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/* 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/. */
import {
actionCreators as ac,
actionTypes as at,
} from "common/Actions.sys.mjs";
import { perfService as perfSvc } from "content-src/lib/perf-service";
const VISIBLE = "visible";
const VISIBILITY_CHANGE_EVENT = "visibilitychange";
export class DetectUserSessionStart {
constructor(store, options = {}) {
this._store = store;
// Overrides for testing
this.document = options.document || global.document;
this._perfService = options.perfService || perfSvc;
this._onVisibilityChange = this._onVisibilityChange.bind(this);
}
/**
* sendEventOrAddListener - Notify immediately if the page is already visible,
* or else set up a listener for when visibility changes.
* This is needed for accurate session tracking for telemetry,
* because tabs are pre-loaded.
*/
sendEventOrAddListener() {
if (this.document.visibilityState === VISIBLE) {
// If the document is already visible, to the user, send a notification
// immediately that a session has started.
this._sendEvent();
} else {
// If the document is not visible, listen for when it does become visible.
this.document.addEventListener(
VISIBILITY_CHANGE_EVENT,
this._onVisibilityChange
);
}
}
/**
* _sendEvent - Sends a message to the main process to indicate the current
* tab is now visible to the user, includes the
* visibility_event_rcvd_ts time in ms from the UNIX epoch.
*/
_sendEvent() {
this._perfService.mark("visibility_event_rcvd_ts");
try {
let visibility_event_rcvd_ts = this._perfService.getMostRecentAbsMarkStartByName(
"visibility_event_rcvd_ts"
);
this._store.dispatch(
ac.AlsoToMain({
type: at.SAVE_SESSION_PERF_DATA,
data: { visibility_event_rcvd_ts },
})
);
} catch (ex) {
// If this failed, it's likely because the `privacy.resistFingerprinting`
// pref is true. We should at least not blow up.
}
}
/**
* _onVisibilityChange - If the visibility has changed to visible, sends a notification
* and removes the event listener. This should only be called once per tab.
*/
_onVisibilityChange() {
if (this.document.visibilityState === VISIBLE) {
this._sendEvent();
this.document.removeEventListener(
VISIBILITY_CHANGE_EVENT,
this._onVisibilityChange
);
}
}
}
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