The entry_count field is the amount of index entries covered by a
particular cache entry, that is how many files are there (recursively)
under a particular directory.
The current code that attemps to do this is severely defincient and is
trying to count the amount of children, which always comes up to zero.
We don't even need to recount, since we have the information during the
cache creation. We can take that number and keep it, as we only ever
invalidate or replace.
Keeping the cache around after read-tree is only one part of the
optimisation opportunities. In order to share the cache between program
instances, we need to write the TREE extension to the index.
Do so, taking the opportunity to rename 'entries' to 'entry_count' to
match the name given in the format description. The included test is
rather trivial, but works as a sanity check.
When reading from a tree, we know what every tree is going to look like,
so we can fill in the tree cache completely, making use of the index for
modification of trees a lot quicker.
This simplifies freeing the entries quite a bit; though there aren't
that many failure paths right now, introducing filling the cache from a
tree will introduce more. This makes sure not to leak memory on errors.
While I was looking at the conflict cleanup code, I looked over at
the tree cache code, since we clear the tree cache for each entry
that gets removed and there is some redundancy there. I made some
small tweaks to avoid extra calls to strchr and strlen in a few
circumstances.
While C Git has been writing entry count -1 (ie. never other negative
numbers) as invalid since day 1, it accepts all negative entry counts
as invalid. JGit follows the same rule. libgit2 should also follow, or
the index that works with C Git or JGit may someday be rejected by
libgit2.
Other reimplementations like dulwich and grit have not bothered with
parsing or writing tree cache.
The code used to assume that there had to be data after the newline in
a tree cache extension entry. This isn't true for a childless
invalidated entry if it's the last one, as there won't be any children
nor a hash to take up space.
Adapt the off-by-one comparison to also work in this case. Fixes#633.
Whenever a file is updated in the index, each tree leading towards it
needs to be invalidated. Provide the supporting function.
Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
The fix introduced in a02fc2cd1 (2011-05-24; index: correctly parse
invalidated TREE extensions) threw out the rest of the data in the
extension if it found an invalidated entry. This was the result of
incorrect reading of the documentation.
Insted, keep reading the extension, as there may be cached data we can
use.
Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
