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git/t/t4001-diff-rename.sh
Elijah Newren bd24aa2f97 diffcore-rename: guide inexact rename detection based on basenames
Make use of the new find_basename_matches() function added in the last
two patches, to find renames more rapidly in cases where we can match up
files based on basenames.  As a quick reminder (see the last two commit
messages for more details), this means for example that
docs/extensions.txt and docs/config/extensions.txt are considered likely
renames if there are no remaining 'extensions.txt' files elsewhere among
the added and deleted files, and if a similarity check confirms they are
similar, then they are marked as a rename without looking for a better
similarity match among other files.  This is a behavioral change, as
covered in more detail in the previous commit message.

We do not use this heuristic together with either break or copy
detection.  The point of break detection is to say that filename
similarity does not imply file content similarity, and we only want to
know about file content similarity.  The point of copy detection is to
use more resources to check for additional similarities, while this is
an optimization that uses far less resources but which might also result
in finding slightly fewer similarities.  So the idea behind this
optimization goes against both of those features, and will be turned off
for both.

For the testcases mentioned in commit 557ac0350d ("merge-ort: begin
performance work; instrument with trace2_region_* calls", 2020-10-28),
this change improves the performance as follows:

                            Before                  After
    no-renames:       13.815 s ±  0.062 s    13.294 s ±  0.103 s
    mega-renames:   1799.937 s ±  0.493 s   187.248 s ±  0.882 s
    just-one-mega:    51.289 s ±  0.019 s     5.557 s ±  0.017 s

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-02-15 18:02:16 -08:00

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#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano
#
test_description='Test rename detection in diff engine.
'
. ./test-lib.sh
. "$TEST_DIRECTORY"/diff-lib.sh
test_expect_success 'setup' '
cat >path0 <<-\EOF &&
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
Line 9
Line 10
line 11
Line 12
Line 13
Line 14
Line 15
EOF
cat >expected <<-\EOF &&
diff --git a/path0 b/path1
rename from path0
rename to path1
--- a/path0
+++ b/path1
@@ -8,7 +8,7 @@ Line 7
Line 8
Line 9
Line 10
-line 11
+Line 11
Line 12
Line 13
Line 14
EOF
cat >no-rename <<-\EOF
diff --git a/path0 b/path0
deleted file mode 100644
index fdbec44..0000000
--- a/path0
+++ /dev/null
@@ -1,15 +0,0 @@
-Line 1
-Line 2
-Line 3
-Line 4
-Line 5
-Line 6
-Line 7
-Line 8
-Line 9
-Line 10
-line 11
-Line 12
-Line 13
-Line 14
-Line 15
diff --git a/path1 b/path1
new file mode 100644
index 0000000..752c50e
--- /dev/null
+++ b/path1
@@ -0,0 +1,15 @@
+Line 1
+Line 2
+Line 3
+Line 4
+Line 5
+Line 6
+Line 7
+Line 8
+Line 9
+Line 10
+Line 11
+Line 12
+Line 13
+Line 14
+Line 15
EOF
'
test_expect_success \
'update-index --add a file.' \
'git update-index --add path0'
test_expect_success \
'write that tree.' \
'tree=$(git write-tree) && echo $tree'
sed -e 's/line/Line/' <path0 >path1
rm -f path0
test_expect_success \
'renamed and edited the file.' \
'git update-index --add --remove path0 path1'
test_expect_success \
'git diff-index -p -M after rename and editing.' \
'git diff-index -p -M $tree >current'
test_expect_success \
'validate the output.' \
'compare_diff_patch current expected'
test_expect_success 'test diff.renames=true' '
git -c diff.renames=true diff --cached $tree >current &&
compare_diff_patch current expected
'
test_expect_success 'test diff.renames=false' '
git -c diff.renames=false diff --cached $tree >current &&
compare_diff_patch current no-rename
'
test_expect_success 'test diff.renames unset' '
git diff --cached $tree >current &&
compare_diff_patch current expected
'
test_expect_success 'favour same basenames over different ones' '
cp path1 another-path &&
git add another-path &&
git commit -m 1 &&
git rm path1 &&
mkdir subdir &&
git mv another-path subdir/path1 &&
git status >out &&
test_i18ngrep "renamed: .*path1 -> subdir/path1" out
'
test_expect_success 'test diff.renames=true for git status' '
git -c diff.renames=true status >out &&
test_i18ngrep "renamed: .*path1 -> subdir/path1" out
'
test_expect_success 'test diff.renames=false for git status' '
git -c diff.renames=false status >out &&
test_i18ngrep ! "renamed: .*path1 -> subdir/path1" out &&
test_i18ngrep "new file: .*subdir/path1" out &&
test_i18ngrep "deleted: .*[^/]path1" out
'
test_expect_success 'favour same basenames even with minor differences' '
git show HEAD:path1 | sed "s/15/16/" > subdir/path1 &&
git status >out &&
test_i18ngrep "renamed: .*path1 -> subdir/path1" out
'
test_expect_success 'two files with same basename and same content' '
git reset --hard &&
mkdir -p dir/A dir/B &&
cp path1 dir/A/file &&
cp path1 dir/B/file &&
git add dir &&
git commit -m 2 &&
git mv dir other-dir &&
git status >out &&
test_i18ngrep "renamed: .*dir/A/file -> other-dir/A/file" out
'
test_expect_success 'setup for many rename source candidates' '
git reset --hard &&
for i in 0 1 2 3 4 5 6 7 8 9;
do
for j in 0 1 2 3 4 5 6 7 8 9;
do
echo "$i$j" >"path$i$j"
done
done &&
git add "path??" &&
test_tick &&
git commit -m "hundred" &&
(cat path1 && echo new) >new-path &&
echo old >>path1 &&
git add new-path path1 &&
git diff -l 4 -C -C --cached --name-status >actual 2>actual.err &&
sed -e "s/^\([CM]\)[0-9]* /\1 /" actual >actual.munged &&
cat >expect <<-EOF &&
C path1 new-path
M path1
EOF
test_cmp expect actual.munged &&
grep warning actual.err
'
test_expect_success 'rename pretty print with nothing in common' '
mkdir -p a/b/ &&
: >a/b/c &&
git add a/b/c &&
git commit -m "create a/b/c" &&
mkdir -p c/b/ &&
git mv a/b/c c/b/a &&
git commit -m "a/b/c -> c/b/a" &&
git diff -M --summary HEAD^ HEAD >output &&
test_i18ngrep " a/b/c => c/b/a " output &&
git diff -M --stat HEAD^ HEAD >output &&
test_i18ngrep " a/b/c => c/b/a " output
'
test_expect_success 'rename pretty print with common prefix' '
mkdir -p c/d &&
git mv c/b/a c/d/e &&
git commit -m "c/b/a -> c/d/e" &&
git diff -M --summary HEAD^ HEAD >output &&
test_i18ngrep " c/{b/a => d/e} " output &&
git diff -M --stat HEAD^ HEAD >output &&
test_i18ngrep " c/{b/a => d/e} " output
'
test_expect_success 'rename pretty print with common suffix' '
mkdir d &&
git mv c/d/e d/e &&
git commit -m "c/d/e -> d/e" &&
git diff -M --summary HEAD^ HEAD >output &&
test_i18ngrep " {c/d => d}/e " output &&
git diff -M --stat HEAD^ HEAD >output &&
test_i18ngrep " {c/d => d}/e " output
'
test_expect_success 'rename pretty print with common prefix and suffix' '
mkdir d/f &&
git mv d/e d/f/e &&
git commit -m "d/e -> d/f/e" &&
git diff -M --summary HEAD^ HEAD >output &&
test_i18ngrep " d/{ => f}/e " output &&
git diff -M --stat HEAD^ HEAD >output &&
test_i18ngrep " d/{ => f}/e " output
'
test_expect_success 'rename pretty print common prefix and suffix overlap' '
mkdir d/f/f &&
git mv d/f/e d/f/f/e &&
git commit -m "d/f/e d/f/f/e" &&
git diff -M --summary HEAD^ HEAD >output &&
test_i18ngrep " d/f/{ => f}/e " output &&
git diff -M --stat HEAD^ HEAD >output &&
test_i18ngrep " d/f/{ => f}/e " output
'
test_expect_success 'diff-tree -l0 defaults to a big rename limit, not zero' '
test_write_lines line1 line2 line3 >myfile &&
git add myfile &&
git commit -m x &&
test_write_lines line1 line2 line4 >myotherfile &&
git rm myfile &&
git add myotherfile &&
git commit -m x &&
git diff-tree -M -l0 HEAD HEAD^ >actual &&
# Verify that a rename from myotherfile to myfile was detected
grep "myotherfile.*myfile" actual
'
test_expect_success 'basename similarity vs best similarity' '
mkdir subdir &&
test_write_lines line1 line2 line3 line4 line5 \
line6 line7 line8 line9 line10 >subdir/file.txt &&
git add subdir/file.txt &&
git commit -m "base txt" &&
git rm subdir/file.txt &&
test_write_lines line1 line2 line3 line4 line5 \
line6 line7 line8 >file.txt &&
test_write_lines line1 line2 line3 line4 line5 \
line6 line7 line8 line9 >file.md &&
git add file.txt file.md &&
git commit -a -m "rename" &&
git diff-tree -r -M --name-status HEAD^ HEAD >actual &&
# subdir/file.txt is 88% similar to file.md, 78% similar to file.txt,
# but since same basenames are checked first...
cat >expected <<-\EOF &&
A file.md
R078 subdir/file.txt file.txt
EOF
test_cmp expected actual
'
test_done