/// <summary>
/// Initializes a new instance of the <see cref="MonotonicUlidRng"/> class.
/// </summary>
/// <param name="rng">The <see cref="IUlidRng"/> to get the random numbers from.</param>
/// <param name="lastValue">The last value to 'continue from'; use <see langword="null"/> for defaults.</param>
/// <exception cref="ArgumentNullException">Thrown when <paramref name="rng"/> is null.</exception>
public MonotonicUlidRng(IUlidRng rng, Ulid?lastValue = null)
{
_rng = rng ?? throw new ArgumentNullException(nameof(rng));
_lastvalue = lastValue == null ? new byte[RANDLEN] : lastValue.Value.Random;
_lastgen = Ulid.ToUnixTimeMilliseconds(lastValue == null ? Ulid.EPOCH : lastValue.Value.Time);
}
/// <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)));
}
/// <summary>
/// Initializes a new instance of the <see cref="MonotonicUlidRng"/> class.
/// </summary>
/// <param name="rng">The <see cref="IUlidRng"/> to get the random numbers from.</param>
/// <param name="maskMsbBits">
/// The number of (most significant) bits to mask out / set to 0 when generating a random value for a given
/// timestamp
/// </param>
/// <param name="lastValue">The last value to 'continue from'; use <see langword="null"/> for defaults.</param>
/// <exception cref="ArgumentNullException">Thrown when <paramref name="rng"/> is null.</exception>
/// <exception cref="ArgumentOutOfRangeException">
/// Thrown when <paramref name="maskMsbBits"/> is less than 0 or more than 70.
/// </exception>
public MonotonicUlidRng(IUlidRng rng, int maskMsbBits = DEFAULTMSBMASKBITS, Ulid?lastValue = null)
{
_rng = rng ?? throw new ArgumentNullException(nameof(rng));
var maskbits = maskMsbBits >= 0 && maskMsbBits <= 80 - DEFAULTMSBMASKBITS ? maskMsbBits : throw new ArgumentOutOfRangeException(nameof(maskMsbBits));
_lastvalue = lastValue == null ? new byte[RANDLEN] : lastValue.Value.Random;
_lastgen = Ulid.ToUnixTimeMilliseconds(lastValue == null ? Ulid.EPOCH : lastValue.Value.Time);
// Prepare (or 'pre-compute') mask
for (var i = 0; i < _mask.Length; i++)
{
var bits = maskbits > 8 ? 8 : maskbits; // Calculate number of bits to mask from this byte
maskbits -= bits; // Decrease number of bits needing to mask total
_mask[i] = (byte)((1 << 8 - bits) - 1);
}
}
/// <summary> /// Creates and returns a new <see cref="Ulid"/> based on the current (UTC) time and using the specified RNG. /// </summary> /// <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(IUlidRng rng) => NewUlid(DateTimeOffset.UtcNow, rng);
/// <summary>
/// Creates and returns a new <see cref="Ulid"/> based on the current (UTC) time and using the specified RNG.
/// </summary>
/// <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(IUlidRng rng)
{
return(NewUlid(DateTimeOffset.UtcNow, rng));
}
/// <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)));
}
/// <summary>
/// Initializes a new instance of the <see cref="MonotonicUlidRng"/> class with a specified
/// <see cref="IUlidRng"/> and default number of mask bits.
/// </summary>
/// <param name="rng">The <see cref="IUlidRng"/> to get the random numbers from.</param>
public MonotonicUlidRng(IUlidRng rng)
: this(rng, DEFAULTMSBMASKBITS)
{
}
