[Tokenomics] Use big.Rat to calculate new difficulty hash #831
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Olshansk
requested changes
Sep 24, 2024
| if isDecreasingDifficulty && bytes.Equal(prevTargetHash, BaseRelayDifficultyHashBz) { | ||
| difficultyScalingRatio := big.NewRat(int64(targetNumRelays), int64(newRelaysEma)) | ||
| scaledDifficultyHashBz := ScaleRelayDifficultyHash(prevTargetHash, difficultyScalingRatio) | ||
| // If scaledDifficultyHash is longer than BaseRelayDifficultyHashBz, then use |
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Are you sure about this?
Let's assume BaseRelayDifficulty is fff (allow all relays)
Let's assume ScaledDifficulty is 0001 (allow almost no relays)
We're going to get a completely wrong output.
I think my previous business logic was a bit different for this reason.
- If I'm wrong -> cool. Can you explain?
- If I'm right -> can you add a test case to mitigate the regression?
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ScaleRelayDifficultyHash is getting its hash bytes from a big.Int which should not append or pad left zero bytes.
To make it extra safe, I'll trim any extra zeros on the left side.
red-0ne
changed the title
bryanchriswhite
approved these changes
Sep 30, 2024
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| scaledHashRat := new(big.Rat).Mul(difficultyHashRat, difficultyScalingRatio) | ||
| scaledHashInt := new(big.Int).Div(scaledHashRat.Num(), scaledHashRat.Denom()) |
| require.Equal(t, len(expectedNewHashBz), len(newDifficultyHash), "scaled down difficulty should have been padded") | ||
| } else if targetNumRelays > newRelaysEma { | ||
| require.Greater(t, len(expectedScaledHashBz), len(newDifficultyHash)) | ||
| require.Equal(t, len(expectedNewHashBz), len(newDifficultyHash), "scaled down difficulty should have been padded") |
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Suggested change
| require.Equal(t, len(expectedNewHashBz), len(newDifficultyHash), "scaled down difficulty should have been padded") | |
| require.Equal(t, len(expectedNewHashBz), len(newDifficultyHash), "scaled up difficulty should have been truncated") |
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Summary
Refactor the difficulty hash calculation to use
big.Ratinstead of floats to avoid precision loss. It delays integer conversion as much as possible.Fix relay difficulty tests to use
big.Ratand avoid architecture dependent floating point calculations.Issue
Type of change
Select one or more from the following:
consensus-breakinglabel if so. See [Infra] Automatically add theconsensus-breakinglabel #791 for detailsTesting
make go_develop_and_testmake test_e2edevnet-test-e2elabel to the PR.Sanity Checklist