Re: Performance issue of 'git branch'

> On Fri, 24 Jul 2009, Linus Torvalds wrote:
>>
>> ie we're talking a _huge_ hit in startup times for that curl support.
>> That's really really sad - especially considering how all the curl support
>> is for very random occasional stuff. I never use it myself, for example,
>> since I don't use http at all. And even for people who do, they only need
>> it for non-local operations.
>>
>> I wonder if there is some way to only load the crazy curl stuff when we
>> actually want open a http: connection.
>
> Here's the simple step#1: make 'git-http-fetch' be an external program
> rather than a built-in.
>
> Sadly, I have no idea hot to turn the transport.c code into an external
> walker sanely (turn the ref/object walkers into an exec of an external
> program). So we still end up linking with curl. But maybe somebody
> (Daniel? Dscho?) who knows the transport code could try to make it an
> external process?
>
> The performance angle of http fetching is non-existent, we really should
> try very hard to make the curl-dependent parts be in a binary of their
> own.

> 		Linus
>
> ---
>> From 3cfc50d497266dc73a414ed1460b36b712ad10de Mon Sep 17 00:00:00 2001
> From: Linus Torvalds <torvalds@linux-foundation.org>
> Date: Fri, 24 Jul 2009 14:54:55 -0700
> Subject: [PATCH] git-http-fetch: not a builtin
>
> We should really try to avoid having a dependency on the curl libraries
> for the core 'git' executable. It adds huge overheads, for no advantage.
>
> This splits up git-http-fetch so that it isn't built-in.  We still do
> end up linking with curl for the git binary due to the transport.c http
> walker, but that's at least partially an independent issue.
>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> ---
> Makefile                             |    8 +++++++-
> git.c                                |    3 ---
> builtin-http-fetch.c => http-fetch.c |    5 ++++-
> 3 files changed, 11 insertions(+), 5 deletions(-)
> rename builtin-http-fetch.c => http-fetch.c (95%)
>
> diff --git a/Makefile b/Makefile
> index bde27ed..8cbd863 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -978,9 +978,12 @@ else
> 	else
> 		CURL_LIBCURL = -lcurl
> 	endif
> -	BUILTIN_OBJS += builtin-http-fetch.o
> +	PROGRAMS += git-http-fetch$X
> +
> +	# FIXME! Sadly 'transport.c' still needs these for the builtin case
> 	EXTLIBS += $(CURL_LIBCURL)
> 	LIB_OBJS += http.o http-walker.o
> +
> 	curl_check := $(shell (echo 070908; curl-config --vernum) | sort -r | sed -ne 2p)
> 	ifeq "$(curl_check)" "070908"
> 		ifndef NO_EXPAT
> @@ -1485,6 +1488,9 @@ git-imap-send$X: imap-send.o $(GITLIBS)
>
> http.o http-walker.o http-push.o transport.o: http.h
>
> +git-http-fetch$X: revision.o http.o http-push.o $(GITLIBS)
> +	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
> +		$(LIBS) $(CURL_LIBCURL) $(EXPAT_LIBEXPAT)
> git-http-push$X: revision.o http.o http-push.o $(GITLIBS)
> 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
> 		$(LIBS) $(CURL_LIBCURL) $(EXPAT_LIBEXPAT)
> diff --git a/git.c b/git.c
> index 807d875..c1e8f05 100644
> --- a/git.c
> +++ b/git.c
> @@ -309,9 +309,6 @@ static void handle_internal_command(int argc, const char **argv)
> 		{ "get-tar-commit-id", cmd_get_tar_commit_id },
> 		{ "grep", cmd_grep, RUN_SETUP | USE_PAGER },
> 		{ "help", cmd_help },
> -#ifndef NO_CURL
> -		{ "http-fetch", cmd_http_fetch, RUN_SETUP },
> -#endif
> 		{ "init", cmd_init_db },
> 		{ "init-db", cmd_init_db },
> 		{ "log", cmd_log, RUN_SETUP | USE_PAGER },
> diff --git a/builtin-http-fetch.c b/http-fetch.c
> similarity index 95%
> rename from builtin-http-fetch.c
> rename to http-fetch.c
> index f3e63d7..e8f44ba 100644
> --- a/builtin-http-fetch.c
> +++ b/http-fetch.c
> @@ -1,8 +1,9 @@
> #include "cache.h"
> #include "walker.h"
>
> -int cmd_http_fetch(int argc, const char **argv, const char *prefix)
> +int main(int argc, const char **argv)
> {
> +	const char *prefix;
> 	struct walker *walker;
> 	int commits_on_stdin = 0;
> 	int commits;
> @@ -18,6 +19,8 @@ int cmd_http_fetch(int argc, const char **argv, const char *prefix)
> 	int get_verbosely = 0;
> 	int get_recover = 0;
>
> +	prefix = setup_git_directory();
> +
> 	git_config(git_default_config, NULL);
>
> 	while (arg < argc && argv[arg][0] == '-') {
>