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feature/relayserver: use eventbus.Monitor to simplify lifecycle management (#17234)

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Instead of using separate channels to manage the lifecycle of the eventbus
client, use the recently-added eventbus.Monitor, which handles signaling the
processing loop to stop and waiting for it to complete.  This allows us to
simplify some of the setup and cleanup code in the relay server.

Updates #15160

Change-Id: Ia1a47ce2e5a31bc8f546dca4c56c3141a40d67af
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
This commit is contained in:
M. J. Fromberger 2025-10-02 09:18:55 -07:00 committed by GitHub
parent 1d93bdce20
commit 3c32f87624
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GPG Key ID: B5690EEEBB952194
2 changed files with 71 additions and 78 deletions
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137
feature/relayserver/relayserver.go
View File

@ -82,11 +82,11 @@ type extension struct {
logf logger.Logf logf logger.Logf
bus *eventbus.Bus bus *eventbus.Bus
mu sync.Mutex // guards the following fields mu sync.Mutex // guards the following fields
shutdown bool shutdown bool
port *int // ipn.Prefs.RelayServerPort, nil if disabled port *int // ipn.Prefs.RelayServerPort, nil if disabled
disconnectFromBusCh chan struct{} // non-nil if consumeEventbusTopics is running, closed to signal it to return eventSubs *eventbus.Monitor // nil if not connected to eventbus
busDoneCh chan struct{} // non-nil if consumeEventbusTopics is running, closed when it returns
debugSessionsCh chan chan []status.ServerSession // non-nil if consumeEventbusTopics is running debugSessionsCh chan chan []status.ServerSession // non-nil if consumeEventbusTopics is running
hasNodeAttrDisableRelayServer bool // tailcfg.NodeAttrDisableRelayServer hasNodeAttrDisableRelayServer bool // tailcfg.NodeAttrDisableRelayServer
} }
@ -119,15 +119,13 @@ func (e *extension) handleBusLifetimeLocked() {
if !busShouldBeRunning { if !busShouldBeRunning {
e.disconnectFromBusLocked() e.disconnectFromBusLocked()
return return
} } else if e.eventSubs != nil {
if e.busDoneCh != nil {
return // already running return // already running
} }
port := *e.port
e.disconnectFromBusCh = make(chan struct{}) ec := e.bus.Client("relayserver.extension")
e.busDoneCh = make(chan struct{})
e.debugSessionsCh = make(chan chan []status.ServerSession) e.debugSessionsCh = make(chan chan []status.ServerSession)
go e.consumeEventbusTopics(port) e.eventSubs = ptr.To(ec.Monitor(e.consumeEventbusTopics(ec, *e.port)))
} }
func (e *extension) selfNodeViewChanged(nodeView tailcfg.NodeView) { func (e *extension) selfNodeViewChanged(nodeView tailcfg.NodeView) {
@ -175,77 +173,72 @@ var overrideAddrs = sync.OnceValue(func() (ret []netip.Addr) {
// consumeEventbusTopics serves endpoint allocation requests over the eventbus. // consumeEventbusTopics serves endpoint allocation requests over the eventbus.
// It also serves [relayServer] debug information on a channel. // It also serves [relayServer] debug information on a channel.
// consumeEventbusTopics must never acquire [extension.mu], which can be held by // consumeEventbusTopics must never acquire [extension.mu], which can be held
// other goroutines while waiting to receive on [extension.busDoneCh] or the // by other goroutines while waiting to receive on [extension.eventSubs] or the
// inner [extension.debugSessionsCh] channel. // inner [extension.debugSessionsCh] channel.
func (e *extension) consumeEventbusTopics(port int) { func (e *extension) consumeEventbusTopics(ec *eventbus.Client, port int) func(*eventbus.Client) {
defer close(e.busDoneCh) reqSub := eventbus.Subscribe[magicsock.UDPRelayAllocReq](ec)
respPub := eventbus.Publish[magicsock.UDPRelayAllocResp](ec)
debugSessionsCh := e.debugSessionsCh
eventClient := e.bus.Client("relayserver.extension") return func(ec *eventbus.Client) {
reqSub := eventbus.Subscribe[magicsock.UDPRelayAllocReq](eventClient) var rs relayServer // lazily initialized
respPub := eventbus.Publish[magicsock.UDPRelayAllocResp](eventClient) defer func() {
defer eventClient.Close() if rs != nil {
rs.Close()
var rs relayServer // lazily initialized
defer func() {
if rs != nil {
rs.Close()
}
}()
for {
select {
case <-e.disconnectFromBusCh:
return
case <-eventClient.Done():
return
case respCh := <-e.debugSessionsCh:
if rs == nil {
// Don't initialize the server simply for a debug request.
respCh <- nil
continue
} }
sessions := rs.GetSessions() }()
respCh <- sessions for {
case req := <-reqSub.Events(): select {
if rs == nil { case <-ec.Done():
var err error return
rs, err = udprelay.NewServer(e.logf, port, overrideAddrs()) case respCh := <-debugSessionsCh:
if err != nil { if rs == nil {
e.logf("error initializing server: %v", err) // Don't initialize the server simply for a debug request.
respCh <- nil
continue continue
} }
} sessions := rs.GetSessions()
se, err := rs.AllocateEndpoint(req.Message.ClientDisco[0], req.Message.ClientDisco[1]) respCh <- sessions
if err != nil { case req := <-reqSub.Events():
e.logf("error allocating endpoint: %v", err) if rs == nil {
continue var err error
} rs, err = udprelay.NewServer(e.logf, port, overrideAddrs())
respPub.Publish(magicsock.UDPRelayAllocResp{ if err != nil {
ReqRxFromNodeKey: req.RxFromNodeKey, e.logf("error initializing server: %v", err)
ReqRxFromDiscoKey: req.RxFromDiscoKey, continue
Message: &disco.AllocateUDPRelayEndpointResponse{ }
Generation: req.Message.Generation, }
UDPRelayEndpoint: disco.UDPRelayEndpoint{ se, err := rs.AllocateEndpoint(req.Message.ClientDisco[0], req.Message.ClientDisco[1])
ServerDisco: se.ServerDisco, if err != nil {
ClientDisco: se.ClientDisco, e.logf("error allocating endpoint: %v", err)
LamportID: se.LamportID, continue
VNI: se.VNI, }
BindLifetime: se.BindLifetime.Duration, respPub.Publish(magicsock.UDPRelayAllocResp{
SteadyStateLifetime: se.SteadyStateLifetime.Duration, ReqRxFromNodeKey: req.RxFromNodeKey,
AddrPorts: se.AddrPorts, ReqRxFromDiscoKey: req.RxFromDiscoKey,
Message: &disco.AllocateUDPRelayEndpointResponse{
Generation: req.Message.Generation,
UDPRelayEndpoint: disco.UDPRelayEndpoint{
ServerDisco: se.ServerDisco,
ClientDisco: se.ClientDisco,
LamportID: se.LamportID,
VNI: se.VNI,
BindLifetime: se.BindLifetime.Duration,
SteadyStateLifetime: se.SteadyStateLifetime.Duration,
AddrPorts: se.AddrPorts,
},
}, },
}, })
}) }
} }
} }
} }
func (e *extension) disconnectFromBusLocked() { func (e *extension) disconnectFromBusLocked() {
if e.busDoneCh != nil { if e.eventSubs != nil {
close(e.disconnectFromBusCh) e.eventSubs.Close()
<-e.busDoneCh e.eventSubs = nil
e.busDoneCh = nil
e.disconnectFromBusCh = nil
e.debugSessionsCh = nil e.debugSessionsCh = nil
} }
} }
@ -270,7 +263,7 @@ func (e *extension) serverStatus() status.ServerStatus {
UDPPort: nil, UDPPort: nil,
Sessions: nil, Sessions: nil,
} }
if e.port == nil || e.busDoneCh == nil { if e.port == nil || e.eventSubs == nil {
return st return st
} }
st.UDPPort = ptr.To(*e.port) st.UDPPort = ptr.To(*e.port)
@ -281,7 +274,7 @@ func (e *extension) serverStatus() status.ServerStatus {
resp := <-ch resp := <-ch
st.Sessions = resp st.Sessions = resp
return st return st
case <-e.busDoneCh: case <-e.eventSubs.Done():
return st return st
} }
} }

12
feature/relayserver/relayserver_test.go
View File

@ -101,8 +101,8 @@ func Test_extension_profileStateChanged(t *testing.T) {
} }
defer e.disconnectFromBusLocked() defer e.disconnectFromBusLocked()
e.profileStateChanged(ipn.LoginProfileView{}, tt.args.prefs, tt.args.sameNode) e.profileStateChanged(ipn.LoginProfileView{}, tt.args.prefs, tt.args.sameNode)
if tt.wantBusRunning != (e.busDoneCh != nil) { if tt.wantBusRunning != (e.eventSubs != nil) {
t.Errorf("wantBusRunning: %v != (e.busDoneCh != nil): %v", tt.wantBusRunning, e.busDoneCh != nil) t.Errorf("wantBusRunning: %v != (e.eventSubs != nil): %v", tt.wantBusRunning, e.eventSubs != nil)
} }
if (tt.wantPort == nil) != (e.port == nil) { if (tt.wantPort == nil) != (e.port == nil) {
t.Errorf("(tt.wantPort == nil): %v != (e.port == nil): %v", tt.wantPort == nil, e.port == nil) t.Errorf("(tt.wantPort == nil): %v != (e.port == nil): %v", tt.wantPort == nil, e.port == nil)
@ -118,7 +118,7 @@ func Test_extension_handleBusLifetimeLocked(t *testing.T) {
name string name string
shutdown bool shutdown bool
port *int port *int
busDoneCh chan struct{} eventSubs *eventbus.Monitor
hasNodeAttrDisableRelayServer bool hasNodeAttrDisableRelayServer bool
wantBusRunning bool wantBusRunning bool
}{ }{
@ -157,13 +157,13 @@ func Test_extension_handleBusLifetimeLocked(t *testing.T) {
bus: eventbus.New(), bus: eventbus.New(),
shutdown: tt.shutdown, shutdown: tt.shutdown,
port: tt.port, port: tt.port,
busDoneCh: tt.busDoneCh, eventSubs: tt.eventSubs,
hasNodeAttrDisableRelayServer: tt.hasNodeAttrDisableRelayServer, hasNodeAttrDisableRelayServer: tt.hasNodeAttrDisableRelayServer,
} }
e.handleBusLifetimeLocked() e.handleBusLifetimeLocked()
defer e.disconnectFromBusLocked() defer e.disconnectFromBusLocked()
if tt.wantBusRunning != (e.busDoneCh != nil) { if tt.wantBusRunning != (e.eventSubs != nil) {
t.Errorf("wantBusRunning: %v != (e.busDoneCh != nil): %v", tt.wantBusRunning, e.busDoneCh != nil) t.Errorf("wantBusRunning: %v != (e.eventSubs != nil): %v", tt.wantBusRunning, e.eventSubs != nil)
} }
}) })
} }