11917: Do not clear rails cache at boot time.

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

diff --git a/services/ws/event_source.go b/services/ws/event_source.go
index 622084c61227d5c0caad1986611c58ceccacba62..a4e886872c49829a27a1223d6cdfd691a2e5efff 100644 (file)
--- a/services/ws/event_source.go
+++ b/services/ws/event_source.go
@@ -1,3 +1,7 @@
+// Copyright (C) The Arvados Authors. All rights reserved.
+//
+// SPDX-License-Identifier: AGPL-3.0
+
 package main
 
 import (
@@ -29,8 +33,9 @@ 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 +48,9 @@ type pgEventSource struct {
        eventsOut  uint64
 
        cancel func()
+
+       setupOnce sync.Once
+       ready     chan bool
 }
 
 var _ debugStatuser = (*pgEventSource)(nil)
@@ -63,12 +71,36 @@ 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()
@@ -85,11 +117,15 @@ 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
@@ -97,11 +133,16 @@ 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)
 
@@ -205,6 +246,12 @@ func (ps *pgEventSource) DB() *sql.DB {
        return ps.db
 }
 
+func (ps *pgEventSource) DBHealth() error {
+       ctx, _ := context.WithDeadline(context.Background(), time.Now().Add(time.Second))
+       var i int
+       return ps.db.QueryRowContext(ctx, "SELECT 1").Scan(&i)
+}
+
 func (ps *pgEventSource) DebugStatus() interface{} {
        ps.mtx.Lock()
        defer ps.mtx.Unlock()
@@ -220,6 +267,7 @@ func (ps *pgEventSource) DebugStatus() interface{} {
                "QueueDelay":   stats.Duration(ps.lastQDelay),
                "Sinks":        len(ps.sinks),
                "SinksBlocked": blocked,
+               "DBStats":      ps.db.Stats(),
        }
 }