[MM-63314] Fix ClaimJob in HA environments (#30383)

* ClaimJob now returns newly claimed job

* internal code affected by change

* test changes required

* two branches: for mysql, use transaction; for postgres, use returning

* two branches: for mysql, use transaction; for postgres, use returning

* use same millis value for LastActivityAt and StartAt

* blank commit

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/platform/services/searchengine/bleveengine/indexer/indexing_job.go

@@ -150,12 +150,12 @@ func (worker *BleveIndexerWorker) DoJob(job *model.Job) {
 	logger := worker.logger.With(jobs.JobLoggerFields(job)...)
 	logger.Debug("Worker: Received a new candidate job.")
 
-	claimed, err := worker.jobServer.ClaimJob(job)
-	if err != nil {
-		logger.Warn("Worker: Error occurred while trying to claim job", mlog.Err(err))
+	var appErr *model.AppError
+	job, appErr = worker.jobServer.ClaimJob(job)
+	if appErr != nil {
+		logger.Warn("Worker: Error occurred while trying to claim job", mlog.Err(appErr))
 		return
-	}
-	if !claimed {
+	} else if job == nil {
 		return
 	}
 

server/platform/services/searchengine/bleveengine/indexer/indexing_job_test.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"testing"
 
+	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
 
 	"github.com/mattermost/mattermost/server/public/model"
@@ -29,9 +30,13 @@ func TestBleveIndexer(t *testing.T) {
 			Status:   model.JobStatusPending,
 			Type:     model.JobTypeBlevePostIndexing,
 		}
+		retJob := *job
+		retJob.Status = model.JobStatusInProgress
 
-		mockStore.JobStore.On("UpdateStatusOptimistically", job.Id, model.JobStatusPending, model.JobStatusInProgress).Return(true, nil)
-		mockStore.JobStore.On("UpdateOptimistically", job, model.JobStatusInProgress).Return(true, nil)
+		mockStore.JobStore.
+			On("UpdateStatusOptimistically", job.Id, model.JobStatusPending, model.JobStatusInProgress).
+			Return(&retJob, nil)
+		mockStore.JobStore.On("UpdateOptimistically", mock.AnythingOfType("*model.Job"), model.JobStatusInProgress).Return(true, nil)
 		mockStore.PostStore.On("GetOldestEntityCreationTime").Return(int64(1), errors.New("")) // intentionally return error to return from function
 
 		tempDir, err := os.MkdirTemp("", "setupConfigFile")