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QLocalSocket

ModuleQCoroNetwork
Include
#include <QCoroLocalSocket>
CMake
target_link_libraries(myapp QCoro::QCoroNetwork)
InheritsQCoroIODevice

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 or whether the operation has timed out. The coroutine is not suspended if the socket is already connected.

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

Awaitable auto QCoroLocalSocket::waitForConnected(int timeout_msecs = 30'000);
Awaitable auto QCoroLocalSocket::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 QLocalSocket::waitForDisconnected() for details.

Awaitable auto QCoroLocalSocket::waitForDisconnected(timeout_msecs = 30'000);
Awaitable auto 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.

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

Awaitable auto QCoroLocalSocket::connectToServer(QIODevice::OpenMode openMode = QIODevice::ReadOnly);
Awaitable auto QCoroLocalSocket::connectToServer(const QString &name, QIODevice::OpenMode openMode = QIODevice::ReadOnly);

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;
}