blockchain: Make version 5 update atomic. #1529
Merged
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Outdated suggestions cannot be applied.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.
This modifies the version 5 migration code to update the database version atomically with setting a reindex tip and resetting the best chain tip back to the genesis block so the chain can be reindexed.
This is necessary because, unlike the modifications that come before it, storing the current chain tip and resetting it is not idempotent, so lack of atomicity in those updates can lead to failure to recover in unclean shutdown circumstances.
Thanks to @alexlyp for providing the logs which triggered the condition and helping test the resolution.