From 28b395bef4887b55392af08f88aa345ea67b3d23 Mon Sep 17 00:00:00 2001 From: chrislu Date: Sat, 26 Feb 2022 02:16:47 -0800 Subject: [PATCH] better control for reader caching --- weed/filer/filechunk_manifest.go | 30 ++-- weed/filer/reader_at.go | 130 ++------------- weed/filer/reader_at_test.go | 17 +- weed/filer/reader_cache.go | 187 ++++++++++++++++++++++ weed/filer/stream.go | 18 +-- weed/server/filer_server_handlers_read.go | 5 +- weed/util/chunk_cache/chunk_cache.go | 103 ------------ 7 files changed, 240 insertions(+), 250 deletions(-) create mode 100644 weed/filer/reader_cache.go diff --git a/weed/filer/filechunk_manifest.go b/weed/filer/filechunk_manifest.go index b6a64b30d..2c9dc5e74 100644 --- a/weed/filer/filechunk_manifest.go +++ b/weed/filer/filechunk_manifest.go @@ -3,6 +3,7 @@ package filer import ( "bytes" "fmt" + "github.com/chrislusf/seaweedfs/weed/util/mem" "github.com/chrislusf/seaweedfs/weed/wdclient" "io" "math" @@ -77,7 +78,9 @@ func ResolveOneChunkManifest(lookupFileIdFn wdclient.LookupFileIdFunctionType, c } // IsChunkManifest - data, err := fetchChunk(lookupFileIdFn, chunk.GetFileIdString(), chunk.CipherKey, chunk.IsCompressed) + data := mem.Allocate(int(chunk.Size)) + defer mem.Free(data) + _, err := fetchChunk(data, lookupFileIdFn, chunk.GetFileIdString(), chunk.CipherKey, chunk.IsCompressed) if err != nil { return nil, fmt.Errorf("fail to read manifest %s: %v", chunk.GetFileIdString(), err) } @@ -92,38 +95,37 @@ func ResolveOneChunkManifest(lookupFileIdFn wdclient.LookupFileIdFunctionType, c } // TODO fetch from cache for weed mount? -func fetchChunk(lookupFileIdFn wdclient.LookupFileIdFunctionType, fileId string, cipherKey []byte, isGzipped bool) ([]byte, error) { +func fetchChunk(data []byte, lookupFileIdFn wdclient.LookupFileIdFunctionType, fileId string, cipherKey []byte, isGzipped bool) (int, error) { urlStrings, err := lookupFileIdFn(fileId) if err != nil { glog.Errorf("operation LookupFileId %s failed, err: %v", fileId, err) - return nil, err + return 0, err } - return retriedFetchChunkData(urlStrings, cipherKey, isGzipped, true, 0, 0) + return retriedFetchChunkData(data, urlStrings, cipherKey, isGzipped, true, 0) } -func fetchChunkRange(lookupFileIdFn wdclient.LookupFileIdFunctionType, fileId string, cipherKey []byte, isGzipped bool, offset int64, size int) ([]byte, error) { +func fetchChunkRange(data []byte, lookupFileIdFn wdclient.LookupFileIdFunctionType, fileId string, cipherKey []byte, isGzipped bool, offset int64) (int, error) { urlStrings, err := lookupFileIdFn(fileId) if err != nil { glog.Errorf("operation LookupFileId %s failed, err: %v", fileId, err) - return nil, err + return 0, err } - return retriedFetchChunkData(urlStrings, cipherKey, isGzipped, false, offset, size) + return retriedFetchChunkData(data, urlStrings, cipherKey, isGzipped, false, offset) } -func retriedFetchChunkData(urlStrings []string, cipherKey []byte, isGzipped bool, isFullChunk bool, offset int64, size int) ([]byte, error) { +func retriedFetchChunkData(buffer []byte, urlStrings []string, cipherKey []byte, isGzipped bool, isFullChunk bool, offset int64) (n int, err error) { - var err error var shouldRetry bool - receivedData := make([]byte, 0, size) for waitTime := time.Second; waitTime < util.RetryWaitTime; waitTime += waitTime / 2 { for _, urlString := range urlStrings { - receivedData = receivedData[:0] + n = 0 if strings.Contains(urlString, "%") { urlString = url.PathEscape(urlString) } - shouldRetry, err = util.ReadUrlAsStream(urlString+"?readDeleted=true", cipherKey, isGzipped, isFullChunk, offset, size, func(data []byte) { - receivedData = append(receivedData, data...) + shouldRetry, err = util.ReadUrlAsStream(urlString+"?readDeleted=true", cipherKey, isGzipped, isFullChunk, offset, len(buffer), func(data []byte) { + x := copy(buffer[n:], data) + n += x }) if !shouldRetry { break @@ -142,7 +144,7 @@ func retriedFetchChunkData(urlStrings []string, cipherKey []byte, isGzipped bool } } - return receivedData, err + return n, err } diff --git a/weed/filer/reader_at.go b/weed/filer/reader_at.go index b1c15152f..c3d801515 100644 --- a/weed/filer/reader_at.go +++ b/weed/filer/reader_at.go @@ -12,21 +12,15 @@ import ( "github.com/chrislusf/seaweedfs/weed/util" "github.com/chrislusf/seaweedfs/weed/util/chunk_cache" "github.com/chrislusf/seaweedfs/weed/wdclient" - "github.com/golang/groupcache/singleflight" ) type ChunkReadAt struct { - masterClient *wdclient.MasterClient - chunkViews []*ChunkView - lookupFileId wdclient.LookupFileIdFunctionType - readerLock sync.Mutex - fileSize int64 - - fetchGroup singleflight.Group - chunkCache chunk_cache.ChunkCache - lastChunkFileId string - lastChunkData []byte - readerPattern *ReaderPattern + masterClient *wdclient.MasterClient + chunkViews []*ChunkView + readerLock sync.Mutex + fileSize int64 + readerCache *ReaderCache + readerPattern *ReaderPattern } var _ = io.ReaderAt(&ChunkReadAt{}) @@ -90,16 +84,14 @@ func NewChunkReaderAtFromClient(lookupFn wdclient.LookupFileIdFunctionType, chun return &ChunkReadAt{ chunkViews: chunkViews, - lookupFileId: lookupFn, - chunkCache: chunkCache, fileSize: fileSize, + readerCache: newReaderCache(5, chunkCache, lookupFn), readerPattern: NewReaderPattern(), } } func (c *ChunkReadAt) Close() error { - c.lastChunkData = nil - c.lastChunkFileId = "" + c.readerCache.destroy() return nil } @@ -142,16 +134,13 @@ func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) { continue } // glog.V(4).Infof("read [%d,%d), %d/%d chunk %s [%d,%d)", chunkStart, chunkStop, i, len(c.chunkViews), chunk.FileId, chunk.LogicOffset-chunk.Offset, chunk.LogicOffset-chunk.Offset+int64(chunk.Size)) - var buffer []byte bufferOffset := chunkStart - chunk.LogicOffset + chunk.Offset - bufferLength := chunkStop - chunkStart - buffer, err = c.readChunkSlice(chunk, nextChunk, uint64(bufferOffset), uint64(bufferLength)) + copied, err := c.readChunkSliceAt(p[startOffset-offset:chunkStop-chunkStart+startOffset-offset], chunk, nextChunk, uint64(bufferOffset)) if err != nil { glog.Errorf("fetching chunk %+v: %v\n", chunk, err) - return + return copied, err } - copied := copy(p[startOffset-offset:chunkStop-chunkStart+startOffset-offset], buffer) n += copied startOffset, remaining = startOffset+int64(copied), remaining-int64(copied) } @@ -173,104 +162,15 @@ func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) { } -func (c *ChunkReadAt) readChunkSlice(chunkView *ChunkView, nextChunkViews *ChunkView, offset, length uint64) ([]byte, error) { +func (c *ChunkReadAt) readChunkSliceAt(buffer []byte, chunkView *ChunkView, nextChunkViews *ChunkView, offset uint64) (n int, err error) { - var chunkSlice []byte - if chunkView.LogicOffset == 0 { - chunkSlice = c.chunkCache.GetChunkSlice(chunkView.FileId, offset, length) - } - if len(chunkSlice) > 0 { - return chunkSlice, nil - } - if c.lookupFileId == nil { - return nil, nil - } if c.readerPattern.IsRandomMode() { - return c.doFetchRangeChunkData(chunkView, offset, length) - } - chunkData, err := c.readFromWholeChunkData(chunkView, nextChunkViews) - if err != nil { - return nil, err + return c.readerCache.ReadChunkAt(buffer, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int64(offset), int(chunkView.ChunkSize), chunkView.LogicOffset == 0) } - wanted := min(int64(length), int64(len(chunkData))-int64(offset)) - return chunkData[offset : int64(offset)+wanted], nil -} -func (c *ChunkReadAt) readFromWholeChunkData(chunkView *ChunkView, nextChunkViews ...*ChunkView) (chunkData []byte, err error) { - - if c.lastChunkFileId == chunkView.FileId { - return c.lastChunkData, nil + n, err = c.readerCache.ReadChunkAt(buffer, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int64(offset), int(chunkView.ChunkSize), chunkView.LogicOffset == 0) + if nextChunkViews != nil { + c.readerCache.MaybeCache(nextChunkViews.FileId, nextChunkViews.CipherKey, nextChunkViews.IsGzipped, int(nextChunkViews.ChunkSize)) } - - v, doErr := c.readOneWholeChunk(chunkView) - - if doErr != nil { - return nil, doErr - } - - chunkData = v.([]byte) - - c.lastChunkData = chunkData - c.lastChunkFileId = chunkView.FileId - - for _, nextChunkView := range nextChunkViews { - if c.chunkCache != nil && nextChunkView != nil { - go c.readOneWholeChunk(nextChunkView) - } - } - return } - -func (c *ChunkReadAt) readOneWholeChunk(chunkView *ChunkView) (interface{}, error) { - - var err error - - return c.fetchGroup.Do(chunkView.FileId, func() (interface{}, error) { - - glog.V(4).Infof("readFromWholeChunkData %s offset %d [%d,%d) size at least %d", chunkView.FileId, chunkView.Offset, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size), chunkView.ChunkSize) - - var data []byte - if chunkView.LogicOffset == 0 { - data = c.chunkCache.GetChunk(chunkView.FileId, chunkView.ChunkSize) - } - if data != nil { - glog.V(4).Infof("cache hit %s [%d,%d)", chunkView.FileId, chunkView.LogicOffset-chunkView.Offset, chunkView.LogicOffset-chunkView.Offset+int64(len(data))) - } else { - var err error - data, err = c.doFetchFullChunkData(chunkView) - if err != nil { - return data, err - } - if chunkView.LogicOffset == 0 { - // only cache the first chunk - c.chunkCache.SetChunk(chunkView.FileId, data) - } - } - return data, err - }) -} - -func (c *ChunkReadAt) doFetchFullChunkData(chunkView *ChunkView) ([]byte, error) { - - glog.V(4).Infof("+ doFetchFullChunkData %s", chunkView.FileId) - - data, err := fetchChunk(c.lookupFileId, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped) - - glog.V(4).Infof("- doFetchFullChunkData %s", chunkView.FileId) - - return data, err - -} - -func (c *ChunkReadAt) doFetchRangeChunkData(chunkView *ChunkView, offset, length uint64) ([]byte, error) { - - glog.V(4).Infof("+ doFetchFullChunkData %s", chunkView.FileId) - - data, err := fetchChunkRange(c.lookupFileId, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int64(offset), int(length)) - - glog.V(4).Infof("- doFetchFullChunkData %s", chunkView.FileId) - - return data, err - -} diff --git a/weed/filer/reader_at_test.go b/weed/filer/reader_at_test.go index 411d7eb3b..2d7bf90e9 100644 --- a/weed/filer/reader_at_test.go +++ b/weed/filer/reader_at_test.go @@ -21,8 +21,12 @@ func (m *mockChunkCache) GetChunk(fileId string, minSize uint64) (data []byte) { return data } -func (m *mockChunkCache) GetChunkSlice(fileId string, offset, length uint64) []byte { - return m.GetChunk(fileId, length) +func (m *mockChunkCache) ReadChunkAt(data []byte, fileId string, offset uint64) (n int, err error) { + x, _ := strconv.Atoi(fileId) + for i := 0; i < len(data); i++ { + data[i] = byte(x) + } + return len(data), nil } func (m *mockChunkCache) SetChunk(fileId string, data []byte) { @@ -65,10 +69,9 @@ func TestReaderAt(t *testing.T) { readerAt := &ChunkReadAt{ chunkViews: ViewFromVisibleIntervals(visibles, 0, math.MaxInt64), - lookupFileId: nil, readerLock: sync.Mutex{}, fileSize: 10, - chunkCache: &mockChunkCache{}, + readerCache: newReaderCache(3, &mockChunkCache{}, nil), readerPattern: NewReaderPattern(), } @@ -116,10 +119,9 @@ func TestReaderAt0(t *testing.T) { readerAt := &ChunkReadAt{ chunkViews: ViewFromVisibleIntervals(visibles, 0, math.MaxInt64), - lookupFileId: nil, readerLock: sync.Mutex{}, fileSize: 10, - chunkCache: &mockChunkCache{}, + readerCache: newReaderCache(3, &mockChunkCache{}, nil), readerPattern: NewReaderPattern(), } @@ -145,10 +147,9 @@ func TestReaderAt1(t *testing.T) { readerAt := &ChunkReadAt{ chunkViews: ViewFromVisibleIntervals(visibles, 0, math.MaxInt64), - lookupFileId: nil, readerLock: sync.Mutex{}, fileSize: 20, - chunkCache: &mockChunkCache{}, + readerCache: newReaderCache(3, &mockChunkCache{}, nil), readerPattern: NewReaderPattern(), } diff --git a/weed/filer/reader_cache.go b/weed/filer/reader_cache.go new file mode 100644 index 000000000..f6dac6e0a --- /dev/null +++ b/weed/filer/reader_cache.go @@ -0,0 +1,187 @@ +package filer + +import ( + "fmt" + "github.com/chrislusf/seaweedfs/weed/glog" + "github.com/chrislusf/seaweedfs/weed/util/chunk_cache" + "github.com/chrislusf/seaweedfs/weed/util/mem" + "github.com/chrislusf/seaweedfs/weed/wdclient" + "sync" + "time" +) + +type ReaderCache struct { + chunkCache chunk_cache.ChunkCache + lookupFileIdFn wdclient.LookupFileIdFunctionType + sync.Mutex + downloaders map[string]*SingleChunkCacher + limit int +} + +type SingleChunkCacher struct { + sync.RWMutex + parent *ReaderCache + chunkFileId string + data []byte + err error + cipherKey []byte + isGzipped bool + chunkSize int + shouldCache bool + wg sync.WaitGroup + completedTime time.Time +} + +func newReaderCache(limit int, chunkCache chunk_cache.ChunkCache, lookupFileIdFn wdclient.LookupFileIdFunctionType) *ReaderCache { + return &ReaderCache{ + limit: limit, + chunkCache: chunkCache, + lookupFileIdFn: lookupFileIdFn, + downloaders: make(map[string]*SingleChunkCacher), + } +} + +func (rc *ReaderCache) MaybeCache(fileId string, cipherKey []byte, isGzipped bool, chunkSize int) { + rc.Lock() + defer rc.Unlock() + if _, found := rc.downloaders[fileId]; found { + return + } + if rc.lookupFileIdFn == nil { + return + } + + // if too many, delete one of them? + glog.V(0).Infof("downloader2 %d", len(rc.downloaders)) + if len(rc.downloaders) >= rc.limit { + oldestFid, oldestTime := "", time.Now() + for fid, downloader := range rc.downloaders { + if !downloader.completedTime.IsZero() { + if downloader.completedTime.Before(oldestTime) { + oldestFid, oldestTime = fid, downloader.completedTime + } + } + } + if oldestFid != "" { + oldDownloader := rc.downloaders[oldestFid] + delete(rc.downloaders, oldestFid) + oldDownloader.destroy() + } else { + // if still no slots, return + return + } + } + + cacher := newSingleChunkCacher(rc, fileId, cipherKey, isGzipped, chunkSize, false) + cacher.wg.Add(1) + go cacher.startCaching() + cacher.wg.Wait() + rc.downloaders[fileId] = cacher + + return +} + +func (rc *ReaderCache) ReadChunkAt(buffer []byte, fileId string, cipherKey []byte, isGzipped bool, offset int64, chunkSize int, shouldCache bool) (int, error) { + rc.Lock() + defer rc.Unlock() + if cacher, found := rc.downloaders[fileId]; found { + return cacher.readChunkAt(buffer, offset) + } + if shouldCache || rc.lookupFileIdFn == nil { + n, err := rc.chunkCache.ReadChunkAt(buffer, fileId, uint64(offset)) + if n > 0 { + return n, err + } + } + + glog.V(0).Infof("downloader1 %d", len(rc.downloaders)) + if len(rc.downloaders) >= rc.limit { + oldestFid, oldestTime := "", time.Now() + for fid, downloader := range rc.downloaders { + if !downloader.completedTime.IsZero() { + if downloader.completedTime.Before(oldestTime) { + oldestFid, oldestTime = fid, downloader.completedTime + } + } + } + if oldestFid != "" { + oldDownloader := rc.downloaders[oldestFid] + delete(rc.downloaders, oldestFid) + oldDownloader.destroy() + } + } + + cacher := newSingleChunkCacher(rc, fileId, cipherKey, isGzipped, chunkSize, shouldCache) + cacher.wg.Add(1) + go cacher.startCaching() + cacher.wg.Wait() + rc.downloaders[fileId] = cacher + + return cacher.readChunkAt(buffer, offset) +} + +func (rc *ReaderCache) destroy() { + rc.Lock() + defer rc.Unlock() + + for _, downloader := range rc.downloaders { + downloader.destroy() + } + +} + +func newSingleChunkCacher(parent *ReaderCache, fileId string, cipherKey []byte, isGzipped bool, chunkSize int, shouldCache bool) *SingleChunkCacher { + t := &SingleChunkCacher{ + parent: parent, + chunkFileId: fileId, + cipherKey: cipherKey, + isGzipped: isGzipped, + chunkSize: chunkSize, + shouldCache: shouldCache, + } + return t +} + +func (s *SingleChunkCacher) startCaching() { + s.Lock() + defer s.Unlock() + + s.wg.Done() // means this has been started + + urlStrings, err := s.parent.lookupFileIdFn(s.chunkFileId) + if err != nil { + s.err = fmt.Errorf("operation LookupFileId %s failed, err: %v", s.chunkFileId, err) + return + } + + s.data = mem.Allocate(s.chunkSize) + + _, s.err = retriedFetchChunkData(s.data, urlStrings, s.cipherKey, s.isGzipped, true, 0) + if s.err != nil { + mem.Free(s.data) + s.data = nil + return + } + + s.completedTime = time.Now() + if s.shouldCache { + s.parent.chunkCache.SetChunk(s.chunkFileId, s.data) + } + + return +} + +func (s *SingleChunkCacher) destroy() { + if s.data != nil { + mem.Free(s.data) + s.data = nil + } +} + +func (s *SingleChunkCacher) readChunkAt(buf []byte, offset int64) (int, error) { + s.RLock() + defer s.RUnlock() + + return copy(buf, s.data[offset:]), s.err + +} diff --git a/weed/filer/stream.go b/weed/filer/stream.go index e5163f2d9..b65641cbf 100644 --- a/weed/filer/stream.go +++ b/weed/filer/stream.go @@ -133,30 +133,30 @@ func writeZero(w io.Writer, size int64) (err error) { return } -func ReadAll(masterClient *wdclient.MasterClient, chunks []*filer_pb.FileChunk) ([]byte, error) { - - buffer := bytes.Buffer{} +func ReadAll(buffer []byte, masterClient *wdclient.MasterClient, chunks []*filer_pb.FileChunk) error { lookupFileIdFn := func(fileId string) (targetUrls []string, err error) { return masterClient.LookupFileId(fileId) } - chunkViews := ViewFromChunks(lookupFileIdFn, chunks, 0, math.MaxInt64) + chunkViews := ViewFromChunks(lookupFileIdFn, chunks, 0, int64(len(buffer))) + + idx := 0 for _, chunkView := range chunkViews { urlStrings, err := lookupFileIdFn(chunkView.FileId) if err != nil { glog.V(1).Infof("operation LookupFileId %s failed, err: %v", chunkView.FileId, err) - return nil, err + return err } - data, err := retriedFetchChunkData(urlStrings, chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.Offset, int(chunkView.Size)) + n, err := retriedFetchChunkData(buffer[idx:idx+int(chunkView.Size)], urlStrings, chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.Offset) if err != nil { - return nil, err + return err } - buffer.Write(data) + idx += n } - return buffer.Bytes(), nil + return nil } // ---------------- ChunkStreamReader ---------------------------------- diff --git a/weed/server/filer_server_handlers_read.go b/weed/server/filer_server_handlers_read.go index 2c51931c1..431eea979 100644 --- a/weed/server/filer_server_handlers_read.go +++ b/weed/server/filer_server_handlers_read.go @@ -4,6 +4,7 @@ import ( "bytes" "context" "fmt" + "github.com/chrislusf/seaweedfs/weed/util/mem" "io" "mime" "net/http" @@ -189,7 +190,9 @@ func (fs *FilerServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request) } width, height, mode, shouldResize := shouldResizeImages(ext, r) if shouldResize { - data, err := filer.ReadAll(fs.filer.MasterClient, entry.Chunks) + data := mem.Allocate(int(totalSize)) + defer mem.Free(data) + err := filer.ReadAll(data, fs.filer.MasterClient, entry.Chunks) if err != nil { glog.Errorf("failed to read %s: %v", path, err) w.WriteHeader(http.StatusNotModified) diff --git a/weed/util/chunk_cache/chunk_cache.go b/weed/util/chunk_cache/chunk_cache.go index 5c4be17a1..3f3b264b1 100644 --- a/weed/util/chunk_cache/chunk_cache.go +++ b/weed/util/chunk_cache/chunk_cache.go @@ -11,8 +11,6 @@ import ( var ErrorOutOfBounds = errors.New("attempt to read out of bounds") type ChunkCache interface { - GetChunk(fileId string, minSize uint64) (data []byte) - GetChunkSlice(fileId string, offset, length uint64) []byte ReadChunkAt(data []byte, fileId string, offset uint64) (n int, err error) SetChunk(fileId string, data []byte) } @@ -45,107 +43,6 @@ func NewTieredChunkCache(maxEntries int64, dir string, diskSizeInUnit int64, uni return c } -func (c *TieredChunkCache) GetChunk(fileId string, minSize uint64) (data []byte) { - if c == nil { - return - } - - c.RLock() - defer c.RUnlock() - - return c.doGetChunk(fileId, minSize) -} - -func (c *TieredChunkCache) doGetChunk(fileId string, minSize uint64) (data []byte) { - - if minSize <= c.onDiskCacheSizeLimit0 { - data = c.memCache.GetChunk(fileId) - if len(data) >= int(minSize) { - return data - } - } - - fid, err := needle.ParseFileIdFromString(fileId) - if err != nil { - glog.Errorf("failed to parse file id %s", fileId) - return nil - } - - if minSize <= c.onDiskCacheSizeLimit0 { - data = c.diskCaches[0].getChunk(fid.Key) - if len(data) >= int(minSize) { - return data - } - } - if minSize <= c.onDiskCacheSizeLimit1 { - data = c.diskCaches[1].getChunk(fid.Key) - if len(data) >= int(minSize) { - return data - } - } - { - data = c.diskCaches[2].getChunk(fid.Key) - if len(data) >= int(minSize) { - return data - } - } - - return nil - -} - -func (c *TieredChunkCache) GetChunkSlice(fileId string, offset, length uint64) []byte { - if c == nil { - return nil - } - - c.RLock() - defer c.RUnlock() - - return c.doGetChunkSlice(fileId, offset, length) -} - -func (c *TieredChunkCache) doGetChunkSlice(fileId string, offset, length uint64) (data []byte) { - - minSize := offset + length - if minSize <= c.onDiskCacheSizeLimit0 { - data, err := c.memCache.getChunkSlice(fileId, offset, length) - if err != nil { - glog.Errorf("failed to read from memcache: %s", err) - } - if len(data) >= int(minSize) { - return data - } - } - - fid, err := needle.ParseFileIdFromString(fileId) - if err != nil { - glog.Errorf("failed to parse file id %s", fileId) - return nil - } - - if minSize <= c.onDiskCacheSizeLimit0 { - data = c.diskCaches[0].getChunkSlice(fid.Key, offset, length) - if len(data) >= int(minSize) { - return data - } - } - if minSize <= c.onDiskCacheSizeLimit1 { - data = c.diskCaches[1].getChunkSlice(fid.Key, offset, length) - if len(data) >= int(minSize) { - return data - } - } - { - data = c.diskCaches[2].getChunkSlice(fid.Key, offset, length) - if len(data) >= int(minSize) { - return data - } - } - - return nil -} - func (c *TieredChunkCache) ReadChunkAt(data []byte, fileId string, offset uint64) (n int, err error) { if c == nil { return 0, nil