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author | Derrick Stolee <dstolee@microsoft.com> | 2019-12-13 21:09:53 +0300 |
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committer | Junio C Hamano <gitster@pobox.com> | 2019-12-13 23:01:02 +0300 |
commit | 190a65f9db8db9d87d54351429f7879fcb4ad608 (patch) | |
tree | 69147479da50321ae236a5910783c6d7a62e365f /Documentation | |
parent | cff4e9138d8df45e3b6199171092ee781cdadaeb (diff) |
sparse-checkout: respect core.ignoreCase in cone mode
When a user uses the sparse-checkout feature in cone mode, they
add patterns using "git sparse-checkout set <dir1> <dir2> ..."
or by using "--stdin" to provide the directories line-by-line over
stdin. This behaviour naturally looks a lot like the way a user
would type "git add <dir1> <dir2> ..."
If core.ignoreCase is enabled, then "git add" will match the input
using a case-insensitive match. Do the same for the sparse-checkout
feature.
Perform case-insensitive checks while updating the skip-worktree
bits during unpack_trees(). This is done by changing the hash
algorithm and hashmap comparison methods to optionally use case-
insensitive methods.
When this is enabled, there is a small performance cost in the
hashing algorithm. To tease out the worst possible case, the
following was run on a repo with a deep directory structure:
git ls-tree -d -r --name-only HEAD |
git sparse-checkout set --stdin
The 'set' command was timed with core.ignoreCase disabled or
enabled. For the repo with a deep history, the numbers were
core.ignoreCase=false: 62s
core.ignoreCase=true: 74s (+19.3%)
For reproducibility, the equivalent test on the Linux kernel
repository had these numbers:
core.ignoreCase=false: 3.1s
core.ignoreCase=true: 3.6s (+16%)
Now, this is not an entirely fair comparison, as most users
will define their sparse cone using more shallow directories,
and the performance improvement from eb42feca97 ("unpack-trees:
hash less in cone mode" 2019-11-21) can remove most of the
hash cost. For a more realistic test, drop the "-r" from the
ls-tree command to store only the first-level directories.
In that case, the Linux kernel repository takes 0.2-0.25s in
each case, and the deep repository takes one second, plus or
minus 0.05s, in each case.
Thus, we _can_ demonstrate a cost to this change, but it is
unlikely to matter to any reasonable sparse-checkout cone.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/git-sparse-checkout.txt | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/git-sparse-checkout.txt b/Documentation/git-sparse-checkout.txt index b975285673..9c3c66cc37 100644 --- a/Documentation/git-sparse-checkout.txt +++ b/Documentation/git-sparse-checkout.txt @@ -150,6 +150,11 @@ expecting patterns of these types. Git will warn if the patterns do not match. If the patterns do match the expected format, then Git will use faster hash- based algorithms to compute inclusion in the sparse-checkout. +If `core.ignoreCase=true`, then the pattern-matching algorithm will use a +case-insensitive check. This corrects for case mismatched filenames in the +'git sparse-checkout set' command to reflect the expected cone in the working +directory. + SEE ALSO -------- |