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Merge pull request #542 from Arceliar/switch

Switch
This commit is contained in:
Neil Alexander 2019-09-18 20:26:48 +01:00 committed by GitHub
commit 64570a8d3e
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@ -143,6 +143,7 @@ type switchPort uint64
type tableElem struct {
port switchPort
locator switchLocator
time time.Time
}
// This is the subset of the information about all peers needed to make routing decisions, and it stored separately in an atomically accessed table, which gets hammered in the "hot loop" of the routing logic (see: peer.handleTraffic in peers.go).
@ -175,7 +176,7 @@ type switchTable struct {
table atomic.Value // lookupTable
phony.Inbox // Owns the below
queues switch_buffers // Queues - not atomic so ONLY use through the actor
idle map[switchPort]time.Time // idle peers - not atomic so ONLY use through the actor
idle map[switchPort]struct{} // idle peers - not atomic so ONLY use through the actor
}
// Minimum allowed total size of switch queues.
@ -201,7 +202,7 @@ func (t *switchTable) init(core *Core) {
}
core.config.Mutex.RUnlock()
t.queues.bufs = make(map[string]switch_buffer)
t.idle = make(map[switchPort]time.Time)
t.idle = make(map[switchPort]struct{})
})
}
@ -562,6 +563,7 @@ func (t *switchTable) updateTable() {
newTable.elems[pinfo.port] = tableElem{
locator: loc,
port: pinfo.port,
time: pinfo.time,
}
}
t.table.Store(newTable)
@ -581,7 +583,7 @@ func (t *switchTable) start() error {
}
type closerInfo struct {
port switchPort
elem tableElem
dist int
}
@ -598,7 +600,7 @@ func (t *switchTable) getCloser(dest []byte) []closerInfo {
for _, info := range table.elems {
dist := info.locator.dist(dest)
if dist < myDist {
t.queues.closer = append(t.queues.closer, closerInfo{info.port, dist})
t.queues.closer = append(t.queues.closer, closerInfo{info, dist})
}
}
return t.queues.closer
@ -662,7 +664,7 @@ 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]time.Time) bool {
func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]struct{}) bool {
coords := switch_getPacketCoords(packet)
closer := t.getCloser(coords)
if len(closer) == 0 {
@ -671,49 +673,48 @@ func (t *switchTable) _handleIn(packet []byte, idle map[switchPort]time.Time) bo
self.sendPacketsFrom(t, [][]byte{packet})
return true
}
var best *peer
var bestDist int
var bestTime time.Time
var best *closerInfo
ports := t.core.peers.getPorts()
for _, cinfo := range closer {
to := ports[cinfo.port]
thisTime, isIdle := idle[cinfo.port]
to := ports[cinfo.elem.port]
var update bool
switch {
case to == nil:
// no port was found, ignore it
case !isIdle:
// 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
// better candidate port to use instead
update = true
case cinfo.dist < bestDist:
case cinfo.dist < best.dist:
// the port takes a shorter path/is more direct than our current
// candidate, so select that instead
update = true
case cinfo.dist > bestDist:
case cinfo.dist > best.dist:
// the port takes a longer path/is less direct than our current candidate,
// ignore it
case thisTime.After(bestTime):
// all else equal, this port was used more recently than our current
// candidate, so choose that instead. this should mean that, in low
// traffic scenarios, we consistently pick the same link which helps with
// packet ordering
case cinfo.elem.locator.tstamp > best.elem.locator.tstamp:
// has a newer tstamp from the root, so presumably a better path
update = true
case cinfo.elem.locator.tstamp < best.elem.locator.tstamp:
// 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
update = true
default:
// the search for a port has finished
}
if update {
best = to
bestDist = cinfo.dist
bestTime = thisTime
b := cinfo // because cinfo gets mutated by the iteration
best = &b
}
}
if best != nil {
// Send to the best idle next hop
delete(idle, best.port)
best.sendPacketsFrom(t, [][]byte{packet})
if _, isIdle := idle[best.elem.port]; !isIdle {
return false
}
delete(idle, best.elem.port)
ports[best.elem.port].sendPacketsFrom(t, [][]byte{packet})
return true
}
// Didn't find anyone idle to send it to
@ -870,6 +871,6 @@ func (t *switchTable) _idleIn(port switchPort) {
// Try to find something to send to this peer
if !t._handleIdle(port) {
// Didn't find anything ready to send yet, so stay idle
t.idle[port] = time.Now()
t.idle[port] = struct{}{}
}
}