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io.c (rb_update_max_fd): use F_GETFL if possible

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On 64-bit Linux, fstat() needs to fill out a 144 byte struct
while F_GETFL only needs to return 8 bytes.

Fwiw, F_GETFD requires an additional rcu_read_lock and bitmap
check; so it's obviously more expensive than F_GETFL on Linux.

Reduce stack usage of rb_update_max_fd from 184 to 24 bytes.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66060 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
normal 2018-11-28 01:10:40 +00:00
parent c5fe904f6e
commit db7338fd75
1 changed files with 10 additions and 2 deletions
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12
io.c
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@ -193,14 +193,22 @@ static rb_atomic_t max_file_descriptor = NOFILE;
void
rb_update_max_fd(int fd)
{
struct stat buf;
rb_atomic_t afd = (rb_atomic_t)fd;
rb_atomic_t max_fd = max_file_descriptor;
int err;
if (afd <= max_fd)
return;
if (fstat(fd, &buf) != 0 && errno == EBADF) {
#if defined(HAVE_FCNTL) && defined(F_GETFL)
err = fcntl(fd, F_GETFL) == -1;
#else
{
struct stat buf;
err = fstat(fd, &buf) != 0;
}
#endif
if (err && errno == EBADF) {
rb_bug("rb_update_max_fd: invalid fd (%d) given.", fd);
}