Make using requestIdleCallback optional to overcome it's not being reliably called in Electron

[elyulka]

What version of WebTorrent?

0.103.1

What operating system and Node.js version?

Node 10.15.3, OS X 10.14.4

What browser and version? (if using WebTorrent in the browser)

Electron 4.2.2

What did you expect to happen?

requestIdleCallback must be called to perform downloading of data.

What actually happened?

It's called sometimes in unpredictable manner. Mostly not called at all.

My proposal is to make using requestIdleCallback optional. Thanks.

[lacker]

I had a similar problem, with requestIdleCallback not existing in Chrome extensions. A hacky workaround is to do window.requestIdleCallback = f => f(); at the beginning of your application - that will just make any requestIdleCallback callbacks run immediately.

[guanzo]

Related to #1615

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[feross]

@lacker I'm confused why you'd need to do include window.requestIdleCallback = f => f() as we already check if requestIdleCallback exists before attempting to use it:

webtorrent/lib/torrent.js

Line 1177 in e5a3a91

if (typeof window !== 'undefined' && typeof window.requestIdleCallback === 'function') {

[feross]

This issue should be fixed now that #1615 is merged and released as 0.107.11

[lacker]

I should have been more specific. In a Chrome extension background page, requestIdleCallback does exist. However, it doesn't do anything. The callback you pass to it never gets called. I'm not totally sure why, but I did find this stack overflow page explaining it as "This function is frame-based just like rAF so it doesn't work in a nonrenderable context such as the background page." https://stackoverflow.com/questions/55461030/does-requestidlecallback-work-in-the-background-page-of-chrome-extensions

So, it doesn't seem like this change will fix the behavior in extensions, but my workaround is working fine for me so I'm fine with the status quo. Just leaving this comment here in case future people run into it.

[feross]

@lacker Very informative. Thanks for the comment!