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socket: avoid redundant fcntl on Linux

* ext/socket/ancdata.c (bsock_sendmsg_internal,
  bsock_recvmsg_internal):
  avoid redundant fcntl on Linux
  [ruby-core:69154] [Feature #11145]
* ext/socket/init.c (rsock_s_recvfrom_nonblock): ditto
* ext/socket/rubysocket.h (MSG_DONTWAIT_RELIABLE): new macro

MSG_DONTWAIT is enough to force non-blocking I/O under Linux,
so avoid changing the state of a socket.  This will allow certain
threads to do a non-destructive non-blocking "peek" while others
block (without relying on an extra ppoll syscall).

We shall be conservative about enabling this feature since some
OSes may have incomplete support for MSG_DONTWAIT.  I shall
defer to a FreeBSD expert to enable that for FreeBSD.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50666 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
normal 2015-05-29 02:24:18 +00:00
parent 1dd4c763c0
commit d8bbb5eda8
4 changed files with 26 additions and 3 deletions

View file

@ -1,3 +1,12 @@
Fri May 29 11:18:58 2015 Eric Wong <e@80x24.org>
* ext/socket/ancdata.c (bsock_sendmsg_internal,
bsock_recvmsg_internal):
avoid redundant fcntl on Linux
[ruby-core:69154] [Feature #11145]
* ext/socket/init.c (rsock_s_recvfrom_nonblock): ditto
* ext/socket/rubysocket.h (MSG_DONTWAIT_RELIABLE): new macro
Fri May 29 10:30:34 2015 Eric Wong <e@80x24.org>
* lib/net/resolv.rb (request): use monotonic clock

View file

@ -1277,7 +1277,7 @@ bsock_sendmsg_internal(int argc, VALUE *argv, VALUE sock, int nonblock)
#endif
rb_io_check_closed(fptr);
if (nonblock)
if (nonblock && !MSG_DONTWAIT_RELIABLE)
rb_io_set_nonblock(fptr);
ss = rb_sendmsg(fptr->fd, &mh, flags);
@ -1595,7 +1595,7 @@ bsock_recvmsg_internal(int argc, VALUE *argv, VALUE sock, int nonblock)
flags |= MSG_PEEK;
rb_io_check_closed(fptr);
if (nonblock)
if (nonblock && !MSG_DONTWAIT_RELIABLE)
rb_io_set_nonblock(fptr);
ss = rb_recvmsg(fptr->fd, &mh, flags);

View file

@ -211,7 +211,10 @@ rsock_s_recvfrom_nonblock(VALUE sock, int argc, VALUE *argv, enum sock_recv_type
str = rb_tainted_str_new(0, buflen);
rb_io_check_closed(fptr);
if (!MSG_DONTWAIT_RELIABLE)
rb_io_set_nonblock(fptr);
len0 = alen;
slen = recvfrom(fd, RSTRING_PTR(str), buflen, flags, &buf.addr, &alen);
if (slen != -1 && len0 < alen)

View file

@ -407,9 +407,20 @@ NORETURN(void rsock_sys_fail_raddrinfo_or_sockaddr(const char *, VALUE addr, VAL
#if defined(__linux__)
static inline int rsock_maybe_fd_writable(int fd) { return 1; }
static inline void rsock_maybe_wait_fd(int fd) { }
# ifdef MSG_DONTWAIT
# define MSG_DONTWAIT_RELIABLE 1
# endif
#else /* some systems (mswin/mingw) need these. ref: r36946 */
# define rsock_maybe_fd_writable(fd) rb_thread_fd_writable((fd))
# define rsock_maybe_wait_fd(fd) rb_thread_wait_fd((fd))
#endif
/*
* some OSes may support MSG_DONTWAIT inconsistently depending on socket
* type, we only expect Linux to support it consistently for all socket types.
*/
#ifndef MSG_DONTWAIT_RELIABLE
# define MSG_DONTWAIT_RELIABLE 0
#endif
#endif