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 ¶
- func UintIn(n uint) []byte
- func UintOut(bye []byte) uint
- type Filter
- func (cf *Filter) Count() uint
- func (cf *Filter) Delete(data []byte) bool
- func (cf *Filter) Encode() []byte
- func (cf *Filter) Expand()
- func (cf *Filter) Insert(data []byte) bool
- func (cf *Filter) InsertUnique(data []byte) bool
- func (cf *Filter) Lookup(data []byte) bool
- func (cf *Filter) ReadFile() error
- func (cf *Filter) Reset()
- func (cf *Filter) SaveFile() error
- type LCG
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type Filter ¶
type Filter struct { FilePath string // 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