QLocalSocket

Module	Network
Include	#include <QCoroLocalSocket>
CMake	target_link_libraries(myapp QCoro::Network)
QMake	QT += QCoroNetwork
Inherits	QCoroIODevice

QLocalSocket has several 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 QLocalSocket doesn't provide the ability to co_await those operations, QCoro provides a wrapper calss QCoroLocalSocket. To wrap a QLocalSocket object into the QCoroLocalSocket wrapper, use qCoro():

QCoroLocalSocket qCoro(QLocalSocket &);
QCoroLocalSocket qCoro(QLocalSocket *);

Same as QLocalSocket is a subclass of QIODevice, QCoroLocalSocket 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 (true) or whether the operation has timed out or another error has occurred (false). Returns immeditelly if the socket is already in connected state.

If the timeout is -1, the operation will never time out.

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

QCoro::Task<bool> QCoroLocalSocket::waitForConnected(int timeout_msecs = 30'000);
QCoro::Task<bool> QCoroLocalSocket::waitForConnected(std::chrono::milliseconds timeout);

waitForDisconnected()

Waits for the socket to disconnect from the server or until the operation times out. Returns immediatelly if the socket is not in connected state.

If the timeout is -1, the operation will never time out.

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

QCoro::Task<bool> QCoroLocalSocket::waitForDisconnected(timeout_msecs = 30'000);
QCoro::Task<bool> QCoroLocalSocket::waitForDisconnected(std::chrono::milliseconds timeout);

connectToServer()

QCoroLocalSocket provides an additional method called connectToServer() which is equivalent to calling QLocalSocket::connectToServer() followed by QLocalSocket::waitForConnected(). This operation is co_awaitable as well.

If the timeout is -1, the operation will never time out.

See the documentation for QLocalSocket::connectToServer() and QLocalSocket::waitForConnected() for details.

QCoro::Task<bool> QCoroLocalSocket::connectToServer(QIODevice::OpenMode openMode = QIODevice::ReadOnly,
                                                    std::chrono::milliseconds timeout = std::chrono::seconds(30));
QCoro::Taks<bool> QCoroLocalSocket::connectToServer(const QString &name, QIODevice::OpenMode openMode = QIODevice::ReadOnly,
                                                    std::chrono::milliseconds timeout = std::chrono::seconds(30));

Examples

QCoro::Task<QByteArray> requestDataFromServer(const QString &serverName) {
    QLocalSocket socket;
    if (!co_await qCoro(socket).connectToServer(serverName)) {
        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;
}