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/broofa/node-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;