Probably not any particular speedup in this, since most of these logs
are not written to often. Possibly chunk log writing is sped up, but
writes to chunk logs are interleaved with expensive data transfers to
remotes, so unlikely to be a noticiable speedup.
MetaField was already limited to alphanumerics, so it makes sense to use
Text for it.
Note that technically a UUID can contain invalid UTF-8, and so
remoteMetaDataPrefix's use of T.pack . fromUUID could replace non-UTF8
values with '?' or whatever. In practice, a UUID is usually also text,
I only kept open the possibility of it containing invalid UTF-8 to avoid
breaking parsing of strange UUIDs in git-annex branch files. So, I
decided to let this edge case slip by.
Have not updated the rest of the code base yet for this change, as the
change took 2.5 hours longer than I expected to get working properly.
Tested on an older ghc by enabling MonadFailDesugaring globally.
In TransferQueue, the lack of a MonadFail for STM exposed what would
normally be a bug in the pattern matching, although in this case an
earlier check that the queue was not empty avoided a pattern match
failure.
My concern with using bytestring for this is the file needs to be split
into lines, and the encoding is not known. It's safe to split a utf-8
encoded file on the \n byte; only newlines get encoded to that byte in utf-8.
And this code already assumes utf-8 or ascii encoding, because it used
the filesystem encoding.
