1 files changed, 99 insertions, 0 deletions
diff --git a/src/net/z_last_test.go b/src/net/z_last_test.go
new file mode 100644
index 000000000..716c103db
--- /dev/null
+++ b/src/net/z_last_test.go
@@ -0,0 +1,99 @@
+// Copyright 2009 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 net
+
+import (
+	"flag"
+	"fmt"
+	"testing"
+	"time"
+)
+
+var testDNSFlood = flag.Bool("dnsflood", false, "whether to test dns query flooding")
+
+func TestDNSThreadLimit(t *testing.T) {
+	if !*testDNSFlood {
+		t.Skip("test disabled; use -dnsflood to enable")
+	}
+
+	const N = 10000
+	c := make(chan int, N)
+	for i := 0; i < N; i++ {
+		go func(i int) {
+			LookupIP(fmt.Sprintf("%d.net-test.golang.org", i))
+			c <- 1
+		}(i)
+	}
+	// Don't bother waiting for the stragglers; stop at 0.9 N.
+	for i := 0; i < N*9/10; i++ {
+		if i%100 == 0 {
+			//println("TestDNSThreadLimit:", i)
+		}
+		<-c
+	}
+
+	// If we're still here, it worked.
+}
+
+func TestLookupIPDeadline(t *testing.T) {
+	if !*testDNSFlood {
+		t.Skip("test disabled; use -dnsflood to enable")
+	}
+
+	const N = 5000
+	const timeout = 3 * time.Second
+	c := make(chan error, 2*N)
+	for i := 0; i < N; i++ {
+		name := fmt.Sprintf("%d.net-test.golang.org", i)
+		go func() {
+			_, err := lookupIPDeadline(name, time.Now().Add(timeout/2))
+			c <- err
+		}()
+		go func() {
+			_, err := lookupIPDeadline(name, time.Now().Add(timeout))
+			c <- err
+		}()
+	}
+	qstats := struct {
+		succeeded, failed         int
+		timeout, temporary, other int
+		unknown                   int
+	}{}
+	deadline := time.After(timeout + time.Second)
+	for i := 0; i < 2*N; i++ {
+		select {
+		case <-deadline:
+			t.Fatal("deadline exceeded")
+		case err := <-c:
+			switch err := err.(type) {
+			case nil:
+				qstats.succeeded++
+			case Error:
+				qstats.failed++
+				if err.Timeout() {
+					qstats.timeout++
+				}
+				if err.Temporary() {
+					qstats.temporary++
+				}
+				if !err.Timeout() && !err.Temporary() {
+					qstats.other++
+				}
+			default:
+				qstats.failed++
+				qstats.unknown++
+			}
+		}
+	}
+
+	// A high volume of DNS queries for sub-domain of golang.org
+	// would be coordinated by authoritative or recursive server,
+	// or stub resolver which implements query-response rate
+	// limitation, so we can expect some query successes and more
+	// failures including timeout, temporary and other here.
+	// As a rule, unknown must not be shown but it might possibly
+	// happen due to issue 4856 for now.
+	t.Logf("%v succeeded, %v failed (%v timeout, %v temporary, %v other, %v unknown)", qstats.succeeded, qstats.failed, qstats.timeout, qstats.temporary, qstats.other, qstats.unknown)
+}