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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
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
2 changed files with 71 additions and 78 deletions
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49
feature/relayserver/relayserver.go
View File

@ -84,9 +84,9 @@ type extension struct {
mu sync.Mutex // guards the following fields
shutdown bool
port *int // ipn.Prefs.RelayServerPort, nil if disabled
disconnectFromBusCh chan struct{} // non-nil if consumeEventbusTopics is running, closed to signal it to return
busDoneCh chan struct{} // non-nil if consumeEventbusTopics is running, closed when it returns
eventSubs *eventbus.Monitor // nil if not connected to eventbus
debugSessionsCh chan chan []status.ServerSession // non-nil if consumeEventbusTopics is running
hasNodeAttrDisableRelayServer bool // tailcfg.NodeAttrDisableRelayServer
}
@ -119,15 +119,13 @@ func (e *extension) handleBusLifetimeLocked() {
if !busShouldBeRunning {
e.disconnectFromBusLocked()
return
}
if e.busDoneCh != nil {
} else if e.eventSubs != nil {
return // already running
}
port := *e.port
e.disconnectFromBusCh = make(chan struct{})
e.busDoneCh = make(chan struct{})
ec := e.bus.Client("relayserver.extension")
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) {
@ -175,17 +173,15 @@ var overrideAddrs = sync.OnceValue(func() (ret []netip.Addr) {
// consumeEventbusTopics serves endpoint allocation requests over the eventbus.
// It also serves [relayServer] debug information on a channel.
// consumeEventbusTopics must never acquire [extension.mu], which can be held by
// other goroutines while waiting to receive on [extension.busDoneCh] or the
// consumeEventbusTopics must never acquire [extension.mu], which can be held
// by other goroutines while waiting to receive on [extension.eventSubs] or the
// inner [extension.debugSessionsCh] channel.
func (e *extension) consumeEventbusTopics(port int) {
defer close(e.busDoneCh)
eventClient := e.bus.Client("relayserver.extension")
reqSub := eventbus.Subscribe[magicsock.UDPRelayAllocReq](eventClient)
respPub := eventbus.Publish[magicsock.UDPRelayAllocResp](eventClient)
defer eventClient.Close()
func (e *extension) consumeEventbusTopics(ec *eventbus.Client, port int) func(*eventbus.Client) {
reqSub := eventbus.Subscribe[magicsock.UDPRelayAllocReq](ec)
respPub := eventbus.Publish[magicsock.UDPRelayAllocResp](ec)
debugSessionsCh := e.debugSessionsCh
return func(ec *eventbus.Client) {
var rs relayServer // lazily initialized
defer func() {
if rs != nil {
@ -194,11 +190,9 @@ func (e *extension) consumeEventbusTopics(port int) {
}()
for {
select {
case <-e.disconnectFromBusCh:
case <-ec.Done():
return
case <-eventClient.Done():
return
case respCh := <-e.debugSessionsCh:
case respCh := <-debugSessionsCh:
if rs == nil {
// Don't initialize the server simply for a debug request.
respCh <- nil
@ -239,13 +233,12 @@ func (e *extension) consumeEventbusTopics(port int) {
}
}
}
}
func (e *extension) disconnectFromBusLocked() {
if e.busDoneCh != nil {
close(e.disconnectFromBusCh)
<-e.busDoneCh
e.busDoneCh = nil
e.disconnectFromBusCh = nil
if e.eventSubs != nil {
e.eventSubs.Close()
e.eventSubs = nil
e.debugSessionsCh = nil
}
}
@ -270,7 +263,7 @@ func (e *extension) serverStatus() status.ServerStatus {
UDPPort: nil,
Sessions: nil,
}
if e.port == nil || e.busDoneCh == nil {
if e.port == nil || e.eventSubs == nil {
return st
}
st.UDPPort = ptr.To(*e.port)
@ -281,7 +274,7 @@ func (e *extension) serverStatus() status.ServerStatus {
resp := <-ch
st.Sessions = resp
return st
case <-e.busDoneCh:
case <-e.eventSubs.Done():
return st
}
}

12
feature/relayserver/relayserver_test.go
View File

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