This repository was archived by the owner on Sep 8, 2025. It is now read-only.
Lock in storage changes before transaction starts #1894
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Currently, because we don't do this, there is a bug in EIP-2200, net gas metering. When looking up the "original value", the EVM must get the storage value at the beginning of the transaction, not the beginning of the block. So we lock in changes at the beginning of every transaction, to make sure we don't read values from older transactions, when reading the original value.
|
Just confirmed that this allows us to successfully process block 9069000, the Istanbul fork block |
Storage value lookups with from_journal=False must pin to the value at the time of the latest lock_changes() call.
lithp
reviewed
Dec 9, 2019
| """ | ||
| Locks in changes to storage, typically just as a transaction starts. | ||
| This is used, for example, to look up the storage value from the start |
There was a problem hiding this comment.
Alternative: "This is used to ensure that reads which skip the journal read state as of the beginning of the transaction, rather than state as of the beginning of the block"
lithp
approved these changes
Dec 10, 2019
There was a problem hiding this comment.
Over DM I mentioned that this is aesthetically a little sub-optimal, we already have a mechanism for doing snapshots that this is kind of reproducing. Let's ship it though! py-evm should support Istanbul and getting this to work using snapshots would require a fair amount of more work.
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
What was wrong?
Currently, because we don't do this, there is a bug in EIP-2200, net gas
metering. When looking up the "original value", the EVM must get the
storage value at the beginning of the transaction, not the beginning of
the block.
Fixes #1893
How was it fixed?
So we lock in changes at the beginning of every transaction,
to make sure we don't read values from older transactions, when reading
the original value.
To-Do
Cute Animal Picture