QAbstractSocket

class QCoroAbstractSocket : public QCoroIODevice;

QAbstractSocket is a base class for QTcpSocket and QUdpSocket and has some potentially asynchronous operations. In addition to reading and writing, which are provided by QIODevice baseclass and can be used with coroutines thanks to QCoro's QCoroIODevice. Those operations are connecting to and disconnecting from the server.

Since QAbstractSocket doesn't provide the ability to co_await those operations, QCoro provides a wrapper calss QCoroAbstractSocket. To wrap a QAbstractSocket object into the QCoroAbstractSocket wrapper, use qCoro():

QCoroAbstractSocket qCoro(QAbstractSocket &);
QCoroAbstractSocket qCoro(QAbstractSocket *);

Same as QAbstractSocket is a subclass of QIODevice, QCoroAbstractSocket subclasses QCoroIODevice, so it also provides the awaitable interface for selected QIODevice functions. See QCoroIODevice documentation for details.

waitForConnected()

Waits for the socket to connect or until it times out. Returns bool indicating whether connection has been established or whether the operation has timed out. The coroutine is not suspended if the socket is already connected.

See documentation for QAbstractSocket::waitForConnected() for details.

Awaitable auto QCoroAbstractSocket::waitForConnected(int timeout_msecs = 30'000);
Awaitable auto QCoroAbstractSocket::waitForConnected(std::chrono::milliseconds timeout);

waitForDisconnected()

Waits for the socket to disconnect from the server or until the operation times out. The coroutine is not suspended if the socket is already disconnected.

See documentation for QAbstractSocket::waitForDisconnected() for details.

Awaitable auto QCoroAbstractSocket::waitForDisconnected(timeout_msecs = 30'000);
Awaitable auto QCoroAbstractSocket::waitForDisconnected(std::chrono::milliseconds timeout);

connectToHost()

QCoroAbstractSocket provides an additional method called connectToHost() which is equivalent to calling QAbstractSocket::connectToHost() followed by QAbstractSocket::waitForConnected(). This operation is co_awaitable as well.

See the documentation for [QAbstractSocket::connectToHost()][qtdoc-qabstractsocket-connectToHost] and QAbstractSocket::waitForConnected() for details.

Awaitable auto QCoroAbstractSocket::connectToHost(const QHostAddress &address, quint16 port,
                                                  QIODevice::OpenMode openMode = QIODevice::ReadOnly);
Awaitable auto QCoroAbstractSocket::connectToHost(const QString &hostName, quint16 port,
                                                  QIODevice::OpenMode openMode = QIODevice::ReadOnly,
                                                  QAbstractSocket::NetworkLayerProtocol protocol = QAbstractSocket::AnyIPProtocol);

Examples

QCoro::Task<QByteArray> requestDataFromServer(const QString &hostName) {
    QTcpSocket socket;
    if (!co_await qCoro(socket).connectToHost(hostName)) {
        qWarning() << "Failed to connect to the server";
        co_return QByteArray{};
    }

    socket.write("SEND ME DATA!");

    QByteArray data;
    while (!data.endsWith("\r\n.\r\n")) {
        data += co_await qCoro(socket).readAll();
    }

    co_return data;
}