nats
Version:
Node.js client for NATS, a lightweight, high-performance cloud native messaging system
120 lines • 3.3 kB
JavaScript
/*
* Copyright 2016-2021 The NATS Authors
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.nuid = exports.Nuid = void 0;
const digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const base = 36;
const preLen = 12;
const seqLen = 10;
const maxSeq = 3656158440062976; // base^seqLen == 36^10
const minInc = 33;
const maxInc = 333;
const totalLen = preLen + seqLen;
function _getRandomValues(a) {
for (let i = 0; i < a.length; i++) {
a[i] = Math.floor(Math.random() * 255);
}
}
function fillRandom(a) {
var _a;
if ((_a = globalThis === null || globalThis === void 0 ? void 0 : globalThis.crypto) === null || _a === void 0 ? void 0 : _a.getRandomValues) {
globalThis.crypto.getRandomValues(a);
}
else {
_getRandomValues(a);
}
}
/**
* Create and initialize a nuid.
*
* @api private
*/
class Nuid {
constructor() {
this.buf = new Uint8Array(totalLen);
this.inited = false;
}
/**
* Initializes a nuid with a crypto random prefix,
* and pseudo-random sequence and increment.
*
* @api private
*/
init() {
this.inited = true;
this.setPre();
this.initSeqAndInc();
this.fillSeq();
}
/**
* Initializes the pseudo randmon sequence number and the increment range.
*
* @api private
*/
initSeqAndInc() {
this.seq = Math.floor(Math.random() * maxSeq);
this.inc = Math.floor(Math.random() * (maxInc - minInc) + minInc);
}
/**
* Sets the prefix from crypto random bytes. Converts to base36.
*
* @api private
*/
setPre() {
const cbuf = new Uint8Array(preLen);
fillRandom(cbuf);
for (let i = 0; i < preLen; i++) {
const di = cbuf[i] % base;
this.buf[i] = digits.charCodeAt(di);
}
}
/**
* Fills the sequence part of the nuid as base36 from this.seq.
*
* @api private
*/
fillSeq() {
let n = this.seq;
for (let i = totalLen - 1; i >= preLen; i--) {
this.buf[i] = digits.charCodeAt(n % base);
n = Math.floor(n / base);
}
}
/**
* Returns the next nuid.
*
* @api private
*/
next() {
if (!this.inited) {
this.init();
}
this.seq += this.inc;
if (this.seq > maxSeq) {
this.setPre();
this.initSeqAndInc();
}
this.fillSeq();
// @ts-ignore - Uint8Arrays can be an argument
return String.fromCharCode.apply(String, this.buf);
}
reset() {
this.init();
}
}
exports.Nuid = Nuid;
exports.nuid = new Nuid();
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