Documentation ¶
Overview ¶
Package cuckoo provides a Cuckoo Filter, a Bloom filter replacement for approximated set-membership queries.
While Bloom filters are well-known space-efficient data structures to serve queries like "if item x is in a set?", they do not support deletion. Their variances to enable deletion (like counting Bloom filters) usually require much more space.
Cuckoo filters provide the flexibility to add and remove items dynamically. A cuckoo filter is based on cuckoo hashing (and therefore named as cuckoo filter). It is essentially a cuckoo hash table storing each key's fingerprint. Cuckoo hash tables can be highly compact, thus a cuckoo filter could use less space than conventional Bloom filters, for applications that require low false positive rates (< 3%).
For details about the algorithm and citations please use this article:
"Cuckoo Filter: Better Than Bloom" by Bin Fan, Dave Andersen and Michael Kaminsky (https://www.cs.cmu.edu/~dga/papers/cuckoo-conext2014.pdf)
Note: This implementation uses a a static bucket size of 4 fingerprints and a fingerprint size of 1 byte based on my understanding of an optimal bucket/fingerprint/size ratio from the aforementioned paper.
Index ¶
- Constants
- func SetDefaultHasher(hasher Hasher)
- type Filter
- type Hasher
- type ScalableCuckooFilter
- func (sf *ScalableCuckooFilter) Count() uint
- func (sf *ScalableCuckooFilter) DecodeWithParam(fBytes []byte, opts ...option) (*ScalableCuckooFilter, error)
- func (sf *ScalableCuckooFilter) Delete(data []byte) bool
- func (sf *ScalableCuckooFilter) Encode() []byte
- func (sf *ScalableCuckooFilter) Insert(data []byte) bool
- func (sf *ScalableCuckooFilter) InsertUnique(data []byte) bool
- func (sf *ScalableCuckooFilter) Lookup(data []byte) bool
- func (sf *ScalableCuckooFilter) Reset()
- type Store
Constants ¶
const ( DefaultLoadFactor = 0.9 DefaultCapacity = 10000 )
Variables ¶
This section is empty.
Functions ¶
func SetDefaultHasher ¶
func SetDefaultHasher(hasher Hasher)
Types ¶
type Filter ¶
type Filter struct {
// contains filtered or unexported fields
}
Filter is a probabilistic counter
func NewFilter ¶
NewFilter returns a new cuckoofilter with a given capacity. A capacity of 1000000 is a normal default, which allocates about ~1MB on 64-bit machines.
func (*Filter) InsertUnique ¶
InsertUnique inserts data into the counter if not exists and returns true upon success
type ScalableCuckooFilter ¶
type ScalableCuckooFilter struct {
// contains filtered or unexported fields
}
func DecodeScalableFilter ¶
func DecodeScalableFilter(fBytes []byte) (*ScalableCuckooFilter, error)
func NewScalableCuckooFilter ¶
func NewScalableCuckooFilter(opts ...option) *ScalableCuckooFilter
by default option the grow capacity is: capacity , total 4096 4096 8192 12288
16384 28672 32768 61440 65536 126,976
func (*ScalableCuckooFilter) Count ¶
func (sf *ScalableCuckooFilter) Count() uint
func (*ScalableCuckooFilter) DecodeWithParam ¶
func (sf *ScalableCuckooFilter) DecodeWithParam(fBytes []byte, opts ...option) (*ScalableCuckooFilter, error)
func (*ScalableCuckooFilter) Delete ¶
func (sf *ScalableCuckooFilter) Delete(data []byte) bool
func (*ScalableCuckooFilter) Encode ¶
func (sf *ScalableCuckooFilter) Encode() []byte
func (*ScalableCuckooFilter) Insert ¶
func (sf *ScalableCuckooFilter) Insert(data []byte) bool
func (*ScalableCuckooFilter) InsertUnique ¶
func (sf *ScalableCuckooFilter) InsertUnique(data []byte) bool
func (*ScalableCuckooFilter) Lookup ¶
func (sf *ScalableCuckooFilter) Lookup(data []byte) bool
func (*ScalableCuckooFilter) Reset ¶
func (sf *ScalableCuckooFilter) Reset()