Changes since previous version: * Fixed an overflow error in the binary search. I sent a separate patch to fix this error in existing searches; that patch should be applied before this one. * Removed test-list-objects and test-abbrev in favor of a new git log test in p4211-line-log.sh. Limited perf numbers for Linux repo are given in cover letter and commit 4/4. * Silently skip packfiles that fail to open with open_pack_index() Thanks for all the comments from Jeff, Junio, Ramsey, and Stefan! Thanks, Stolee --- When displaying object ids, we frequently want to see an abbreviation for easier typing. That abbreviation must be unambiguous among all object ids. The current implementation of find_unique_abbrev() performs a loop checking if each abbreviation length is unambiguous until finding one that works. This causes multiple round-trips to the disk when starting with the default abbreviation length (usually 7) but needing up to 12 characters for an unambiguous short-sha. For very large repos, this effect is pronounced and causes issues with several commands, from obvious consumers `status` and `log` to less obvious commands such as `fetch` and `push`. This patch improves performance by iterating over objects matching the short abbreviation only once, inspecting each object id, and reporting the minimum length of an unambiguous abbreviation. Add a new perf test for testing the performance of log while computing OID abbreviations. Using --oneline --raw and --parents options maximizes the number of OIDs to abbreviate while still spending some time computing diffs. Below we report performance statistics for perf test 4211.6 from p4211-line-log.sh using three copies of the Linux repo: | Packs | Loose | Base Time | New Time | Rel% | |-------|--------|-----------|----------|-------| | 1 | 0 | 41.27 s | 38.93 s | -4.8% | | 24 | 0 | 98.04 s | 91.35 s | -5.7% | | 23 | 323952 | 117.78 s | 112.18 s | -4.8% | Derrick Stolee (4): p4211-line-log.sh: add log --online --raw --parents perf test sha1_name: Unroll len loop in find_unique_abbrev_r sha1_name: Parse less while finding common prefix sha1_name: Minimize OID comparisons during disambiguation sha1_name.c | 129 +++++++++++++++++++++++++++++++++++++++++------ t/perf/p4211-line-log.sh | 4 ++ 2 files changed, 118 insertions(+), 15 deletions(-) -- 2.14.1.538.g56ec8fc98.dirty
