Flipcall refinements.

Note that some of these changes affect the protocol in
backward-incompatible ways.

- Replace use of "initially-active" and "initially-inactive" with
"client" and "server" respectively for clarity.

- Fix a race condition involving Endpoint.Shutdown() by repeatedly
invoking FUTEX_WAKE until it is confirmed that no local thread is
blocked in FUTEX_WAIT.

- Drop flipcall.ControlMode.

PiperOrigin-RevId: 260981382

1 files changed, 13 insertions, 7 deletions

diff --git a/pkg/flipcall/flipcall_example_test.go b/pkg/flipcall/flipcall_example_test.go
index 572a1f119..edb6a8bef 100644
--- a/pkg/flipcall/flipcall_example_test.go
+++ b/pkg/flipcall/flipcall_example_test.go
@@ -17,6 +17,7 @@ package flipcall
 import (
 	"bytes"
 	"fmt"
+	"sync"
 )
 
 func Example() {
@@ -36,20 +37,21 @@ func Example() {
 	if err != nil {
 		panic(err)
 	}
-	clientEP, err := NewEndpoint(ControlModeFutex, pwd)
-	if err != nil {
+	var clientEP Endpoint
+	if err := clientEP.Init(pwd); err != nil {
 		panic(err)
 	}
 	defer clientEP.Destroy()
-	serverEP, err := NewEndpoint(ControlModeFutex, pwd)
-	if err != nil {
+	var serverEP Endpoint
+	if err := serverEP.Init(pwd); err != nil {
 		panic(err)
 	}
 	defer serverEP.Destroy()
 
-	serverDone := make(chan struct{})
+	var serverRun sync.WaitGroup
+	serverRun.Add(1)
 	go func() {
-		defer func() { serverDone <- struct{}{} }()
+		defer serverRun.Done()
 		i := 0
 		var buf bytes.Buffer
 		// wait for first request
@@ -76,9 +78,13 @@ func Example() {
 	}()
 	defer func() {
 		serverEP.Shutdown()
-		<-serverDone
+		serverRun.Wait()
 	}()
 
+	// establish connection as client
+	if err := clientEP.Connect(); err != nil {
+		panic(err)
+	}
 	var buf bytes.Buffer
 	for i := 0; i < count; i++ {
 		// write request