forked from mirrors/gecko-dev
f6db0ee557
# ignore-this-changeset Differential Revision: https://phabricator.services.mozilla.com/D35884 --HG-- extra : source : 60e4496cf9699dc59f2f4738cb60f87cbdb01e67
77 lines
2.3 KiB
JavaScript
77 lines
2.3 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
"use strict";
|
|
|
|
const Services = require("Services");
|
|
|
|
loader.lazyRequireGetter(this, "asyncStorage", "devtools/shared/async-storage");
|
|
|
|
/**
|
|
* Downloads and caches a JSON file from an URL given by a pref.
|
|
*
|
|
* @param {String} prefName
|
|
* The preference for the target URL
|
|
*
|
|
* @return {Promise}
|
|
* - Resolved with the JSON object in case of successful request
|
|
* or cache hit
|
|
* - Rejected with an error message in case of failure
|
|
*/
|
|
exports.getJSON = function(prefName) {
|
|
return new Promise((resolve, reject) => {
|
|
const xhr = new XMLHttpRequest();
|
|
|
|
// We used to store cached data in preferences, but now we use asyncStorage
|
|
// Migration step: if it still exists, move this now useless preference in its
|
|
// new location and clear it
|
|
if (Services.prefs.prefHasUserValue(prefName + "_cache")) {
|
|
const json = Services.prefs.getCharPref(prefName + "_cache");
|
|
asyncStorage.setItem(prefName + "_cache", json).catch(function(e) {
|
|
// Could not move the cache, let's log the error but continue
|
|
console.error(e);
|
|
});
|
|
Services.prefs.clearUserPref(prefName + "_cache");
|
|
}
|
|
|
|
function readFromStorage(networkError) {
|
|
asyncStorage
|
|
.getItem(prefName + "_cache")
|
|
.then(function(json) {
|
|
if (!json) {
|
|
return reject("Empty cache for " + prefName);
|
|
}
|
|
return resolve(json);
|
|
})
|
|
.catch(function(e) {
|
|
reject(
|
|
"JSON not available, CDN error: " +
|
|
networkError +
|
|
", storage error: " +
|
|
e
|
|
);
|
|
});
|
|
}
|
|
|
|
xhr.onload = () => {
|
|
try {
|
|
const json = JSON.parse(xhr.responseText);
|
|
asyncStorage.setItem(prefName + "_cache", json).catch(function(e) {
|
|
// Could not update cache, let's log the error but continue
|
|
console.error(e);
|
|
});
|
|
resolve(json);
|
|
} catch (e) {
|
|
readFromStorage(e);
|
|
}
|
|
};
|
|
|
|
xhr.onerror = e => {
|
|
readFromStorage(e);
|
|
};
|
|
|
|
xhr.open("get", Services.prefs.getCharPref(prefName));
|
|
xhr.send();
|
|
});
|
|
};
|