move vendor to external

external/github.com/lucas-clemente/quic-go/internal/flowcontrol/base_flow_controller.go

@@ -0,0 +1,122 @@
+package flowcontrol
+
+import (
+	"sync"
+	"time"
+
+	"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/congestion"
+	"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/protocol"
+	"v2ray.com/core/external/github.com/lucas-clemente/quic-go/internal/utils"
+)
+
+type baseFlowController struct {
+	// for sending data
+	bytesSent     protocol.ByteCount
+	sendWindow    protocol.ByteCount
+	lastBlockedAt protocol.ByteCount
+
+	// for receiving data
+	mutex                sync.RWMutex
+	bytesRead            protocol.ByteCount
+	highestReceived      protocol.ByteCount
+	receiveWindow        protocol.ByteCount
+	receiveWindowSize    protocol.ByteCount
+	maxReceiveWindowSize protocol.ByteCount
+
+	epochStartTime   time.Time
+	epochStartOffset protocol.ByteCount
+	rttStats         *congestion.RTTStats
+
+	logger utils.Logger
+}
+
+// IsNewlyBlocked says if it is newly blocked by flow control.
+// For every offset, it only returns true once.
+// If it is blocked, the offset is returned.
+func (c *baseFlowController) IsNewlyBlocked() (bool, protocol.ByteCount) {
+	if c.sendWindowSize() != 0 || c.sendWindow == c.lastBlockedAt {
+		return false, 0
+	}
+	c.lastBlockedAt = c.sendWindow
+	return true, c.sendWindow
+}
+
+func (c *baseFlowController) AddBytesSent(n protocol.ByteCount) {
+	c.bytesSent += n
+}
+
+// UpdateSendWindow should be called after receiving a WindowUpdateFrame
+// it returns true if the window was actually updated
+func (c *baseFlowController) UpdateSendWindow(offset protocol.ByteCount) {
+	if offset > c.sendWindow {
+		c.sendWindow = offset
+	}
+}
+
+func (c *baseFlowController) sendWindowSize() protocol.ByteCount {
+	// this only happens during connection establishment, when data is sent before we receive the peer's transport parameters
+	if c.bytesSent > c.sendWindow {
+		return 0
+	}
+	return c.sendWindow - c.bytesSent
+}
+
+func (c *baseFlowController) AddBytesRead(n protocol.ByteCount) {
+	c.mutex.Lock()
+	defer c.mutex.Unlock()
+
+	// pretend we sent a WindowUpdate when reading the first byte
+	// this way auto-tuning of the window size already works for the first WindowUpdate
+	if c.bytesRead == 0 {
+		c.startNewAutoTuningEpoch()
+	}
+	c.bytesRead += n
+}
+
+func (c *baseFlowController) hasWindowUpdate() bool {
+	bytesRemaining := c.receiveWindow - c.bytesRead
+	// update the window when more than the threshold was consumed
+	return bytesRemaining <= protocol.ByteCount((float64(c.receiveWindowSize) * float64((1 - protocol.WindowUpdateThreshold))))
+}
+
+// getWindowUpdate updates the receive window, if necessary
+// it returns the new offset
+func (c *baseFlowController) getWindowUpdate() protocol.ByteCount {
+	if !c.hasWindowUpdate() {
+		return 0
+	}
+
+	c.maybeAdjustWindowSize()
+	c.receiveWindow = c.bytesRead + c.receiveWindowSize
+	return c.receiveWindow
+}
+
+// maybeAdjustWindowSize increases the receiveWindowSize if we're sending updates too often.
+// For details about auto-tuning, see https://docs.google.com/document/d/1SExkMmGiz8VYzV3s9E35JQlJ73vhzCekKkDi85F1qCE/edit?usp=sharing.
+func (c *baseFlowController) maybeAdjustWindowSize() {
+	bytesReadInEpoch := c.bytesRead - c.epochStartOffset
+	// don't do anything if less than half the window has been consumed
+	if bytesReadInEpoch <= c.receiveWindowSize/2 {
+		return
+	}
+	rtt := c.rttStats.SmoothedRTT()
+	if rtt == 0 {
+		return
+	}
+
+	fraction := float64(bytesReadInEpoch) / float64(c.receiveWindowSize)
+	if time.Since(c.epochStartTime) < time.Duration(4*fraction*float64(rtt)) {
+		// window is consumed too fast, try to increase the window size
+		c.receiveWindowSize = utils.MinByteCount(2*c.receiveWindowSize, c.maxReceiveWindowSize)
+	}
+	c.startNewAutoTuningEpoch()
+}
+
+func (c *baseFlowController) startNewAutoTuningEpoch() {
+	c.epochStartTime = time.Now()
+	c.epochStartOffset = c.bytesRead
+}
+
+func (c *baseFlowController) checkFlowControlViolation() bool {
+	return c.highestReceived > c.receiveWindow
+}