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Auto merge of #41039 - alexcrichton:process-poll, r=nagisa

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std: Use `poll` instead of `select`

This gives us the benefit of supporting file descriptors over the limit that
select supports, which...

Closes #40894
This commit is contained in:
bors 2017-04-06 11:21:55 +00:00
commit 44855a4cef
1 changed files with 9 additions and 13 deletions
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22
src/libstd/sys/unix/pipe.rs
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@ -8,11 +8,9 @@
// option. This file may not be copied, modified, or distributed // option. This file may not be copied, modified, or distributed
// except according to those terms. // except according to those terms.
use cmp;
use io; use io;
use libc::{self, c_int}; use libc::{self, c_int};
use mem; use mem;
use ptr;
use sys::{cvt, cvt_r}; use sys::{cvt, cvt_r};
use sys::fd::FileDesc; use sys::fd::FileDesc;
@ -80,16 +78,14 @@ pub fn read2(p1: AnonPipe,
p1.set_nonblocking(true)?; p1.set_nonblocking(true)?;
p2.set_nonblocking(true)?; p2.set_nonblocking(true)?;
let max = cmp::max(p1.raw(), p2.raw()); let mut fds: [libc::pollfd; 2] = unsafe { mem::zeroed() };
fds[0].fd = p1.raw();
fds[0].events = libc::POLLIN;
fds[1].fd = p2.raw();
fds[1].events = libc::POLLIN;
loop { loop {
// wait for either pipe to become readable using `select` // wait for either pipe to become readable using `poll`
cvt_r(|| unsafe { cvt_r(|| unsafe { libc::poll(fds.as_mut_ptr(), 2, -1) })?;
let mut read: libc::fd_set = mem::zeroed();
libc::FD_SET(p1.raw(), &mut read);
libc::FD_SET(p2.raw(), &mut read);
libc::select(max + 1, &mut read, ptr::null_mut(), ptr::null_mut(),
ptr::null_mut())
})?;
// Read as much as we can from each pipe, ignoring EWOULDBLOCK or // Read as much as we can from each pipe, ignoring EWOULDBLOCK or
// EAGAIN. If we hit EOF, then this will happen because the underlying // EAGAIN. If we hit EOF, then this will happen because the underlying
@ -109,11 +105,11 @@ pub fn read2(p1: AnonPipe,
} }
} }
}; };
if read(&p1, v1)? { if fds[0].revents != 0 && read(&p1, v1)? {
p2.set_nonblocking(false)?; p2.set_nonblocking(false)?;
return p2.read_to_end(v2).map(|_| ()); return p2.read_to_end(v2).map(|_| ());
} }
if read(&p2, v2)? { if fds[1].revents != 0 && read(&p2, v2)? {
p1.set_nonblocking(false)?; p1.set_nonblocking(false)?;
return p1.read_to_end(v1).map(|_| ()); return p1.read_to_end(v1).map(|_| ());
} }