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Merge pull request #556 from Arceliar/switch

Switch hack
This commit is contained in:
Arceliar 2019-09-25 17:58:01 -05:00 committed by GitHub
commit a87581b0fa
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3 changed files with 48 additions and 13 deletions

View File

@ -276,6 +276,13 @@ func (intf *linkInterface) notifySending(size int, isLinkTraffic bool) {
})
}
// called by an AfterFunc if we seem to be blocked in a send syscall for a long time
func (intf *linkInterface) _notifySyscall() {
intf.link.core.switchTable.Act(intf, func() {
intf.link.core.switchTable._sendingIn(intf.peer.port)
})
}
// we just sent something, so cancel any pending timer to send keep-alive traffic
func (intf *linkInterface) _cancelStallTimer() {
if intf.stallTimer != nil {
@ -284,9 +291,11 @@ func (intf *linkInterface) _cancelStallTimer() {
}
}
// called by an AfterFunc if we appear to have timed out
// This gets called from a time.AfterFunc, and notifies the switch that we appear
// to have gotten blocked on a write, so the switch should start routing traffic
// through other links, if alternatives exist
func (intf *linkInterface) notifyBlockedSend() {
intf.Act(nil, func() { // Sent from a time.AfterFunc
intf.Act(nil, func() {
if intf.sendTimer != nil {
//As far as we know, we're still trying to send, and the timer fired.
intf.link.core.switchTable.blockPeer(intf.peer.port)
@ -380,7 +389,19 @@ func (w *linkWriter) sendFrom(from phony.Actor, bss [][]byte, isLinkTraffic bool
size += len(bs)
}
w.intf.notifySending(size, isLinkTraffic)
// start a timer that will fire if we get stuck in writeMsgs for an oddly long time
var once sync.Once
timer := time.AfterFunc(time.Millisecond, func() {
// 1 ms is kind of arbitrary
// the rationale is that this should be very long compared to a syscall
// but it's still short compared to end-to-end latency or human perception
once.Do(func() {
w.intf.Act(nil, w.intf._notifySyscall)
})
})
w.intf.msgIO.writeMsgs(bss)
// Make sure we either stop the timer from doing anything or wait until it's done
once.Do(func() { timer.Stop() })
w.intf.notifySent(size, isLinkTraffic)
// Cleanup
for _, bs := range bss {

View File

@ -177,6 +177,7 @@ type switchTable struct {
phony.Inbox // Owns the below
queues switch_buffers // Queues - not atomic so ONLY use through the actor
idle map[switchPort]struct{} // idle peers - not atomic so ONLY use through the actor
sending map[switchPort]struct{} // peers known to be blocked in a send (somehow)
}
// Minimum allowed total size of switch queues.
@ -203,6 +204,7 @@ func (t *switchTable) init(core *Core) {
core.config.Mutex.RUnlock()
t.queues.bufs = make(map[string]switch_buffer)
t.idle = make(map[switchPort]struct{})
t.sending = make(map[switchPort]struct{})
})
}
@ -527,7 +529,7 @@ func (t *switchTable) unlockedHandleMsg(msg *switchMsg, fromPort switchPort, rep
t.parent = sender.port
t.core.peers.sendSwitchMsgs(t)
}
if doUpdate {
if true || doUpdate {
t.updater.Store(&sync.Once{})
}
return
@ -664,7 +666,7 @@ func (t *switchTable) bestPortForCoords(coords []byte) switchPort {
// Handle an incoming packet
// Either send it to ourself, or to the first idle peer that's free
// Returns true if the packet has been handled somehow, false if it should be queued
func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]struct{}) bool {
func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]struct{}, sending map[switchPort]struct{}) bool {
coords := switch_getPacketCoords(packet)
closer := t.getCloser(coords)
if len(closer) == 0 {
@ -677,12 +679,13 @@ func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]struct{}) boo
ports := t.core.peers.getPorts()
for _, cinfo := range closer {
to := ports[cinfo.elem.port]
_, isIdle := idle[cinfo.elem.port]
//_, isIdle := idle[cinfo.elem.port]
_, isSending := sending[cinfo.elem.port]
var update bool
switch {
case to == nil:
// no port was found, ignore it
case !isIdle:
case isSending:
// the port is busy, ignore it
case best == nil:
// this is the first idle port we've found, so select it until we find a
@ -702,6 +705,7 @@ func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]struct{}) boo
// has a n older tstamp, so presumably a worse path
case cinfo.elem.time.Before(best.elem.time):
// same tstamp, but got it earlier, so presumably a better path
//t.core.log.Println("DEBUG new best:", best.elem.time, cinfo.elem.time)
update = true
default:
// the search for a port has finished
@ -712,10 +716,11 @@ func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]struct{}) boo
}
}
if best != nil {
// Send to the best idle next hop
delete(idle, best.elem.port)
ports[best.elem.port].sendPacketsFrom(t, [][]byte{packet})
return true
if _, isIdle := idle[best.elem.port]; isIdle {
delete(idle, best.elem.port)
ports[best.elem.port].sendPacketsFrom(t, [][]byte{packet})
return true
}
}
// Didn't find anyone idle to send it to
return false
@ -785,6 +790,7 @@ func (b *switch_buffers) _cleanup(t *switchTable) {
// Loops over packets and sends the newest one that's OK for this peer to send
// Returns true if the peer is no longer idle, false if it should be added to the idle list
func (t *switchTable) _handleIdle(port switchPort) bool {
// TODO? only send packets for which this is the best next hop that isn't currently blocked sending
to := t.core.peers.getPorts()[port]
if to == nil {
return true
@ -842,7 +848,7 @@ func (t *switchTable) packetInFrom(from phony.Actor, bytes []byte) {
func (t *switchTable) _packetIn(bytes []byte) {
// Try to send it somewhere (or drop it if it's corrupt or at a dead end)
if !t._handleIn(bytes, t.idle) {
if !t._handleIn(bytes, t.idle, t.sending) {
// There's nobody free to take it right now, so queue it for later
packet := switch_packetInfo{bytes, time.Now()}
streamID := switch_getPacketStreamID(packet.bytes)
@ -869,8 +875,15 @@ func (t *switchTable) _packetIn(bytes []byte) {
func (t *switchTable) _idleIn(port switchPort) {
// Try to find something to send to this peer
delete(t.sending, port)
if !t._handleIdle(port) {
// Didn't find anything ready to send yet, so stay idle
t.idle[port] = struct{}{}
}
}
func (t *switchTable) _sendingIn(port switchPort) {
if _, isIn := t.idle[port]; !isIn {
t.sending[port] = struct{}{}
}
}

View File

@ -233,8 +233,9 @@ func (t *tcp) call(saddr string, options interface{}, sintf string) {
}
defer func() {
// Block new calls for a little while, to mitigate livelock scenarios
time.Sleep(default_timeout)
time.Sleep(time.Duration(rand.Intn(1000)) * time.Millisecond)
rand.Seed(time.Now().UnixNano())
delay := default_timeout + time.Duration(rand.Intn(10000))*time.Millisecond
time.Sleep(delay)
t.mutex.Lock()
delete(t.calls, callname)
t.mutex.Unlock()