consensus/ethash, core: implement Metropolis EIP 100 #14733
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holiman
reviewed
Jun 30, 2017
| @@ -218,6 +218,7 @@ func makeHeader(config *params.ChainConfig, parent *types.Block, state *state.St | |||
| Number: parent.Number(), | |||
| Time: new(big.Int).Sub(time, big.NewInt(10)), | |||
| Difficulty: parent.Difficulty(), | |||
| UncleHash: parent.UncleHash(), | |||
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What is the effect of this change ?
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This is only used in our tests when we create artificial chains to test various corner cases. The chain maker is messing around with incomplete blocks/headers to get around certain validity checks (to evoke failures), so here we don't have a "real" parent block to calculate the difficulty of the child's based on, but instead make one up on the fly. The difficulty algo didn't require access to the uncles until now, so we just skipped copying that field over. It's however needed in metro.
This PR polishes the EIP 100 difficulty adjustment algorithm to match the same mechanisms as the Homestead was implemented to keep the code uniform. It also avoids a few memory allocs by reusing big1 and big2, pulling it out of the common package and into ethash. The commit also fixes chain maker to forward the uncle hash when creating a simulated chain (it wasn't needed until now so we just skipped a copy there).
Arachnid
approved these changes
Jun 30, 2017
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Implements ethereum/EIPs#100.