[gjs: 1/2] Add support for async calls in DBusProxyWrapper

[Philip Chimento <pchimento src gnome org>]

commit 7087f0501141a3dbaa87caffebdaf67aa4ddc16d
Author: Sergio Costas <rastersoft gmail com>
Date:   Sat Feb 26 19:55:25 2022 +0100

    Add support for async calls in DBusProxyWrapper
    
    Currently, DBusProxyWrapper dynamically creates two methods for
    each method available in the DBus interface: one with the suffix
    Sync (which blocks the calling thread until the call returns),
    and another with the suffix Remote (which accepts a callback,
    called when the DBus calls returns).
    
    Since GJS has support for async/await, it is a good idea to use
    them for DBus. Unfortunately, that means creating some plumbing
    using Promises. It is not complex, but it is a repetitive task.
    
    This MR fixes this by adding a third method, suffixed with
    Async, that returns a Promise that calls the DBus method and
    returns the result with `resolve` (or `reject` if an error
    occurs). This allows to call a DBus method from an async
    function and wait for the result using `await`.

 installed-tests/js/testGDBus.js | 13 +++++++++++++
 modules/core/overrides/Gio.js   | 16 +++++++++++++++-
 2 files changed, 28 insertions(+), 1 deletion(-)
---
diff --git a/installed-tests/js/testGDBus.js b/installed-tests/js/testGDBus.js
index 78907e48a..88c5831b5 100644
--- a/installed-tests/js/testGDBus.js
+++ b/installed-tests/js/testGDBus.js
@@ -407,6 +407,19 @@ describe('Exported DBus object', function () {
         loop.run();
     });
 
+    async function testAsync(value) {
+        let result = await proxy.nonJsonFrobateStuffAsync(value);
+        return result;
+    }
+
+    it('can call a remote method using AWAIT', function () {
+        testAsync(1).then(result => {
+            expect(result[0]).toEqual('Oops');
+            loop.quit();
+        });
+        loop.run();
+    });
+
     it('can call a remote method with no in parameter', function () {
         proxy.noInParameterRemote(([result], excp) => {
             expect(result).toEqual('Yes!');
diff --git a/modules/core/overrides/Gio.js b/modules/core/overrides/Gio.js
index be2e52470..6cc29b17e 100644
--- a/modules/core/overrides/Gio.js
+++ b/modules/core/overrides/Gio.js
@@ -185,8 +185,22 @@ function _addDBusConvenience() {
     let i, methods = info.methods;
     for (i = 0; i < methods.length; i++) {
         var method = methods[i];
-        this[`${method.name}Remote`] = _makeProxyMethod(methods[i], false);
+        let remoteMethod = _makeProxyMethod(methods[i], false);
+        this[`${method.name}Remote`] = remoteMethod;
         this[`${method.name}Sync`] = _makeProxyMethod(methods[i], true);
+        this[`${method.name}Async`] = function (...args) {
+            return new Promise((resolve, reject) => {
+                args.push((result, error, fdList) => {
+                    if (error)
+                        reject(error);
+                    else if (fdList)
+                        resolve([result, fdList]);
+                    else
+                        resolve(result);
+                });
+                remoteMethod.call(this, ...args);
+            });
+        };
     }
 
     let properties = info.properties;