http: add bindings to GET /

[tynes]

Add bindings object to GET / HTTP endpoint. Users sometime experience extremely slow IBD without realizing that it is using the Javascript backend. d553f0a might be enough to prevent this problem from happening again, opening this for discussion.

[codecov-io]

Codecov Report

Merging #901 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #901      +/-   ##
==========================================
+ Coverage   61.72%   61.72%   +<.01%     
==========================================
  Files         155      155              
  Lines       26058    26059       +1     
==========================================
+ Hits        16085    16086       +1     
  Misses       9973     9973

Impacted Files	Coverage Δ
lib/node/http.js	59.68% <100%> (+0.1%)	⬆️

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[pinheadmz]

Do we still need this after #729 ?

[pinheadmz]

Couldn't there also be the nodejs backend?

[tynes]

Couldn't there also be the nodejs backend?

Good point. I was thinking JavaScript is JavaScript when I wrote this. From the last time that I looked at the code, the main difference between the node backend and the js backend was the usage of BigInt in the node backend but browsers also natively support BigInt these days. Ideally, there would be an integer <--> string mapping of these values in bcrypto

[tynes]

Thoughts

Was thinking about the viability of some sort of GET /stats endpoint that this could be added instead of adding it to GET / to prevent too much bloat on a single endpoint. GET / already does include a memory property, which under the hood calls process.memoryUsage

• https://nodejs.org/docs/latest-v12.x/api/process.html#process_process_memoryusage
• https://github.com/bcoin-org/blgr/blob/master/lib/logger.js#L544

node.js has recently added process.resourceUsage which returns a very large object that corresponds to a uv_rusage_t but has some interesting data in it, in particular fsRead and fsWrite.

• https://nodejs.org/docs/latest-v12.x/api/process.html#process_process_resourceusage
• Performance profiles for typical Node.js applications nodejs/diagnostics#161

It looks like other node.js developers have attempted to build some tools that can get in depth stats of the event loop, but based on their conversation it isn't easy and there isn't much reliable open source code doing this. Its done by writing some native code that plugs into libuv hooks. The behavior also differs between versions of node.js

• Measure between whole iterations of the event loop ably-forks/event-loop-stats#1
• Detect synchronous blocks bripkens/event-loop-stats#7

It seems like a closed source platform called N|Solid has implemented event loop metrics for their JavaScript runtime and they mentioned in one of the PRs above that it was not easy.

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Conclusion

• Adding the bindings property to GET / may or may not be useful
• It may be viable to add a new method to blgr that calls process.getResourceUsage and formats the output into a smaller object to get better stats on the process