README
¶
go-blooms
From Wiki
Bloom Filter: A space-efficient probabilistic data structure that is used to test whether an element is a member of a set. False positive matches are possible, but false negatives are not; i.e. a query returns either "possibly in set" or "definitely not in set". Elements can be added to the set, but not removed.
This bloom filter implementation is backed by bool slice for simplicity.
And the hashing functions used are fnv and murmur both 64 bit versions.
Installation
go get -u github.com/theodesp/go-blooms
Usage
package example
import "github.com/theodesp/go-blooms"
const (
size = 64 * 1024
)
bf := go_blooms.New(size, go_blooms.DefaultHashFunctions)
value := "hello"
bf.Add([]byte(value)) // we accept only a byte slice
if bf.Test([]byte(value)) { // probably true, could be false
// whatever
}
anotherValue := "world"
if bf.Test([]byte(anotherValue) { // Bloom filter guarantees that anotherValue is not in the set
panic("This should never happen")
}
Complexity
Time
If we are using a bloom filter with bits and hash function, insertion and search will both take time. In both cases, we just need to run the input through all of the hash functions. Then we just check the output bits.
| Operation | Complexity |
|---|---|
| insertion | O(k) |
| search | O(k) |
Space The space of the actual data structure (what holds the data).
| Complexity |
|---|
| O(m) |
Where m is the size of the slice.
Benchmarks
m=1024, k=3
PASS: bloomFilter_test.go:66: MySuite.BenchmarkAdd 10000000 231 ns/op
PASS: bloomFilter_test.go:74: MySuite.BenchmarkTest 10000000 231 ns/op
License
Copyright © 2017 Theo Despoudis MIT license
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
DefaultHashFunctions for BloomFilter
Functions ¶
This section is empty.
Types ¶
type BloomFilter ¶
type BloomFilter struct {
// contains filtered or unexported fields
}
BloomFilter probabilistic data structure definition
func (*BloomFilter) Add ¶
func (bf *BloomFilter) Add(item []byte)
Adds the item into the bloom filter set by hashing in over the hash functions
func (*BloomFilter) Test ¶
func (bf *BloomFilter) Test(item []byte) bool
Test if the item into the bloom filter is set by hashing in over the hash functions
Source Files