eth/tracers: add golang 4byte tracer

[wardbradt]

No description provided.

[holiman]

LGTM, thanks!

[holiman]

Some timing stats

native: 8m22.495952253s:

INFO [11-11|08:30:28.658] Chain tracing finished                   start=13,401,259 end=13,402,259 transactions=188,695 elapsed=8m22.495952253s

js: 12m24.845998177s

INFO [11-11|08:53:48.225] Chain tracing finished                   start=13,401,259 end=13,402,259 transactions=188,695 elapsed=12m24.845998177s

js-legacy: 30m36.802869401s

INFO [11-11|09:48:25.003] Chain tracing finished                   start=13,401,259 end=13,402,259 transactions=188,695 elapsed=30m36.802869401s

I'm going to go through the results and see if there are any discrepancies

[holiman]

I've found zero discrepancies between js and go, however, there are differences between (js/go) vs legacy. They are of this type:

{
    ...skipped 2 object properties...,
    "traces": [
        ...skipped 50 array elements...,
        {
            "result": {
                ...skipped 1 object property...,
                "0x60806040-1708": 1,
                ...skipped 1 object property...
            }
        },
        ...skipped 106 array elements...,
        {
            "result": {
                "0x3d602d80-51": 1,
                ...skipped 8 object properties...
            }
        },

Which looks like code, to me. I suspect the legacy one correctly does not catch initcode, but the newer traces doesn't. So the new tracers needs to fixed. I'll push a fix

[holiman]

After a fix-up, the discrepancies are gone.
@wardbradt you seem to have disabled maintainer-commit on your fork of geth, so I can't push to this branch.
Can you cherry-pick this commit holiman@d57724b -- of my fixup branch?

[s1na]

Very cool, thanks!

[s1na]

So this would introduce a new tracer. If we want to make it the default it has to be called 4byteTracer

[holiman]

Second attempt,

js : 12m15.214591921s
native (warmed up by the previous run): 4m30.635180831s

Yes, I think we should make the go-tracer be the default, so register it as 4byteTracer

Need additional fix-commit

[holiman]

LGTM

[holiman]

TODO for follow-up PR: make the golang tracer default