Flush msgs to remoteProxyApp automatically

proxy/remote_app_conn.go

@@ -15,6 +15,7 @@ import (
 )
 
 const maxResponseSize = 1048576 // 1MB
+const flushThrottleMS = 20      // Don't wait longer than...
 
 // This is goroutine-safe, but users should beware that
 // the application in general is not meant to be interfaced
@@ -23,7 +24,8 @@ type remoteAppConn struct {
 	QuitService
 	sync.Mutex // [EB]: is this even used?
 
-	reqQueue chan *reqRes
+	reqQueue   chan *reqRes
+	flushTimer *ThrottleTimer
 
 	mtx       sync.Mutex
 	conn      net.Conn
@@ -35,7 +37,9 @@ type remoteAppConn struct {
 
 func NewRemoteAppConn(conn net.Conn, bufferSize int) *remoteAppConn {
 	app := &remoteAppConn{
-		reqQueue:  make(chan *reqRes, bufferSize),
+		reqQueue:   make(chan *reqRes, bufferSize),
+		flushTimer: NewThrottleTimer("remoteAppConn", flushThrottleMS),
+
 		conn:      conn,
 		bufWriter: bufio.NewWriter(conn),
 		reqSent:   list.New(),
@@ -57,6 +61,7 @@ func (app *remoteAppConn) OnStop() {
 	app.conn.Close()
 }
 
+// NOTE: callback may get internally generated flush responses.
 func (app *remoteAppConn) SetResponseCallback(resCb Callback) {
 	app.mtx.Lock()
 	defer app.mtx.Unlock()
@@ -86,12 +91,16 @@ func (app *remoteAppConn) sendRequestsRoutine() {
 		var n int
 		var err error
 		select {
+		case <-app.flushTimer.Ch:
+			select {
+			case app.reqQueue <- newReqRes(tmsp.RequestFlush{}):
+			default:
+				// Probably will fill the buffer, or retry later.
+			}
 		case <-app.QuitService.Quit:
 			return
 		case reqres := <-app.reqQueue:
-
 			app.willSendReq(reqres)
-
 			wire.WriteBinaryLengthPrefixed(struct{ tmsp.Request }{reqres.Request}, app.bufWriter, &n, &err) // Length prefix
 			if err != nil {
 				app.StopForError(err)
@@ -234,9 +243,18 @@ func (app *remoteAppConn) GetHashSync() (hash []byte, err error) {
 //----------------------------------------
 
 func (app *remoteAppConn) queueRequest(req tmsp.Request) *reqRes {
-	reqres := NewreqRes(req)
+	reqres := newReqRes(req)
 	// TODO: set app.err if reqQueue times out
 	app.reqQueue <- reqres
+
+	// Maybe auto-flush, or unset auto-flush
+	switch req.(type) {
+	case tmsp.RequestFlush:
+		app.flushTimer.Unset()
+	default:
+		app.flushTimer.Set()
+	}
+
 	return reqres
 }
 
@@ -274,7 +292,7 @@ type reqRes struct {
 	tmsp.Response // Not set atomically, so be sure to use WaitGroup.
 }
 
-func NewreqRes(req tmsp.Request) *reqRes {
+func newReqRes(req tmsp.Request) *reqRes {
 	return &reqRes{
 		Request:   req,
 		WaitGroup: waitGroup1(),