Change timeout handling in TokenManager

Checklist

[ ] Tick to sign-off your agreement to the Developer Certificate of Origin (DCO) 1.1
[ ] Added tests for code changes or test/build only changes
[ ] Updated the change log file (CHANGES.md|CHANGELOG.md) or test/build only changes
[ ] Completed the PR template below:

Description

According to the snapshot created by Eric, clearly can be seen there is a setTimeout that binds data to the native context.

Native objects are everything else which is not in the JavaScript heap.

Screenshot 2021-04-01 at 15 06 45

This code part refers to this:

setTimeout(this._autoRenew.bind(this, defaultMaxAgeSecs), delayMSecs).unref()

Here is small code example that produce the same memory trace:

var heapdump = require('heapdump');

function sleep(seconds){
    var waitUntil = new Date().getTime() + seconds*1000;
    while(new Date().getTime() < waitUntil) true;
}

function print() {
    console.log("Hello")
}

setTimeout(print, 10).unref();

sleep(2)

heapdump.writeSnapshot('./timeout-unref.heapsnapshot');

This produce the same memory trace: Screenshot 2021-04-01 at 15 35 15

Approach

Extending the sample code with a timer clear looks like this:

var heapdump = require('heapdump');

function sleep(seconds){
    var waitUntil = new Date().getTime() + seconds*1000;
    while(new Date().getTime() < waitUntil) true;
}

function print() {
    console.log("Hello")
}

myTimer = setTimeout(print, 10);

sleep(1)

clearTimeout(myTimer)
myTimer = setTimeout(print, 10);

sleep(1)

clearTimeout(myTimer)

heapdump.writeSnapshot('./timeout-var.heapsnapshot');

And this code memory trace looks this way: Screenshot 2021-04-01 at 15 52 43

This means that the referenced object will be placed into the global not into the system/context scope.

cloudant / nodejs-cloudant