From cbd96c3385df1e0a0c43d094c2d5ae994744c37d Mon Sep 17 00:00:00 2001 From: Miles Bader Date: Sat, 20 Jul 1996 17:33:17 +0000 Subject: [PATCH] (__select): Don't poll on the last call __io_select unless there's only a single descriptor, as each descriptor now has its own reply port. If there is only a single descriptor, just use its reply port for everything and don't bother creating the port set. --- sysdeps/mach/hurd/select.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/sysdeps/mach/hurd/select.c b/sysdeps/mach/hurd/select.c index 188f65b..60bb489 100644 --- a/sysdeps/mach/hurd/select.c +++ b/sysdeps/mach/hurd/select.c @@ -126,15 +126,22 @@ DEFUN(__select, (nfds, readfds, writefds, exceptfds, timeout), int type = d[i].type; d[i].reply_port = __mach_reply_port (); err = __io_select (d[i].io_port, d[i].reply_port, - /* Poll for each but the last. */ - (i == lastfd && got == 0) ? to : 0, + /* Poll only when there's a single descriptor. */ + (firstfd == lastfd) ? to : 0, &type); switch (err) { case MACH_RCV_TIMED_OUT: /* No immediate response. This is normal. */ err = 0; - if (got == 0) + if (firstfd == lastfd) + /* When there's a single descriptor, we don't need a portset, + so just pretend we have one, but really use the single reply + port. */ + portset = d[i].reply_port; + else if (got == 0) + /* We've got multiple reply ports, so we need a port set to + multiplex them. */ { /* We will wait again for a reply later. */ if (portset == MACH_PORT_NULL) @@ -276,7 +283,10 @@ DEFUN(__select, (nfds, readfds, writefds, exceptfds, timeout), for (i = firstfd; i <= lastfd; ++i) if (d[i].type) __mach_port_destroy (__mach_task_self (), d[i].reply_port); - if (portset != MACH_PORT_NULL) + if (firstfd != lastfd && portset != MACH_PORT_NULL) + /* Destroy PORTSET, but only if it's not actually the reply port for a + single descriptor (in which case it's destroyed in the previous loop; + not doing it here is just a bit more efficient). */ __mach_port_destroy (__mach_task_self (), portset); if (err) -- 2.7.4