109 lines
3.3 KiB
JavaScript
109 lines
3.3 KiB
JavaScript
var rng = require('./lib/rng');
|
|
var bytesToUuid = require('./lib/bytesToUuid');
|
|
|
|
// **`v1()` - Generate time-based UUID**
|
|
//
|
|
// Inspired by https://github.com/LiosK/UUID.js
|
|
// and http://docs.python.org/library/uuid.html
|
|
|
|
var _nodeId;
|
|
var _clockseq;
|
|
|
|
// Previous uuid creation time
|
|
var _lastMSecs = 0;
|
|
var _lastNSecs = 0;
|
|
|
|
// See https://github.com/uuidjs/uuid for API details
|
|
function v1(options, buf, offset) {
|
|
var i = buf && offset || 0;
|
|
var b = buf || [];
|
|
|
|
options = options || {};
|
|
var node = options.node || _nodeId;
|
|
var clockseq = options.clockseq !== undefined ? options.clockseq : _clockseq;
|
|
|
|
// node and clockseq need to be initialized to random values if they're not
|
|
// specified. We do this lazily to minimize issues related to insufficient
|
|
// system entropy. See #189
|
|
if (node == null || clockseq == null) {
|
|
var seedBytes = rng();
|
|
if (node == null) {
|
|
// Per 4.5, create and 48-bit node id, (47 random bits + multicast bit = 1)
|
|
node = _nodeId = [
|
|
seedBytes[0] | 0x01,
|
|
seedBytes[1], seedBytes[2], seedBytes[3], seedBytes[4], seedBytes[5]
|
|
];
|
|
}
|
|
if (clockseq == null) {
|
|
// Per 4.2.2, randomize (14 bit) clockseq
|
|
clockseq = _clockseq = (seedBytes[6] << 8 | seedBytes[7]) & 0x3fff;
|
|
}
|
|
}
|
|
|
|
// UUID timestamps are 100 nano-second units since the Gregorian epoch,
|
|
// (1582-10-15 00:00). JSNumbers aren't precise enough for this, so
|
|
// time is handled internally as 'msecs' (integer milliseconds) and 'nsecs'
|
|
// (100-nanoseconds offset from msecs) since unix epoch, 1970-01-01 00:00.
|
|
var msecs = options.msecs !== undefined ? options.msecs : new Date().getTime();
|
|
|
|
// Per 4.2.1.2, use count of uuid's generated during the current clock
|
|
// cycle to simulate higher resolution clock
|
|
var nsecs = options.nsecs !== undefined ? options.nsecs : _lastNSecs + 1;
|
|
|
|
// Time since last uuid creation (in msecs)
|
|
var dt = (msecs - _lastMSecs) + (nsecs - _lastNSecs)/10000;
|
|
|
|
// Per 4.2.1.2, Bump clockseq on clock regression
|
|
if (dt < 0 && options.clockseq === undefined) {
|
|
clockseq = clockseq + 1 & 0x3fff;
|
|
}
|
|
|
|
// Reset nsecs if clock regresses (new clockseq) or we've moved onto a new
|
|
// time interval
|
|
if ((dt < 0 || msecs > _lastMSecs) && options.nsecs === undefined) {
|
|
nsecs = 0;
|
|
}
|
|
|
|
// Per 4.2.1.2 Throw error if too many uuids are requested
|
|
if (nsecs >= 10000) {
|
|
throw new Error('uuid.v1(): Can\'t create more than 10M uuids/sec');
|
|
}
|
|
|
|
_lastMSecs = msecs;
|
|
_lastNSecs = nsecs;
|
|
_clockseq = clockseq;
|
|
|
|
// Per 4.1.4 - Convert from unix epoch to Gregorian epoch
|
|
msecs += 12219292800000;
|
|
|
|
// `time_low`
|
|
var tl = ((msecs & 0xfffffff) * 10000 + nsecs) % 0x100000000;
|
|
b[i++] = tl >>> 24 & 0xff;
|
|
b[i++] = tl >>> 16 & 0xff;
|
|
b[i++] = tl >>> 8 & 0xff;
|
|
b[i++] = tl & 0xff;
|
|
|
|
// `time_mid`
|
|
var tmh = (msecs / 0x100000000 * 10000) & 0xfffffff;
|
|
b[i++] = tmh >>> 8 & 0xff;
|
|
b[i++] = tmh & 0xff;
|
|
|
|
// `time_high_and_version`
|
|
b[i++] = tmh >>> 24 & 0xf | 0x10; // include version
|
|
b[i++] = tmh >>> 16 & 0xff;
|
|
|
|
// `clock_seq_hi_and_reserved` (Per 4.2.2 - include variant)
|
|
b[i++] = clockseq >>> 8 | 0x80;
|
|
|
|
// `clock_seq_low`
|
|
b[i++] = clockseq & 0xff;
|
|
|
|
// `node`
|
|
for (var n = 0; n < 6; ++n) {
|
|
b[i + n] = node[n];
|
|
}
|
|
|
|
return buf ? buf : bytesToUuid(b);
|
|
}
|
|
|
|
module.exports = v1;
|