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block.go
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block.go
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package splitblockbloom
import (
"encoding/binary"
"errors"
"io"
"math/bits"
"unsafe"
)
var salt = [...]uint64{
0x44974d91,
0x47b6137b,
0xa2b7289d,
0x8824ad5b,
0x2df1424b,
0x705495c7,
0x5c6bfb31,
0x9efc4947,
}
var (
_ io.ReaderFrom = (*Block)(nil)
_ io.WriterTo = (*Block)(nil)
)
type Block [wordsPerBlock]uint32
func (blk *Block) AddHash(hash uint64) {
blk[0] |= 1 << ((uint32(hash) * uint32(salt[0])) >> (27))
blk[1] |= 1 << ((uint32(hash) * uint32(salt[1])) >> (27))
blk[2] |= 1 << ((uint32(hash) * uint32(salt[2])) >> (27))
blk[3] |= 1 << ((uint32(hash) * uint32(salt[3])) >> (27))
blk[4] |= 1 << ((uint32(hash) * uint32(salt[4])) >> (27))
blk[5] |= 1 << ((uint32(hash) * uint32(salt[5])) >> (27))
blk[6] |= 1 << ((uint32(hash) * uint32(salt[6])) >> (27))
blk[7] |= 1 << ((uint32(hash) * uint32(salt[7])) >> (27))
}
func (blk *Block) Contains(hash uint64) bool {
return blk[0]&(1<<((uint32(hash)*uint32(salt[0]))>>(27))) != 0 &&
blk[1]&(1<<((uint32(hash)*uint32(salt[1]))>>(27))) != 0 &&
blk[2]&(1<<((uint32(hash)*uint32(salt[2]))>>(27))) != 0 &&
blk[3]&(1<<((uint32(hash)*uint32(salt[3]))>>(27))) != 0 &&
blk[4]&(1<<((uint32(hash)*uint32(salt[4]))>>(27))) != 0 &&
blk[5]&(1<<((uint32(hash)*uint32(salt[5]))>>(27))) != 0 &&
blk[6]&(1<<((uint32(hash)*uint32(salt[6]))>>(27))) != 0 &&
blk[7]&(1<<((uint32(hash)*uint32(salt[7]))>>(27))) != 0
}
func (blk *Block) AddHashIfNotContains(hash uint64) bool {
changed := false
changed = changed || blk[0]&(1<<((uint32(hash)*uint32(salt[0]))>>(27))) == 0
changed = changed || blk[1]&(1<<((uint32(hash)*uint32(salt[1]))>>(27))) == 0
changed = changed || blk[2]&(1<<((uint32(hash)*uint32(salt[2]))>>(27))) == 0
changed = changed || blk[3]&(1<<((uint32(hash)*uint32(salt[3]))>>(27))) == 0
changed = changed || blk[4]&(1<<((uint32(hash)*uint32(salt[4]))>>(27))) == 0
changed = changed || blk[5]&(1<<((uint32(hash)*uint32(salt[5]))>>(27))) == 0
changed = changed || blk[6]&(1<<((uint32(hash)*uint32(salt[6]))>>(27))) == 0
changed = changed || blk[7]&(1<<((uint32(hash)*uint32(salt[7]))>>(27))) == 0
blk[0] |= 1 << ((uint32(hash) * uint32(salt[0])) >> (27))
blk[1] |= 1 << ((uint32(hash) * uint32(salt[1])) >> (27))
blk[2] |= 1 << ((uint32(hash) * uint32(salt[2])) >> (27))
blk[3] |= 1 << ((uint32(hash) * uint32(salt[3])) >> (27))
blk[4] |= 1 << ((uint32(hash) * uint32(salt[4])) >> (27))
blk[5] |= 1 << ((uint32(hash) * uint32(salt[5])) >> (27))
blk[6] |= 1 << ((uint32(hash) * uint32(salt[6])) >> (27))
blk[7] |= 1 << ((uint32(hash) * uint32(salt[7])) >> (27))
return changed
}
func (blk *Block) Merge(other *Block) {
blk[0] |= other[0]
blk[1] |= other[1]
blk[2] |= other[2]
blk[3] |= other[3]
blk[4] |= other[4]
blk[5] |= other[5]
blk[6] |= other[6]
blk[7] |= other[7]
}
func (blk *Block) UnmarshalBinary(bs []byte) error {
if len(bs) < blockSizeInBytes {
return errors.New("block: not enough bytes to unmarshal")
}
blk[0] = binary.LittleEndian.Uint32(bs[0*4:])
blk[1] = binary.LittleEndian.Uint32(bs[1*4:])
blk[2] = binary.LittleEndian.Uint32(bs[2*4:])
blk[3] = binary.LittleEndian.Uint32(bs[3*4:])
blk[4] = binary.LittleEndian.Uint32(bs[4*4:])
blk[5] = binary.LittleEndian.Uint32(bs[5*4:])
blk[6] = binary.LittleEndian.Uint32(bs[6*4:])
blk[7] = binary.LittleEndian.Uint32(bs[7*4:])
return nil
}
func (blk *Block) AppendTo(bs []byte) []byte {
return append(bs, unsafe.Slice((*byte)(unsafe.Pointer(&blk[0])), blockSizeInBytes)...)
}
func (blk *Block) WriteTo(w io.Writer) (int64, error) {
var b [blockSizeInBytes]byte
blk.AppendTo(b[:])
n, err := w.Write(b[:])
if n != blockSizeInBytes {
return int64(n), io.ErrShortWrite
}
return int64(n), err
}
func (blk *Block) ReadFrom(r io.Reader) (int64, error) {
var b [blockSizeInBytes]byte
n, err := io.ReadFull(r, b[:])
if err != nil {
return int64(n), err
}
if err := blk.UnmarshalBinary(b[:]); err != nil {
return int64(n), err
}
return int64(n), nil
}
func (blk *Block) EstimateCardinality() int {
var count int
count += bits.OnesCount32(blk[0])
count += bits.OnesCount32(blk[1])
count += bits.OnesCount32(blk[2])
count += bits.OnesCount32(blk[3])
count += bits.OnesCount32(blk[4])
count += bits.OnesCount32(blk[5])
count += bits.OnesCount32(blk[6])
count += bits.OnesCount32(blk[7])
return count / 8
}