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54 lines
1.6 KiB
54 lines
1.6 KiB
package idx
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import (
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"io"
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"github.com/seaweedfs/seaweedfs/weed/glog"
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"github.com/seaweedfs/seaweedfs/weed/storage/types"
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)
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// walks through the index file, calls fn function with each key, offset, size
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// stops with the error returned by the fn function
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func WalkIndexFile(r io.ReaderAt, startFrom uint64, fn func(key types.NeedleId, offset types.Offset, size types.Size) error) error {
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readerOffset := int64(startFrom * types.NeedleMapEntrySize)
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bytes := make([]byte, types.NeedleMapEntrySize*RowsToRead)
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count, e := r.ReadAt(bytes, readerOffset)
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if count == 0 && e == io.EOF {
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return nil
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}
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glog.V(3).Infof("readerOffset %d count %d err: %v", readerOffset, count, e)
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readerOffset += int64(count)
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var (
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key types.NeedleId
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offset types.Offset
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size types.Size
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i int
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)
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for count > 0 && e == nil || e == io.EOF {
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for i = 0; i+types.NeedleMapEntrySize <= count; i += types.NeedleMapEntrySize {
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key, offset, size = IdxFileEntry(bytes[i : i+types.NeedleMapEntrySize])
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if e = fn(key, offset, size); e != nil {
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return e
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}
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}
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if e == io.EOF {
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return nil
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}
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count, e = r.ReadAt(bytes, readerOffset)
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glog.V(3).Infof("readerOffset %d count %d err: %v", readerOffset, count, e)
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readerOffset += int64(count)
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}
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return e
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}
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func IdxFileEntry(bytes []byte) (key types.NeedleId, offset types.Offset, size types.Size) {
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key = types.BytesToNeedleId(bytes[:types.NeedleIdSize])
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offset = types.BytesToOffset(bytes[types.NeedleIdSize : types.NeedleIdSize+types.OffsetSize])
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size = types.BytesToSize(bytes[types.NeedleIdSize+types.OffsetSize : types.NeedleIdSize+types.OffsetSize+types.SizeSize])
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return
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}
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const (
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RowsToRead = 1024
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)
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