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