The new Distance object knows how to perform various types of distance
calculations (expression, equality, number, priority, string).
It will keep track of each individual penalty that has been applied so
that we can utilise that information in the UI and when making decisions
about the recommendation level.
We now display the top 3 penalties (sorted by weight) on the release
list (and "..." if there are more than 3), and we display all penalties
on the album info line and track change line.
The implementation of the `max_rec` setting has been simplified by
removing duplicate validation and instead looking at the penalties that
have been applied to a distance. As a result, we can now configure a
maximum recommendation for any penalty that might be applied.
We have a few new checks when calculating album distance:
`match: preferred: countries` and `match: preferred: media` can each be
set to a list of countries and media in order of your preference. These
are empty by default. A value that matches the first item will have no
penalty, and a value that doesn't match any item will have an unweighted
penalty of 1.0.
If `match: preferred: original_year` is set to "yes", beets will apply
an unweighted penalty of 1.0 for each year of difference between the
release year and the original year.
We now configure individual weights for `mediums` (disctotal), `label`,
`catalognum`, `country` and `albumdisambig` instead of a single generic
`minor` weight. This gives more control, but more importantly separates
and names the applied penalties so that the UI can convey exactly which
fields have contributed to the overall distance penalty.
Likewise, `missing tracks` and `unmatched tracks` are penalised and
displayed in the UI separately, instead of a combined `partial` penalty.
Display non-MusicBrainz source in the disambiguation string, and
"source" in the list of penalties if a release is penalised for being
a non-MusicBrainz.
The 'decode' call fails in what is already a unicode string. I'm not
sure under what circumstances the string is or isn't unicode (apparently
it varies), so I added a check. The test passes with the patch, at
least.
This allows matches to indicate both missing and unmatched tracks in their
candidates and solves some of the spaghetti tuples that were passed around
during autotagging.
In an attempt to finally address the longstanding SQLite locking issues, I'm
introducing a way to explicitly, lexically scope transactions. The Transaction
class is a context manager that always fully fetches after SELECTs and
automatically commits on exit. No direct access to the library is allowed, so
all changes will eventually be committed and all queries will be completed. This
will also provide a debugging mechanism to show where concurrent transactions
are beginning and ending.
To support composition (transaction reentrancy), an internal, per-Library stack
of transactions is maintained. Commits only happen when the outermost
transaction exits. This means that, while it's possible to introduce atomicity
bugs by invoking Library methods outside of a transaction, you can conveniently
call them *without* a currently-active transaction to get a single atomic
action.
Note that this "transaction stack" concepts assumes a single Library object per
thread. Because we need to duplicate Library objects for concurrent access due
to sqlite3 limitation already, this is fine for now. Later, the interface should
provide one transaction stack per thread for shared Library objects.
Instead of parsing the template at each call to destination(), it's now possible
to parse them *once*, a priori, and re-use the resulting template object. This
is analogous to the re module's compiled expressions.
There's no longer a distinction between Unix and Windows substitutions. Enough
users reported problems with Windows-forbidden characters on Samba shares that
it seems appropriate to make all filenames Windows-safe, even on Unix. Users who
really want those additional characters (<>:"?*|\) can re-enable them via the
"replace" option. Nobody has complained about beets being *too* conservative.
This also adds sanitization of control characters, which is an all-around good
idea, and the substitution now runs in the Unicode (rather than byte) domain.
