3 files changed, 62 insertions, 2 deletions
diff --git a/vendor/github.com/google/gops/agent/agent.go b/vendor/github.com/google/gops/agent/agent.go
index 59a03cf5..441814c9 100644
--- a/vendor/github.com/google/gops/agent/agent.go
+++ b/vendor/github.com/google/gops/agent/agent.go
@@ -8,6 +8,7 @@ package agent
 
 import (
 	"bufio"
+	"context"
 	"encoding/binary"
 	"fmt"
 	"io"
@@ -55,6 +56,13 @@ type Options struct {
 	// can call Close before shutting down.
 	// Optional.
 	ShutdownCleanup bool
+
+	// ReuseSocketAddrAndPort determines whether the SO_REUSEADDR and
+	// SO_REUSEADDR socket options should be set on the listening socket of
+	// the agent. This option is only effective on unix-like OSes and if
+	// Addr is set to a fixed host:port.
+	// Optional.
+	ReuseSocketAddrAndPort bool
 }
 
 // Listen starts the gops agent on a host process. Once agent started, users
@@ -96,11 +104,14 @@ func Listen(opts Options) error {
 	if addr == "" {
 		addr = defaultAddr
 	}
-	ln, err := net.Listen("tcp", addr)
+	var lc net.ListenConfig
+	if opts.ReuseSocketAddrAndPort {
+		lc.Control = setsockoptReuseAddrAndPort
+	}
+	listener, err = lc.Listen(context.Background(), "tcp", addr)
 	if err != nil {
 		return err
 	}
-	listener = ln
 	port := listener.Addr().(*net.TCPAddr).Port
 	portfile = fmt.Sprintf("%s/%d", gopsdir, os.Getpid())
 	err = ioutil.WriteFile(portfile, []byte(strconv.Itoa(port)), os.ModePerm)
diff --git a/vendor/github.com/google/gops/agent/sockopt_unix.go b/vendor/github.com/google/gops/agent/sockopt_unix.go
new file mode 100644
index 00000000..7edaf209
--- /dev/null
+++ b/vendor/github.com/google/gops/agent/sockopt_unix.go
@@ -0,0 +1,36 @@
+// Copyright 2020 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.
+
+// +build !js,!plan9,!windows
+
+package agent
+
+import (
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+// setsockoptReuseAddrAndPort sets the SO_REUSEADDR and SO_REUSEPORT socket
+// options on c's underlying socket in order to increase the chance to re-bind()
+// to the same address and port upon agent restart.
+func setsockoptReuseAddrAndPort(network, address string, c syscall.RawConn) error {
+	var soerr error
+	if err := c.Control(func(su uintptr) {
+		sock := int(su)
+		// Allow reuse of recently-used addresses. This socket option is
+		// set by default on listeners in Go's net package, see
+		// net.setDefaultSockopts.
+		soerr = unix.SetsockoptInt(sock, unix.SOL_SOCKET, unix.SO_REUSEADDR, 1)
+		if soerr != nil {
+			return
+		}
+		// Allow reuse of recently-used ports. This gives the agent a
+		// better chance to re-bind upon restarts.
+		soerr = unix.SetsockoptInt(sock, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
+	}); err != nil {
+		return err
+	}
+	return soerr
+}
diff --git a/vendor/github.com/google/gops/agent/sockopt_unsupported.go b/vendor/github.com/google/gops/agent/sockopt_unsupported.go
new file mode 100644
index 00000000..df3223bd
--- /dev/null
+++ b/vendor/github.com/google/gops/agent/sockopt_unsupported.go
@@ -0,0 +1,13 @@
+// Copyright 2020 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.
+
+// +build js,wasm plan9 windows
+
+package agent
+
+import "syscall"
+
+func setsockoptReuseAddrAndPort(network, address string, c syscall.RawConn) error {
+	return nil
+}