metacache: Check only one disk for updates (#10809)

Check only one disk for updates.

This will reduce IO while waiting for lists to finish.

cmd/metacache-manager.go

@@ -182,19 +182,14 @@ func (o listPathOptions) checkMetacacheState(ctx context.Context, rpc *peerRESTC
 	if cache.status == scanStateNone || cache.fileNotFound {
 		return errFileNotFound
 	}
-	if cache.status == scanStateSuccess {
+	if cache.status == scanStateSuccess || cache.status == scanStateStarted {
 		if time.Since(cache.lastUpdate) > metacacheMaxRunningAge {
-			return fmt.Errorf("timeout: list %s finished and no update for 1 minute", cache.id)
+			return fmt.Errorf("timeout: list %s not updated for 1 minute", cache.id)
 		}
 		return nil
 	}
 	if cache.error != "" {
 		return fmt.Errorf("async cache listing failed with: %s", cache.error)
 	}
-	if cache.status == scanStateStarted {
-		if time.Since(cache.lastUpdate) > metacacheMaxRunningAge {
-			return fmt.Errorf("cache id %s listing not updating. Last update %s seconds ago", cache.id, time.Since(cache.lastUpdate).Round(time.Second))
-		}
-	}
 	return nil
 }

cmd/metacache-set.go

@@ -351,23 +351,42 @@ func (er *erasureObjects) streamMetadataParts(ctx context.Context, o listPathOpt
 		default:
 		}
 
+		// If many failures, check the cache state.
+		if retries > 10 {
+			err := o.checkMetacacheState(ctx, rpc)
+			if debugPrint {
+				logger.Info("waiting for first part (%s), err: %v", o.objectPath(0), err)
+			}
+			if err != nil {
+				return entries, err
+			}
+			retries = 1
+		}
+
 		const retryDelay = 500 * time.Millisecond
 		// Load first part metadata...
 		// All operations are performed without locks, so we must be careful and allow for failures.
+		// Read metadata associated with the object from a disk.
+		if retries > 0 {
+			disks := er.getOnlineDisks()
+			if len(disks) == 0 {
+				time.Sleep(retryDelay)
+				retries++
+				continue
+			}
+
+			_, err := disks[0].ReadVersion(ctx, minioMetaBucket, o.objectPath(0), "", false)
+			if err != nil {
+				time.Sleep(retryDelay)
+				retries++
+				continue
+			}
+		}
+
+		// Read metadata associated with the object from all disks.
 		fi, metaArr, onlineDisks, err := er.getObjectFileInfo(ctx, minioMetaBucket, o.objectPath(0), ObjectOptions{})
 		if err != nil {
 			if err == errFileNotFound || errors.Is(err, errErasureReadQuorum) || errors.Is(err, InsufficientReadQuorum{}) {
-				// Not ready yet...
-				if retries == 10 {
-					err := o.checkMetacacheState(ctx, rpc)
-					if debugPrint {
-						logger.Info("waiting for first part (%s), err: %v", o.objectPath(0), err)
-					}
-					if err != nil {
-						return entries, err
-					}
-					retries = -1
-				}
 				retries++
 				time.Sleep(retryDelay)
 				continue
@@ -414,28 +433,41 @@ func (er *erasureObjects) streamMetadataParts(ctx context.Context, o listPathOpt
 			}
 
 			if partN != loadedPart {
+				if retries > 10 {
+					err := o.checkMetacacheState(ctx, rpc)
+					if debugPrint {
+						logger.Info("waiting for part data (%v), err: %v", o.objectPath(partN), err)
+					}
+					if err != nil {
+						return entries, err
+					}
+					retries = 1
+				}
+
+				if retries > 0 {
+					// Load from one disk only
+					disks := er.getOnlineDisks()
+					if len(disks) == 0 {
+						time.Sleep(retryDelay)
+						retries++
+						continue
+					}
+
+					_, err := disks[0].ReadVersion(ctx, minioMetaBucket, o.objectPath(partN), "", false)
+					if err != nil {
+						time.Sleep(retryDelay)
+						retries++
+						continue
+					}
+				}
 				// Load first part metadata...
 				fi, metaArr, onlineDisks, err = er.getObjectFileInfo(ctx, minioMetaBucket, o.objectPath(partN), ObjectOptions{})
 				switch err {
 				case errFileNotFound, errErasureReadQuorum, InsufficientReadQuorum{}:
-					if retries >= 10 {
-						err := o.checkMetacacheState(ctx, rpc)
-						if debugPrint {
-							logger.Info("waiting for part data (%v), err: %v", o.objectPath(partN), err)
-						}
-						if err != nil {
-							return entries, err
-						}
-						retries = -1
-					}
 					time.Sleep(retryDelay)
+					retries++
 					continue
 				default:
-					if retries >= 20 {
-						// We had at least 10 retries without getting a result.
-						logger.LogIf(ctx, err)
-						return entries, err
-					}
 					time.Sleep(retryDelay)
 					retries++
 					continue
@@ -457,13 +489,8 @@ func (er *erasureObjects) streamMetadataParts(ctx context.Context, o listPathOpt
 			err := er.getObjectWithFileInfo(ctx, minioMetaBucket, o.objectPath(partN), 0, fi.Size, &buf, fi, metaArr, onlineDisks)
 			switch err {
 			case errFileNotFound, errErasureReadQuorum, InsufficientReadQuorum{}:
-				if retries >= 20 {
-					// We had at least 10 retries without getting a result.
-					logger.LogIf(ctx, err)
-					return entries, err
-				}
-				retries++
 				time.Sleep(retryDelay)
+				retries++
 				continue
 			default:
 				logger.LogIf(ctx, err)
@@ -495,6 +522,7 @@ func (er *erasureObjects) streamMetadataParts(ctx context.Context, o listPathOpt
 					return entries, io.EOF
 				}
 				partN++
+				retries = 0
 			case nil:
 				// We stopped within the listing, we are done for now...
 				return entries, nil