为什么 Gio.Socket.create_source() 返回 null？

Question

我是套接字的新手，试图在 GJS/Gio 中完成一些套接字编程，但遇到了创建 GLib.Source 来处理从套接字接收的问题。相关代码（我认为）是：

const DeviceChannel = new Lang.Class({
    Name: "DeviceChannel",

    _init: function (device) {
        this.device = device;

        this.connection = null;
        this.inStream = null;
        this.outStream = null;
        this.socket = null;
        this.sock_source = 0;
    },

    open: function () {
        let client = new Gio.SocketClient();

        this.addr = new Gio.InetSocketAddress({
            address: this.device.tcpHost,
            port: this.device.tcpPort
        });

        let conn = client.connect_async(
            this.addr,
            null,
            Lang.bind(this, this.opened)
        );
    },

    opened: function (client, res) {
        this.connection = client.connect_finish(res);

        // Streams
        this.inStream = new Gio.DataInputStream({
            base_stream: this.connection.get_input_stream()
        });

        this.outStream = new Gio.DataOutputStream({
            base_stream: this.connection.get_output_stream()
        });

        // Socket
        this.socket = this.connection.get_socket();
        this.socket.set_option(6, 4, 10);   // TCP_KEEPIDLE
        this.socket.set_option(6, 5, 5);    // TCP_KEEPINTVL
        this.socket.set_option(6, 6, 3);    // TCP_KEEPCNT
        this.socket.set_keepalive(true);

        this.sock_source = this.socket.create_source(GLib.IOCondition.IN, null);
        this.sock_source.set_callback(Lang.bind(this, this._io_ready));
        this.sock_source.attach(null);
    },

    _io_ready: function (condition) {
        return true;
    }
});

一切顺利，直到我调用 this.sock_source.set_callback() 时出现错误：

(JSConnect:15118): Gjs-WARNING **: JS ERROR: TypeError: this.sock_source is null
DeviceChannel<.opened@application.js:184:9
wrapper@resource:///org/gnome/gjs/modules/lang.js:178:22
@application.js:427:2

我在代码的另一部分调用了另一个套接字（尽管是 UDP）上的 Gio.Socket.create_source()，它工作正常。调用 create_source() 本身不会抛出任何错误（即使我运行我的脚本使用 G_MESSAGES_DEBUG=all）并且没有提到函数返回 null in the documentation 所以我对我做错了什么感到困惑。

编辑：

有 3 年前的评论 here 指出：

This does not work since 1) Socket.create_source doesn't exist in typelib as it is marked with (skip) in Glib/gio/gsocket.c

但我假设这不再是真的，因为我已经在我的 UDP 套接字上创建了一个源，尽管那个套接字 "hand-made" 不是使用 Gio.SocketClient().

Answer 1

您可能无意中调用了 Gio.DatagramBased.create_source() method. Looking at the source code, this will call g_socket_create_source() eventually, but does some checks first and returns null if those fail. Here are the checks: https://github.com/GNOME/glib/blob/master/gio/gsocket.c#L1114

看起来 the method will simply return null 甚至没有打印 check_datagram_based() 中的错误的小错误。

为什么 Gio.Socket.create_source() 返回 null？

Why is Gio.Socket.create_source() returning null?

sockets

gio

gjs