/
bucket.go
58 lines (47 loc) · 1.2 KB
/
bucket.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
package linearhash
import (
"errors"
"fmt"
"unsafe"
)
const bucketSz = int(unsafe.Sizeof(bucket{}))
type bucket struct {
id uint32 // id of this bucket
overflow uint32 // overflow bucket id. (0 means no overflow)
flags uint32 // control flags
ptr uint32 // dummy pointer to slots
}
func (b bucket) next(idx *LinearHash) (*bucket, error) {
if b.overflow == 0 {
return nil, nil
}
nextBucket := bucket{}
if err := idx.pager.Unmarshal(int(b.overflow), &nextBucket); err != nil {
return nil, err
}
return &nextBucket, nil
}
func (b *bucket) slot(id int) *slot {
slots := (*[0xFFFF]slot)(unsafe.Pointer(&b.ptr))
return &(slots)[id]
}
func (b bucket) MarshalBinary() ([]byte, error) {
mem := (*[0xFFFF]byte)(unsafe.Pointer(&b))
return append([]byte(nil), (*mem)[0:bucketSz]...), nil
}
func (b *bucket) UnmarshalBinary(d []byte) error {
if b == nil {
return errors.New("cannot unamarshal into nil slot")
} else if len(d) < bucketSz {
return fmt.Errorf("need at-least %d bytes, got only %d", bucketSz, len(d))
}
buckets := (*[0xFFFFF]bucket)(unsafe.Pointer(&d[0]))
*b = (*buckets)[0]
return nil
}
type slot struct {
hash uint64
blobID uint64
keySz uint32
checksum uint32
}