Hold the event source when there are no listeners (#15725)

* Hold the event source when there are no listeners

The event source does not need to run when there are no listeners. Therefore
pause it when there are none.

* add some more logging

Signed-off-by: Andrew Thornton <art27@cantab.net>
This commit is contained in:
zeripath 2021-05-15 22:46:13 +01:00 committed by GitHub
parent f582ec4e53
commit 8e32eeb5de
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2 changed files with 35 additions and 0 deletions

View file

@ -13,6 +13,7 @@ type Manager struct {
mutex sync.Mutex mutex sync.Mutex
messengers map[int64]*Messenger messengers map[int64]*Messenger
connection chan struct{}
} }
var manager *Manager var manager *Manager
@ -20,6 +21,7 @@ var manager *Manager
func init() { func init() {
manager = &Manager{ manager = &Manager{
messengers: make(map[int64]*Messenger), messengers: make(map[int64]*Messenger),
connection: make(chan struct{}, 1),
} }
} }
@ -36,6 +38,10 @@ func (m *Manager) Register(uid int64) <-chan *Event {
messenger = NewMessenger(uid) messenger = NewMessenger(uid)
m.messengers[uid] = messenger m.messengers[uid] = messenger
} }
select {
case m.connection <- struct{}{}:
default:
}
m.mutex.Unlock() m.mutex.Unlock()
return messenger.Register() return messenger.Register()
} }

View file

@ -34,6 +34,35 @@ loop:
timer.Stop() timer.Stop()
break loop break loop
case <-timer.C: case <-timer.C:
m.mutex.Lock()
connectionCount := len(m.messengers)
if connectionCount == 0 {
log.Trace("Event source has no listeners")
// empty the connection channel
select {
case <-m.connection:
default:
}
}
m.mutex.Unlock()
if connectionCount == 0 {
// No listeners so the source can be paused
log.Trace("Pausing the eventsource")
select {
case <-ctx.Done():
break loop
case <-m.connection:
log.Trace("Connection detected - restarting the eventsource")
// OK we're back so lets reset the timer and start again
// We won't change the "then" time because there could be concurrency issues
select {
case <-timer.C:
default:
}
continue
}
}
now := timeutil.TimeStampNow().Add(-2) now := timeutil.TimeStampNow().Add(-2)
uidCounts, err := models.GetUIDsAndNotificationCounts(then, now) uidCounts, err := models.GetUIDsAndNotificationCounts(then, now)