update vendor

Signed-off-by: Jess Frazelle <acidburn@microsoft.com>

vendor/golang.org/x/net/netutil/listen.go

@@ -0,0 +1,74 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package netutil provides network utility functions, complementing the more
+// common ones in the net package.
+package netutil // import "golang.org/x/net/netutil"
+
+import (
+	"net"
+	"sync"
+)
+
+// LimitListener returns a Listener that accepts at most n simultaneous
+// connections from the provided Listener.
+func LimitListener(l net.Listener, n int) net.Listener {
+	return &limitListener{
+		Listener: l,
+		sem:      make(chan struct{}, n),
+		done:     make(chan struct{}),
+	}
+}
+
+type limitListener struct {
+	net.Listener
+	sem       chan struct{}
+	closeOnce sync.Once     // ensures the done chan is only closed once
+	done      chan struct{} // no values sent; closed when Close is called
+}
+
+// acquire acquires the limiting semaphore. Returns true if successfully
+// accquired, false if the listener is closed and the semaphore is not
+// acquired.
+func (l *limitListener) acquire() bool {
+	select {
+	case <-l.done:
+		return false
+	case l.sem <- struct{}{}:
+		return true
+	}
+}
+func (l *limitListener) release() { <-l.sem }
+
+func (l *limitListener) Accept() (net.Conn, error) {
+	acquired := l.acquire()
+	// If the semaphore isn't acquired because the listener was closed, expect
+	// that this call to accept won't block, but immediately return an error.
+	c, err := l.Listener.Accept()
+	if err != nil {
+		if acquired {
+			l.release()
+		}
+		return nil, err
+	}
+	return &limitListenerConn{Conn: c, release: l.release}, nil
+}
+
+func (l *limitListener) Close() error {
+	err := l.Listener.Close()
+	l.closeOnce.Do(func() { close(l.done) })
+	return err
+}
+
+type limitListenerConn struct {
+	net.Conn
+	releaseOnce sync.Once
+	release     func()
+}
+
+func (l *limitListenerConn) Close() error {
+	err := l.Conn.Close()
+	l.releaseOnce.Do(l.release)
+	return err
+}

vendor/golang.org/x/net/netutil/listen_test.go

@@ -0,0 +1,147 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package netutil
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"golang.org/x/net/internal/nettest"
+)
+
+func TestLimitListener(t *testing.T) {
+	const max = 5
+	attempts := (nettest.MaxOpenFiles() - max) / 2
+	if attempts > 256 { // maximum length of accept queue is 128 by default
+		attempts = 256
+	}
+
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer l.Close()
+	l = LimitListener(l, max)
+
+	var open int32
+	go http.Serve(l, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if n := atomic.AddInt32(&open, 1); n > max {
+			t.Errorf("%d open connections, want <= %d", n, max)
+		}
+		defer atomic.AddInt32(&open, -1)
+		time.Sleep(10 * time.Millisecond)
+		fmt.Fprint(w, "some body")
+	}))
+
+	var wg sync.WaitGroup
+	var failed int32
+	for i := 0; i < attempts; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			c := http.Client{Timeout: 3 * time.Second}
+			r, err := c.Get("http://" + l.Addr().String())
+			if err != nil {
+				t.Log(err)
+				atomic.AddInt32(&failed, 1)
+				return
+			}
+			defer r.Body.Close()
+			io.Copy(ioutil.Discard, r.Body)
+		}()
+	}
+	wg.Wait()
+
+	// We expect some Gets to fail as the kernel's accept queue is filled,
+	// but most should succeed.
+	if int(failed) >= attempts/2 {
+		t.Errorf("%d requests failed within %d attempts", failed, attempts)
+	}
+}
+
+type errorListener struct {
+	net.Listener
+}
+
+func (errorListener) Accept() (net.Conn, error) {
+	return nil, errFake
+}
+
+var errFake = errors.New("fake error from errorListener")
+
+// This used to hang.
+func TestLimitListenerError(t *testing.T) {
+	donec := make(chan bool, 1)
+	go func() {
+		const n = 2
+		ll := LimitListener(errorListener{}, n)
+		for i := 0; i < n+1; i++ {
+			_, err := ll.Accept()
+			if err != errFake {
+				t.Fatalf("Accept error = %v; want errFake", err)
+			}
+		}
+		donec <- true
+	}()
+	select {
+	case <-donec:
+	case <-time.After(5 * time.Second):
+		t.Fatal("timeout. deadlock?")
+	}
+}
+
+func TestLimitListenerClose(t *testing.T) {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ln.Close()
+	ln = LimitListener(ln, 1)
+
+	doneCh := make(chan struct{})
+	defer close(doneCh)
+	go func() {
+		c, err := net.Dial("tcp", ln.Addr().String())
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer c.Close()
+		<-doneCh
+	}()
+
+	c, err := ln.Accept()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	acceptDone := make(chan struct{})
+	go func() {
+		c, err := ln.Accept()
+		if err == nil {
+			c.Close()
+			t.Errorf("Unexpected successful Accept()")
+		}
+		close(acceptDone)
+	}()
+
+	// Wait a tiny bit to ensure the Accept() is blocking.
+	time.Sleep(10 * time.Millisecond)
+	ln.Close()
+
+	select {
+	case <-acceptDone:
+	case <-time.After(5 * time.Second):
+		t.Fatalf("Accept() still blocking")
+	}
+}