cmd/mount: add max-downloads option to limit concurrent get for object storage

cmd/flags.go

@@ -128,6 +128,11 @@ func storageFlags() []cli.Flag {
 			Value: 20,
 			Usage: "number of connections to upload",
 		},
+		&cli.IntFlag{
+			Name:  "max-downloads",
+			Value: 200,
+			Usage: "number of connections to download",
+		},
 		&cli.IntFlag{
 			Name:  "max-stage-write",
 			Value: 1000, // large enough for normal cases, also prevents unlimited concurrency in abnormal cases

cmd/mount.go

@@ -367,6 +367,7 @@ func getChunkConf(c *cli.Context, format *meta.Format) *chunk.Config {
 		GetTimeout:             utils.Duration(c.String("get-timeout")),
 		PutTimeout:             utils.Duration(c.String("put-timeout")),
 		MaxUpload:              c.Int("max-uploads"),
+		MaxDownload:            c.Int("max-downloads"),
 		MaxStageWrite:          c.Int("max-stage-write"),
 		MaxRetries:             c.Int("io-retries"),
 		Writeback:              c.Bool("writeback"),

pkg/chunk/cached_store.go

@@ -152,46 +152,9 @@ func (s *rSlice) ReadAt(ctx context.Context, page *Page, off int) (n int, err er
 
 	if s.store.seekable &&
 		(!s.store.conf.CacheEnabled() || (boff > 0 && len(p) <= blockSize/4)) {
-		if s.store.downLimit != nil {
-			s.store.downLimit.Wait(int64(len(p)))
-		}
-		fullPage, err := s.store.group.TryPiggyback(key)
-		if fullPage != nil {
-			defer fullPage.Release()
-			if err == nil { // piggybacked a full read
-				n = copy(p, fullPage.Data[boff:])
-				return n, nil
-			}
-		}
-		// partial read
-		st := time.Now()
-		var (
-			reqID string
-			sc    = object.DefaultStorageClass
-		)
-		page.Acquire()
-		err = utils.WithTimeout(ctx, func(cCtx context.Context) error {
-			defer page.Release()
-			in, err := s.store.storage.Get(cCtx, key, int64(boff), int64(len(p)), object.WithRequestID(&reqID), object.WithStorageClass(&sc))
-			if err == nil {
-				n, err = io.ReadFull(in, p)
-				_ = in.Close()
-			}
-			return err
-		}, s.store.conf.GetTimeout)
-		used := time.Since(st)
-		logRequest("GET", key, fmt.Sprintf("RANGE(%d,%d) ", boff, len(p)), reqID, err, used)
-		if errors.Is(err, context.Canceled) {
-			return 0, err
-		}
-		s.store.objectDataBytes.WithLabelValues("GET", sc).Add(float64(n))
-		s.store.objectReqsHistogram.WithLabelValues("GET", sc).Observe(used.Seconds())
-		if err == nil {
-			s.store.fetcher.fetch(key)
-			return n, nil
-		} else {
-			s.store.objectReqErrors.Add(1)
-			// fall back to full read
+		n, err = s.store.loadRange(ctx, key, page, boff)
+		if err == nil || !errors.Is(err, errTryFullRead) {
+			return n, err
 		}
 	}
 
@@ -476,7 +439,7 @@ func (s *wSlice) upload(indx int) {
 				s.errors <- nil
 				if s.store.conf.UploadDelay == 0 && s.store.canUpload() {
 					select {
-					case s.store.currentUpload <- true:
+					case s.store.currentUpload <- struct{}{}:
 						defer func() { <-s.store.currentUpload }()
 						if err = s.store.upload(key, block, nil); err == nil {
 							s.store.bcache.uploaded(key, blen)
@@ -495,7 +458,7 @@ func (s *wSlice) upload(indx int) {
 				return
 			}
 		}
-		s.store.currentUpload <- true
+		s.store.currentUpload <- struct{}{}
 		defer func() { <-s.store.currentUpload }()
 		s.errors <- s.store.upload(key, block, s)
 	}()
@@ -572,6 +535,7 @@ type Config struct {
 	AutoCreate             bool
 	Compress               string
 	MaxUpload              int
+	MaxDownload            int
 	MaxStageWrite          int
 	MaxRetries             int
 	UploadLimit            int64 // bytes per second
@@ -604,6 +568,16 @@ func (c *Config) SelfCheck(uuid string) {
 		logger.Warnf("max-uploads should be greater than 0, set it to 1")
 		c.MaxUpload = 1
 	}
+	if c.UploadLimit > 0 && int64(c.MaxUpload*c.BlockSize) > c.UploadLimit*int64(c.GetTimeout/time.Second)/2 {
+		logger.Warnf("max-upload %d may exceed bandwidth limit (bw: %d Mbps)", c.MaxUpload, c.UploadDelay*8>>20)
+	}
+	if c.MaxDownload <= 0 {
+		logger.Warnf("max-downloads should be greater than 0, set it to 200")
+		c.MaxDownload = 200
+	}
+	if c.DownloadLimit > 0 && int64(c.MaxDownload*c.BlockSize) > c.DownloadLimit*int64(c.GetTimeout/time.Second)/2 {
+		logger.Warnf("max-download %d may exceed bandwidth limit (bw: %d Mbps)", c.MaxDownload, (c.DownloadLimit*8)>>20)
+	}
 	if c.BufferSize <= 32<<20 {
 		logger.Warnf("buffer-size is too small, setting it to 32 MiB")
 		c.BufferSize = 32 << 20
@@ -686,21 +660,22 @@ func (c *Config) CacheEnabled() bool {
 }
 
 type cachedStore struct {
-	storage       object.ObjectStorage
-	bcache        CacheManager
-	fetcher       *prefetcher
-	conf          Config
-	group         *Controller
-	currentUpload chan bool
-	pendingCh     chan *pendingItem
-	pendingKeys   map[string]*pendingItem
-	pendingMutex  sync.Mutex
-	startHour     int
-	endHour       int
-	compressor    compress.Compressor
-	seekable      bool
-	upLimit       *ratelimit.Bucket
-	downLimit     *ratelimit.Bucket
+	storage         object.ObjectStorage
+	bcache          CacheManager
+	fetcher         *prefetcher
+	conf            Config
+	group           *Controller
+	currentUpload   chan struct{}
+	currentDownload chan struct{}
+	pendingCh       chan *pendingItem
+	pendingKeys     map[string]*pendingItem
+	pendingMutex    sync.Mutex
+	startHour       int
+	endHour         int
+	compressor      compress.Compressor
+	seekable        bool
+	upLimit         *ratelimit.Bucket
+	downLimit       *ratelimit.Bucket
 
 	cacheHits           prometheus.Counter
 	cacheMiss           prometheus.Counter
@@ -722,13 +697,66 @@ func logRequest(typeStr, key, param, reqID string, err error, used time.Duration
 	}
 }
 
+var errTryFullRead = errors.New("try full read")
+
+func (store *cachedStore) loadRange(ctx context.Context, key string, page *Page, off int) (n int, err error) {
+	p := page.Data
+	fullPage, err := store.group.TryPiggyback(key)
+	if fullPage != nil {
+		defer fullPage.Release()
+		if err == nil { // piggybacked a full read
+			n = copy(p, fullPage.Data[off:])
+			return n, nil
+		}
+	}
+
+	store.currentDownload <- struct{}{}
+	defer func() { <-store.currentDownload }()
+	if store.downLimit != nil {
+		store.downLimit.Wait(int64(len(p)))
+	}
+
+	start := time.Now()
+	var (
+		reqID string
+		sc    = object.DefaultStorageClass
+	)
+	page.Acquire()
+	err = utils.WithTimeout(ctx, func(cCtx context.Context) error {
+		defer page.Release()
+		in, err := store.storage.Get(cCtx, key, int64(off), int64(len(p)), object.WithRequestID(&reqID), object.WithStorageClass(&sc))
+		if err == nil {
+			n, err = io.ReadFull(in, p)
+			_ = in.Close()
+		}
+		return err
+	}, store.conf.GetTimeout)
+
+	used := time.Since(start)
+	logRequest("GET", key, fmt.Sprintf("RANGE(%d,%d) ", off, len(p)), reqID, err, used)
+	if errors.Is(err, context.Canceled) {
+		return 0, err
+	}
+	store.objectDataBytes.WithLabelValues("GET", sc).Add(float64(n))
+	store.objectReqsHistogram.WithLabelValues("GET", sc).Observe(used.Seconds())
+	if err == nil {
+		store.fetcher.fetch(key)
+		return n, nil
+	}
+	store.objectReqErrors.Add(1)
+	// fall back to full read
+	return 0, errTryFullRead
+}
+
 func (store *cachedStore) load(ctx context.Context, key string, page *Page, cache bool, forceCache bool) (err error) {
 	defer func() {
 		e := recover()
 		if e != nil {
 			err = fmt.Errorf("recovered from %s", e)
 		}
 	}()
+	store.currentDownload <- struct{}{}
+	defer func() { <-store.currentDownload }()
 	needed := store.compressor.CompressBound(len(page.Data))
 	compressed := needed > len(page.Data)
 	// we don't know the actual size for compressed block
@@ -806,14 +834,15 @@ func NewCachedStore(storage object.ObjectStorage, config Config, reg prometheus.
 		config.PutTimeout = time.Second * 60
 	}
 	store := &cachedStore{
-		storage:       storage,
-		conf:          config,
-		currentUpload: make(chan bool, config.MaxUpload),
-		compressor:    compressor,
-		seekable:      compressor.CompressBound(0) == 0,
-		pendingCh:     make(chan *pendingItem, 100*config.MaxUpload),
-		pendingKeys:   make(map[string]*pendingItem),
-		group:         NewController(),
+		storage:         storage,
+		conf:            config,
+		currentUpload:   make(chan struct{}, config.MaxUpload),
+		currentDownload: make(chan struct{}, config.MaxDownload),
+		compressor:      compressor,
+		seekable:        compressor.CompressBound(0) == 0,
+		pendingCh:       make(chan *pendingItem, 100*config.MaxUpload),
+		pendingKeys:     make(map[string]*pendingItem),
+		group:           NewController(),
 	}
 	if config.UploadLimit > 0 {
 		// there are overheads coming from HTTP/TCP/IP
@@ -993,7 +1022,7 @@ func parseObjOrigSize(key string) int {
 }
 
 func (store *cachedStore) uploadStagingFile(key string, stagingPath string) {
-	store.currentUpload <- true
+	store.currentUpload <- struct{}{}
 	defer func() {
 		<-store.currentUpload
 	}()