Re: [PATCH 3/3] completion: match ctags symbol names in grep patterns

Jonathan Nieder [off-list ref] writes:

In this new tags/cscope example, one could make an argument that
running exactly once is similarly better than running as needed (as in
(ii) above), by pointing out that

	make tags TAGS cscope

would have to check for a working "git ls-files" once instead of three
times.

I tend to agree that once instead of three times is not such an
improvement, especially given how cheap builtin-invocation of ls-files is,
but then once every invocation of $(MAKE) would also be negligible (it is
not once every internal target evaluation).

In any case, here is what I'll queue. I like the fact that your suggestion
avoids an extra "test invocation" that spends cycles to read the full
index without contributing to the end result.

By the way, did anybody know that "git ls-files >/dev/null" is more
expensive than "git ls-files '~/' >/dev/null" as a way to see if there is
ls-files command available?

-- >8 --
Subject: [PATCH] Makefile: ask "ls-files" to list source files if available

The [ce]tags and cscope targets used to run "find" looking for any paths
that match '*.[chS]' to feed the list of source files to downstream xargs.

Use "git ls-files" if it is already available to us, and otherwise use a
tighter "find" expression that does not list directories and does not go
into our .git directory.

Signed-off-by: Junio C Hamano <redacted>
---
 Makefile |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 8d6d451..badfb77 100644
--- a/Makefile
+++ b/Makefile

@@ -2115,17 +2115,21 @@ po/git.pot: $(LOCALIZED_C)
 
 pot: po/git.pot
 
+FIND_SOURCE_FILES = ( git ls-files '*.[hcS]' 2>/dev/null || \
+			$(FIND) . \( -name .git -type d -prune \) \
+				-o \( -name '*.[hcS]' -type f -print \) )
+
 $(ETAGS_TARGET): FORCE
 	$(RM) $(ETAGS_TARGET)
-	$(FIND) . -name '*.[hcS]' -print | xargs etags -a -o $(ETAGS_TARGET)
+	$(FIND_SOURCE_FILES) | xargs etags -a -o $(ETAGS_TARGET)
 
 tags: FORCE
 	$(RM) tags
-	$(FIND) . -name '*.[hcS]' -print | xargs ctags -a
+	$(FIND_SOURCE_FILES) | xargs ctags -a
 
 cscope:
 	$(RM) cscope*
-	$(FIND) . -name '*.[hcS]' -print | xargs cscope -b
+	$(FIND_SOURCE_FILES) | xargs cscope -b
 
 ### Detect prefix changes
 TRACK_CFLAGS = $(CC):$(subst ','\'',$(ALL_CFLAGS)):\

-- 
1.7.7.388.g3a4b7