A package implementing bloom filter using redis as backend.
npm install bloomfilter-redis 
Bloomfilter-redis is a node.js package implementing bloom filter using redis as backend. 🚢
murmur3 and FNV-1a for double hashing- depends on redis package
- you specify the filter size in redis, up to 512M
- Redis-server installed and running
- Node.js >= 6
``
npm install bloomfilter-redis
`javascript
const BloomFilter = require('bloomfilter-redis');
const redis = require("redis");
let bf = new BloomFilter({//all params have a default value, and I choose some to present below
redisSize: 16, // this will create a string value which is 16 MegaBytes in length
hashesNum: 8, // how many hash functions do we use
redisKey: 'test', //this will create a string which keyname is test
redisClient: redis.createClient(), //you can choose to create the client by yourself
});
promise = bf.init(); // invokes SETBIT to allocate memory in redis.For details https://redis.io/commands/setbit
promise.then(() => {
return bf.add('abc'); // add "abc"
})
.then(() => {
return bf.add('hello'); // add "hello"
})
.then(() => {
return bf.add('world'); // add "world"
})
.then(() => {
return bf.add('nihao'); // add "nihao"
})
.then(() => {
return bf.contains('hola');
})
.then((result) => {
console.log("hola" in the set? ${result}); // "hola" in the set? false"hello" in the set? ${result}
})
.then(() => {
return bf.contains('hello');
})
.then((result) => {
console.log(); // "hello" in the set? true
}).catch(function(err) {
console.error(err);
});
`
Or for an easier way, use promise.all()
`javascript
const BloomFilter = require('bloomfilter-redis');
const redis = require("redis");
let bf = new BloomFilter();
promise = bf.init();
// both array has I love you
arr = ['我爱你', 'I love you', 'je t\'aime', 'ich liebe dich', 'Ti Amo', 'te amo vos amo'];
testArr = ['사랑해요', 'I love you', '爱してる'];
promiseAddArr = [];
promiseContainsArr = [];
arr.forEach(str => {
promiseAddArr.push(bf.add(str)); // assembly add tasks
});
testArr.forEach(str => {
promiseContainsArr.push(bf.contains(str)); // assembly contains tasks
});
//lauch!
Promise.all(promiseAddArr).then(() => {
Promise.all(promiseContainsArr).then(results => {
console.log(results); // [ false, true, false ]. Yeah, that's the right answer
})
});
`
,BloomFilter.add and BloomFilter.contains all returns a Promise.- As there are various options when creating a redis-client using
redis.createClient method, it may be a good choice to let users create the redis-client by themselves. Pass the redis-client as a parameter when contructing BloomFilter.
Why choose 32bit hash
- we use redis string as the filter.- A redis string value can be at max 512 Megabytes in length, that is totally
5122^208` bits.- Javascript does not support 64bit integer calculations.
- 32bit hash is suffient.
MIT