package filer import ( "context" "fmt" "github.com/chrislusf/seaweedfs/weed/glog" "github.com/chrislusf/seaweedfs/weed/pb/filer_pb" "github.com/chrislusf/seaweedfs/weed/util/chunk_cache" "github.com/chrislusf/seaweedfs/weed/wdclient" "github.com/golang/groupcache/singleflight" "io" "math/rand" "sync" ) type ChunkReadAt struct { masterClient *wdclient.MasterClient chunkViews []*ChunkView lookupFileId LookupFileIdFunctionType readerLock sync.Mutex fileSize int64 fetchGroup singleflight.Group lastChunkFileId string lastChunkData []byte chunkCache chunk_cache.ChunkCache } // var _ = io.ReaderAt(&ChunkReadAt{}) type LookupFileIdFunctionType func(fileId string) (targetUrls []string, err error) func LookupFn(filerClient filer_pb.FilerClient) LookupFileIdFunctionType { vidCache := make(map[string]*filer_pb.Locations) return func(fileId string) (targetUrls []string, err error) { vid := VolumeId(fileId) locations, found := vidCache[vid] if !found { // println("looking up volume", vid) err = filerClient.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error { resp, err := client.LookupVolume(context.Background(), &filer_pb.LookupVolumeRequest{ VolumeIds: []string{vid}, }) if err != nil { return err } locations = resp.LocationsMap[vid] if locations == nil || len(locations.Locations) == 0 { glog.V(0).Infof("failed to locate %s", fileId) return fmt.Errorf("failed to locate %s", fileId) } vidCache[vid] = locations return nil }) } for _, loc := range locations.Locations { volumeServerAddress := filerClient.AdjustedUrl(loc.Url) targetUrl := fmt.Sprintf("http://%s/%s", volumeServerAddress, fileId) targetUrls = append(targetUrls, targetUrl) } for i := len(targetUrls) - 1; i > 0; i-- { j := rand.Intn(i + 1) targetUrls[i], targetUrls[j] = targetUrls[j], targetUrls[i] } return } } func NewChunkReaderAtFromClient(filerClient filer_pb.FilerClient, chunkViews []*ChunkView, chunkCache chunk_cache.ChunkCache, fileSize int64) *ChunkReadAt { return &ChunkReadAt{ chunkViews: chunkViews, lookupFileId: LookupFn(filerClient), chunkCache: chunkCache, fileSize: fileSize, } } func (c *ChunkReadAt) ReadAt(p []byte, offset int64) (n int, err error) { c.readerLock.Lock() defer c.readerLock.Unlock() glog.V(4).Infof("ReadAt [%d,%d) of total file size %d bytes %d chunk views", offset, offset+int64(len(p)), c.fileSize, len(c.chunkViews)) return c.doReadAt(p[n:], offset+int64(n)) } func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) { var buffer []byte startOffset, remaining := offset, int64(len(p)) var nextChunk *ChunkView for i, chunk := range c.chunkViews { if remaining <= 0 { break } if i+1 < len(c.chunkViews) { nextChunk = c.chunkViews[i+1] } else { nextChunk = nil } if startOffset < chunk.LogicOffset { gap := int(chunk.LogicOffset - startOffset) glog.V(4).Infof("zero [%d,%d)", startOffset, startOffset+int64(gap)) n += int(min(int64(gap), remaining)) startOffset, remaining = chunk.LogicOffset, remaining-int64(gap) if remaining <= 0 { break } } // fmt.Printf(">>> doReadAt [%d,%d), chunk[%d,%d)\n", offset, offset+int64(len(p)), chunk.LogicOffset, chunk.LogicOffset+int64(chunk.Size)) chunkStart, chunkStop := max(chunk.LogicOffset, startOffset), min(chunk.LogicOffset+int64(chunk.Size), startOffset+remaining) if chunkStart >= chunkStop { 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)) buffer, err = c.readFromWholeChunkData(chunk, nextChunk) if err != nil { glog.Errorf("fetching chunk %+v: %v\n", chunk, err) return } bufferOffset := chunkStart - chunk.LogicOffset + chunk.Offset copied := copy(p[startOffset-offset:chunkStop-chunkStart+startOffset-offset], buffer[bufferOffset:bufferOffset+chunkStop-chunkStart]) n += copied startOffset, remaining = startOffset+int64(copied), remaining-int64(copied) } glog.V(4).Infof("doReadAt [%d,%d), n:%v, err:%v", offset, offset+int64(len(p)), n, err) if err == nil && remaining > 0 && c.fileSize > startOffset { delta := int(min(remaining, c.fileSize-startOffset)) glog.V(4).Infof("zero2 [%d,%d) of file size %d bytes", startOffset, startOffset+int64(delta), c.fileSize) n += delta } if err == nil && offset+int64(len(p)) > c.fileSize { err = io.EOF } // fmt.Printf("~~~ filled %d, err: %v\n\n", n, err) return } func (c *ChunkReadAt) readFromWholeChunkData(chunkView *ChunkView, nextChunkViews ...*ChunkView) (chunkData []byte, err error) { if c.lastChunkFileId == chunkView.FileId { return c.lastChunkData, nil } 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) 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 } 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 }