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dakk / tezpool

Tezos baking redistribution software
https://dakk.github.io/tezpool/
MIT License
23 stars 6 forks source link

getCycleSnapshot is incorrect #8

Open vogelito opened 6 years ago

vogelito commented 6 years ago

the getCycleSnapshot function currently uses the following to determine the block index of the snapshot at a given cycle:

https://github.com/dakk/tezpool/blob/847f855ff26246039bc1d477a99eaf3c7038a6a1/tezpool.py#L81 This is wrong. However, when looking into fixing it I noticed that just above that there's a commented bit that's a lot closer to what I'd expect would be correct: https://github.com/dakk/tezpool/blob/847f855ff26246039bc1d477a99eaf3c7038a6a1/tezpool.py#L76-L79

Before I started digging in more, I wanted to ask why are the bits commented out?

dakk commented 6 years ago

@vogelito I'm not sure why, I think it wasn't working..

vogelito commented 6 years ago

Great... Thanks...

I believe the commented out code to be correct...

curl localhost:8732/chains/main/blocks/head/context/raw/json/rolls/owner/snapshot/42 --silent 
[5]

((42-5-2)4096)+((5+1)256) = 144896 (which is what tzscan reports as the snapshot block index for cycle 42)

I validated a few other ones:

curl localhost:8732/chains/main/blocks/head/context/raw/json/rolls/owner/snapshot/37 --silent 
[7]

((37-5-2)4096)+((7+1)256) = 124928 (also matches the snapshot block on tzscan)

The only problem is that the RPC calls takes a really long time (e.g. over 15 seconds sometimes):

$ time curl localhost:8732/chains/main/blocks/head/context/raw/json/rolls/owner/snapshot/39 --silent 
[1]

real    0m17.320s
user    0m0.004s
sys 0m0.000s

I reported this bug on the tezos issue tracker for now: https://gitlab.com/tezos/tezos/issues/384

Moving back to your original code is definitely the right thing to do, but unfortunately it'll slow things down considerably. Any thoughts?