[bugfix] Lock when checking/creating notifs to avoid race (#2890)

* [bugfix] Lock when checking/creating notifs to avoid race

* test notif spam

internal/processing/workers/surfacenotify_test.go

@@ -0,0 +1,115 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package workers_test
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/gotosocial/internal/filter/visibility"
+	"github.com/superseriousbusiness/gotosocial/internal/gtscontext"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/processing/workers"
+)
+
+type SurfaceNotifyTestSuite struct {
+	WorkersTestSuite
+}
+
+func (suite *SurfaceNotifyTestSuite) TestSpamNotifs() {
+	testStructs := suite.SetupTestStructs()
+	defer suite.TearDownTestStructs(testStructs)
+
+	surface := &workers.Surface{
+		State:       testStructs.State,
+		Converter:   testStructs.TypeConverter,
+		Stream:      testStructs.Processor.Stream(),
+		Filter:      visibility.NewFilter(testStructs.State),
+		EmailSender: testStructs.EmailSender,
+	}
+
+	var (
+		ctx              = context.Background()
+		notificationType = gtsmodel.NotificationFollow
+		targetAccount    = suite.testAccounts["local_account_1"]
+		originAccount    = suite.testAccounts["local_account_2"]
+	)
+
+	// Set up a bunch of goroutines to surface
+	// a notification at exactly the same time.
+	wg := sync.WaitGroup{}
+	wg.Add(20)
+	startAt := time.Now().Add(2 * time.Second)
+
+	for i := 0; i < 20; i++ {
+		go func() {
+			defer wg.Done()
+
+			// Wait for it....
+			untilTick := time.Until(startAt)
+			<-time.Tick(untilTick)
+
+			// ...Go!
+			if err := surface.Notify(ctx,
+				notificationType,
+				targetAccount,
+				originAccount,
+				"",
+			); err != nil {
+				suite.FailNow(err.Error())
+			}
+		}()
+	}
+
+	// Wait for all notif creation
+	// attempts to complete.
+	wg.Wait()
+
+	// Get all notifs for this account.
+	notifs, err := testStructs.State.DB.GetAccountNotifications(
+		gtscontext.SetBarebones(ctx),
+		targetAccount.ID,
+		"", "", "", 0, nil,
+	)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	var gotOne bool
+	for _, notif := range notifs {
+		if notif.NotificationType == notificationType &&
+			notif.TargetAccountID == targetAccount.ID &&
+			notif.OriginAccountID == originAccount.ID {
+			// This is the notif...
+			if gotOne {
+				// We already had
+				// the notif, d'oh!
+				suite.FailNow("already had notif")
+			} else {
+				gotOne = true
+			}
+		}
+	}
+}
+
+func TestSurfaceNotifyTestSuite(t *testing.T) {
+	suite.Run(t, new(SurfaceNotifyTestSuite))
+}