auto merge of #13604 : alexcrichton/rust/connect-timeout, r=brson

This adds a `TcpStream::connect_timeout` function in order to assist opening
connections with a timeout (cc #13523). There isn't really much design space for
this specific operation (unlike timing out normal blocking reads/writes), so I
am fairly confident that this is the correct interface for this function.

The function is marked #[experimental] because it takes a u64 timeout argument,
and the u64 type is likely to change in the future.

src/test/run-pass/tcp-connect-timeouts.rs

@@ -0,0 +1,92 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-pretty
+// compile-flags:--test
+// exec-env:RUST_TEST_TASKS=1
+
+// Tests for the connect_timeout() function on a TcpStream. This runs with only
+// one test task to ensure that errors are timeouts, not file descriptor
+// exhaustion.
+
+#![feature(macro_rules, globs)]
+#![allow(experimental)]
+
+extern crate native;
+extern crate green;
+extern crate rustuv;
+
+#[cfg(test)] #[start]
+fn start(argc: int, argv: **u8) -> int {
+    green::start(argc, argv, rustuv::event_loop, __test::main)
+}
+
+macro_rules! iotest (
+    { fn $name:ident() $b:block $($a:attr)* } => (
+        mod $name {
+            #![allow(unused_imports)]
+
+            use std::io::*;
+            use std::io::net::tcp::*;
+            use std::io::test::*;
+            use std::io;
+
+            fn f() $b
+
+            $($a)* #[test] fn green() { f() }
+            $($a)* #[test] fn native() {
+                use native;
+                let (tx, rx) = channel();
+                native::task::spawn(proc() { tx.send(f()) });
+                rx.recv();
+            }
+        }
+    )
+)
+
+iotest!(fn eventual_timeout() {
+    use native;
+    let addr = next_test_ip4();
+
+    // Use a native task to receive connections because it turns out libuv is
+    // really good at accepting connections and will likely run out of file
+    // descriptors before timing out.
+    let (tx1, rx1) = channel();
+    let (_tx2, rx2) = channel::<()>();
+    native::task::spawn(proc() {
+        let _l = TcpListener::bind(addr).unwrap().listen();
+        tx1.send(());
+        let _ = rx2.recv_opt();
+    });
+    rx1.recv();
+
+    let mut v = Vec::new();
+    for _ in range(0, 10000) {
+        match TcpStream::connect_timeout(addr, 100) {
+            Ok(e) => v.push(e),
+            Err(ref e) if e.kind == io::TimedOut => return,
+            Err(e) => fail!("other error: {}", e),
+        }
+    }
+    fail!("never timed out!");
+})
+
+iotest!(fn timeout_success() {
+    let addr = next_test_ip4();
+    let _l = TcpListener::bind(addr).unwrap().listen();
+
+    assert!(TcpStream::connect_timeout(addr, 1000).is_ok());
+})
+
+iotest!(fn timeout_error() {
+    let addr = next_test_ip4();
+
+    assert!(TcpStream::connect_timeout(addr, 1000).is_err());
+})