QtCore.QSharedMemory Class Reference

The QSharedMemory class provides access to a shared memory segment. More...

Inheritance diagram for QtCore.QSharedMemory:

Collaboration diagram for QtCore.QSharedMemory:

Public Types
enum	AccessMode { ReadOnly = 0, ReadWrite = 1 }
enum	SharedMemoryError {   AlreadyExists = 4, InvalidSize = 2, KeyError = 3, LockError = 6,   NoError = 0, NotFound = 5, OutOfResources = 7, PermissionDenied = 1,   UnknownError = 8 }

Public Member Functions
	QSharedMemory (QObject parent=null)
	QSharedMemory (string key, QObject parent=null)
override void	CreateProxy ()
new bool	Attach (QSharedMemory.AccessMode mode=QSharedMemory.AccessMode.ReadWrite)
new bool	Create (int size, QSharedMemory.AccessMode mode=QSharedMemory.AccessMode.ReadWrite)
new bool	Detach ()
new QSharedMemory.SharedMemoryError	Error ()
new string	ErrorString ()
new bool	IsAttached ()
new bool	Lock ()
new int	Size ()
new bool	Unlock ()
new void	Dispose ()
Public Member Functions inherited from QtCore.QObject
	QObject (QObject parent=null)
new bool	BlockSignals (bool b)
new System.Collections.Generic.List < QObject >	Children ()
new bool	Connect (QObject sender, string signal, string member, Qt.ConnectionType type=Qt.ConnectionType.AutoConnection)
new void	DeleteLater ()
new bool	Disconnect (QObject receiver, string member=null)
new bool	Disconnect (string signal=null, QObject receiver=null, string member=null)
new void	DumpObjectInfo ()
new void	DumpObjectTree ()
new System.Collections.Generic.List < QByteArray >	DynamicPropertyNames ()
virtual bool	OnEvent (QEvent arg1)
virtual bool	EventFilter (QObject arg1, QEvent arg2)
new bool	Inherits (string classname)
new void	InstallEventFilter (QObject arg1)
new bool	IsWidgetType ()
new void	KillTimer (int id)
new object	Property (string name)
new void	RemoveEventFilter (QObject arg1)
new bool	SetProperty (string name, object value)
new void	SetUserData (uint id, QObjectUserData data)
new bool	SignalsBlocked ()
new int	StartTimer (int interval)
new QObjectUserData	UserData (uint id)
new void	Dispose ()
Public Member Functions inherited from QtCore.Qt
delegate QTextStream	FuncQTextStreamQTextStream (QTextStream qTextStream)
delegate string	FuncStringQByteArray (QByteArray qByteArray)
delegate QByteArray	FuncQByteArrayString (string @string)
delegate void	ActionQtMsgTypeString (QtMsgType qtMsgType, string @string)
delegate QObject	FuncQObject ()

Static Public Member Functions
static string	Tr (string s, string c=null)
static string	Tr (string s, string c, int n)
static string	TrUtf8 (string s, string c=null)
static string	TrUtf8 (string s, string c, int n)
Static Public Member Functions inherited from QtCore.QObject
static bool	Connect (QObject sender, QMetaMethod signal, QObject receiver, QMetaMethod method, Qt.ConnectionType type=Qt.ConnectionType.AutoConnection)
static bool	Connect (QObject sender, string signal, QObject receiver, string member, Qt.ConnectionType arg5=Qt.ConnectionType.AutoConnection)
static bool	Disconnect (QObject sender, QMetaMethod signal, QObject receiver, QMetaMethod member)
static bool	Disconnect (QObject sender, string signal, QObject receiver, string member)
static uint	RegisterUserData ()
static string	Tr (string s, string c=null)
static string	Tr (string s, string c, int n)
static string	TrUtf8 (string s, string c=null)
static string	TrUtf8 (string s, string c, int n)
Static Public Member Functions inherited from QtCore.Qt
static QDataStream	Write (QDataStream s, object p)
static QDataStream	Write (QDataStream arg1, QSizeF arg2)
static QTextStream	Write (QTextStream s, Qt.FuncQTextStreamQTextStream f)
static QDataStream	Write (QDataStream arg1, QPoint arg2)
static QDataStream	Write (QDataStream arg1, QLineF arg2)
static QDataStream	Write (QDataStream arg1, QPointF arg2)
static QDataStream	Write (QDataStream arg1, QChar arg2)
static QDataStream	Write (QDataStream arg1, QByteArray arg2)
static QDataStream	Write (QDataStream arg1, QEasingCurve arg2)
static QDataStream	Write (QDataStream arg1, QRectF arg2)
static QDataStream	Write (QDataStream arg1, QDateTime arg2)
static QDataStream	Write (QDataStream arg1, QUrl arg2)
static QDataStream	Write (QDataStream arg1, QTime arg2)
static QDataStream	Write (QDataStream arg1, QLocale arg2)
static QDataStream	Write (QDataStream arg1, QBitArray arg2)
static QDataStream	Write (QDataStream arg1, QUuid arg2)
static QDataStream	Write (QDataStream arg1, QLine arg2)
static QDataStream	Write (QDataStream arg1, QDate arg2)
static QDataStream	Write (QDataStream @out, QRegExp regExp)
static QDataStream	Write (QDataStream arg1, QRect arg2)
static QDataStream	Write (QDataStream arg1, QSize arg2)
static QDataStream	Write (QDataStream s, QVariant.Type p)
static QDataStream	Write (QDataStream arg1, string arg2)
static QDataStream	Write (QDataStream @out, System.Collections.Generic.List< string > list)
static QDataStream	Read (QDataStream arg1, QChar arg2)
static QDataStream	Read (QDataStream arg1, QLocale arg2)
static QDataStream	Read (QDataStream arg1, QRect arg2)
static QDataStream	Read (QDataStream arg1, QEasingCurve arg2)
static QDataStream	Read (QDataStream arg1, QDate arg2)
static QDataStream	Read (QDataStream arg1, QUrl arg2)
static QDataStream	Read (QDataStream arg1, QUuid arg2)
static QTextStream	Read (QTextStream s, Qt.FuncQTextStreamQTextStream f)
static QDataStream	Read (QDataStream arg1, QLineF arg2)
static QDataStream	Read (QDataStream arg1, QRectF arg2)
static QDataStream	Read (QDataStream arg1, QPointF arg2)
static QDataStream	Read (QDataStream arg1, QLine arg2)
static QDataStream	Read (QDataStream arg1, QBitArray arg2)
static QDataStream	Read (QDataStream arg1, QSize arg2)
static QDataStream	Read (QDataStream arg1, QDateTime arg2)
static QDataStream	Read (QDataStream arg1, QTime arg2)
static QDataStream	Read (QDataStream arg1, QPoint arg2)
static QDataStream	Read (QDataStream @in, QRegExp regExp)
static QDataStream	Read (QDataStream s, object p)
static QDataStream	Read (QDataStream arg1, QByteArray arg2)
static QDataStream	Read (QDataStream arg1, QSizeF arg2)
static QDataStream	Read (QDataStream arg1, string arg2)
static QDataStream	Read (QDataStream s, QVariant.Type p)
static QDataStream	Read (QDataStream @in, System.Collections.Generic.List< string > list)
static double	qAcos (double v)
static void	qAddPostRoutine (System.Action arg1)
static string	qAppName ()
static double	qAsin (double v)
static double	qAtan (double v)
static double	qAtan2 (double x, double y)
static void	qBadAlloc ()
static int	qCeil (double v)
static ushort	qChecksum (string s, uint len)
static QByteArray	qCompress (QByteArray data)
static QByteArray	qCompress (QByteArray data, int compressionLevel=-1)
static QByteArray	qCompress (Pointer< byte > data, int nbytes)
static QByteArray	qCompress (Pointer< byte > data, int nbytes, int compressionLevel=-1)
static double	qCos (double v)
static double	qExp (double v)
static double	qFabs (double v)
static double	qFastCos (double x)
static double	qFastSin (double x)
static string	qFlagLocation (string method)
static int	qFloor (double v)
static bool	qFuzzyCompare (double p1, double p2)
static bool	qFuzzyCompare (float p1, float p2)
static bool	qFuzzyIsNull (double d)
static bool	qFuzzyIsNull (float f)
static uint	qHash (QBitArray key)
static uint	qHash (QChar key)
static uint	qHash (QStringRef key)
static uint	qHash (QUrl url)
static uint	qHash (QPersistentModelIndex index)
static uint	qHash (QByteArray key)
static uint	qHash (QModelIndex index)
static uint	qHash (uint key)
static uint	qHash (sbyte key)
static uint	qHash (byte key)
static uint	qHash (short key)
static uint	qHash (NativeLong key)
static uint	qHash (ushort key)
static uint	qHash (long key)
static uint	qHash (ulong key)
static uint	qHash (int key)
static uint	qHash (string key)
static uint	qHash (NativeULong key)
static double	qInf ()
static Qt.ActionQtMsgTypeString	qInstallMsgHandler (Qt.ActionQtMsgTypeString arg1)
static int	qIntCast (float f)
static int	qIntCast (double f)
static bool	qIsFinite (double d)
static bool	qIsFinite (float f)
static bool	qIsInf (float f)
static bool	qIsInf (double d)
static bool	qIsNaN (float f)
static bool	qIsNaN (double d)
static bool	qIsNull (float f)
static bool	qIsNull (double d)
static double	qLn (double v)
static double	qPow (double x, double y)
static double	qQNaN ()
static void	qRegisterStaticPluginInstanceFunction (Qt.FuncQObject function)
static void	qRemovePostRoutine (System.Action arg1)
static int	qRound (double d)
static long	qRound64 (double d)
static double	qSNaN ()
static bool	qSharedBuild ()
static double	qSin (double v)
static double	qSqrt (double v)
static bool	qStringComparisonHelper (QStringRef s1, string s2)
static double	qTan (double v)
static QByteArray	qUncompress (QByteArray data)
static QByteArray	qUncompress (Pointer< byte > data, int nbytes)
static string	qVersion ()
static void	Qbswap_helper (Pointer< byte > src, Pointer< byte > dest, int size)
static QByteArray	Qgetenv (string varName)
static bool	Qputenv (string varName, QByteArray value)
static int	Qrand ()
static void	Qsrand (uint seed)
static int	Qstrcmp (QByteArray str1, QByteArray str2)
static int	Qstrcmp (QByteArray str1, string str2)
static int	Qstrcmp (string str1, QByteArray str2)
static int	Qstrcmp (string str1, string str2)
static Pointer< sbyte >	Qstrcpy (Pointer< sbyte > dst, string src)
static Pointer< sbyte >	Qstrdup (string arg1)
static int	Qstricmp (string arg1, string arg2)
static uint	Qstrlen (string str)
static int	Qstrncmp (string str1, string str2, uint len)
static Pointer< sbyte >	Qstrncpy (Pointer< sbyte > dst, string src, uint len)
static int	Qstrnicmp (string arg1, string arg2, uint len)
static uint	Qstrnlen (string str, uint maxlen)
static string	QtTrId (string id, int n=-1)

Protected Member Functions
	QSharedMemory (System.Type dummy)
Protected Member Functions inherited from QtCore.QObject
	QObject (System.Type dummy)
virtual void	OnChildEvent (QChildEvent arg1)
virtual void	ConnectNotify (string signal)
virtual void	OnCustomEvent (QEvent arg1)
new void	OnDestroyed (QObject arg1=null)
virtual void	DisconnectNotify (string signal)
new int	Receivers (string signal)
new QObject	Sender ()
new int	SenderSignalIndex ()
virtual void	OnTimerEvent (QTimerEvent arg1)

Properties
new string	Key [get, set]
new string	NativeKey [get, set]
static new QMetaObject	StaticMetaObject [get]
new IQSharedMemorySignals	Emit [get]
Properties inherited from QtCore.QObject
virtual EventHandler < QEventArgs< QChildEvent > >	ChildEvent
virtual EventHandler < QEventArgs< QEvent > >	CustomEvent
virtual EventHandler < QEventArgs< QEvent > >	Event
virtual EventHandler < QEventArgs< QTimerEvent > >	TimerEvent
Slot< QObject >	DestroyedQObject
Slot	Destroyed
new QObject	Parent [get, set]
virtual System.IntPtr	SmokeObject [get, set]
new string	ObjectName [get, set]
static new QMetaObject	StaticMetaObject [get]
static new QMetaObject	StaticQtMetaObject [get]
new IQObjectSignals	Emit [get]

Additional Inherited Members
Protected Attributes inherited from QtCore.QObject
object	Q_EMIT = null
SmokeInvocation	interceptor
readonly List< QEventHandler >	eventFilters = new List<QEventHandler>()

Detailed Description

The QSharedMemory class provides access to a shared memory segment.

QSharedMemory provides access to a shared memory segment by multiple threads and processes. It also provides a way for a single thread or process to lock the memory for exclusive access.

When using this class, be aware of the following platform differences:

Windows: QSharedMemory does not "own" the shared memory segment. When all threads or processes that have an instance of QSharedMemory attached to a particular shared memory segment have either destroyed their instance of QSharedMemory or exited, the Windows kernel releases the shared memory segment automatically.

Unix: QSharedMemory "owns" the shared memory segment. When the last thread or process that has an instance of QSharedMemory attached to a particular shared memory segment detaches from the segment by destroying its instance of QSharedMemory, the Unix kernel release the shared memory segment. But if that last thread or process crashes without running the QSharedMemory destructor, the shared memory segment survives the crash.

QNX: Due to possible race conditions in the POSIX IPC implementation, create() should be called prior to any attach() calls (even across multiple threads).

HP-UX: Only one attach to a shared memory segment is allowed per process. This means that QSharedMemory should not be used across multiple threads in the same process in HP-UX.

Symbian: QSharedMemory does not "own" the shared memory segment. When all threads or processes that have an instance of QSharedMemory attached to a particular shared memory segment have either destroyed their instance of QSharedMemory or exited, the Symbian kernel releases the shared memory segment automatically. Also, access to a shared memory segment cannot be limited to read-only in Symbian.

Remember to lock the shared memory with lock() before reading from or writing to the shared memory, and remember to release the lock with unlock() after you are done.

Unlike QtSharedMemory, QSharedMemory automatically destroys the shared memory segment when the last instance of QSharedMemory is detached from the segment, and no references to the segment remain. Do not mix using QtSharedMemory and QSharedMemory. Port everything to QSharedMemory.

Warning: QSharedMemory changes the key in a Qt-specific way, unless otherwise specified. Interoperation with non-Qt applications is achieved by first creating a default shared memory with QSharedMemory() and then setting a native key with setNativeKey(). When using native keys, shared memory is not protected against multiple accesses on it (e.g. unable to lock()) and a user-defined mechanism should be used to achieve a such protection.

Member Enumeration Documentation

enum QtCore.QSharedMemory.AccessMode

Enumerator:

ReadOnly	The shared memory segment is read-only. Writing to the shared memory segment is not allowed. An attempt to write to a shared memory segment created with ReadOnly causes the program to abort.
ReadWrite	Reading and writing the shared memory segment are both allowed.

enum QtCore.QSharedMemory.SharedMemoryError

Enumerator:

AlreadyExists	A create() operation failed because a shared memory segment with the specified key already existed.
InvalidSize	A create operation failed because the requested size was invalid.
KeyError	The operation failed because of an invalid key.
LockError	The attempt to lock() the shared memory segment failed because create() or attach() failed and returned false, or because a system error occurred in QSystemSemaphore::acquire().
NoError	No error occurred.
NotFound	An attach() failed because a shared memory segment with the specified key could not be found.
OutOfResources	A create() operation failed because there was not enough memory available to fill the request.
PermissionDenied	The operation failed because the caller didn't have the required permissions.
UnknownError	Something else happened and it was bad.

Constructor & Destructor Documentation

QtCore.QSharedMemory.QSharedMemory ( System.Type  dummy )

protected

QtCore.QSharedMemory.QSharedMemory

(

QObject

parent = null

)

This function overloads QSharedMemory().

Constructs a shared memory object with the given parent. The shared memory object's key is not set by the constructor, so the shared memory object does not have an underlying shared memory segment attached. The key must be set with setKey() or setNativeKey() before create() or attach() can be used.

See also setKey().

QtCore.QSharedMemory.QSharedMemory	(	string	key,
		QObject	parent = null
	)

Constructs a shared memory object with the given parent and with its key set to key. Because its key is set, its create() and attach() functions can be called.

See also setKey(), create(), and attach().

Member Function Documentation

new bool QtCore.QSharedMemory.Attach

(

QSharedMemory.AccessMode

mode = QSharedMemory.AccessMode.ReadWrite

)

Attempts to attach the process to the shared memory segment identified by the key that was passed to the constructor or to a call to setKey() or setNativeKey(). The access mode is ReadWrite by default. It can also be ReadOnly. Returns true if the attach operation is successful. If false is returned, call error() to determine which error occurred. After attaching the shared memory segment, a pointer to the shared memory can be obtained by calling data().

See also isAttached(), detach(), and create().

new bool QtCore.QSharedMemory.Create	(	int	size,
		QSharedMemory.AccessMode	mode = QSharedMemory.AccessMode.ReadWrite
	)

Creates a shared memory segment of size bytes with the key passed to the constructor, set with setKey() or set with setNativeKey(), then attaches to the new shared memory segment with the given access mode and returns true. If a shared memory segment identified by the key already exists, the attach operation is not performed and false is returned. When the return value is false, call error() to determine which error occurred.

See also error().

override void QtCore.QSharedMemory.CreateProxy ( )

virtual

Reimplemented from QtCore.QObject.

new bool QtCore.QSharedMemory.Detach

(

)

Detaches the process from the shared memory segment. If this was the last process attached to the shared memory segment, then the shared memory segment is released by the system, i.e., the contents are destroyed. The function returns true if it detaches the shared memory segment. If it returns false, it usually means the segment either isn't attached, or it is locked by another process.

See also attach() and isAttached().

new void QtCore.QSharedMemory.Dispose

(

)

new QSharedMemory.SharedMemoryError QtCore.QSharedMemory.Error

(

)

Returns a value indicating whether an error occurred, and, if so, which error it was.

See also errorString().

new string QtCore.QSharedMemory.ErrorString

(

)

Returns a text description of the last error that occurred. If error() returns an error value, call this function to get a text string that describes the error.

See also error().

new bool QtCore.QSharedMemory.IsAttached

(

)

Returns true if this process is attached to the shared memory segment.

See also attach() and detach().

new bool QtCore.QSharedMemory.Lock

(

)

This is a semaphore that locks the shared memory segment for access by this process and returns true. If another process has locked the segment, this function blocks until the lock is released. Then it acquires the lock and returns true. If this function returns false, it means that you have ignored a false return from create() or attach(), that you have set the key with setNativeKey() or that QSystemSemaphore::acquire() failed due to an unknown system error.

See also unlock(), data(), and QSystemSemaphore::acquire().

new int QtCore.QSharedMemory.Size

(

)

Returns the size of the attached shared memory segment. If no shared memory segment is attached, 0 is returned.

See also create() and attach().

static string QtCore.QSharedMemory.Tr ( string  s, string  c = null  )

static

static string QtCore.QSharedMemory.Tr ( string  s, string  c, int  n  )

static

static string QtCore.QSharedMemory.TrUtf8 ( string  s, string  c = null  )

static

static string QtCore.QSharedMemory.TrUtf8 ( string  s, string  c, int  n  )

static

new bool QtCore.QSharedMemory.Unlock

(

)

Releases the lock on the shared memory segment and returns true, if the lock is currently held by this process. If the segment is not locked, or if the lock is held by another process, nothing happens and false is returned.

See also lock().

Property Documentation

new IQSharedMemorySignals QtCore.QSharedMemory.Emit

getprotected

new string QtCore.QSharedMemory.Key

getset

Returns the key assigned with setKey() to this shared memory, or a null key if no key has been assigned, or if the segment is using a nativeKey(). The key is the identifier used by Qt applications to identify the shared memory segment.

You can find the native, platform specific, key used by the operating system by calling nativeKey().

Sets the platform independent key for this shared memory object. If key is the same as the current key, the function returns without doing anything.

You can call key() to retrieve the platform independent key. Internally, QSharedMemory converts this key into a platform specific key. If you instead call nativeKey(), you will get the platform specific, converted key.

If the shared memory object is attached to an underlying shared memory segment, it will detach from it before setting the new key. This function does not do an attach().

new string QtCore.QSharedMemory.NativeKey

getset

Returns the native, platform specific, key for this shared memory object. The native key is the identifier used by the operating system to identify the shared memory segment.

You can use the native key to access shared memory segments that have not been created by Qt, or to grant shared memory access to non-Qt applications.

This function was introduced in Qt 4.8.

Sets the native, platform specific, key for this shared memory object. If key is the same as the current native key, the function returns without doing anything. If all you want is to assign a key to a segment, you should call setKey() instead.

You can call nativeKey() to retrieve the native key. If a native key has been assigned, calling key() will return a null string.

If the shared memory object is attached to an underlying shared memory segment, it will detach from it before setting the new key. This function does not do an attach().

The application will not be portable if you set a native key.

This function was introduced in Qt 4.8.

new QMetaObject QtCore.QSharedMemory.StaticMetaObject

staticget