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authorJunio C Hamano <gitster@pobox.com>2016-10-28 09:01:17 -0700
committerJunio C Hamano <gitster@pobox.com>2016-10-28 09:01:17 -0700
commit39000e849970a554a257577dcb2fb844a523a1d1 (patch)
tree26911732b4cb4f2c6389cbb7bbfb437c9e406025 /t
parent96ec83ce5207be0aac3c1df1ac92356f9de9ad81 (diff)
parent5827a03545663f6d6b491a35edb313900608568b (diff)
downloadgit-39000e849970a554a257577dcb2fb844a523a1d1.tar.gz
git-39000e849970a554a257577dcb2fb844a523a1d1.tar.xz
Merge branch 'jk/fetch-quick-tag-following' into maint
When fetching from a remote that has many tags that are irrelevant to branches we are following, we used to waste way too many cycles when checking if the object pointed at by a tag (that we are not going to fetch!) exists in our repository too carefully. * jk/fetch-quick-tag-following: fetch: use "quick" has_sha1_file for tag following
Diffstat (limited to 't')
-rwxr-xr-xt/perf/p5550-fetch-tags.sh99
1 files changed, 99 insertions, 0 deletions
diff --git a/t/perf/p5550-fetch-tags.sh b/t/perf/p5550-fetch-tags.sh
new file mode 100755
index 000000000..a5dc39f86
--- /dev/null
+++ b/t/perf/p5550-fetch-tags.sh
@@ -0,0 +1,99 @@
+#!/bin/sh
+
+test_description='performance of tag-following with many tags
+
+This tests a fairly pathological case, so rather than rely on a real-world
+case, we will construct our own repository. The situation is roughly as
+follows.
+
+The parent repository has a large number of tags which are disconnected from
+the rest of history. That makes them candidates for tag-following, but we never
+actually grab them (and thus they will impact each subsequent fetch).
+
+The child repository is a clone of parent, without the tags, and is at least
+one commit behind the parent (meaning that we will fetch one object and then
+examine the tags to see if they need followed). Furthermore, it has a large
+number of packs.
+
+The exact values of "large" here are somewhat arbitrary; I picked values that
+start to show a noticeable performance problem on my machine, but without
+taking too long to set up and run the tests.
+'
+. ./perf-lib.sh
+
+# make a long nonsense history on branch $1, consisting of $2 commits, each
+# with a unique file pointing to the blob at $2.
+create_history () {
+ perl -le '
+ my ($branch, $n, $blob) = @ARGV;
+ for (1..$n) {
+ print "commit refs/heads/$branch";
+ print "committer nobody <nobody@example.com> now";
+ print "data 4";
+ print "foo";
+ print "M 100644 $blob $_";
+ }
+ ' "$@" |
+ git fast-import --date-format=now
+}
+
+# make a series of tags, one per commit in the revision range given by $@
+create_tags () {
+ git rev-list "$@" |
+ perl -lne 'print "create refs/tags/$. $_"' |
+ git update-ref --stdin
+}
+
+# create $1 nonsense packs, each with a single blob
+create_packs () {
+ perl -le '
+ my ($n) = @ARGV;
+ for (1..$n) {
+ print "blob";
+ print "data <<EOF";
+ print "$_";
+ print "EOF";
+ }
+ ' "$@" |
+ git fast-import &&
+
+ git cat-file --batch-all-objects --batch-check='%(objectname)' |
+ while read sha1
+ do
+ echo $sha1 | git pack-objects .git/objects/pack/pack
+ done
+}
+
+test_expect_success 'create parent and child' '
+ git init parent &&
+ git -C parent commit --allow-empty -m base &&
+ git clone parent child &&
+ git -C parent commit --allow-empty -m trigger-fetch
+'
+
+test_expect_success 'populate parent tags' '
+ (
+ cd parent &&
+ blob=$(echo content | git hash-object -w --stdin) &&
+ create_history cruft 3000 $blob &&
+ create_tags cruft &&
+ git branch -D cruft
+ )
+'
+
+test_expect_success 'create child packs' '
+ (
+ cd child &&
+ git config gc.auto 0 &&
+ git config gc.autopacklimit 0 &&
+ create_packs 500
+ )
+'
+
+test_perf 'fetch' '
+ # make sure there is something to fetch on each iteration
+ git -C child update-ref -d refs/remotes/origin/master &&
+ git -C child fetch
+'
+
+test_done