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author | Derrick Stolee <dstolee@microsoft.com> | 2019-11-21 22:04:41 +0000 |
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committer | Junio C Hamano <gitster@pobox.com> | 2019-11-22 16:11:44 +0900 |
commit | 96cc8ab5318cd57c8bc203b8f064b35883b2386f (patch) | |
tree | 34c7c46a9525f853ba710fe070fd191060ac2cdd /linear-assignment.h | |
parent | sparse-checkout: add 'cone' mode (diff) | |
download | tgif-96cc8ab5318cd57c8bc203b8f064b35883b2386f.tar.xz |
sparse-checkout: use hashmaps for cone patterns
The parent and recursive patterns allowed by the "cone mode"
option in sparse-checkout are restrictive enough that we
can avoid using the regex parsing. Everything is based on
prefix matches, so we can use hashsets to store the prefixes
from the sparse-checkout file. When checking a path, we can
strip path entries from the path and check the hashset for
an exact match.
As a test, I created a cone-mode sparse-checkout file for the
Linux repository that actually includes every file. This was
constructed by taking every folder in the Linux repo and creating
the pattern pairs here:
/$folder/
!/$folder/*/
This resulted in a sparse-checkout file sith 8,296 patterns.
Running 'git read-tree -mu HEAD' on this file had the following
performance:
core.sparseCheckout=false: 0.21 s (0.00 s)
core.sparseCheckout=true: 3.75 s (3.50 s)
core.sparseCheckoutCone=true: 0.23 s (0.01 s)
The times in parentheses above correspond to the time spent
in the first clear_ce_flags() call, according to the trace2
performance traces.
While this example is contrived, it demonstrates how these
patterns can slow the sparse-checkout feature.
Helped-by: Eric Wong <e@80x24.org>
Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'linear-assignment.h')
0 files changed, 0 insertions, 0 deletions