fix: change timedValue to return the previously cached value (#15169)

fix: change timedvalue to return previous cached value

caller can interpret the underlying error and decide
accordingly, places where we do not interpret the
errors upon timedValue.Get() - we should simply use
the previously cached value instead of returning "empty".

Bonus: remove some unused code

cmd/erasure-sets.go

@@ -92,8 +92,6 @@ type erasureSets struct {
 	distributionAlgo string
 	deploymentID     [16]byte
 
-	disksStorageInfoCache timedValue
-
 	lastConnectDisksOpTime time.Time
 }
 
@@ -629,47 +627,6 @@ func (s *erasureSets) ParityCount() int {
 	return s.defaultParityCount
 }
 
-// StorageUsageInfo - combines output of StorageInfo across all erasure coded object sets.
-// This only returns disk usage info for ServerPools to perform placement decision, this call
-// is not implemented in Object interface and is not meant to be used by other object
-// layer implementations.
-func (s *erasureSets) StorageUsageInfo(ctx context.Context) StorageInfo {
-	storageUsageInfo := func() StorageInfo {
-		var storageInfo StorageInfo
-		storageInfos := make([]StorageInfo, len(s.sets))
-		storageInfo.Backend.Type = madmin.Erasure
-
-		g := errgroup.WithNErrs(len(s.sets))
-		for index := range s.sets {
-			index := index
-			g.Go(func() error {
-				// ignoring errors on purpose
-				storageInfos[index], _ = s.sets[index].StorageInfo(ctx)
-				return nil
-			}, index)
-		}
-
-		// Wait for the go routines.
-		g.Wait()
-
-		for _, lstorageInfo := range storageInfos {
-			storageInfo.Disks = append(storageInfo.Disks, lstorageInfo.Disks...)
-		}
-
-		return storageInfo
-	}
-
-	s.disksStorageInfoCache.Once.Do(func() {
-		s.disksStorageInfoCache.TTL = time.Second
-		s.disksStorageInfoCache.Update = func() (interface{}, error) {
-			return storageUsageInfo(), nil
-		}
-	})
-
-	v, _ := s.disksStorageInfoCache.Get()
-	return v.(StorageInfo)
-}
-
 // StorageInfo - combines output of StorageInfo across all erasure coded object sets.
 func (s *erasureSets) StorageInfo(ctx context.Context) (StorageInfo, []error) {
 	var storageInfo madmin.StorageInfo

cmd/metrics-v2.go

@@ -264,18 +264,7 @@ func (m *Metric) copyMetric() Metric {
 // once the TTL expires "read()" registered function is called
 // to return the new values and updated.
 func (g *MetricsGroup) Get() (metrics []Metric) {
-	var c interface{}
+	c, _ := g.metricsCache.Get()
-	var err error
-	if g.cacheInterval <= 0 {
-		c, err = g.metricsCache.Update()
-	} else {
-		c, err = g.metricsCache.Get()
-	}
-
-	if err != nil {
-		return []Metric{}
-	}
-
 	m, ok := c.([]Metric)
 	if !ok {
 		return []Metric{}

cmd/storage-rest-client.go

@@ -127,7 +127,6 @@ type storageRESTClient struct {
 	poolIndex, setIndex, diskIndex int
 
 	diskInfoCache timedValue
-	diskHealCache timedValue
 }
 
 // Retrieve location indexes.
@@ -187,25 +186,9 @@ func (client *storageRESTClient) Endpoint() Endpoint {
 }
 
 func (client *storageRESTClient) Healing() *healingTracker {
-	client.diskHealCache.Once.Do(func() {
+	// This call is not implemented for remote client on purpose.
-		// Update at least every second.
+	// healing tracker is always for local disks.
-		client.diskHealCache.TTL = time.Second
+	return nil
-		client.diskHealCache.Update = func() (interface{}, error) {
-			ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-			defer cancel()
-			b, err := client.ReadAll(ctx, minioMetaBucket,
-				pathJoin(bucketMetaPrefix, healingTrackerFilename))
-			if err != nil {
-				// If error, likely not healing.
-				return (*healingTracker)(nil), nil
-			}
-			var h healingTracker
-			_, err = h.UnmarshalMsg(b)
-			return &h, err
-		}
-	})
-	val, _ := client.diskHealCache.Get()
-	return val.(*healingTracker)
 }
 
 func (client *storageRESTClient) NSScanner(ctx context.Context, cache dataUsageCache, updates chan<- dataUsageEntry, scanMode madmin.HealScanMode) (dataUsageCache, error) {
@@ -269,24 +252,6 @@ func (client *storageRESTClient) SetDiskID(id string) {
 	client.diskID = id
 }
 
-func (client *storageRESTClient) diskInfo() (interface{}, error) {
-	var info DiskInfo
-	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-	defer cancel()
-	respBody, err := client.call(ctx, storageRESTMethodDiskInfo, nil, nil, -1)
-	if err != nil {
-		return info, err
-	}
-	defer xhttp.DrainBody(respBody)
-	if err = msgp.Decode(respBody, &info); err != nil {
-		return info, err
-	}
-	if info.Error != "" {
-		return info, toStorageErr(errors.New(info.Error))
-	}
-	return info, nil
-}
-
 // DiskInfo - fetch disk information for a remote disk.
 func (client *storageRESTClient) DiskInfo(ctx context.Context) (info DiskInfo, err error) {
 	if !client.IsOnline() {
@@ -299,7 +264,23 @@ func (client *storageRESTClient) DiskInfo(ctx context.Context) (info DiskInfo, e
 	}
 	client.diskInfoCache.Once.Do(func() {
 		client.diskInfoCache.TTL = time.Second
-		client.diskInfoCache.Update = client.diskInfo
+		client.diskInfoCache.Update = func() (interface{}, error) {
+			var info DiskInfo
+			ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
+			defer cancel()
+			respBody, err := client.call(ctx, storageRESTMethodDiskInfo, nil, nil, -1)
+			if err != nil {
+				return info, err
+			}
+			defer xhttp.DrainBody(respBody)
+			if err = msgp.Decode(respBody, &info); err != nil {
+				return info, err
+			}
+			if info.Error != "" {
+				return info, toStorageErr(errors.New(info.Error))
+			}
+			return info, nil
+		}
 	})
 	val, err := client.diskInfoCache.Get()
 	if val != nil {

cmd/utils.go

@@ -950,13 +950,20 @@ type timedValue struct {
 // Get will return a cached value or fetch a new one.
 // If the Update function returns an error the value is forwarded as is and not cached.
 func (t *timedValue) Get() (interface{}, error) {
-	v := t.get()
+	v := t.get(t.ttl())
 	if v != nil {
 		return v, nil
 	}
 
 	v, err := t.Update()
 	if err != nil {
+		// if update fails, return current
+		// cached value along with error.
+		//
+		// Let the caller decide if they want
+		// to use the returned value based
+		// on error.
+		v = t.get(0)
 		return v, err
 	}
 
@@ -964,14 +971,21 @@ func (t *timedValue) Get() (interface{}, error) {
 	return v, nil
 }
 
-func (t *timedValue) get() (v interface{}) {
+func (t *timedValue) ttl() time.Duration {
 	ttl := t.TTL
 	if ttl <= 0 {
 		ttl = time.Second
 	}
+	return ttl
+}
+
+func (t *timedValue) get(ttl time.Duration) (v interface{}) {
 	t.mu.RLock()
 	defer t.mu.RUnlock()
 	v = t.value
+	if ttl <= 0 {
+		return v
+	}
 	if time.Since(t.lastUpdate) < ttl {
 		return v
 	}

cmd/xl-storage.go

@@ -575,22 +575,19 @@ func (s *xlStorage) DiskInfo(context.Context) (info DiskInfo, err error) {
 			dcinfo.FreeInodes = di.Ffree
 			dcinfo.FSType = di.FSType
 			diskID, err := s.GetDiskID()
-			if errors.Is(err, errUnformattedDisk) {
+			// Healing is 'true' when
-				// if we found an unformatted disk then
+			// - if we found an unformatted disk (no 'format.json')
-				// healing is automatically true.
+			// - if we found healing tracker 'healing.bin'
-				dcinfo.Healing = true
+			dcinfo.Healing = errors.Is(err, errUnformattedDisk) || (s.Healing() != nil)
-			} else {
-				// Check if the disk is being healed if GetDiskID
-				// returned any error other than fresh disk
-				dcinfo.Healing = s.Healing() != nil
-			}
 			dcinfo.ID = diskID
 			return dcinfo, err
 		}
 	})
 
 	v, err := s.diskInfoCache.Get()
-	info = v.(DiskInfo)
+	if v != nil {
+		info = v.(DiskInfo)
+	}
 	return info, err
 }