1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
package quic
import (
"net"
"github.com/quic-go/quic-go/internal/protocol"
)
type sender interface {
Send(p *packetBuffer, gsoSize uint16, ecn protocol.ECN)
SendProbe(*packetBuffer, net.Addr)
Run() error
WouldBlock() bool
Available() <-chan struct{}
Close()
}
type queueEntry struct {
buf *packetBuffer
gsoSize uint16
ecn protocol.ECN
}
type sendQueue struct {
queue chan queueEntry
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 queueEntry, 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, gsoSize uint16, ecn protocol.ECN) {
select {
case h.queue <- queueEntry{buf: p, gsoSize: gsoSize, ecn: ecn}:
// clear available channel if we've reached capacity
if len(h.queue) == sendQueueCapacity {
select {
case <-h.available:
default:
}
}
case <-h.runStopped:
default:
panic("sendQueue.Send would have blocked")
}
}
func (h *sendQueue) SendProbe(p *packetBuffer, addr net.Addr) {
h.conn.WriteTo(p.Data, addr)
}
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 e := <-h.queue:
if err := h.conn.Write(e.buf.Data, e.gsoSize, e.ecn); 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 !isSendMsgSizeErr(err) {
return err
}
}
e.buf.Release()
select {
case h.available <- struct{}{}:
default:
}
}
}
}
func (h *sendQueue) Close() {
close(h.closeCalled)
// wait until the run loop returned
<-h.runStopped
}
|
