grpc: introduce new DialOption and ServerOption to configure initial window size without disabling BDP estimation.

dialoptions.go

@@ -213,6 +213,7 @@
 func WithInitialWindowSize(s int32) DialOption {
 	return newFuncDialOption(func(o *dialOptions) {
 		o.copts.InitialWindowSize = s
+		o.copts.StaticWindowSize = false
 	})
 }
 
@@ -222,6 +223,26 @@
 func WithInitialConnWindowSize(s int32) DialOption {
 	return newFuncDialOption(func(o *dialOptions) {
 		o.copts.InitialConnWindowSize = s
+		o.copts.StaticWindowSize = false
+	})
+}
+
+// WithStaticStreamWindowSize returns a DialOption which sets the initial
+// stream window size to the value provided and disables dynamic flow control.
+func WithStaticStreamWindowSize(s int32) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.InitialWindowSize = s
+		o.copts.StaticWindowSize = true
+	})
+}
+
+// WithStaticConnWindowSize returns a DialOption which sets the initial
+// connection window size to the value provided and disables dynamic flow
+// control.
+func WithStaticConnWindowSize(s int32) DialOption {
+	return newFuncDialOption(func(o *dialOptions) {
+		o.copts.InitialConnWindowSize = s
+		o.copts.StaticWindowSize = true
 	})
 }
 

internal/transport/http2_client.go

@@ -309,11 +309,10 @@ func NewHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 			scheme = "https"
 		}
 	}
-	dynamicWindow := true
 	icwz := int32(initialWindowSize)
 	if opts.InitialConnWindowSize >= defaultWindowSize {
 		icwz = opts.InitialConnWindowSize
-		dynamicWindow = false
+		opts.StaticWindowSize = false
 	}
 	writeBufSize := opts.WriteBufferSize
 	readBufSize := opts.ReadBufferSize
@@ -381,9 +380,9 @@ func NewHTTP2Client(connectCtx, ctx context.Context, addr resolver.Address, opts
 	t.controlBuf = newControlBuffer(t.ctxDone)
 	if opts.InitialWindowSize >= defaultWindowSize {
 		t.initialWindowSize = opts.InitialWindowSize
-		dynamicWindow = false
+		opts.StaticWindowSize = false
 	}
-	if dynamicWindow {
+	if opts.StaticWindowSize {
 		t.bdpEst = &bdpEstimator{
 			bdp:               initialWindowSize,
 			updateFlowControl: t.updateFlowControl,

internal/transport/http2_server.go

@@ -176,16 +176,15 @@ func NewServerTransport(conn net.Conn, config *ServerConfig) (_ ServerTransport,
 			Val: config.MaxStreams,
 		})
 	}
-	dynamicWindow := true
 	iwz := int32(initialWindowSize)
 	if config.InitialWindowSize >= defaultWindowSize {
 		iwz = config.InitialWindowSize
-		dynamicWindow = false
+		config.StaticWindowSize = false
 	}
 	icwz := int32(initialWindowSize)
 	if config.InitialConnWindowSize >= defaultWindowSize {
 		icwz = config.InitialConnWindowSize
-		dynamicWindow = false
+		config.StaticWindowSize = false
 	}
 	if iwz != defaultWindowSize {
 		isettings = append(isettings, http2.Setting{
@@ -285,7 +284,7 @@ func NewServerTransport(conn net.Conn, config *ServerConfig) (_ ServerTransport,
 	t.logger = prefixLoggerForServerTransport(t)
 
 	t.controlBuf = newControlBuffer(t.done)
-	if dynamicWindow {
+	if config.StaticWindowSize {
 		t.bdpEst = &bdpEstimator{
 			bdp:               initialWindowSize,
 			updateFlowControl: t.updateFlowControl,

internal/transport/transport.go

@@ -466,6 +466,7 @@ type ServerConfig struct {
 	MaxHeaderListSize     *uint32
 	HeaderTableSize       *uint32
 	BufferPool            mem.BufferPool
+	StaticWindowSize      bool
 }
 
 // ConnectOptions covers all relevant options for communicating with the server.
@@ -504,6 +505,8 @@ type ConnectOptions struct {
 	MaxHeaderListSize *uint32
 	// The mem.BufferPool to use when reading/writing to the wire.
 	BufferPool mem.BufferPool
+	// StaticWindowSize controls whether dynamic window sizing is enabled.
+	StaticWindowSize bool
 }
 
 // WriteOptions provides additional hints and information for message

server.go

@@ -179,6 +179,7 @@ type serverOptions struct {
 	numServerWorkers      uint32
 	bufferPool            mem.BufferPool
 	waitForHandlers       bool
+	staticWindowSize      bool
 }
 
 var defaultServerOptions = serverOptions{
@@ -279,6 +280,7 @@ func ReadBufferSize(s int) ServerOption {
 func InitialWindowSize(s int32) ServerOption {
 	return newFuncServerOption(func(o *serverOptions) {
 		o.initialWindowSize = s
+		o.staticWindowSize = false
 	})
 }
 
@@ -287,6 +289,29 @@ func InitialWindowSize(s int32) ServerOption {
 func InitialConnWindowSize(s int32) ServerOption {
 	return newFuncServerOption(func(o *serverOptions) {
 		o.initialConnWindowSize = s
+		o.staticWindowSize = false
+	})
+}
+
+// StaticStreamWindowSize returns a ServerOption to set the initial stream
+// window size to the value provided and disables dynamic flow control.
+// The lower bound for window size is 64K and any value smaller than that
+// will be ignored.
+func StaticStreamWindowSize(s int32) ServerOption {
+	return newFuncServerOption(func(o *serverOptions) {
+		o.initialWindowSize = s
+		o.staticWindowSize = true
+	})
+}
+
+// StaticConnWindowSize returns a ServerOption to set the initial connection
+// window size to the value provided and disables dynamic flow control.
+// The lower bound for window size is 64K and any value smaller than that
+// will be ignored.
+func StaticConnWindowSize(s int32) ServerOption {
+	return newFuncServerOption(func(o *serverOptions) {
+		o.initialConnWindowSize = s
+		o.staticWindowSize = true
 	})
 }
 
@@ -986,6 +1011,7 @@ func (s *Server) newHTTP2Transport(c net.Conn) transport.ServerTransport {
 		MaxHeaderListSize:     s.opts.maxHeaderListSize,
 		HeaderTableSize:       s.opts.headerTableSize,
 		BufferPool:            s.opts.bufferPool,
+		StaticWindowSize:      s.opts.staticWindowSize,
 	}
 	st, err := transport.NewServerTransport(c, config)
 	if err != nil {

test/end2end_test.go

@@ -4225,6 +4225,10 @@ func testClientInitialHeaderEndStream(t *testing.T, e env) {
 	// checking.
 	handlerDone := make(chan struct{})
 	te := newTest(t, e)
+	te.customServerOptions = append(te.customServerOptions,
+		grpc.StaticStreamWindowSize(64000),
+		grpc.StaticConnWindowSize(10000),
+	)
 	ts := &funcServer{streamingInputCall: func(stream testgrpc.TestService_StreamingInputCallServer) error {
 		defer close(handlerDone)
 		// Block on serverTester receiving RST_STREAM. This ensures server has closed
@@ -4269,6 +4273,10 @@ func testClientSendDataAfterCloseSend(t *testing.T, e env) {
 	// checking.
 	handlerDone := make(chan struct{})
 	te := newTest(t, e)
+	te.customServerOptions = append(te.customServerOptions,
+		grpc.StaticStreamWindowSize(64000),
+		grpc.StaticConnWindowSize(10000),
+	)
 	ts := &funcServer{streamingInputCall: func(stream testgrpc.TestService_StreamingInputCallServer) error {
 		defer close(handlerDone)
 		// Block on serverTester receiving RST_STREAM. This ensures server has closed