commitlog: Handle empty tail segments upon resumption#4863
Open
commitlog: Handle empty tail segments upon resumption#4863
Conversation
In #4338, the read-only path was made resilient against empty segments at the end of the log, but corresponding logic was not applied to re-opening the commitlog for writing. This patch rectifies that by ignoring and removing segments from the tail of the log if they contain less than `segment::Header::LEN` bytes. Additionally, zero-sized segments are eliminated entirely by ensuring that the header is written before moving the segment into place atomically. The benefit of this is not huge, but could simplify commitlog-consuming code by not having to worry about empty (zero-sized) segments. Happy to revert if that is deemed too less of a benefit.
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
In #4338, the read-only path was made resilient against empty segments at the end of the log, but corresponding logic was not applied to re-opening the commitlog for writing.
This patch rectifies that by ignoring and removing segments from the tail of the log if they contain equal to or less than
segment::Header::LENbytes.Additionally, zero-sized segments are eliminated entirely by ensuring that the header is written before moving the segment into place atomically. The benefit of this is not huge, but could simplify commitlog-consuming code by not having to worry about empty (zero-sized) segments. Happy to revert if that is deemed too less of a benefit.
Expected complexity level and risk
2
Testing
Adds a test.