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::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.
# Expected complexity level and risk
2
# Testing
Adds a test.
Kim Altintop
997b5a6e8f