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156 lines
4.2 KiB
156 lines
4.2 KiB
package filer2
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"sync"
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"github.com/chrislusf/seaweedfs/weed/glog"
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"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
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"github.com/chrislusf/seaweedfs/weed/util"
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"github.com/chrislusf/seaweedfs/weed/util/chunk_cache"
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"github.com/chrislusf/seaweedfs/weed/wdclient"
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)
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type ChunkReadAt struct {
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masterClient *wdclient.MasterClient
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chunkViews []*ChunkView
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buffer []byte
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bufferOffset int64
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lookupFileId func(fileId string) (targetUrl string, err error)
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readerLock sync.Mutex
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chunkCache *chunk_cache.ChunkCache
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}
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// var _ = io.ReaderAt(&ChunkReadAt{})
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type LookupFileIdFunctionType func(fileId string) (targetUrl string, err error)
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func LookupFn(filerClient filer_pb.FilerClient) LookupFileIdFunctionType {
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return func(fileId string) (targetUrl string, err error) {
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err = filerClient.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
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vid := VolumeId(fileId)
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resp, err := client.LookupVolume(context.Background(), &filer_pb.LookupVolumeRequest{
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VolumeIds: []string{vid},
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})
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if err != nil {
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return err
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}
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locations := resp.LocationsMap[vid]
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if locations == nil || len(locations.Locations) == 0 {
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glog.V(0).Infof("failed to locate %s", fileId)
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return fmt.Errorf("failed to locate %s", fileId)
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}
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volumeServerAddress := filerClient.AdjustedUrl(locations.Locations[0].Url)
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targetUrl = fmt.Sprintf("http://%s/%s", volumeServerAddress, fileId)
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return nil
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})
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return
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}
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}
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func NewChunkReaderAtFromClient(filerClient filer_pb.FilerClient, chunkViews []*ChunkView, chunkCache *chunk_cache.ChunkCache) *ChunkReadAt {
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return &ChunkReadAt{
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chunkViews: chunkViews,
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lookupFileId: LookupFn(filerClient),
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bufferOffset: -1,
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chunkCache: chunkCache,
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}
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}
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func (c *ChunkReadAt) ReadAt(p []byte, offset int64) (n int, err error) {
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c.readerLock.Lock()
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defer c.readerLock.Unlock()
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for n < len(p) && err == nil {
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readCount, readErr := c.doReadAt(p[n:], offset+int64(n))
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n += readCount
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err = readErr
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if readCount == 0 {
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return n, nil
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}
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}
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return
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}
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func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
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var found bool
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for _, chunk := range c.chunkViews {
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if chunk.LogicOffset <= offset && offset < chunk.LogicOffset+int64(chunk.Size) {
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found = true
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if c.bufferOffset != chunk.LogicOffset {
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c.buffer, err = c.fetchChunkData(chunk)
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c.bufferOffset = chunk.LogicOffset
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}
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break
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}
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}
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if !found {
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return 0, io.EOF
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}
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n = copy(p, c.buffer[offset-c.bufferOffset:])
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// fmt.Printf("> doReadAt [%d,%d), buffer:[%d,%d)\n", offset, offset+int64(n), c.bufferOffset, c.bufferOffset+int64(len(c.buffer)))
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return
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}
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func (c *ChunkReadAt) fetchChunkData(chunkView *ChunkView) (data []byte, err error) {
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// fmt.Printf("fetching %s [%d,%d)\n", chunkView.FileId, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size))
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hasDataInCache := false
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chunkData := c.chunkCache.GetChunk(chunkView.FileId, chunkView.ChunkSize)
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if chunkData != nil {
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glog.V(3).Infof("cache hit %s [%d,%d)", chunkView.FileId, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size))
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hasDataInCache = true
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} else {
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chunkData, err = c.doFetchFullChunkData(chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped)
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if err != nil {
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return nil, err
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}
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}
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if int64(len(chunkData)) < chunkView.Offset+int64(chunkView.Size) {
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return nil, fmt.Errorf("unexpected larger chunkView [%d,%d) than chunk %d", chunkView.Offset, chunkView.Offset+int64(chunkView.Size), len(chunkData))
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}
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data = chunkData[chunkView.Offset : chunkView.Offset+int64(chunkView.Size)]
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if !hasDataInCache {
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c.chunkCache.SetChunk(chunkView.FileId, chunkData)
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}
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return data, nil
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}
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func (c *ChunkReadAt) doFetchFullChunkData(fileId string, cipherKey []byte, isGzipped bool) ([]byte, error) {
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urlString, err := c.lookupFileId(fileId)
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if err != nil {
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glog.V(1).Infof("operation LookupFileId %s failed, err: %v", fileId, err)
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return nil, err
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}
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var buffer bytes.Buffer
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err = util.ReadUrlAsStream(urlString, cipherKey, isGzipped, true, 0, 0, func(data []byte) {
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buffer.Write(data)
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})
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if err != nil {
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glog.V(1).Infof("read %s failed, err: %v", fileId, err)
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return nil, err
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}
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return buffer.Bytes(), nil
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}
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