class QLocalSocket#

The QLocalSocket class provides a local socket. More…

Synopsis#

Properties#

socketOptionsᅟ - The socket options

Methods#

def __init__()
def abort()
def connectToServer()
def disconnectFromServer()
def error()
def flush()
def fullServerName()
def isValid()
def readBufferSize()
def serverName()
def setReadBufferSize()
def setServerName()
def setSocketDescriptor()
def setSocketOptions()
def socketDescriptor()
def socketOptions()
def state()
def waitForConnected()
def waitForDisconnected()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description#

On Windows this is a named pipe and on Unix this is a local domain socket.

If an error occurs, error() returns the type of error, and errorString() can be called to get a human readable description of what happened.

Although QLocalSocket is designed for use with an event loop, it’s possible to use it without one. In that case, you must use waitForConnected() , waitForReadyRead() , waitForBytesWritten() , and waitForDisconnected() which blocks until the operation is complete or the timeout expires.

See also

QLocalServer

class LocalSocketError#

The LocalServerError enumeration represents the errors that can occur. The most recent error can be retrieved through a call to error() .

Constant

Description

QLocalSocket.ConnectionRefusedError

The connection was refused by the peer (or timed out).

QLocalSocket.PeerClosedError

The remote socket closed the connection. Note that the client socket (i.e., this socket) will be closed after the remote close notification has been sent.

QLocalSocket.ServerNotFoundError

The local socket name was not found.

QLocalSocket.SocketAccessError

The socket operation failed because the application lacked the required privileges.

QLocalSocket.SocketResourceError

The local system ran out of resources (e.g., too many sockets).

QLocalSocket.SocketTimeoutError

The socket operation timed out.

QLocalSocket.DatagramTooLargeError

The datagram was larger than the operating system’s limit (which can be as low as 8192 bytes).

QLocalSocket.ConnectionError

An error occurred with the connection.

QLocalSocket.UnsupportedSocketOperationError

The requested socket operation is not supported by the local operating system.

QLocalSocket.OperationError

An operation was attempted while the socket was in a state that did not permit it.

QLocalSocket.UnknownSocketError

An unidentified error occurred.

Constant	Description
QLocalSocket.ConnectionRefusedError	The connection was refused by the peer (or timed out).
QLocalSocket.PeerClosedError	The remote socket closed the connection. Note that the client socket (i.e., this socket) will be closed after the remote close notification has been sent.
QLocalSocket.ServerNotFoundError	The local socket name was not found.
QLocalSocket.SocketAccessError	The socket operation failed because the application lacked the required privileges.
QLocalSocket.SocketResourceError	The local system ran out of resources (e.g., too many sockets).
QLocalSocket.SocketTimeoutError	The socket operation timed out.
QLocalSocket.DatagramTooLargeError	The datagram was larger than the operating system’s limit (which can be as low as 8192 bytes).
QLocalSocket.ConnectionError	An error occurred with the connection.
QLocalSocket.UnsupportedSocketOperationError	The requested socket operation is not supported by the local operating system.
QLocalSocket.OperationError	An operation was attempted while the socket was in a state that did not permit it.
QLocalSocket.UnknownSocketError	An unidentified error occurred.

class LocalSocketState#

This enum describes the different states in which a socket can be.

Constant

Description

QLocalSocket.UnconnectedState

The socket is not connected.

QLocalSocket.ConnectingState

The socket has started establishing a connection.

QLocalSocket.ConnectedState

A connection is established.

QLocalSocket.ClosingState

The socket is about to close (data may still be waiting to be written).

See also

state()

Constant	Description
QLocalSocket.UnconnectedState	The socket is not connected.
QLocalSocket.ConnectingState	The socket has started establishing a connection.
QLocalSocket.ConnectedState	A connection is established.
QLocalSocket.ClosingState	The socket is about to close (data may still be waiting to be written).

class SocketOption#

(inherits enum.Flag) This enum describes the possible options that can be used to connect to a server. Currently, on Linux and Android it is used for specifying connection to a server listening to a socket bound to an abstract address.

Constant

Description

QLocalSocket.NoOptions

No options have been set.

QLocalSocket.AbstractNamespaceOption

The socket will try to connect to an abstract address. This flag is specific to Linux and Android. On other platforms is ignored.

See also

socketOptions

Constant	Description
QLocalSocket.NoOptions	No options have been set.
QLocalSocket.AbstractNamespaceOption	The socket will try to connect to an abstract address. This flag is specific to Linux and Android. On other platforms is ignored.

Note

Properties can be used directly when from __feature__ import true_property is used or via accessor functions otherwise.

property socketOptionsᅟ: Combination of QLocalServer.SocketOption#

This property holds the socket options..

Options must be set while the socket is in UnconnectedState state.

See also

connectToServer()

Access functions:

socketOptions()
setSocketOptions()

__init__([parent=None])#

Parameters:: parent – QObject

Creates a new local socket. The parent argument is passed to QObject’s constructor.

abort()#

Aborts the current connection and resets the socket. Unlike disconnectFromServer() , this function immediately closes the socket, clearing any pending data in the write buffer.

See also

disconnectFromServer() close()

connectToServer([openMode=QIODeviceBase.OpenModeFlag.ReadWrite])#

Parameters:: openMode – Combination of OpenModeFlag

Attempts to make a connection to serverName() . setServerName() must be called before you open the connection. Alternatively you can use connectToServer(const QString &name, OpenMode openMode);

The socket is opened in the given openMode and first enters ConnectingState . If a connection is established, QLocalSocket enters ConnectedState and emits connected() .

After calling this function, the socket can emit errorOccurred() to signal that an error occurred.

See also

state() serverName() waitForConnected()

connectToServer(name[, openMode=QIODeviceBase.OpenModeFlag.ReadWrite])

Parameters:

name – str
openMode – Combination of OpenModeFlag

This is an overloaded function.

Set the server name and attempts to make a connection to it.

The socket is opened in the given openMode and first enters ConnectingState . If a connection is established, QLocalSocket enters ConnectedState and emits connected() .

After calling this function, the socket can emit errorOccurred() to signal that an error occurred.

See also

state() serverName() waitForConnected()

connected()#

This signal is emitted after connectToServer() has been called and a connection has been successfully established.

See also

connectToServer() disconnected()

disconnectFromServer()#

Attempts to close the socket. If there is pending data waiting to be written, QLocalSocket will enter ClosingState and wait until all data has been written. Eventually, it will enter UnconnectedState and emit the disconnected() signal.

See also

connectToServer()

disconnected()#

This signal is emitted when the socket has been disconnected.

See also

connectToServer() disconnectFromServer() abort() connected()

error()#

Return type:: LocalSocketError

Returns the type of error that last occurred.

See also

state() errorString()

errorOccurred(socketError)#

Parameters:: socketError – LocalSocketError

This signal is emitted after an error occurred. The socketError parameter describes the type of error that occurred.

LocalSocketError is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType().

See also

error() errorString()Creating Custom Qt Types

flush()#

Return type:: bool

This function writes as much as possible from the internal write buffer to the socket, without blocking. If any data was written, this function returns true; otherwise false is returned.

Call this function if you need QLocalSocket to start sending buffered data immediately. The number of bytes successfully written depends on the operating system. In most cases, you do not need to call this function, because QLocalSocket will start sending data automatically once control goes back to the event loop. In the absence of an event loop, call waitForBytesWritten() instead.

See also

waitForBytesWritten()

fullServerName()#

Return type:: str

Returns the server path that the socket is connected to.

Note

The return value of this function is platform specific.

See also

connectToServer() serverName()

isValid()#

Return type:: bool

Returns true if the socket is valid and ready for use; otherwise returns false.

Note

The socket’s state must be ConnectedState before reading and writing can occur.

See also

state() connectToServer()

readBufferSize()#

Return type:: int

Returns the size of the internal read buffer. This limits the amount of data that the client can receive before you call read() or readAll(). A read buffer size of 0 (the default) means that the buffer has no size limit, ensuring that no data is lost.

See also

setReadBufferSize() read()

serverName()#

Return type:: str

Returns the name of the peer as specified by setServerName() , or an empty QString if setServerName() has not been called or connectToServer() failed.

See also

setServerName() connectToServer() fullServerName()

setReadBufferSize(size)#

Parameters:: size – int

Sets the size of QLocalSocket ‘s internal read buffer to be size bytes.

If the buffer size is limited to a certain size, QLocalSocket won’t buffer more than this size of data. Exceptionally, a buffer size of 0 means that the read buffer is unlimited and all incoming data is buffered. This is the default.

This option is useful if you only read the data at certain points in time (e.g., in a real-time streaming application) or if you want to protect your socket against receiving too much data, which may eventually cause your application to run out of memory.

See also

readBufferSize() read()

setServerName(name)#

Parameters:: name – str

Set the name of the peer to connect to. On Windows name is the name of a named pipe; on Unix name is the name of a local domain socket.

This function must be called when the socket is not connected.

See also

serverName()

setSocketDescriptor(socketDescriptor[, socketState=QLocalSocket.LocalSocketState.ConnectedState[, openMode=QIODeviceBase.OpenModeFlag.ReadWrite]])#

Parameters:

socketDescriptor – qintptr
socketState – LocalSocketState
openMode – Combination of OpenModeFlag

Return type:

bool

Initializes QLocalSocket with the native socket descriptor socketDescriptor. Returns true if socketDescriptor is accepted as a valid socket descriptor; otherwise returns false. The socket is opened in the mode specified by openMode, and enters the socket state specified by socketState.

Note

It is not possible to initialize two local sockets with the same native socket descriptor.

setSocketOptions(option)#

Parameters:: option – Combination of SocketOption

See also

socketOptions()

socketDescriptor()#

Return type:: qintptr

Returns the native socket descriptor of the QLocalSocket object if this is available; otherwise returns -1.

The socket descriptor is not available when QLocalSocket is in UnconnectedState . The type of the descriptor depends on the platform:

On Windows, the returned value is a Winsock 2 Socket Handle.

On INTEGRITY, the returned value is the QTcpSocket socket descriptor and the type is defined by socketDescriptor .

On all other UNIX-like operating systems, the type is a file descriptor representing a socket.

See also

setSocketDescriptor()

socketOptions()#

Return type:: Combination of SocketOption

See also

setSocketOptions()

state()#

Return type:: LocalSocketState

Returns the state of the socket.

See also

error()

stateChanged(socketState)#

Parameters:: socketState – LocalSocketState

This signal is emitted whenever QLocalSocket ‘s state changes. The socketState parameter is the new state.

QLocalSocket::SocketState is not a registered metatype, so for queued connections, you will have to register it with Q_DECLARE_METATYPE() and qRegisterMetaType().

See also

state() Creating Custom Qt Types

waitForConnected([msecs=30000])#

Parameters:: msecs – int
Return type:: bool

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Waits until the socket is connected, up to msecs milliseconds. If the connection has been established, this function returns true; otherwise it returns false. In the case where it returns false, you can call error() to determine the cause of the error.

The following example waits up to one second for a connection to be established:

socket.connectToServer("market")
if socket.waitForConnected(1000):
    qDebug("Connected!")

If msecs is -1, this function will not time out.

See also

connectToServer() connected()

waitForDisconnected([msecs=30000])#

Parameters:: msecs – int
Return type:: bool

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Waits until the socket has disconnected, up to msecs milliseconds. If the connection was successfully disconnected, this function returns true; otherwise it returns false (if the operation timed out, if an error occurred, or if this QLocalSocket is already disconnected). In the case where it returns false, you can call error() to determine the cause of the error.

The following example waits up to one second for a connection to be closed:

socket.disconnectFromServer()
if (socket.state() == QLocalSocket.UnconnectedState
    or socket.waitForDisconnected(1000)) {
    qDebug("Disconnected!")

If msecs is -1, this function will not time out.

See also

disconnectFromServer() close()