Re: [PATCH v2] Prefer sysconf(_SC_OPEN_MAX) over getrlimit(RLIMIT_NOFILE,...)
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Aug 24, 2012, 16:43 UTC
- Message-ID
- <7v393c1br5.fsf@alter.siamese.dyndns.org>
- In-Reply-To
- <002f01cd81de$28f43bf0$7adcb3d0$@schmitz-digital.de>
"Joachim Schmitz" <jojo@schmitz-digital.de> writes:
> Signed-off-by: Joachim Schmitz <jojo@schmitz-digital.de> > --- > As discussed now as a small helper function rather than #ifdef/#endif in the primary flow of the code. > And hopefully without having screwed up whitespace and line breaks
The formatting looks fine.
Perhaps I am being overly paranoid, but I would prefer not to change things for people who have been using getrlimit(). For them, if they also have sysconf(_SC_OPEN_MAX), your code _ought to_ work, but if it does not work for whatever reason (perhaps some platforms claim to have both, but getrlimit() works and sysconf(_SC_OPEN_MAX) is broken), it will given them an unnecessary regression.
So how about doing it this way instead?
-- >8 -- Subject: sha1_file.c: introduce get_max_fd_limit() helper
Not all platforms have getrlimit(), but there are other ways to see the maximum number of files that a process can have open. If getrlimit() is unavailable, fall back to sysconf(_SC_OPEN_MAX) if available, and use OPEN_MAX from <limits.h>.
Signed-off-by: Joachim Schmitz <jojo@schmitz-digital.de> Signed-off-by: Junio C Hamano <gitster@pobox.com> --- sha1_file.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-)
diff --git c/sha1_file.c w/sha1_file.c index af5cfbd..9152974 100644 --- c/sha1_file.c +++ w/sha1_file.c @@ -731,6 +731,24 @@ void free_pack_by_name(const char *pack_name) } } +static unsigned int get_max_fd_limit(void) +{ +#ifdef RLIMIT_NOFILE + struct rlimit lim; + + if (getrlimit(RLIMIT_NOFILE, &lim)) + die_errno("cannot get RLIMIT_NOFILE"); + + return lim.rlim_cur; +#elif defined(_SC_OPEN_MAX) + return sysconf(_SC_OPEN_MAX); +#elif defined(OPEN_MAX) + return OPEN_MAX; +#else + return 1; /* see the caller ;-) */ +#endif +} + /* * Do not call this directly as this leaks p->pack_fd on error return; * call open_packed_git() instead. @@ -747,13 +765,7 @@ static int open_packed_git_1(struct packed_git *p) return error("packfile %s index unavailable", p->pack_name); if (!pack_max_fds) { - struct rlimit lim; - unsigned int max_fds; - - if (getrlimit(RLIMIT_NOFILE, &lim)) - die_errno("cannot get RLIMIT_NOFILE"); - - max_fds = lim.rlim_cur; + unsigned int max_fds = get_max_fd_limit(); /* Save 3 for stdin/stdout/stderr, 22 for work */ if (25 < max_fds)