/// <summary>
/// Creates and returns random bytes based on internal <see cref="IUlidRng"/>.
/// </summary>
/// <param name="dateTime">
/// DateTime for which the random bytes need to be generated; this value is used to determine wether a sequence
/// needs to be incremented (same timestamp with millisecond resolution) or reset to a new random value.
/// </param>
/// <returns>Random bytes.</returns>
/// <exception cref="InvalidOperationException">
/// Thrown when the specified <paramref name="dateTime"/> is before the last time this method was called.
/// </exception>
public override byte[] GetRandomBytes(DateTimeOffset dateTime)
{
lock (_genlock)
{
// Get unix time for given datetime
var timestamp = Ulid.ToUnixTimeMilliseconds(dateTime);
if (timestamp <= _lastgen) // Same or earlier timestamp as last time we generated random values?
{
// Increment our random value by one.
var i = RANDLEN;
while (--i >= 0 && ++_lastvalue[i] == 0)
{
;
}
// If i made it all the way to -1 we have an overflow and we throw
if (i < 0)
{
throw new OverflowException();
}
}
else // New(er) timestamp, so generate a new random value and store the new(er) timestamp
{
_lastvalue = _rng.GetRandomBytes(dateTime); // Use internal RNG to get bytes from
_lastvalue[0] = (byte)(_lastvalue[0] & 0x7F); // Mask out bit 0 of the random part
_lastgen = timestamp; // Store last timestamp
}
return(_lastvalue);
}
}
/// <summary>
/// Creates and returns a new <see cref="Ulid"/> based on the specified time and using the specified RNG.
/// </summary>
/// <param name="time">
/// The <see cref="DateTimeOffset"/> to use for the time-part of the <see cref="Ulid"/>.
/// </param>
/// <param name="rng">The <see cref="IUlidRng"/> to use for random number generation.</param>
/// <returns>Returns a new <see cref="Ulid"/>.</returns>
/// <exception cref="ArgumentNullException">Thrown when <paramref name="rng"/> is <see langword="null"/>.</exception>
public static Ulid NewUlid(DateTimeOffset time, IUlidRng rng)
{
if (rng == null)
{
throw new ArgumentNullException(nameof(rng));
}
return(new Ulid(time, rng.GetRandomBytes(time)));
}
public static Guid NewGuid()
{
var timePart = DateTime.Now;
var randomPart = DEFAULTRNG.GetRandomBytes(10);
var d = DateTimeOffsetToByteArray(timePart);
byte[] bytes = new byte[] { d[3], d[2], d[1], d[0], d[5], d[4], d[7], d[6],
randomPart[0], randomPart[1], randomPart[2], randomPart[3],
randomPart[4], randomPart[5], randomPart[6], randomPart[7] };
return(new Guid(bytes));
//return new byte[] { _d, _c, _b, _a, _f, _e, _h, _g, _i, _j, _k, _l, _m, _n, _o, _p };
}
/// <summary>
/// Creates and returns random bytes based on internal <see cref="IUlidRng"/>.
/// </summary>
/// <param name="dateTime">
/// DateTime for which the random bytes need to be generated; this value is used to determine wether a sequence
/// needs to be incremented (same timestamp with millisecond resolution) or reset to a new random value.
/// </param>
/// <returns>Random bytes.</returns>
/// <exception cref="InvalidOperationException">
/// Thrown when the specified <paramref name="dateTime"/> is before the last time this method was called.
/// </exception>
public override byte[] GetRandomBytes(DateTimeOffset dateTime)
{
lock (_genlock)
{
// Get unix time for given datetime
var timestamp = Ulid.ToUnixTimeMilliseconds(dateTime);
if (timestamp < _lastgen)
{
throw new InvalidOperationException("Clock moved backwards; this is not supported.");
}
if (timestamp == _lastgen) // Same timestamp as last time we generated random values?
{
// Increment our random value by one.
var i = RANDLEN;
while (--i >= 0 && ++_lastvalue[i] == 0)
{
;
}
// If i made it all the way to -1 we have an overflow and we throw
if (i < 0)
{
throw new OverflowException();
}
}
else // New(er) timestamp, so generate a new random value and store the new(er) timestamp
{
_lastvalue = _rng.GetRandomBytes(dateTime); // Use internal RNG to get bytes from
for (var i = 0; i < _mask.Length && _mask[i] < 255; i++) // Mask out desired number of MSB's
{
_lastvalue[i] = (byte)(_lastvalue[i] & _mask[i]);
}
_lastgen = timestamp; // Store last timestamp
}
return(_lastvalue);
}
}
/// <summary>
/// Creates and returns a new <see cref="Ulid"/> based on the specified time and using the specified RNG.
/// </summary>
/// <param name="time">
/// The <see cref="DateTimeOffset"/> to use for the time-part of the <see cref="Ulid"/>.
/// </param>
/// <param name="rng">The <see cref="IUlidRng"/> to use for random number generation.</param>
/// <returns>Returns a new <see cref="Ulid"/>.</returns>
public static Ulid NewUlid(DateTimeOffset time, IUlidRng rng)
{
return(new Ulid(time, rng.GetRandomBytes(10)));
}
