forked from quic-go/quic-go
741dc28d74
The RTTStats are used by the logging package. In order to instrument the congestion package, the RTTStats can't be part of that package any more (to avoid an import loop).
123 lines
3.7 KiB
Go
123 lines
3.7 KiB
Go
package flowcontrol
|
|
|
|
import (
|
|
"sync"
|
|
"time"
|
|
|
|
"github.com/lucas-clemente/quic-go/internal/protocol"
|
|
"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 *utils.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(time.Now())
|
|
}
|
|
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)*(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)
|
|
now := time.Now()
|
|
if now.Sub(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(now)
|
|
}
|
|
|
|
func (c *baseFlowController) startNewAutoTuningEpoch(now time.Time) {
|
|
c.epochStartTime = now
|
|
c.epochStartOffset = c.bytesRead
|
|
}
|
|
|
|
func (c *baseFlowController) checkFlowControlViolation() bool {
|
|
return c.highestReceived > c.receiveWindow
|
|
}
|