switch from time to systemtime

.github/workflows/ci-build.yml

@@ -8,6 +8,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
+      - run: cargo check --package ulid-cli
       - run: cargo test
       - run: cargo test --all-features
       - run: cargo test --no-default-features --features=std

Cargo.toml

@@ -14,13 +14,13 @@ repository = "https://github.com/dylanhart/ulid-rs"
 
 [features]
 default = ["std"]
-std = ["rand", "time"]
+std = ["rand"]
+time = []
 
 [dependencies]
 serde = { version = "1.0", features = ["derive"], optional = true }
 rand = { version = "0.8", optional = true }
 # -- Sync versions with the WASM target below --
-time = { version = "0.3", optional = true }
 uuid = { version = "1.1", optional = true }
 
 [dev-dependencies]

benches/bench.rs

@@ -1,9 +1,9 @@
 use bencher::{benchmark_group, benchmark_main, Bencher};
-use time::OffsetDateTime;
+use std::time::SystemTime;
 use ulid::{Generator, Ulid, ULID_LEN};
 
 fn bench_new(b: &mut Bencher) {
-    b.iter(|| Ulid::new());
+    b.iter(Ulid::new);
 }
 
 fn bench_generator_generate(b: &mut Bencher) {
@@ -12,7 +12,7 @@ fn bench_generator_generate(b: &mut Bencher) {
 }
 
 fn bench_from_time(b: &mut Bencher) {
-    let time = OffsetDateTime::now_utc();
+    let time = SystemTime::now();
     b.iter(|| Ulid::from_datetime(time));
 }
 

cli/Cargo.toml

@@ -16,3 +16,4 @@ edition = "2018"
 [dependencies]
 structopt = "0.2"
 ulid = { version = "*", path = ".." }
+time = "0.3.11"

cli/src/bin/ulid.rs

@@ -62,7 +62,7 @@ fn generate(count: u32, monotonic: bool) {
 
 fn inspect(values: &[String]) {
     for val in values {
-        let ulid = Ulid::from_string(&val);
+        let ulid = Ulid::from_string(val);
         match ulid {
             Ok(ulid) => {
                 let upper_hex = format!("{:X}", ulid.0);
@@ -81,7 +81,7 @@ COMPONENTS:
 ",
                     ulid.to_string(),
                     upper_hex,
-                    ulid.datetime(),
+                    time::OffsetDateTime::from(ulid.datetime()),
                     ulid.timestamp_ms(),
                     upper_hex.chars().skip(6).collect::<String>()
                 );

src/generator.rs

@@ -1,4 +1,4 @@
-use time::OffsetDateTime;
+use std::time::{Duration, SystemTime};
 
 use std::fmt;
 
@@ -42,7 +42,7 @@ impl Generator {
     /// assert!(ulid1 < ulid2);
     /// ```
     pub fn generate(&mut self) -> Result<Ulid, MonotonicError> {
-        let now = OffsetDateTime::now_utc();
+        let now = SystemTime::now();
         self.generate_from_datetime(now)
     }
 
@@ -53,9 +53,9 @@ impl Generator {
     /// # Example
     /// ```rust
     /// use ulid::Generator;
-    /// use time::OffsetDateTime;
+    /// use std::time::SystemTime;
     ///
-    /// let dt = OffsetDateTime::now_utc();
+    /// let dt = SystemTime::now();
     /// let mut gen = Generator::new();
     ///
     /// let ulid1 = gen.generate_from_datetime(dt).unwrap();
@@ -64,10 +64,7 @@ impl Generator {
     /// assert_eq!(ulid1.datetime(), ulid2.datetime());
     /// assert!(ulid1 < ulid2);
     /// ```
-    pub fn generate_from_datetime(
-        &mut self,
-        datetime: OffsetDateTime,
-    ) -> Result<Ulid, MonotonicError> {
+    pub fn generate_from_datetime(&mut self, datetime: SystemTime) -> Result<Ulid, MonotonicError> {
         self.generate_from_datetime_with_source(datetime, &mut rand::thread_rng())
     }
 
@@ -79,7 +76,7 @@ impl Generator {
     /// ```rust
     /// use ulid::Generator;
     /// use ulid::Ulid;
-    /// use time::OffsetDateTime;
+    /// use std::time::SystemTime;
     /// use rand::prelude::*;
     ///
     /// let mut rng = StdRng::from_entropy();
@@ -94,7 +91,7 @@ impl Generator {
     where
         R: rand::Rng,
     {
-        let now = OffsetDateTime::now_utc();
+        let now = SystemTime::now();
         self.generate_from_datetime_with_source(now, source)
     }
 
@@ -105,10 +102,10 @@ impl Generator {
     /// # Example
     /// ```rust
     /// use ulid::Generator;
-    /// use time::OffsetDateTime;
+    /// use std::time::SystemTime;
     /// use rand::prelude::*;
     ///
-    /// let dt = OffsetDateTime::now_utc();
+    /// let dt = SystemTime::now();
     /// let mut rng = StdRng::from_entropy();
     /// let mut gen = Generator::new();
     ///
@@ -120,16 +117,21 @@ impl Generator {
     /// ```
     pub fn generate_from_datetime_with_source<R>(
         &mut self,
-        datetime: OffsetDateTime,
+        datetime: SystemTime,
         source: &mut R,
     ) -> Result<Ulid, MonotonicError>
     where
         R: rand::Rng,
     {
-        let last_ms = self.previous.timestamp_ms() as i128;
+        let last_ms = self.previous.timestamp_ms();
         // maybe time went backward, or it is the same ms.
         // increment instead of generating a new random so that it is monotonic
-        if (datetime.unix_timestamp_nanos() / 1_000_000) <= last_ms {
+        if datetime
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .unwrap_or(Duration::ZERO)
+            .as_millis()
+            <= u128::from(last_ms)
+        {
             if let Some(next) = self.previous.increment() {
                 self.previous = next;
                 return Ok(next);
@@ -170,15 +172,15 @@ impl fmt::Display for MonotonicError {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use ::time::Duration;
+    use std::time::Duration;
 
     #[test]
     fn test_order_monotonic() {
-        let dt = OffsetDateTime::now_utc();
+        let dt = SystemTime::now();
         let mut gen = Generator::new();
         let ulid1 = gen.generate_from_datetime(dt).unwrap();
         let ulid2 = gen.generate_from_datetime(dt).unwrap();
-        let ulid3 = Ulid::from_datetime(dt + Duration::milliseconds(1));
+        let ulid3 = Ulid::from_datetime(dt + Duration::from_millis(1));
         assert_eq!(ulid1.0 + 1, ulid2.0);
         assert!(ulid2 < ulid3);
         assert!(ulid2.timestamp_ms() < ulid3.timestamp_ms())

src/lib.rs

@@ -37,11 +37,11 @@ struct ReadMeDoctest;
 
 mod base32;
 #[cfg(feature = "std")]
-mod time;
-#[cfg(feature = "std")]
 mod generator;
 #[cfg(feature = "serde")]
 pub mod serde;
+#[cfg(feature = "std")]
+mod time;
 #[cfg(feature = "uuid")]
 mod uuid;
 
@@ -145,13 +145,13 @@ impl Ulid {
     /// # Example
     /// ```rust
     /// # #[cfg(feature = "std")] {
-    /// use ::time::OffsetDateTime;
+    /// use std::time::{SystemTime, Duration};
     /// use ulid::Ulid;
     ///
-    /// let dt = OffsetDateTime::now_utc();
+    /// let dt = SystemTime::now();
     /// let ulid = Ulid::from_datetime(dt);
     ///
-    /// assert_eq!(ulid.timestamp_ms(), (dt.unix_timestamp_nanos() / 1_000_000) as u64);
+    /// assert_eq!(u128::from(ulid.timestamp_ms()), dt.duration_since(SystemTime::UNIX_EPOCH).unwrap_or(Duration::ZERO).as_millis());
     /// # }
     /// ```
     pub const fn timestamp_ms(&self) -> u64 {

src/time.rs

@@ -1,6 +1,5 @@
-use ::time::OffsetDateTime;
-
 use crate::{bitmask, Ulid};
+use std::time::{Duration, SystemTime};
 
 impl Ulid {
     /// Creates a new Ulid with the current time (UTC)
@@ -12,7 +11,7 @@ impl Ulid {
     /// let my_ulid = Ulid::new();
     /// ```
     pub fn new() -> Ulid {
-        Ulid::from_datetime(OffsetDateTime::now_utc())
+        Ulid::from_datetime(SystemTime::now())
     }
 
     /// Creates a new Ulid using data from the given random number generator
@@ -26,40 +25,49 @@ impl Ulid {
     /// let ulid = Ulid::with_source(&mut rng);
     /// ```
     pub fn with_source<R: rand::Rng>(source: &mut R) -> Ulid {
-        Ulid::from_datetime_with_source(OffsetDateTime::now_utc(), source)
+        Ulid::from_datetime_with_source(SystemTime::now(), source)
     }
 
     /// Creates a new Ulid with the given datetime
     ///
-    /// This can be useful when migrating data to use Ulid identifiers
+    /// 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 time::OffsetDateTime;
+    /// use std::time::{SystemTime, Duration};
     /// use ulid::Ulid;
     ///
-    /// let ulid = Ulid::from_datetime(OffsetDateTime::now_utc());
+    /// let ulid = Ulid::from_datetime(SystemTime::now());
     /// ```
-    pub fn from_datetime(datetime: OffsetDateTime) -> Ulid {
+    pub fn from_datetime(datetime: SystemTime) -> Ulid {
         Ulid::from_datetime_with_source(datetime, &mut rand::thread_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 time::OffsetDateTime;
+    /// use std::time::{SystemTime, Duration};
     /// use rand::prelude::*;
     /// use ulid::Ulid;
     ///
     /// let mut rng = StdRng::from_entropy();
-    /// let ulid = Ulid::from_datetime_with_source(OffsetDateTime::now_utc(), &mut rng);
+    /// let ulid = Ulid::from_datetime_with_source(SystemTime::now(), &mut rng);
     /// ```
-    pub fn from_datetime_with_source<R>(datetime: OffsetDateTime, source: &mut R) -> Ulid
+    pub fn from_datetime_with_source<R>(datetime: SystemTime, source: &mut R) -> Ulid
     where
         R: rand::Rng,
     {
-        let timestamp = datetime.unix_timestamp_nanos() / 1_000_000;
+        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.gen::<u16>());
@@ -71,30 +79,26 @@ impl Ulid {
     ///
     /// # Example
     /// ```rust
-    /// use time::Duration;
-    /// use time::OffsetDateTime;
+    /// use std::time::{SystemTime, Duration};
     /// use ulid::Ulid;
     ///
-    /// let dt = OffsetDateTime::now_utc();
+    /// let dt = SystemTime::now();
     /// let ulid = Ulid::from_datetime(dt);
     ///
-    /// assert!((dt - ulid.datetime()) < Duration::milliseconds(1));
+    /// assert!(
+    ///     dt + Duration::from_millis(1) >= ulid.datetime()
+    ///     && dt - Duration::from_millis(1) <= ulid.datetime()
+    /// );
     /// ```
-    pub fn datetime(&self) -> OffsetDateTime {
+    pub fn datetime(&self) -> SystemTime {
         let stamp = self.timestamp_ms();
-        let secs = stamp / 1000;
-        let millis = stamp % 1000;
-        OffsetDateTime::from_unix_timestamp_nanos(
-            ((secs * 1_000_000_000) + (millis * 1_000_000)) as i128,
-        )
-        .expect("Seconds and Milliseconds are out of range")
+        SystemTime::UNIX_EPOCH + Duration::from_millis(stamp)
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use ::time::Duration;
 
     #[test]
     fn test_dynamic() {
@@ -114,7 +118,7 @@ mod tests {
         let mut source = StepRng::new(123, 0);
 
         let u1 = Ulid::with_source(&mut source);
-        let dt = OffsetDateTime::now_utc() + Duration::milliseconds(1);
+        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);
 
@@ -124,33 +128,51 @@ mod tests {
 
     #[test]
     fn test_order() {
-        let dt = OffsetDateTime::now_utc();
+        let dt = SystemTime::now();
         let ulid1 = Ulid::from_datetime(dt);
-        let ulid2 = Ulid::from_datetime(dt + Duration::milliseconds(1));
+        let ulid2 = Ulid::from_datetime(dt + Duration::from_millis(1));
         assert!(ulid1 < ulid2);
     }
 
     #[test]
     fn test_datetime() {
-        let dt = OffsetDateTime::now_utc();
+        let dt = SystemTime::now();
         let ulid = Ulid::from_datetime(dt);
 
         println!("{:?}, {:?}", dt, ulid.datetime());
         assert!(ulid.datetime() <= dt);
-        assert!(ulid.datetime() + Duration::milliseconds(1) >= dt);
+        assert!(ulid.datetime() + Duration::from_millis(1) >= dt);
     }
 
     #[test]
     fn test_timestamp() {
-        let dt = OffsetDateTime::now_utc();
+        let dt = SystemTime::now();
         let ulid = Ulid::from_datetime(dt);
-        let ts = dt.unix_timestamp() as u64 * 1000 + dt.millisecond() as u64;
+        let ts = dt
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .unwrap()
+            .as_millis();
 
-        assert_eq!(ulid.timestamp_ms(), ts);
+        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() {
+        let before_epoch = SystemTime::UNIX_EPOCH - Duration::from_secs(100);
+        assert!(before_epoch < SystemTime::UNIX_EPOCH);
+        assert_eq!(
+            Ulid::from_datetime(before_epoch).datetime(),
+            SystemTime::UNIX_EPOCH
+        );
+    }
 }