describe: enable sparse index for describe

git describe compares the index with the working tree when (and only
when) it is run with the "--dirty" flag. This is done by the
run_diff_index() function. The function has been made aware of the
sparse-index in the series that led to 8d2c3732 (Merge branch
'ld/sparse-diff-blame', 2021-12-21). Hence we can just set the
requires-full-index to false for "describe".

Performance metrics

  Test                                                     HEAD~1            HEAD
  -------------------------------------------------------------------------------------------------
  2000.2: git describe --dirty (full-v3)                   0.08(0.09+0.01)   0.08(0.06+0.03) +0.0%
  2000.3: git describe --dirty (full-v4)                   0.09(0.07+0.03)   0.08(0.05+0.04) -11.1%
  2000.4: git describe --dirty (sparse-v3)                 0.88(0.82+0.06)   0.02(0.01+0.05) -97.7%
  2000.5: git describe --dirty (sparse-v4)                 0.68(0.60+0.08)   0.02(0.02+0.04) -97.1%
  2000.6: echo >>new && git describe --dirty (full-v3)     0.08(0.04+0.05)   0.08(0.05+0.04) +0.0%
  2000.7: echo >>new && git describe --dirty (full-v4)     0.08(0.07+0.03)   0.08(0.05+0.04) +0.0%
  2000.8: echo >>new && git describe --dirty (sparse-v3)   0.75(0.69+0.07)   0.02(0.03+0.03) -97.3%
  2000.9: echo >>new && git describe --dirty (sparse-v4)   0.81(0.73+0.09)   0.02(0.01+0.05) -97.5%

Signed-off-by: Raghul Nanth A <nanth.raghul@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/describe.c b/builtin/describe.c
index 5b5930f5c8c05dfa7581be78b6fc2f8e73e758d0..7ff9b5e4b20eaa3d2fd500dd815bc72659e7d035 100644 (file)
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -654,6 +654,8 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
                        int fd, result;
 
                        setup_work_tree();
+                       prepare_repo_settings(the_repository);
+                       the_repository->settings.command_requires_full_index = 0;
                        repo_read_index(the_repository);
                        refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED,
                                      NULL, NULL, NULL);

diff --git a/t/perf/p2000-sparse-operations.sh b/t/perf/p2000-sparse-operations.sh
index 3242cfe91a096fef06d11cc589bb1ab415135e96..db7887470f9c6cfff55b19533a87d3d560a18ef1 100755 (executable)
--- a/t/perf/p2000-sparse-operations.sh
+++ b/t/perf/p2000-sparse-operations.sh
@@ -43,6 +43,7 @@ test_expect_success 'setup repo and indexes' '
        done &&
 
        git sparse-checkout init --cone &&
+       git tag -a v1.0 -m "Final" &&
        git sparse-checkout set $SPARSE_CONE &&
        git checkout -b wide $OLD_COMMIT &&
 
@@ -125,5 +126,7 @@ test_perf_on_all git checkout-index -f --all
 test_perf_on_all git update-index --add --remove $SPARSE_CONE/a
 test_perf_on_all "git rm -f $SPARSE_CONE/a && git checkout HEAD -- $SPARSE_CONE/a"
 test_perf_on_all git grep --cached --sparse bogus -- "f2/f1/f1/*"
+test_perf_on_all git describe --dirty
+test_perf_on_all 'echo >>new && git describe --dirty'
 
 test_done

diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index 801919009e1d073735ac785a49b0aa353e565c55..51bebd4fa999e43210699b4a54f34f7fc2528f92 100755 (executable)
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -1514,6 +1514,31 @@ test_expect_success 'sparse-index is not expanded: stash' '
        ensure_not_expanded stash pop
 '
 
+test_expect_success 'describe tested on all' '
+       init_repos &&
+
+       # Add tag to be read by describe
+
+       run_on_all git tag -a v1.0 -m "Version 1" &&
+       test_all_match git describe --dirty &&
+       run_on_all rm g &&
+       test_all_match git describe --dirty
+'
+
+
+test_expect_success 'sparse-index is not expanded: describe' '
+       init_repos &&
+
+       # Add tag to be read by describe
+
+       git -C sparse-index tag -a v1.0 -m "Version 1" &&
+
+       ensure_not_expanded describe --dirty &&
+       echo "test" >>sparse-index/g &&
+       ensure_not_expanded describe --dirty &&
+       ensure_not_expanded describe
+'
+
 test_expect_success 'sparse index is not expanded: diff' '
        init_repos &&