crypto/tls: remove unused variable in benchmark code

This fixes `go test go/types`.

https://golang.org/cl/23487/ introduced this code which contains
two unused variables (declared and assigned to, but never read).
cmd/compile doesn't report the error due open issue #8560 (the
variables are assigned to in a closure), but go/types does. The
build bot only runs go/types tests in -short mode (which doesn't
typecheck the std lib), hence this doesn't show up on the dashboard
either.

We cannot call b.Fatal and friends in the goroutine. Communicating
the error to the invoking function requires a channel or a mutex.
Unless the channel/sycnhronized variable is tested in each iteration
that follows, the iteration blocks if there's a failure. Testing in
each iteration may affect benchmark times.

One could use a time-out but that time depends on the underlying system.
Panicking seems good enough in this unlikely case; better than hanging
or affecting benchmark times.

Change-Id: Idce1172da8058e580fa3b3e398825b0eb4316325
Reviewed-on: https://go-review.googlesource.com/23528
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/crypto/tls/tls_test.go b/src/crypto/tls/tls_test.go
index 47f02beedad25e19eec531e92dfc269de6c43825..5b665bf5322dac6be2c51544e373f2b3dbb48f2b 100644 (file)
--- a/src/crypto/tls/tls_test.go
+++ b/src/crypto/tls/tls_test.go
@@ -481,20 +481,19 @@ func throughput(b *testing.B, totalBytes int64, dynamicRecordSizingDisabled bool
 
        N := b.N
 
-       var serr error
        go func() {
                for i := 0; i < N; i++ {
                        sconn, err := ln.Accept()
                        if err != nil {
-                               serr = err
-                               return
+                               // panic rather than synchronize to avoid benchmark overhead
+                               // (cannot call b.Fatal in goroutine)
+                               panic(fmt.Errorf("accept: %v", err))
                        }
                        serverConfig := *testConfig
                        serverConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
                        srv := Server(sconn, &serverConfig)
                        if err := srv.Handshake(); err != nil {
-                               serr = fmt.Errorf("handshake: %v", err)
-                               return
+                               panic(fmt.Errorf("handshake: %v", err))
                        }
                        io.Copy(srv, srv)
                }
@@ -570,20 +569,19 @@ func latency(b *testing.B, bps int, dynamicRecordSizingDisabled bool) {
 
        N := b.N
 
-       var serr error
        go func() {
                for i := 0; i < N; i++ {
                        sconn, err := ln.Accept()
                        if err != nil {
-                               serr = err
-                               return
+                               // panic rather than synchronize to avoid benchmark overhead
+                               // (cannot call b.Fatal in goroutine)
+                               panic(fmt.Errorf("accept: %v", err))
                        }
                        serverConfig := *testConfig
                        serverConfig.DynamicRecordSizingDisabled = dynamicRecordSizingDisabled
                        srv := Server(&slowConn{sconn, bps}, &serverConfig)
                        if err := srv.Handshake(); err != nil {
-                               serr = fmt.Errorf("handshake: %v", err)
-                               return
+                               panic(fmt.Errorf("handshake: %v", err))
                        }
                        io.Copy(srv, srv)
                }