Follow new naming in GHC.Stats?

[nh2]

There is currently a naming mismatch between EKG and GHC.Stats.

For example, we have

     , ("rts.gc.current_bytes_used"       , Gauge . fromIntegral . Stats.gcdetails_live_bytes . Stats.gc)

so current_bytes_used = gcdetails_live_bytes.

This is due to the 2 years old GHC commit ghc/ghc@24e6594#diff-00007a115377c1a1c96e619128dcb206L236 which did this rename.

Should EKG eventually follow the new naming?

It's weird when some stats have the same names as their GHC.Stats counterparts, but others don't.

[nh2]

There are also oddities like this, where two apparently very different concepts are filled in by the same variable:

     , ("rts.gc.par_tot_bytes_copied"     , Gauge . fromIntegral . Stats.par_copied_bytes)
     , ("rts.gc.par_avg_bytes_copied"     , Gauge . fromIntegral . Stats.par_copied_bytes)

a5cd48c#diff-51685f3c4893c24352025eb92fe6a11eR437-

This is likely because of commit ghc/ghc@ef9e348 which renamed it, but EKG also keeping the old (and as per the GHC commit, wrong and confusing) name seems like something we'd want to clean up enventually.

[23Skidoo]

Let's go for it (unless @tibbe objects). This will require a major version bump.

[nh2]

I'll make a PR for it.

[nh2]

@23Skidoo Shall I base it on #28 ?

Looks like we very very likely want to have that, and I can add in the newly added stats in the same run.

[nh2]

PR at #30

[tibbe]

If long enough time has passed I think it makes sense to break backwards compatibility. Ideally we add the right name in release N and in some later release N+X we remove the old one. This way people don't have to throw ifdefs everywhere.

[nh2]

@tibbe Not sure if you meant that, but since you brought in ifdefs, I may clarify:

The Haskell types backward compat isn't broken by this, the included #ifdefs take care of that.

It's the "dynamic" names of the fileds (e.g. rts.gc.current_bytes_used vs rts.gc.live_bytes) that may, at runtime, break those that rely on these names (for example the ekg UI's JS, which I'm fixing currently).

[nh2]

(Don't merge yet, I noticed that the haddocks also have the old names to be updated, I still need to do that.)

[nh2]

(Don't merge yet, I noticed that the haddocks also have the old names to be updated, I still need to do that.)

I have reworked the haddocks now, please see the amended commit.