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use crate::{bitmask, Ulid};
use std::time::{Duration, SystemTime};
impl Ulid {
/// Creates a new Ulid with the current time (UTC)
///
/// Using this function to generate Ulids will not guarantee monotonic sort order.
/// See [ulid::Generator] for a monotonic sort order.
/// # Example
/// ```rust
/// use ulid::Ulid;
///
/// let my_ulid = Ulid::new();
/// ```
pub fn new() -> Ulid {
Ulid::from_datetime(crate::time_utils::now())
}
/// Creates a new Ulid using data from the given random number generator
///
/// # Example
/// ```rust
/// use rand::prelude::*;
/// use ulid::Ulid;
///
/// let mut rng = StdRng::from_os_rng();
/// let ulid = Ulid::with_source(&mut rng);
/// ```
pub fn with_source<R: rand::Rng>(source: &mut R) -> Ulid {
Ulid::from_datetime_with_source(crate::time_utils::now(), source)
}
/// Creates a new Ulid with the given datetime
///
/// This can be useful when migrating data to use Ulid identifiers.
///
/// This will take the maximum of the `[SystemTime]` argument and `[SystemTime::UNIX_EPOCH]`
/// as earlier times are not valid for a Ulid timestamp
///
/// # Example
/// ```rust
/// use std::time::{SystemTime, Duration};
/// use ulid::Ulid;
///
/// let ulid = Ulid::from_datetime(SystemTime::now());
/// ```
pub fn from_datetime(datetime: SystemTime) -> Ulid {
Ulid::from_datetime_with_source(datetime, &mut rand::rng())
}
/// Creates a new Ulid with the given datetime and random number generator
///
/// This will take the maximum of the `[SystemTime]` argument and `[SystemTime::UNIX_EPOCH]`
/// as earlier times are not valid for a Ulid timestamp
///
/// # Example
/// ```rust
/// use std::time::{SystemTime, Duration};
/// use rand::prelude::*;
/// use ulid::Ulid;
///
/// let mut rng = StdRng::from_os_rng();
/// let ulid = Ulid::from_datetime_with_source(SystemTime::now(), &mut rng);
/// ```
pub fn from_datetime_with_source<R>(datetime: SystemTime, source: &mut R) -> Ulid
where
R: rand::Rng + ?Sized,
{
let timestamp = datetime
.duration_since(SystemTime::UNIX_EPOCH)
.unwrap_or(Duration::ZERO)
.as_millis();
let timebits = (timestamp & bitmask!(Self::TIME_BITS)) as u64;
let msb = timebits << 16 | u64::from(source.random::<u16>());
let lsb = source.random::<u64>();
Ulid::from((msb, lsb))
}
/// Gets the datetime of when this Ulid was created accurate to 1ms
///
/// # Example
/// ```rust
/// use std::time::{SystemTime, Duration};
/// use ulid::Ulid;
///
/// let dt = SystemTime::now();
/// let ulid = Ulid::from_datetime(dt);
///
/// assert!(
/// dt + Duration::from_millis(1) >= ulid.datetime()
/// && dt - Duration::from_millis(1) <= ulid.datetime()
/// );
/// ```
pub fn datetime(&self) -> SystemTime {
let stamp = self.timestamp_ms();
SystemTime::UNIX_EPOCH + Duration::from_millis(stamp)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_dynamic() {
let ulid = Ulid::new();
let encoded = ulid.to_string();
let ulid2 = Ulid::from_string(&encoded).expect("failed to deserialize");
println!("{}", encoded);
println!("{:?}", ulid);
println!("{:?}", ulid2);
assert_eq!(ulid, ulid2);
}
#[test]
fn test_source() {
use rand::rngs::mock::StepRng;
let mut source = StepRng::new(123, 0);
let u1 = Ulid::with_source(&mut source);
let dt = SystemTime::now() + Duration::from_millis(1);
let u2 = Ulid::from_datetime_with_source(dt, &mut source);
let u3 = Ulid::from_datetime_with_source(dt, &mut source);
assert!(u1 < u2);
assert_eq!(u2, u3);
}
#[test]
fn test_order() {
let dt = SystemTime::now();
let ulid1 = Ulid::from_datetime(dt);
let ulid2 = Ulid::from_datetime(dt + Duration::from_millis(1));
assert!(ulid1 < ulid2);
}
#[test]
fn test_datetime() {
let dt = SystemTime::now();
let ulid = Ulid::from_datetime(dt);
println!("{:?}, {:?}", dt, ulid.datetime());
assert!(ulid.datetime() <= dt);
assert!(ulid.datetime() + Duration::from_millis(1) >= dt);
}
#[test]
fn test_timestamp() {
let dt = SystemTime::now();
let ulid = Ulid::from_datetime(dt);
let ts = dt
.duration_since(SystemTime::UNIX_EPOCH)
.unwrap()
.as_millis();
assert_eq!(u128::from(ulid.timestamp_ms()), ts);
}
#[test]
fn default_is_nil() {
assert_eq!(Ulid::default(), Ulid::nil());
}
#[test]
fn nil_is_at_unix_epoch() {
assert_eq!(Ulid::nil().datetime(), SystemTime::UNIX_EPOCH);
}
#[test]
fn truncates_at_unix_epoch() {
if let Some(before_epoch) = SystemTime::UNIX_EPOCH.checked_sub(Duration::from_secs(100)) {
assert!(before_epoch < SystemTime::UNIX_EPOCH);
assert_eq!(
Ulid::from_datetime(before_epoch).datetime(),
SystemTime::UNIX_EPOCH
);
} else {
// Prior dates are not representable (e.g. wasm32-wasi)
}
}
}