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authorLibravatar Derrick Stolee <dstolee@microsoft.com>2019-11-21 22:04:41 +0000
committerLibravatar Junio C Hamano <gitster@pobox.com>2019-11-22 16:11:44 +0900
commit96cc8ab5318cd57c8bc203b8f064b35883b2386f (patch)
tree34c7c46a9525f853ba710fe070fd191060ac2cdd /utf8.c
parentsparse-checkout: add 'cone' mode (diff)
downloadtgif-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>
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