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// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Poll the server to keep the session alive.
*
* @module core/network
* @package core
* @copyright 2019 Damyon Wiese
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
define(['jquery', 'core/ajax', 'core/config', 'core/notification', 'core/str'],
function($, Ajax, Config, Notification, Str) {
var started = false;
var warningDisplayed = false;
var keepAliveFrequency = 0;
var requestTimeout = 0;
var keepAliveMessage = false;
var sessionTimeout = false;
// 1/10 of session timeout, max of 10 minutes.
var checkFrequency = Math.min((Config.sessiontimeout / 10), 600) * 1000;
// 1/5 of sessiontimeout.
var warningLimit = checkFrequency * 2;
/**
* The session time has expired - we can't extend it now.
*/
var timeoutSessionExpired = function() {
sessionTimeout = true;
};
/**
* Ping the server to keep the session alive.
*
* @return {Promise}
*/
var touchSession = function() {
var request = {
methodname: 'core_session_touch',
args: { }
};
if (sessionTimeout) {
// We timed out before we extended the session.
return Str.get_strings([
{key: 'sessionexpired', component: 'error'},
{key: 'sessionerroruser', component: 'error'}
]).then(function(strings) {
Notification.alert(
strings[0], // Title.
strings[1] // Message.
);
return true;
}).fail(Notification.exception);
} else {
return Ajax.call([request], true, true, false, requestTimeout)[0].then(function() {
if (keepAliveFrequency > 0) {
setTimeout(touchSession, keepAliveFrequency);
}
return true;
}).fail(function() {
Notification.alert('', keepAliveMessage);
});
}
};
/**
* Ask the server how much time is remaining in this session and
* show confirm/cancel notifications if the session is about to run out.
*
* @return {Promise}
*/
var checkSession = function() {
var request = {
methodname: 'core_session_time_remaining',
args: { }
};
sessionTimeout = false;
return Ajax.call([request], true, true, true)[0].then(function(args) {
if (args.userid <= 0) {
return false;
}
if (args.timeremaining < 0) {
Str.get_strings([
{key: 'sessionexpired', component: 'error'},
{key: 'sessionerroruser', component: 'error'}
]).then(function(strings) {
Notification.alert(
strings[0], // Title.
strings[1] // Message.
);
return true;
}).fail(Notification.exception);
} else if (args.timeremaining * 1000 < warningLimit && !warningDisplayed) {
// If we don't extend the session before the timeout - warn.
setTimeout(timeoutSessionExpired, args.timeremaining * 1000);
warningDisplayed = true;
Str.get_strings([
{key: 'norecentactivity', component: 'moodle'},
{key: 'sessiontimeoutsoon', component: 'moodle'},
{key: 'extendsession', component: 'moodle'},
{key: 'cancel', component: 'moodle'}
]).then(function(strings) {
Notification.confirm(
strings[0], // Title.
strings[1], // Message.
strings[2], // Extend session.
strings[3], // Cancel.
function() {
touchSession();
warningDisplayed = false;
// First wait is half the session timeout.
setTimeout(checkSession, checkFrequency * 5);
return true;
},
function() {
warningDisplayed = false;
setTimeout(checkSession, checkFrequency);
}
);
return true;
}).fail(Notification.exception);
} else {
setTimeout(checkSession, checkFrequency);
}
return true;
});
// We do not catch the fails from the above ajax call because they will fail when
// we are not logged in - we don't need to take any action then.
};
/**
* Start calling a function to check if the session is still alive.
*/
var start = function() {
if (keepAliveFrequency > 0) {
setTimeout(touchSession, keepAliveFrequency);
} else {
// First wait is half the session timeout.
setTimeout(checkSession, checkFrequency * 5);
}
};
/**
* Don't allow more than one of these polling loops in a single page.
*/
var init = function() {
// We only allow one concurrent instance of this checker.
if (started) {
return;
}
started = true;
start();
};
/**
* Start polling with more specific values for the frequency, timeout and message.
*
* @param {number} freq How ofter to poll the server.
* @param {number} timeout The time to wait for each request to the server.
* @param {string} message The message to display if the session is going to time out.
*/
var keepalive = function(freq, timeout, message) {
// We only allow one concurrent instance of this checker.
if (started) {
return;
}
started = true;
keepAliveFrequency = freq * 1000;
keepAliveMessage = message;
requestTimeout = timeout * 1000;
start();
};
return {
keepalive: keepalive,
init: init
};
});