From 06dec439a3d00fa0b3141a2d52b33d22b941976c Mon Sep 17 00:00:00 2001 From: Jeff King Date: Fri, 22 Jul 2016 11:27:53 -0400 Subject: [PATCH] diff: do not reuse worktree files that need "clean" conversion When accessing a blob for a diff, we may try to reuse file contents in the working tree, under the theory that it is faster to mmap those file contents than it would be to extract the content from the object database. When we have to filter those contents, though, that assumption does not hold. Even for our internal conversions like CRLF, we have to allocate and fill a new buffer anyway. But much worse, for external clean filters we have to exec an arbitrary script, and we have no idea how expensive it may be to run. So let's skip this optimization when conversion into git's "clean" form is required. This applies whenever the "want_file" flag is false. When it's true, the caller actually wants the smudged worktree contents, which the reused file by definition already has (in fact, this is a key optimization going the other direction, since reusing the worktree file there lets us skip smudge filters). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- diff.c | 7 +++++++ t/t0021-conversion.sh | 11 +++++++++++ 2 files changed, 18 insertions(+) diff --git a/diff.c b/diff.c index 059123c5dc..918cedc4ad 100644 --- a/diff.c +++ b/diff.c @@ -2672,6 +2672,13 @@ static int reuse_worktree_file(const char *name, const unsigned char *sha1, int if (!FAST_WORKING_DIRECTORY && !want_file && has_sha1_pack(sha1)) return 0; + /* + * Similarly, if we'd have to convert the file contents anyway, that + * makes the optimization not worthwhile. + */ + if (!want_file && would_convert_to_git(name)) + return 0; + len = strlen(name); pos = cache_name_pos(name, len); if (pos < 0) diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh index 7bac2bcf26..e799e59544 100755 --- a/t/t0021-conversion.sh +++ b/t/t0021-conversion.sh @@ -268,4 +268,15 @@ test_expect_success 'disable filter with empty override' ' test_must_be_empty err ' +test_expect_success 'diff does not reuse worktree files that need cleaning' ' + test_config filter.counter.clean "echo . >>count; sed s/^/clean:/" && + echo "file filter=counter" >.gitattributes && + test_commit one file && + test_commit two file && + + >count && + git diff-tree -p HEAD && + test_line_count = 0 count +' + test_done