make the initial connection flow control window configurable

config.go

@@ -79,6 +79,10 @@ func populateConfig(config *Config) *Config {
 	if maxReceiveStreamFlowControlWindow == 0 {
 		maxReceiveStreamFlowControlWindow = protocol.DefaultMaxReceiveStreamFlowControlWindow
 	}
+	initialConnectionFlowControlWindow := config.InitialConnectionFlowControlWindow
+	if initialConnectionFlowControlWindow == 0 {
+		initialConnectionFlowControlWindow = protocol.DefaultInitialMaxData
+	}
 	maxReceiveConnectionFlowControlWindow := config.MaxReceiveConnectionFlowControlWindow
 	if maxReceiveConnectionFlowControlWindow == 0 {
 		maxReceiveConnectionFlowControlWindow = protocol.DefaultMaxReceiveConnectionFlowControlWindow
@@ -104,6 +108,7 @@ func populateConfig(config *Config) *Config {
 		KeepAlive:                             config.KeepAlive,
 		InitialStreamFlowControlWindow:        initialStreamFlowControlWindow,
 		MaxReceiveStreamFlowControlWindow:     maxReceiveStreamFlowControlWindow,
+		InitialConnectionFlowControlWindow:    initialConnectionFlowControlWindow,
 		MaxReceiveConnectionFlowControlWindow: maxReceiveConnectionFlowControlWindow,
 		MaxIncomingStreams:                    maxIncomingStreams,
 		MaxIncomingUniStreams:                 maxIncomingUniStreams,

config_test.go

@@ -61,6 +61,8 @@ var _ = Describe("Config", func() {
 				f.Set(reflect.ValueOf(uint64(1234)))
 			case "MaxReceiveStreamFlowControlWindow":
 				f.Set(reflect.ValueOf(uint64(9)))
+			case "InitialConnectionFlowControlWindow":
+				f.Set(reflect.ValueOf(uint64(4321)))
 			case "MaxReceiveConnectionFlowControlWindow":
 				f.Set(reflect.ValueOf(uint64(10)))
 			case "MaxIncomingStreams":
@@ -146,6 +148,7 @@ var _ = Describe("Config", func() {
 			Expect(c.HandshakeIdleTimeout).To(Equal(protocol.DefaultHandshakeIdleTimeout))
 			Expect(c.InitialStreamFlowControlWindow).To(BeEquivalentTo(protocol.DefaultInitialMaxStreamData))
 			Expect(c.MaxReceiveStreamFlowControlWindow).To(BeEquivalentTo(protocol.DefaultMaxReceiveStreamFlowControlWindow))
+			Expect(c.InitialConnectionFlowControlWindow).To(BeEquivalentTo(protocol.DefaultInitialMaxData))
 			Expect(c.MaxReceiveConnectionFlowControlWindow).To(BeEquivalentTo(protocol.DefaultMaxReceiveConnectionFlowControlWindow))
 			Expect(c.MaxIncomingStreams).To(BeEquivalentTo(protocol.DefaultMaxIncomingStreams))
 			Expect(c.MaxIncomingUniStreams).To(BeEquivalentTo(protocol.DefaultMaxIncomingUniStreams))

interface.go

@@ -253,6 +253,11 @@ type Config struct {
 	// MaxReceiveStreamFlowControlWindow is the maximum stream-level flow control window for receiving data.
 	// If this value is zero, it will default to 6 MB.
 	MaxReceiveStreamFlowControlWindow uint64
+	// InitialConnectionFlowControlWindow is the initial size of the stream-level flow control window for receiving data.
+	// If the application is consuming data quickly enough, the flow control auto-tuning algorithm
+	// will increase the window up to MaxReceiveConnectionFlowControlWindow.
+	// If this value is zero, it will default to 512 KB.
+	InitialConnectionFlowControlWindow uint64
 	// MaxReceiveConnectionFlowControlWindow is the connection-level flow control window for receiving data.
 	// If this value is zero, it will default to 15 MB.
 	MaxReceiveConnectionFlowControlWindow uint64

internal/protocol/params.go

@@ -24,8 +24,8 @@ const ConnectionFlowControlMultiplier = 1.5
 // DefaultInitialMaxStreamData is the default initial stream-level flow control window for receiving data
 const DefaultInitialMaxStreamData = (1 << 10) * 512 // 512 kb
 
-// InitialMaxData is the connection-level flow control window for receiving data
+// DefaultInitialMaxData is the connection-level flow control window for receiving data
-const InitialMaxData = ConnectionFlowControlMultiplier * DefaultInitialMaxStreamData
+const DefaultInitialMaxData = ConnectionFlowControlMultiplier * DefaultInitialMaxStreamData
 
 // DefaultMaxReceiveStreamFlowControlWindow is the default maximum stream-level flow control window for receiving data
 const DefaultMaxReceiveStreamFlowControlWindow = 6 * (1 << 20) // 6 MB

session.go

@@ -286,7 +286,7 @@ var newSession = func(
 		InitialMaxStreamDataBidiLocal:   protocol.ByteCount(s.config.InitialStreamFlowControlWindow),
 		InitialMaxStreamDataBidiRemote:  protocol.ByteCount(s.config.InitialStreamFlowControlWindow),
 		InitialMaxStreamDataUni:         protocol.ByteCount(s.config.InitialStreamFlowControlWindow),
-		InitialMaxData:                  protocol.InitialMaxData,
+		InitialMaxData:                  protocol.ByteCount(s.config.InitialConnectionFlowControlWindow),
 		MaxIdleTimeout:                  s.config.MaxIdleTimeout,
 		MaxBidiStreamNum:                protocol.StreamNum(s.config.MaxIncomingStreams),
 		MaxUniStreamNum:                 protocol.StreamNum(s.config.MaxIncomingUniStreams),
@@ -410,7 +410,7 @@ var newClientSession = func(
 		InitialMaxStreamDataBidiRemote: protocol.ByteCount(s.config.InitialStreamFlowControlWindow),
 		InitialMaxStreamDataBidiLocal:  protocol.ByteCount(s.config.InitialStreamFlowControlWindow),
 		InitialMaxStreamDataUni:        protocol.ByteCount(s.config.InitialStreamFlowControlWindow),
-		InitialMaxData:                 protocol.InitialMaxData,
+		InitialMaxData:                 protocol.ByteCount(s.config.InitialConnectionFlowControlWindow),
 		MaxIdleTimeout:                 s.config.MaxIdleTimeout,
 		MaxBidiStreamNum:               protocol.StreamNum(s.config.MaxIncomingStreams),
 		MaxUniStreamNum:                protocol.StreamNum(s.config.MaxIncomingUniStreams),
@@ -484,7 +484,7 @@ func (s *session) preSetup() {
 	s.frameParser = wire.NewFrameParser(s.config.EnableDatagrams, s.version)
 	s.rttStats = &utils.RTTStats{}
 	s.connFlowController = flowcontrol.NewConnectionFlowController(
-		protocol.InitialMaxData,
+		protocol.ByteCount(s.config.InitialConnectionFlowControlWindow),
 		protocol.ByteCount(s.config.MaxReceiveConnectionFlowControlWindow),
 		s.onHasConnectionWindowUpdate,
 		s.rttStats,