split the flow controller in stream and connection flow controller

internal/flowcontrol/connection_flow_controller.go

@@ -0,0 +1,55 @@
+package flowcontrol
+
+import (
+	"time"
+
+	"github.com/lucas-clemente/quic-go/congestion"
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+)
+
+type connectionFlowController struct {
+	baseFlowController
+}
+
+// newConnectionFlowController gets a new flow controller for the connection
+func newConnectionFlowController(
+	receiveWindow protocol.ByteCount,
+	maxReceiveWindow protocol.ByteCount,
+	initialSendWindow protocol.ByteCount,
+	rttStats *congestion.RTTStats,
+) *connectionFlowController {
+	return &connectionFlowController{
+		baseFlowController: baseFlowController{
+			rttStats:                  rttStats,
+			receiveWindow:             receiveWindow,
+			receiveWindowIncrement:    receiveWindow,
+			maxReceiveWindowIncrement: maxReceiveWindow,
+			sendWindow:                initialSendWindow,
+		},
+	}
+}
+
+// EnsureMinimumWindowIncrement sets a minimum window increment
+// it should make sure that the connection-level window is increased when a stream-level window grows
+func (c *connectionFlowController) EnsureMinimumWindowIncrement(inc protocol.ByteCount) {
+	if inc > c.receiveWindowIncrement {
+		c.receiveWindowIncrement = utils.MinByteCount(inc, c.maxReceiveWindowIncrement)
+		c.lastWindowUpdateTime = time.Time{} // disables autotuning for the next window update
+	}
+}
+
+// IncrementHighestReceived adds an increment to the highestReceived value
+func (c *connectionFlowController) IncrementHighestReceived(increment protocol.ByteCount) {
+	c.highestReceived += increment
+}
+
+func (c *connectionFlowController) MaybeUpdateWindow() (bool, protocol.ByteCount, protocol.ByteCount) {
+	oldWindowSize := c.receiveWindowIncrement
+	updated, newIncrement, newOffset := c.baseFlowController.MaybeUpdateWindow()
+	// debug log, if the window size was actually increased
+	if oldWindowSize < c.receiveWindowIncrement {
+		utils.Debugf("Increasing receive flow control window for the connection to %d kB", c.receiveWindowIncrement/(1<<10))
+	}
+	return updated, newIncrement, newOffset
+}