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