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package flowcontrol
import (
"errors"
"fmt"
"time"
"github.com/quic-go/quic-go/internal/protocol"
"github.com/quic-go/quic-go/internal/qerr"
"github.com/quic-go/quic-go/internal/utils"
)
type connectionFlowController struct {
baseFlowController
}
var _ ConnectionFlowController = &connectionFlowController{}
// NewConnectionFlowController gets a new flow controller for the connection
// It is created before we receive the peer's transport parameters, thus it starts with a sendWindow of 0.
func NewConnectionFlowController(
receiveWindow protocol.ByteCount,
maxReceiveWindow protocol.ByteCount,
allowWindowIncrease func(size protocol.ByteCount) bool,
rttStats *utils.RTTStats,
logger utils.Logger,
) *connectionFlowController {
return &connectionFlowController{
baseFlowController: baseFlowController{
rttStats: rttStats,
receiveWindow: receiveWindow,
receiveWindowSize: receiveWindow,
maxReceiveWindowSize: maxReceiveWindow,
allowWindowIncrease: allowWindowIncrease,
logger: logger,
},
}
}
// IncrementHighestReceived adds an increment to the highestReceived value
func (c *connectionFlowController) IncrementHighestReceived(increment protocol.ByteCount, now time.Time) error {
c.mutex.Lock()
defer c.mutex.Unlock()
// If this is the first frame received on this connection, start flow-control auto-tuning.
if c.highestReceived == 0 {
c.startNewAutoTuningEpoch(now)
}
c.highestReceived += increment
if c.checkFlowControlViolation() {
return &qerr.TransportError{
ErrorCode: qerr.FlowControlError,
ErrorMessage: fmt.Sprintf("received %d bytes for the connection, allowed %d bytes", c.highestReceived, c.receiveWindow),
}
}
return nil
}
func (c *connectionFlowController) AddBytesRead(n protocol.ByteCount) (hasWindowUpdate bool) {
c.mutex.Lock()
defer c.mutex.Unlock()
c.addBytesRead(n)
return c.hasWindowUpdate()
}
func (c *connectionFlowController) GetWindowUpdate(now time.Time) protocol.ByteCount {
c.mutex.Lock()
defer c.mutex.Unlock()
oldWindowSize := c.receiveWindowSize
offset := c.getWindowUpdate(now)
if c.logger.Debug() && oldWindowSize < c.receiveWindowSize {
c.logger.Debugf("Increasing receive flow control window for the connection to %d kB", c.receiveWindowSize/(1<<10))
}
return offset
}
// EnsureMinimumWindowSize sets a minimum window size
// it should make sure that the connection-level window is increased when a stream-level window grows
func (c *connectionFlowController) EnsureMinimumWindowSize(inc protocol.ByteCount, now time.Time) {
c.mutex.Lock()
defer c.mutex.Unlock()
if inc <= c.receiveWindowSize {
return
}
newSize := min(inc, c.maxReceiveWindowSize)
if delta := newSize - c.receiveWindowSize; delta > 0 && c.allowWindowIncrease(delta) {
c.receiveWindowSize = newSize
if c.logger.Debug() {
c.logger.Debugf("Increasing receive flow control window for the connection to %d, in response to stream flow control window increase", newSize)
}
}
c.startNewAutoTuningEpoch(now)
}
// Reset rests the flow controller. This happens when 0-RTT is rejected.
// All stream data is invalidated, it's as if we had never opened a stream and never sent any data.
// At that point, we only have sent stream data, but we didn't have the keys to open 1-RTT keys yet.
func (c *connectionFlowController) Reset() error {
c.mutex.Lock()
defer c.mutex.Unlock()
if c.bytesRead > 0 || c.highestReceived > 0 || !c.epochStartTime.IsZero() {
return errors.New("flow controller reset after reading data")
}
c.bytesSent = 0
c.lastBlockedAt = 0
c.sendWindow = 0
return nil
}
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