Electron: verification should be faster

[feross]

Prompted by this comment by @dcposch: 664eb30#commitcomment-16936882

simple-sha1 uses async methods to do hashing off the main thread (in browsers that support it). So, using the number of cores actually makes a lot of sense. Support list: http://caniuse.com/#feat=cryptography

This is not working correctly in Electron because Electron ignores the "browser" field in package.json.

Current time to verify an 8GB test torrent on two separate runs:

52089.942ms
58375.643ms

[feross]

I just learned that crypto.subtle uses a thread pool of size 1 in Chrome :( Issue: https://bugs.chromium.org/p/chromium/issues/detail?id=449009 but larger in other browsers.

So it seems like merely making Electron use crypto.subtle is not a solution.

I tried making a worker pool, but it's slowed down by the size of data that needs to be sent to each worker and didn't work reliably with torrents that had really large (~8MB) piece sizes. Too bad IPC calls don't work more like WebWorkers which support instantly transferring binary data to a worker (transferrable objects).

The need for this is obviated (at least for webtorrent-desktop) by this PR: #715

[lock]

This thread has been automatically locked because it has not had recent activity. To discuss futher, please open a new issue.