Note that this is a nearly entirely free feature. The data was already
stored in the metadata log in an easily accessible way, and already was
parsed to a time when parsing the log. The generation of the metadata
fields may even be done lazily, although probably not entirely (the map
has to be evaulated to when queried).
Performance impact: When adding a large tree of new files, this needs
to do some git cat-file queries to check if any of the files already
existed and might need a metadata copy. I tried a benchmark in a copy
of my sound repository (so there was already a significant git tree
to check against.
Adding 10000 small files, with a cold cache:
before: 1m48.539s
after: 1m52.791s
So, impact is 0.0004 seconds per file added. Which seems acceptable, so did
not add some kind of configuration to enable/disable this.
This commit was sponsored by Lisa Feilen.
So the user can now switch to a view and then move files around within it
to manage metadata. For example, moving a file into a new directory
when in the tags=* view adds a tag to it.
Implementation is fairly efficient. One diff-index, which is no more
expensive than the first stage of a git commit, followed by possibly
some cat-file --batch traffic to find the key (when deleting a file).
Very similar to what's done in direct mode when committing. And like
direct mode when updating the WC after a merge, it has to buffer the
diff-tree values in order to make 2 passes over them.
When not in a view, pre-commit now does one extra git symbolic-ref,
which is tiny overhead.
This commit was sponsored by Andrew Eskridge.
Adds metadata log, and command.
Note that unsetting field values seems to currently be broken.
And in general this has had all of 2 minutes worth of testing.
This commit was sponsored by Julien Lefrique.
