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bug 1523104: remote: introduce MessagePromise sync primitive; r=ochameau

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Makes the code slightly more pleasant to read.
This commit is contained in:
Andreas Tolfsen 2019-02-21 13:54:57 +00:00
parent 8a01f77453
commit 1601819536
2 changed files with 30 additions and 9 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

26
remote/Sync.jsm
View file

@ -7,6 +7,7 @@
var EXPORTED_SYMBOLS = [ var EXPORTED_SYMBOLS = [
"DOMContentLoadedPromise", "DOMContentLoadedPromise",
"EventPromise", "EventPromise",
"MessagePromise",
]; ];
const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm"); const {Services} = ChromeUtils.import("resource://gre/modules/Services.jsm");
@ -74,3 +75,28 @@ function DOMContentLoadedPromise(window, options = {mozSystemGroup: true}) {
} }
return new EventPromise(window, "DOMContentLoaded", options); return new EventPromise(window, "DOMContentLoaded", options);
} }
/**
* Awaits a single IPC message.
*
* @param {nsIMessageSender} target
* @param {string} name
*
* @return {Promise}
*
* @throws {TypeError}
* If target is not an nsIMessageSender.
*/
function MessagePromise(target, name) {
if (!(target instanceof Ci.nsIMessageSender)) {
throw new TypeError();
}
return new Promise(resolve => {
const onMessage = (...args) => {
target.removeMessageListener(name, onMessage);
resolve(...args);
};
target.addMessageListener(name, onMessage);
});
}

13
remote/Targets.jsm
View file

@ -6,6 +6,7 @@
var EXPORTED_SYMBOLS = ["Targets"]; var EXPORTED_SYMBOLS = ["Targets"];
const {MessagePromise} = ChromeUtils.import("chrome://remote/content/Sync.jsm");
const {Target} = ChromeUtils.import("chrome://remote/content/Target.jsm"); const {Target} = ChromeUtils.import("chrome://remote/content/Target.jsm");
class Targets { class Targets {
@ -21,16 +22,10 @@ class Targets {
// whereas it is asynchronously set by the custom element class. // whereas it is asynchronously set by the custom element class.
// At least ensure that this property is set before instantiating the target. // At least ensure that this property is set before instantiating the target.
if (!browser.browsingContext) { if (!browser.browsingContext) {
await new Promise(resolve => { await new MessagePromise(browser.messageManager, "Browser:Init");
const onInit = () => {
browser.messageManager.removeMessageListener("Browser:Init", onInit);
resolve();
};
browser.messageManager.addMessageListener("Browser:Init", onInit);
});
} }
const target = new Target(browser);
const target = new Target(browser);
target.connect(); target.connect();
this._targets.set(target.id, target); this._targets.set(target.id, target);
} }
@ -41,8 +36,8 @@ class Targets {
if (!browser.browsingContext) { if (!browser.browsingContext) {
return; return;
} }
let target = this._targets.get(browser.browsingContext.id);
const target = this._targets.get(browser.browsingContext.id);
if (target) { if (target) {
target.disconnect(); target.disconnect();
this._targets.delete(target.id); this._targets.delete(target.id);