rootslab / hazz Goto Github PK

Hazz, a pseudo-random-data-filled-table to generate k indipendent and uniform, very fast (non-cryptographic) hash functions.

If you need to hash arbitrary long length inputs, without using a fixed (big) size pseudo-random table, a fast way is to simulate a set of indipendent hash functions using a single crpyto-digest (with a sha-512 digest we can simulate up to 16 functions). Take a look to Mazz (the fast way of the tonto).

$ npm install hazz [-g]

require:

var Hazz  = require( 'hazz' );

to run all test files, install devDependencies:

 $ cd hazz/
 # install or update devDependencies
 $ npm install 
 # run tests
 $ npm test

to execute a single test file simply do:

 $ node test/file-name.js

Specify how many bytes to parse (at max), from every input key to hash, then the number of functions to use.

NOTE:

• default value for input length is 16 byte.
• default and minimum value for hfn is 2

Arguments between [] are optional.

Hazz( [ Number max_input_length [, Number hfn ] ] )
// or
new Hazz( [ Number max_input_length [, Number hfn ] ] )

/*
 * the table containing pseudo-random data for generating hash numbers.
 * NOTE: the size of the table is: (max_input_length * hfn) kilobytes,
 * it doesn't depends on the expected population.
 */
Hazz.table

/*
 * max input key length  
 */
Hazz.ilength

/*
 * total number of hash functions  
 */
Hazz.hfn

Arguments between [] are optional.

/*
 * re-fill table with fresh pseudo-random numbers
 */
Hazz#refill() : Hazz

/*
 * Specify a positive integer (from 0 to k-1) to use the k-th
 * hash function. If specified it returns a number within a
 * range.
 * 
 * NOTE: 
 *  - the input should be a Buffer (no Strings or Arrays).
 *  - the minimum range is obviously 2 (0, 1).
 *  - the integers produced are at min 4 byte long (>= 2^24),
 *    longer the input parsed, bigger the numbers produced.
 */
Hazz#do( Number hfn, Buffer data [, Number range ] ) : Number

/*
 * hash with all functions in parallel,
 * it returns an array of results
 */
Hazz#all( Buffer data [, Number range ] ) : Array

See examples.

Copyright (c) 2017-present < Guglielmo Ferri : [email protected] >

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.