cloudflared-mirror/vendor/github.com/lucas-clemente/quic-go/send_queue.go

89 lines
2.0 KiB
Go

package quic
type sender interface {
Send(p *packetBuffer)
Run() error
WouldBlock() bool
Available() <-chan struct{}
Close()
}
type sendQueue struct {
queue chan *packetBuffer
closeCalled chan struct{} // runStopped when Close() is called
runStopped chan struct{} // runStopped when the run loop returns
available chan struct{}
conn sendConn
}
var _ sender = &sendQueue{}
const sendQueueCapacity = 8
func newSendQueue(conn sendConn) sender {
return &sendQueue{
conn: conn,
runStopped: make(chan struct{}),
closeCalled: make(chan struct{}),
available: make(chan struct{}, 1),
queue: make(chan *packetBuffer, sendQueueCapacity),
}
}
// Send sends out a packet. It's guaranteed to not block.
// Callers need to make sure that there's actually space in the send queue by calling WouldBlock.
// Otherwise Send will panic.
func (h *sendQueue) Send(p *packetBuffer) {
select {
case h.queue <- p:
case <-h.runStopped:
default:
panic("sendQueue.Send would have blocked")
}
}
func (h *sendQueue) WouldBlock() bool {
return len(h.queue) == sendQueueCapacity
}
func (h *sendQueue) Available() <-chan struct{} {
return h.available
}
func (h *sendQueue) Run() error {
defer close(h.runStopped)
var shouldClose bool
for {
if shouldClose && len(h.queue) == 0 {
return nil
}
select {
case <-h.closeCalled:
h.closeCalled = nil // prevent this case from being selected again
// make sure that all queued packets are actually sent out
shouldClose = true
case p := <-h.queue:
if err := h.conn.Write(p.Data); err != nil {
// This additional check enables:
// 1. Checking for "datagram too large" message from the kernel, as such,
// 2. Path MTU discovery,and
// 3. Eventual detection of loss PingFrame.
if !isMsgSizeErr(err) {
return err
}
}
p.Release()
select {
case h.available <- struct{}{}:
default:
}
}
}
}
func (h *sendQueue) Close() {
close(h.closeCalled)
// wait until the run loop returned
<-h.runStopped
}