Update c_src files to latest from HdrHistogram_c

[jamesvl]

Would there be any interest in updating this project with the latest source files from the C version?

I've done the work in my working branch, but it comes with a number of significant caveats:

• the latest version has removed (or renamed) a number of Histogram struct variables, so this would be a break change
• the performance seems to be about 33% slower - running tests on my system slows down the operations from 10ns/h to ~13.5ns/h.
• it removes the uncompressed option (and tests), since those don't seem to be present in the C version any more

If there's interest in an update like this I'll open a PR -- I'm interested in the update in case the C version has fixed any bugs that this project would want to pick up.

Obviously, if maintaining perfect backwards compatibility and the same level of performance are more important, we can close this Issue out. Thoughts?

[darach]

Hi James,

This has been on my TODO list for a while. The uncompressed option was added by @Licenser as he uses compressed filesystems so didn't need compression. We'd probably need to keep that as an extension.

I'll take a look at your branch over the weekend.

Not sure native binary compatibility is a major issue as long as the erlang side is binary compatible.

Cheers,

Darach.

[jamesvl]

Derach -

That sounds great. I may need some help getting the uncompressed stuff to work again, but I'll dig around in the C source more and see if I can get it working. Let me know if you see any other issues when you get a chance to check...

[jamesvl]

I did take a look at adding the uncompressed writer back in - unfortunately, there's no code path for that anymore in the C version - all write methods will use gzip + base64 encoding, per the Java version. Any suggestions on how to proceed?

[mikeb01]

@darach How important is uncompressed encode/decode? I can add it back in if required.

[tsloughter]

I think we should update hdrhistogram version. @jamesvl did you have any work on this?

If latest hdrhistogram does not support uncompressed then we just have to drop that.

@Licenser would it hurt you that much if only compressed was suported?

[tsloughter]

And I just noticed that neither the C or Rust versions support doubles... Hm.