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core/state: copy the snap when copying the state #22340

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Feb 18, 2021
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core/state: copy the snap when copying the state #22340

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core/state: copy the snap when copying the state
holiman Feb 17, 2021
8226a5c
core/state: deep-copy snap stuff during state Copy
holiman Feb 17, 2021
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25 changes: 25 additions & 0 deletions core/state/statedb.go
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Original file line number Diff line number Diff line change
Expand Up @@ -728,6 +728,31 @@ func (s *StateDB) Copy() *StateDB {
if s.prefetcher != nil {
state.prefetcher = s.prefetcher.copy()
}
if s.snaps != nil {
// In order for the miner to be able to use and make additions
// to the snapshot tree, we need to copy that aswell.
// Otherwise, any block mined by ourselves will cause gaps in the tree,
// and force the miner to operate trie-backed only
state.snaps = s.snaps
state.snap = s.snap
// TODO: Should we copy or make new (empty) ones here?
// If we copy, we need to ensure concurrency safety.
// If we don't copy, we run the risk of consensus breaking.
// In theory, as the state is copied, it's still 'fresh', and these
// should be empty.
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The miner copies the state after running the transactions, but before claiming the block reward. It does this so it ca pile more txs on top. In that case, the state is fresh only if no tx populated it (i.e. post byzantium)

//
// It might be good to check the size first, and if any are non-zero,
// simply avoid copying over the snap
state.snapDestructs = make(map[common.Hash]struct{})
state.snapAccounts = make(map[common.Hash][]byte)
state.snapStorage = make(map[common.Hash]map[common.Hash][]byte)
if len(s.snapAccounts)+len(s.snapDestructs)+len(s.snapStorage) != 0 {
panic("Oy vey!")
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I'd expect this to blow up on pre-byzantium with intermediate root calls?

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So... deep copy then?

}

}

state.snaps = s.snaps
return state
}

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