State history v2 has been shipped and will take effect after the Cancun fork.
However, the state revert function does not differentiate between v1 and v2,
instead blindly using the storage map key for state reversion.
This mismatch between the keys of the live state set and the state history
can trigger a panic: `non-existent storage slot for reverting`.
This flaw has been fixed in this PR.
This pull request delivers the new version of the state history, where
the raw storage key is used instead of the hash.
Before the cancun fork, it's supported by protocol to destruct a
specific account and therefore, all the storage slot owned by it should
be wiped in the same transition.
Technically, storage wiping should be performed through storage
iteration, and only the storage key hash will be available for traversal
if the state snapshot is not available. Therefore, the storage key hash
is chosen as the identifier in the old version state history.
Fortunately, account self-destruction has been deprecated by the
protocol since the Cancun fork, and there are no empty accounts eligible
for deletion under EIP-158. Therefore, we can conclude that no storage
wiping should occur after the Cancun fork. In this case, it makes no
sense to keep using hash.
Besides, another big reason for making this change is the current format
state history is unusable if verkle is activated. Verkle tree has a
different key derivation scheme (merkle uses keccak256), the preimage of
key hash must be provided in order to make verkle rollback functional.
This pull request is a prerequisite for landing verkle.
Additionally, the raw storage key is more human-friendly for those who
want to manually check the history, even though Solidity already
performs some hashing to derive the storage location.
---
This pull request doesn't bump the database version, as I believe the
database should still be compatible if users degrade from the new geth
version to old one, the only side effect is the persistent new version
state history will be unusable.
---------
Co-authored-by: Zsolt Felfoldi <zsfelfoldi@gmail.com>
As SELF-DESTRUCT opcode is disabled in the cancun fork(unless the
account is created within the same transaction, nothing to delete
in this case). The account will only be deleted in the following
cases:
- The account is created within the same transaction. In this case
the original storage was empty.
- The account is empty(zero nonce, zero balance, zero code) and
is touched within the transaction. Fortunately this kind of accounts
are not-existent on ethereum-mainnet.
All in all, after cancun, we are pretty sure there is no large contract
deletion and we don't need this mechanism for oom protection.
rjl493456442
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Martin HS
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