Merge branch '11629-groups-contents-memory'

[arvados.git] / services / ws / event_source.go

diff --git a/services/ws/event_source.go b/services/ws/event_source.go
index 4de1d559eff3dffdcab647f70f05d4b8a11a4507..7c1b58492dd030ef6b579abe8b699d787a758cc2 100644 (file)
--- a/services/ws/event_source.go
+++ b/services/ws/event_source.go
@@ -29,8 +29,9 @@ func (c pgConfig) ConnectionString() string {
 }
 
 type pgEventSource struct {
-       DataSource string
-       QueueSize  int
+       DataSource   string
+       MaxOpenConns int
+       QueueSize    int
 
        db         *sql.DB
        pqListener *pq.Listener
@@ -43,6 +44,9 @@ type pgEventSource struct {
        eventsOut  uint64
 
        cancel func()
+
+       setupOnce sync.Once
+       ready     chan bool
 }
 
 var _ debugStatuser = (*pgEventSource)(nil)
@@ -63,15 +67,40 @@ func (ps *pgEventSource) listenerProblem(et pq.ListenerEventType, err error) {
        ps.cancel()
 }
 
+func (ps *pgEventSource) setup() {
+       ps.ready = make(chan bool)
+}
+
+// Close stops listening for new events and disconnects all clients.
+func (ps *pgEventSource) Close() {
+       ps.WaitReady()
+       ps.cancel()
+}
+
+// WaitReady returns when the event listener is connected.
+func (ps *pgEventSource) WaitReady() {
+       ps.setupOnce.Do(ps.setup)
+       <-ps.ready
+}
+
+// Run listens for event notifications on the "logs" channel and sends
+// them to all subscribers.
 func (ps *pgEventSource) Run() {
        logger(nil).Debug("pgEventSource Run starting")
        defer logger(nil).Debug("pgEventSource Run finished")
 
+       ps.setupOnce.Do(ps.setup)
+       ready := ps.ready
+       defer func() {
+               if ready != nil {
+                       close(ready)
+               }
+       }()
+
        ctx, cancel := context.WithCancel(context.Background())
        ps.cancel = cancel
        defer cancel()
 
-       ps.sinks = make(map[*pgEventSink]bool)
        defer func() {
                // Disconnect all clients
                ps.mtx.Lock()
@@ -84,11 +113,15 @@ func (ps *pgEventSource) Run() {
 
        db, err := sql.Open("postgres", ps.DataSource)
        if err != nil {
-               logger(nil).WithError(err).Fatal("sql.Open failed")
+               logger(nil).WithError(err).Error("sql.Open failed")
                return
        }
+       if ps.MaxOpenConns <= 0 {
+               logger(nil).Warn("no database connection limit configured -- consider setting PostgresPool>0 in arvados-ws configuration file")
+       }
+       db.SetMaxOpenConns(ps.MaxOpenConns)
        if err = db.Ping(); err != nil {
-               logger(nil).WithError(err).Fatal("db.Ping failed")
+               logger(nil).WithError(err).Error("db.Ping failed")
                return
        }
        ps.db = db
@@ -96,11 +129,16 @@ func (ps *pgEventSource) Run() {
        ps.pqListener = pq.NewListener(ps.DataSource, time.Second, time.Minute, ps.listenerProblem)
        err = ps.pqListener.Listen("logs")
        if err != nil {
-               logger(nil).WithError(err).Fatal("pq Listen failed")
+               logger(nil).WithError(err).Error("pq Listen failed")
+               return
        }
        defer ps.pqListener.Close()
        logger(nil).Debug("pq Listen setup done")
 
+       close(ready)
+       // Avoid double-close in deferred func
+       ready = nil
+
        ps.queue = make(chan *event, ps.QueueSize)
        defer close(ps.queue)
 
@@ -192,6 +230,9 @@ func (ps *pgEventSource) NewSink() eventSink {
                source:  ps,
        }
        ps.mtx.Lock()
+       if ps.sinks == nil {
+               ps.sinks = make(map[*pgEventSink]bool)
+       }
        ps.sinks[sink] = true
        ps.mtx.Unlock()
        return sink