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package filer2
import (
"bytes"
"context"
"fmt"
"io"
"sync"
"github.com/chrislusf/seaweedfs/weed/glog"
"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
"github.com/chrislusf/seaweedfs/weed/util"
"github.com/chrislusf/seaweedfs/weed/wdclient"
)
type ChunkReadAt struct {
masterClient *wdclient.MasterClient
chunkViews []*ChunkView
buffer []byte
bufferOffset int64
lookupFileId func(fileId string) (targetUrl string, err error)
readerLock sync.Mutex
}
// var _ = io.ReaderAt(&ChunkReadAt{})
func NewChunkReaderAtFromClient(filerClient filer_pb.FilerClient, chunkViews []*ChunkView) *ChunkReadAt {
return &ChunkReadAt{
chunkViews: chunkViews,
lookupFileId: func(fileId string) (targetUrl string, err error) {
err = filerClient.WithFilerClient(func(client filer_pb.SeaweedFilerClient) error {
vid := VolumeId(fileId)
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)
}
volumeServerAddress := filerClient.AdjustedUrl(locations.Locations[0].Url)
targetUrl = fmt.Sprintf("http://%s/%s", volumeServerAddress, fileId)
return nil
})
return
},
bufferOffset: -1,
}
}
func (c *ChunkReadAt) ReadAt(p []byte, offset int64) (n int, err error) {
c.readerLock.Lock()
defer c.readerLock.Unlock()
for n < len(p) && err == nil {
readCount, readErr := c.doReadAt(p[n:], offset+int64(n))
n += readCount
err = readErr
if readCount == 0 {
return n, nil
}
}
return
}
func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
var found bool
for _, chunk := range c.chunkViews {
if chunk.LogicOffset <= offset && offset < chunk.LogicOffset+int64(chunk.Size) {
found = true
if c.bufferOffset != chunk.LogicOffset {
c.fetchChunkToBuffer(chunk)
}
break
}
}
if !found {
return 0, io.EOF
}
n = copy(p, c.buffer[offset-c.bufferOffset:])
// fmt.Printf("> doReadAt [%d,%d), buffer:[%d,%d)\n", offset, offset+int64(n), c.bufferOffset, c.bufferOffset+int64(len(c.buffer)))
return
}
func (c *ChunkReadAt) fetchChunkToBuffer(chunkView *ChunkView) error {
// fmt.Printf("fetching %s [%d,%d)\n", chunkView.FileId, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size))
urlString, err := c.lookupFileId(chunkView.FileId)
if err != nil {
glog.V(1).Infof("operation LookupFileId %s failed, err: %v", chunkView.FileId, err)
return err
}
var buffer bytes.Buffer
err = util.ReadUrlAsStream(urlString, chunkView.CipherKey, chunkView.isGzipped, chunkView.IsFullChunk, chunkView.Offset, int(chunkView.Size), func(data []byte) {
buffer.Write(data)
})
if err != nil {
glog.V(1).Infof("read %s failed, err: %v", chunkView.FileId, err)
return err
}
c.buffer = buffer.Bytes()
c.bufferOffset = chunkView.LogicOffset
glog.V(3).Infof("read %s [%d,%d)", chunkView.FileId, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size))
return nil
}
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