fix: GetNextRepository to use a list already scanned repositories as input (#3230)

Using just the last repository is not enough as in the case when it is deleted
(either by GC or some other way), GetNextRepository returns empty string
causing the generator to be marked completed without any errors.

An alternative would have been to start over from the first repository,
but this can take hours if multiple repositories need to be deleted,
not to mention the processing power and I/O and S3 load this could take.

Signed-off-by: Andrei Aaron <aaaron@luxoft.com>

pkg/storage/common/common.go

@@ -988,15 +988,28 @@ func (dt *dedupeTask) Name() string {
 	return "DedupeTask"
 }
 
+func NewStorageMetricsInitGenerator(imgStore storageTypes.ImageStore, metrics monitoring.MetricServer, log zlog.Logger,
+) *StorageMetricsInitGenerator {
+	processedRepos := make(map[string]struct{})
+
+	return &StorageMetricsInitGenerator{
+		ImgStore:       imgStore,
+		Metrics:        metrics,
+		Log:            log,
+		processedRepos: processedRepos,
+		MaxDelay:       15, //nolint:mnd
+	}
+}
+
 type StorageMetricsInitGenerator struct {
-	ImgStore storageTypes.ImageStore
-	done     bool
-	Metrics  monitoring.MetricServer
-	lastRepo string
-	nextRun  time.Time
-	rand     *rand.Rand
-	Log      zlog.Logger
-	MaxDelay int
+	ImgStore       storageTypes.ImageStore
+	done           bool
+	Metrics        monitoring.MetricServer
+	processedRepos map[string]struct{}
+	nextRun        time.Time
+	rand           *rand.Rand
+	Log            zlog.Logger
+	MaxDelay       int
 }
 
 func (gen *StorageMetricsInitGenerator) Name() string {
@@ -1004,7 +1017,7 @@ func (gen *StorageMetricsInitGenerator) Name() string {
 }
 
 func (gen *StorageMetricsInitGenerator) Next() (scheduler.Task, error) {
-	if gen.lastRepo == "" && gen.nextRun.IsZero() {
+	if len(gen.processedRepos) == 0 && gen.nextRun.IsZero() {
 		gen.rand = rand.New(rand.NewSource(time.Now().UTC().UnixNano())) //nolint: gosec
 	}
 
@@ -1012,7 +1025,7 @@ func (gen *StorageMetricsInitGenerator) Next() (scheduler.Task, error) {
 
 	gen.nextRun = time.Now().Add(time.Duration(delay) * time.Second)
 
-	repo, err := gen.ImgStore.GetNextRepository(gen.lastRepo)
+	repo, err := gen.ImgStore.GetNextRepository(gen.processedRepos)
 	if err != nil {
 		return nil, err
 	}
@@ -1025,7 +1038,7 @@ func (gen *StorageMetricsInitGenerator) Next() (scheduler.Task, error) {
 		return nil, nil //nolint:nilnil
 	}
 
-	gen.lastRepo = repo
+	gen.processedRepos[repo] = struct{}{}
 
 	return NewStorageMetricsTask(gen.ImgStore, gen.Metrics, repo, gen.Log), nil
 }
@@ -1039,7 +1052,7 @@ func (gen *StorageMetricsInitGenerator) IsReady() bool {
 }
 
 func (gen *StorageMetricsInitGenerator) Reset() {
-	gen.lastRepo = ""
+	gen.processedRepos = make(map[string]struct{})
 	gen.done = false
 	gen.nextRun = time.Time{}
 }