blob: de14a8519edabcd798636e799b59ccfc4abbcbfa [file] [log] [blame]
import {Mutex, withTimeout} from 'async-mutex';
import {getOptions} from './optionsUtils.js';
export default class OptionsWatcher {
constructor(options) {
this.watchedOptions = options;
this.options = [];
for (let o of options) this.options[o] = false;
this.isStale = true;
this.mutex = withTimeout(new Mutex(), 60 * 1000);
// If the extension settings change, set the current cached value as stale.
// We could try only doing this only when we're sure it has changed, but
// there are many factors (if the user has changed it manually, if a kill
// switch was activated, etc.) so we'll do it every time.
chrome.storage.onChanged.addListener((changes, areaName) => {
if (areaName !== 'sync') return;
console.debug('[optionsWatcher] Marking options as stale.');
this.isStale = true;
});
}
// Returns a promise resolving to the value of option |option|.
getOption(option) {
if (!this.watchedOptions.includes(option))
return Promise.reject(new Error(
'[optionsWatcher] We\'re not watching option ' + option + '.'));
// When the cached value is marked as stale, it might be possible that there
// is a flood of calls to isEnabled(), which in turn causes a flood of calls
// to getOptions() because it takes some time for it to be marked as not
// stale. Thus, hiding the logic behind a mutex fixes this.
return this.mutex.runExclusive(() => {
if (!this.isStale) return Promise.resolve(this.options[option]);
return getOptions(this.watchedOptions).then(options => {
this.options = options;
this.isStale = false;
return this.options[option];
});
});
}
// Returns a promise resolving to whether the |feature| is enabled.
isEnabled(feature) {
return this.getOption(feature).then(option => option === true);
}
}