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cljc-bloom

A cross-platform bloom filter implemented in Clojure(Script).

Installation

Include the following dependency in project.clj file:

:dependencies [[davidwclin/cljc-bloom "0.1.1"]]

Example Usage

    (require '[bloom.core :as bf]) 
    (let [upper-cardinality 20
          target-false-positive-rate 0.05]
      (def my-bf
        (bf/->bf upper-cardinality target-false-positive-rate)))
    (doseq [i (range 10)]
      (bf/add! my-bf (str i)))
    (bf/has? my-bf "4")  ;; true
    (bf/has? my-bf "45") ;; false

(de)serialization into (or from) JSON

    ;; serialize in clj
    (bf/serialize my-bf "/tmp/my-bf.json")
    
    ;; deserialize in clj
    (require '[clojure.data.json :as json])
    (def my-bf
      (-> "/tmp/my-bf.json" slurp json/read-str bf/->bf))
    (bf/has? my-bf "4")  ;; true
    (bf/has? my-bf "45") ;; false
    
    ;; deserialize in cljs
    ;; retrieve serialized bf from server. Using just the file content as an example here.
    (let [serialized-string "{\"buckets-\":[174137362,276431338,1342183560,-1029155791],\"seed\":8461509,\"m\":128,\"k\":5}"]
      (def my-bf
        (-> serialized-string js/JSON.parse bf/->bf)))
    (bf/has? my-bf "4")  ;; true
    (bf/has? my-bf "45") ;; false

Implementation

  • Bloom filters require an arbitrary number of hashes, this is achieved by generating linear combinations of two xxHashes.
  • Javscript bitwise ops are 32 bits, so the same is done on the Java side for compatibility.

Inspirations

Development

License

Copyright © 2017 @davidwclin

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.