| 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; |