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123 lines
3.1 KiB
123 lines
3.1 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/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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}
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// var _ = io.ReaderAt(&ChunkReadAt{})
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func NewChunkReaderAtFromClient(filerClient filer_pb.FilerClient, chunkViews []*ChunkView) *ChunkReadAt {
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return &ChunkReadAt{
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chunkViews: chunkViews,
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lookupFileId: 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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bufferOffset: -1,
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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.fetchChunkToBuffer(chunk)
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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) fetchChunkToBuffer(chunkView *ChunkView) 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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urlString, err := c.lookupFileId(chunkView.FileId)
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if err != nil {
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glog.V(1).Infof("operation LookupFileId %s failed, err: %v", chunkView.FileId, err)
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return err
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}
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var buffer bytes.Buffer
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err = util.ReadUrlAsStream(urlString, chunkView.CipherKey, chunkView.isGzipped, chunkView.IsFullChunk, chunkView.Offset, int(chunkView.Size), 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", chunkView.FileId, err)
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return err
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}
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c.buffer = buffer.Bytes()
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c.bufferOffset = chunkView.LogicOffset
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glog.V(3).Infof("read %s [%d,%d)", chunkView.FileId, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size))
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return nil
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}
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