recover"), KGuiItem("Do Not recover")) == KMessageBox::PrimaryAction) {
            recoverFiles(staleFiles);
            return;
        } else {
            // remove the stale files
            for (KAutoSaveFile *stale : staleFiles) {
                stale->open(QIODevice::ReadWrite);
                delete stale;
            }
        }
    }
 
    // create new autosave object
    m_autosave = new KAutoSaveFile(url, this);
 
    // continue the process of opening file 'url'
    ...
}

The function recoverFiles could loop over the list of files and do this:

for (KAutoSaveFile *stale : staleFiles) {
    if (!stale->open(QIODevice::ReadWrite)) {
        // show an error message; we could not steal the lockfile
        // maybe another application got to the file before us?
        delete stale;
        continue;
    }
    Document *doc = new Document;
    doc->m_autosave = stale;
    stale->setParent(doc); // reparent
 
    doc->setUrl(stale->managedFile());
    doc->setContents(stale->readAll());
    doc->setState(Document::Modified); // mark it as modified and unsaved
 
    documentManager->addDocument(doc);
}

If the file is unsaved, periodically write the contents to the save file:

if (!m_autosave->isOpen() && !m_autosave->open(QIODevice::ReadWrite)) {
    // show error: could not open the autosave file
}
m_autosave->write(contents());

When the user saves the file, the autosaved file is no longer necessary and can be removed or emptied.

m_autosave->resize(0); // leaves the file open

m_autosave->remove(); // closes the file

Author: Jacob R Rideout kde@j.nosp@m.acob.nosp@m.rideo.nosp@m.ut.n.nosp@m.et

Definition at line 120 of file kautosavefile.h.

Constructor & Destructor Documentation

◆ KAutoSaveFile() [1/2]

KAutoSaveFile::KAutoSaveFile	(	const QUrl &	filename,
		QObject *	parent = nullptr )

explicit

Constructs a KAutoSaveFile for file filename.

The temporary file is not opened or created until actually needed. The file filename does not have to exist for KAutoSaveFile to be constructed (if it exists, it will not be touched).

Parameters

filename	the filename that this KAutoSaveFile refers to
parent	the parent object

Definition at line 85 of file kautosavefile.cpp.

◆ KAutoSaveFile() [2/2]

KAutoSaveFile::KAutoSaveFile ( QObject * parent = nullptr )

explicit

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

Note that you need to call setManagedFile() before calling open().

Parameters

parent the parent object

Definition at line 92 of file kautosavefile.cpp.

◆ ~KAutoSaveFile()

KAutoSaveFile::~KAutoSaveFile ( )

override

Destroys the KAutoSaveFile object, removes the autosave file and drops the lock being held (if any).

Definition at line 98 of file kautosavefile.cpp.

Member Function Documentation

◆ allStaleFiles()

QList< KAutoSaveFile * > KAutoSaveFile::allStaleFiles ( const QString & applicationName = QString() )

static

Returns all stale autosave files left behind by crashed or otherwise gone instances of this application.

If not given, the application name is obtained from QCoreApplication, so be sure to have set it correctly before calling this function.

See staleFiles() for information on the returned objects.

The application owns all returned KAutoSaveFile objects and is responsible for deleting them when no longer needed. Remember that deleting the KAutoSaveFile will release the file lock and remove the stale autosave file.

Definition at line 227 of file kautosavefile.cpp.

◆ managedFile()

QUrl KAutoSaveFile::managedFile ( ) const

Retrieves the URL of the file managed by KAutoSaveFile.

This is the same URL that was given to setManagedFile() or the KAutoSaveFile constructor.

This is the name of the real file being edited by the application. To get the name of the temporary file where data can be saved, use fileName() (after you have called open()).

Definition at line 104 of file kautosavefile.cpp.

◆ open()

bool KAutoSaveFile::open ( OpenMode openmode )

overridevirtual

Opens the autosave file and locks it if it wasn't already locked.

The name of the temporary file where data can be saved to will be set by this function and can be retrieved with fileName(). It will not change unless releaseLock() is called. No other application will attempt to edit such a file either while the lock is held.

Parameters

openmode the mode that should be used to open the file, probably QIODevice::ReadWrite

Returns: true if the file could be opened (= locked and created), false if the operation failed

Reimplemented from QFile.

Definition at line 128 of file kautosavefile.cpp.

◆ releaseLock()

void KAutoSaveFile::releaseLock ( )

virtual

Closes the autosave file resource and removes the lock file.

The file name returned by fileName() will no longer be protected and can be overwritten by another application at any time. To obtain a new lock, call open() again.

This function calls remove(), so the autosave temporary file will be removed too.

Definition at line 117 of file kautosavefile.cpp.

◆ setManagedFile()

void KAutoSaveFile::setManagedFile ( const QUrl & filename )

Sets the URL of the file managed by KAutoSaveFile.

This should be the name of the real file being edited by the application. If the file was previously set, this function calls releaseLock().

Parameters

filename the filename that this KAutoSaveFile refers to

Definition at line 109 of file kautosavefile.cpp.

◆ staleFiles()

QList< KAutoSaveFile * > KAutoSaveFile::staleFiles	(	const QUrl &	url,
		const QString &	applicationName = QString() )

static

Checks for stale autosave files for the file url.

Returns a list of autosave files that contain autosaved data left behind by other instances of the application, due to crashing or otherwise uncleanly exiting.

It is the application's job to determine what to do with such unsaved data. Generally, this is done by asking the user if he wants to see the recovered data, and then allowing the user to save if he wants to.

If not given, the application name is obtained from QCoreApplication, so be sure to have set it correctly before calling this function.

This function returns a list of unopened KAutoSaveFile objects. By calling open() on them, the application will steal the lock. Subsequent releaseLock() or deleting of the object will then erase the stale autosave file.

Definition at line 199 of file kautosavefile.cpp.

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

KDE's Doxygen guidelines are available online.

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KAutoSaveFile

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ KAutoSaveFile() [1/2]

◆ KAutoSaveFile() [2/2]

◆ ~KAutoSaveFile()

Member Function Documentation

◆ allStaleFiles()

◆ managedFile()

◆ open()

◆ releaseLock()

◆ setManagedFile()

◆ staleFiles()