t/perf/p5551-fetch-rescan.sh

   1 #!/bin/sh
   2
   3 test_description='fetch performance with many packs
   4
   5 It is common for fetch to consider objects that we might not have, and it is an
   6 easy mistake for the code to use a function like `parse_object` that might
   7 give the correct _answer_ on such an object, but do so slowly (due to
   8 re-scanning the pack directory for lookup failures).
   9
  10 The resulting performance drop can be hard to notice in a real repository, but
  11 becomes quite large in a repository with a large number of packs. So this
  12 test creates a more pathological case, since any mistakes would produce a more
  13 noticeable slowdown.
  14 '
  15 . ./perf-lib.sh
  16 . "$TEST_DIRECTORY"/perf/lib-pack.sh
  17
  18 test_expect_success 'create parent and child' '
  19         git init parent &&
  20         git clone parent child
  21 '
  22
  23
  24 test_expect_success 'create refs in the parent' '
  25         (
  26                 cd parent &&
  27                 git commit --allow-empty -m foo &&
  28                 head=$(git rev-parse HEAD) &&
  29                 test_seq 1000 |
  30                 sed "s,.*,update refs/heads/& $head," |
  31                 $MODERN_GIT update-ref --stdin
  32         )
  33 '
  34
  35 test_expect_success 'create many packs in the child' '
  36         (
  37                 cd child &&
  38                 setup_many_packs
  39         )
  40 '
  41
  42 test_perf 'fetch' '
  43         # start at the same state for each iteration
  44         obj=$($MODERN_GIT -C parent rev-parse HEAD) &&
  45         (
  46                 cd child &&
  47                 $MODERN_GIT for-each-ref --format="delete %(refname)" refs/remotes |
  48                 $MODERN_GIT update-ref --stdin &&
  49                 rm -vf .git/objects/$(echo $obj | sed "s|^..|&/|") &&
  50
  51                 git fetch
  52         )
  53 '
  54
  55 test_done