blockingfortuneclient.py

"""PySide6 port of the network/blockingfortunclient example from Qt v5.x, originating from PyQt"""

from PySide6.QtCore import (Signal, QDataStream, QMutex, QMutexLocker,
        QThread, QWaitCondition)
from PySide6.QtGui import QIntValidator
from PySide6.QtWidgets import (QApplication, QDialogButtonBox, QGridLayout,
        QLabel, QLineEdit, QMessageBox, QPushButton, QWidget)
from PySide6.QtNetwork import (QAbstractSocket, QHostAddress, QNetworkInterface,
        QTcpSocket)


class FortuneThread(QThread):
    newFortune = Signal(str)

    error = Signal(int, str)

    def __init__(self, parent=None):
        super(FortuneThread, self).__init__(parent)

        self.quit = False
        self.hostName = ''
        self.cond = QWaitCondition()
        self.mutex = QMutex()
        self.port = 0

    def __del__(self):
        self.mutex.lock()
        self.quit = True
        self.cond.wakeOne()
        self.mutex.unlock()
        self.wait()

    def requestNewFortune(self, hostname, port):
        locker = QMutexLocker(self.mutex)
        self.hostName = hostname
        self.port = port
        if not self.isRunning():
            self.start()
        else:
            self.cond.wakeOne()

    def run(self):
        self.mutex.lock()
        serverName = self.hostName
        serverPort = self.port
        self.mutex.unlock()

        while not self.quit:
            Timeout = 5 * 1000

            socket = QTcpSocket()
            socket.connectToHost(serverName, serverPort)

            if not socket.waitForConnected(Timeout):
                self.error.emit(socket.error(), socket.errorString())
                return

            while socket.bytesAvailable() < 2:
                if not socket.waitForReadyRead(Timeout):
                    self.error.emit(socket.error(), socket.errorString())
                    return

            instr = QDataStream(socket)
            instr.setVersion(QDataStream.Qt_4_0)
            blockSize = instr.readUInt16()

            while socket.bytesAvailable() < blockSize:
                if not socket.waitForReadyRead(Timeout):
                    self.error.emit(socket.error(), socket.errorString())
                    return

            self.mutex.lock()
            fortune = instr.readQString()
            self.newFortune.emit(fortune)

            self.cond.wait(self.mutex)
            serverName = self.hostName
            serverPort = self.port
            self.mutex.unlock()


class BlockingClient(QWidget):
    def __init__(self, parent=None):
        super(BlockingClient, self).__init__(parent)

        self.thread = FortuneThread()
        self.currentFortune = ''

        hostLabel = QLabel("&Server name:")
        portLabel = QLabel("S&erver port:")

        for ipAddress in QNetworkInterface.allAddresses():
            if ipAddress != QHostAddress.LocalHost and ipAddress.toIPv4Address() != 0:
                break
        else:
            ipAddress = QHostAddress(QHostAddress.LocalHost)

        ipAddress = ipAddress.toString()

        self.hostLineEdit = QLineEdit(ipAddress)
        self.portLineEdit = QLineEdit()
        self.portLineEdit.setValidator(QIntValidator(1, 65535, self))

        hostLabel.setBuddy(self.hostLineEdit)
        portLabel.setBuddy(self.portLineEdit)

        self.statusLabel = QLabel(
                "This example requires that you run the Fortune Server example as well.")
        self.statusLabel.setWordWrap(True)

        self.getFortuneButton = QPushButton("Get Fortune")
        self.getFortuneButton.setDefault(True)
        self.getFortuneButton.setEnabled(False)

        quitButton = QPushButton("Quit")

        buttonBox = QDialogButtonBox()
        buttonBox.addButton(self.getFortuneButton, QDialogButtonBox.ActionRole)
        buttonBox.addButton(quitButton, QDialogButtonBox.RejectRole)

        self.getFortuneButton.clicked.connect(self.requestNewFortune)
        quitButton.clicked.connect(self.close)
        self.hostLineEdit.textChanged.connect(self.enableGetFortuneButton)
        self.portLineEdit.textChanged.connect(self.enableGetFortuneButton)
        self.thread.newFortune.connect(self.showFortune)
        self.thread.error.connect(self.displayError)

        mainLayout = QGridLayout()
        mainLayout.addWidget(hostLabel, 0, 0)
        mainLayout.addWidget(self.hostLineEdit, 0, 1)
        mainLayout.addWidget(portLabel, 1, 0)
        mainLayout.addWidget(self.portLineEdit, 1, 1)
        mainLayout.addWidget(self.statusLabel, 2, 0, 1, 2)
        mainLayout.addWidget(buttonBox, 3, 0, 1, 2)
        self.setLayout(mainLayout)

        self.setWindowTitle("Blocking Fortune Client")
        self.portLineEdit.setFocus()

    def requestNewFortune(self):
        self.getFortuneButton.setEnabled(False)
        self.thread.requestNewFortune(self.hostLineEdit.text(),
                int(self.portLineEdit.text()))

    def showFortune(self, nextFortune):
        if nextFortune == self.currentFortune:
            self.requestNewFortune()
            return

        self.currentFortune = nextFortune
        self.statusLabel.setText(self.currentFortune)
        self.getFortuneButton.setEnabled(True)

    def displayError(self, socketError, message):
        if socketError == QAbstractSocket.HostNotFoundError:
            QMessageBox.information(self, "Blocking Fortune Client",
                    "The host was not found. Please check the host and port "
                    "settings.")
        elif socketError == QAbstractSocket.ConnectionRefusedError:
            QMessageBox.information(self, "Blocking Fortune Client",
                    "The connection was refused by the peer. Make sure the "
                    "fortune server is running, and check that the host name "
                    "and port settings are correct.")
        else:
            QMessageBox.information(self, "Blocking Fortune Client",
                    "The following error occurred: %s." % message)

        self.getFortuneButton.setEnabled(True)

    def enableGetFortuneButton(self):
        self.getFortuneButton.setEnabled(self.hostLineEdit.text() != '' and
                self.portLineEdit.text() != '')


if __name__ == '__main__':

    import sys

    app = QApplication(sys.argv)
    client = BlockingClient()
    client.show()
    sys.exit(app.exec_())