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fix!: refactor v7 internal state and options logic, fixes #764 (#779)
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Co-authored-by: Robert Kieffer <robert@broofa.com>
Co-authored-by: Robin Pokorny <me@robinpokorny.com>
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broofa and robinpokorny authored Jul 18, 2024
1 parent 7eff835 commit 9dbd1cd
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4 changes: 2 additions & 2 deletions README.md
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Expand Up @@ -338,10 +338,10 @@ Create an RFC version 7 (random) UUID
| | |
| --- | --- |
| [`options`] | `Object` with one or more of the following properties: |
| [`options.msecs`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch) |
| [`options.msecs`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch). Default = `Date.now()` |
| [`options.random`] | `Array` of 16 random bytes (0-255) |
| [`options.rng`] | Alternative to `options.random`, a `Function` that returns an `Array` of 16 random bytes (0-255) |
| [`options.seq`] | 31 bit monotonic sequence counter as `Number` between 0 - 0x7fffffff |
| [`options.seq`] | 32-bit sequence `Number` between 0 - 0xffffffff. This may be provided to help insure uniqueness for UUIDs generated within the same millisecond time interval. Default = random value. |
| [`buffer`] | `Array \| Buffer` If specified, uuid will be written here in byte-form, starting at `offset` |
| [`offset` = 0] | `Number` Index to start writing UUID bytes in `buffer` |
| _returns_ | UUID `String` if no `buffer` is specified, otherwise returns `buffer` |
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4 changes: 2 additions & 2 deletions README_js.md
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Expand Up @@ -346,10 +346,10 @@ Create an RFC version 7 (random) UUID
| | |
| --- | --- |
| [`options`] | `Object` with one or more of the following properties: |
| [`options.msecs`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch) |
| [`options.msecs`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch). Default = `Date.now()` |
| [`options.random`] | `Array` of 16 random bytes (0-255) |
| [`options.rng`] | Alternative to `options.random`, a `Function` that returns an `Array` of 16 random bytes (0-255) |
| [`options.seq`] | 31 bit monotonic sequence counter as `Number` between 0 - 0x7fffffff |
| [`options.seq`] | 32-bit sequence `Number` between 0 - 0xffffffff. This may be provided to help insure uniqueness for UUIDs generated within the same millisecond time interval. Default = random value. |
| [`buffer`] | `Array \| Buffer` If specified, uuid will be written here in byte-form, starting at `offset` |
| [`offset` = 0] | `Number` Index to start writing UUID bytes in `buffer` |
| _returns_ | UUID `String` if no `buffer` is specified, otherwise returns `buffer` |
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4 changes: 2 additions & 2 deletions package.json
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Expand Up @@ -113,8 +113,8 @@
"test:browser": "wdio run ./wdio.conf.js",
"test:node": "npm-run-all --parallel examples:node:**",
"test:pack": "./scripts/testpack.sh",
"test:watch": "node --test --watch dist/esm/test",
"test": "node --test dist/esm/test"
"test:watch": "node --test --enable-source-maps --watch dist/esm/test",
"test": "node --test --enable-source-maps dist/esm/test"
},
"repository": {
"type": "git",
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233 changes: 123 additions & 110 deletions src/test/v7.test.ts
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@@ -1,72 +1,40 @@
import * as assert from 'assert';
import test, { describe } from 'node:test';
import { Version7Options } from '../_types.js';
import v7 from '../v7.js';
import parse from '../parse.js';
import stringify from '../stringify.js';
import v7, { updateV7State } from '../v7.js';

/**
* fixture bit layout:
* ref: https://www.rfc-editor.org/rfc/rfc9562.html#name-example-of-a-uuidv7-value
*
* expectedBytes was calculated using this script:
* https://gist.github.com/d5382ac3a1ce4ba9ba40a90d9da8cbf1
*
* -------------------------------
* field bits value
* -------------------------------
* unix_ts_ms 48 0x17F22E279B0
* ver 4 0x7
* rand_a 12 0xCC3
* var 2 b10
* rand_b 62 b01, 0x8C4DC0C0C07398F
* -------------------------------
* total 128
* -------------------------------
* final: 017f22e2-79b0-7cc3-98c4-dc0c0c07398f
*/
// Fixture values for testing with the rfc v7 UUID example:
// https://www.rfc-editor.org/rfc/rfc9562.html#name-example-of-a-uuidv7-value
const RFC_V7 = '017f22e2-79b0-7cc3-98c4-dc0c0c07398f';
const RFC_V7_BYTES = parse('017f22e2-79b0-7cc3-98c4-dc0c0c07398f');
const RFC_MSECS = 0x17f22e279b0;

describe('v7', () => {
const msecsFixture = 1645557742000;
const seqFixture = 0x661b189b;

const randomBytesFixture = Uint8Array.of(
0x10,
0x91,
0x56,
0xbe,
0xc4,
0xfb,
0x0c,
0xc3,
0x18,
0xc4,
0xdc,
0x0c,
0x0c,
0x07,
0x39,
0x8f
);
// `option.seq` for the above RFC uuid
const RFC_SEQ = (0x0cc3 << 20) | (0x98c4dc >> 2);

const expectedBytes = Uint8Array.of(
1,
127,
34,
226,
121,
176,
124,
195,
152,
196,
220,
12,
12,
7,
57,
143
);
// `option,random` for the above RFC uuid
const RFC_RANDOM = Uint8Array.of(
0x10,
0x91,
0x56,
0xbe,
0xc4,
0xfb,
0x0c,
0xc3,
0x18,
0xc4,
0x6c,
0x0c,
0x0c,
0x07,
0x39,
0x8f
);

describe('v7', () => {
test('subsequent UUIDs are different', () => {
const id1 = v7();
const id2 = v7();
Expand All @@ -75,25 +43,25 @@ describe('v7', () => {

test('explicit options.random and options.msecs produces expected result', () => {
const id = v7({
random: randomBytesFixture,
msecs: msecsFixture,
seq: seqFixture,
random: RFC_RANDOM,
msecs: RFC_MSECS,
seq: RFC_SEQ,
});
assert.strictEqual(id, '017f22e2-79b0-7cc3-98c4-dc0c0c07398f');
assert.strictEqual(id, RFC_V7);
});

test('explicit options.rng produces expected result', () => {
const id = v7({
rng: () => randomBytesFixture,
msecs: msecsFixture,
seq: seqFixture,
rng: () => RFC_RANDOM,
msecs: RFC_MSECS,
seq: RFC_SEQ,
});
assert.strictEqual(id, '017f22e2-79b0-7cc3-98c4-dc0c0c07398f');
assert.strictEqual(id, RFC_V7);
});

test('explicit options.msecs produces expected result', () => {
const id = v7({
msecs: msecsFixture,
msecs: RFC_MSECS,
});
assert.strictEqual(id.indexOf('017f22e2'), 0);
});
Expand All @@ -102,13 +70,15 @@ describe('v7', () => {
const buffer = new Uint8Array(16);
const result = v7(
{
random: randomBytesFixture,
msecs: msecsFixture,
seq: seqFixture,
random: RFC_RANDOM,
msecs: RFC_MSECS,
seq: RFC_SEQ,
},
buffer
);
assert.deepEqual(buffer, expectedBytes);
stringify(buffer);

assert.deepEqual(buffer, RFC_V7_BYTES);
assert.strictEqual(buffer, result);
});

Expand All @@ -117,25 +87,25 @@ describe('v7', () => {

v7(
{
random: randomBytesFixture,
msecs: msecsFixture,
seq: seqFixture,
random: RFC_RANDOM,
msecs: RFC_MSECS,
seq: RFC_SEQ,
},
buffer,
0
);
v7(
{
random: randomBytesFixture,
msecs: msecsFixture,
seq: seqFixture,
random: RFC_RANDOM,
msecs: RFC_MSECS,
seq: RFC_SEQ,
},
buffer,
16
);
const expected = new Uint8Array(32);
expected.set(expectedBytes);
expected.set(expectedBytes, 16);
expected.set(RFC_V7_BYTES);
expected.set(RFC_V7_BYTES, 16);
assert.deepEqual(buffer, expected);
});

Expand All @@ -146,15 +116,15 @@ describe('v7', () => {
test('lexicographical sorting is preserved', () => {
let id;
let prior;
let msecs = msecsFixture;
let msecs = RFC_MSECS;
for (let i = 0; i < 20000; ++i) {
if (i % 1500 === 0) {
// every 1500 runs increment msecs so seq is
// reinitialized, simulating passage of time
msecs += 1;
}

id = v7({ msecs });
id = v7({ msecs, seq: i });

if (prior !== undefined) {
assert.ok(prior < id, `${prior} < ${id}`);
Expand All @@ -164,46 +134,89 @@ describe('v7', () => {
}
});

test('handles seq rollover', () => {
const msecs = msecsFixture;
const a = v7({
msecs,
seq: 0x7fffffff,
});

v7({ msecs });

const c = v7({ msecs });

assert.ok(a < c, `${a} < ${c}`);
test('internal state updates properly', () => {
const tests = [
{
title: 'new time interval',
state: { msecs: 1, seq: 123 },
now: 2,
expected: {
msecs: 2, // time interval should update
seq: 0x6c318c4, // sequence should be randomized
},
},
{
title: 'same time interval',
state: { msecs: 1, seq: 123 },
now: 1,
expected: {
msecs: 1, // timestamp unchanged
seq: 124, // sequence increments
},
},
{
title: 'same time interval (sequence rollover)',
state: { msecs: 1, seq: 0xffffffff },
now: 1,
expected: {
msecs: 2, // timestamp increments
seq: 0, // sequence rolls over
},
},
{
title: 'time regression',
state: { msecs: 2, seq: 123 },
now: 1,
expected: {
msecs: 2, // timestamp unchanged
seq: 124, // sequence increments
},
},
{
title: 'time regression (sequence rollover)',
state: { msecs: 2, seq: 0xffffffff },
now: 1,
expected: {
// timestamp increments (crazy, right? The system clock goes backwards
// but the UUID timestamp moves forward? Weird, but it's what's
// required to maintain monotonicity... and this is why we have unit
// tests!)
msecs: 3,
seq: 0, // sequence rolls over
},
},
];
for (const { title, state, now, expected } of tests) {
assert.deepStrictEqual(updateV7State(state, now, RFC_RANDOM), expected, `Failed: ${title}`);
}
});

test('can supply seq', () => {
let seq = 0x12345;
let uuid = v7({
msecs: msecsFixture,
msecs: RFC_MSECS,
seq,
});

assert.strictEqual(uuid.substr(0, 25), '017f22e2-79b0-7000-891a-2');
assert.strictEqual(uuid.substr(0, 25), '017f22e2-79b0-7000-848d-1');

seq = 0x6fffffff;
uuid = v7({
msecs: msecsFixture,
msecs: RFC_MSECS,
seq,
});

assert.strictEqual(uuid.substr(0, 25), '017f22e2-79b0-7dff-bfff-f');
assert.strictEqual(uuid.substring(0, 25), '017f22e2-79b0-76ff-bfff-f');
});

test('internal seq is reset upon timestamp change', () => {
v7({
msecs: msecsFixture,
msecs: RFC_MSECS,
seq: 0x6fffffff,
});

const uuid = v7({
msecs: msecsFixture + 1,
msecs: RFC_MSECS + 1,
});

assert.ok(uuid.indexOf('fff') !== 15);
Expand All @@ -216,18 +229,18 @@ describe('v7', () => {
// convert the given number of bits (LE) to number
const asNumber = (bits: number, data: bigint) => Number(BigInt.asUintN(bits, data));

// flip the nth bit (BE) in a BigInt
// flip the nth bit (BE) in a BigInt
const flip = (data: bigint, n: number) => data ^ (1n << BigInt(127 - n));

// Extract v7 `options` from a (BigInt) UUID
const optionsFrom = (data: bigint): Version7Options => {
const ms = asNumber(48, data >> (128n - 48n));
const hi = asNumber(12, data >> (43n + 19n + 2n));
const lo = asNumber(19, data >> 43n);
const r = BigInt.asUintN(43, data);
const ms = asNumber(48, data >> 80n);
const hi = asNumber(12, data >> 64n);
const lo = asNumber(20, data >> 42n);
const r = BigInt.asUintN(42, data);
return {
msecs: ms,
seq: (hi << 19) | lo,
seq: (hi << 20) | lo,
random: Uint8Array.from([
...Array(10).fill(0),
...Array(6)
Expand All @@ -247,8 +260,8 @@ describe('v7', () => {
}
const flipped = flip(data, i);
assert.strictEqual(
asBigInt(v7(optionsFrom(flipped), buf)),
flipped,
asBigInt(v7(optionsFrom(flipped), buf)).toString(16),
flipped.toString(16),
`Unequal uuids at bit ${i}`
);
assert.notStrictEqual(stringify(buf), id);
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