From 8d6b9343e06e97da5238b24db938e2d961a9735c Mon Sep 17 00:00:00 2001
From: Ryan P <r.pridgeon@f5.com>
Date: Mon, 22 Dec 2025 15:45:12 -0500
Subject: [PATCH 1/3] SystemTime::duration_since and UNIX_EPOCH

---
 src/time/mod.rs | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/time/mod.rs b/src/time/mod.rs
index ff99832..2b94f9b 100644
--- a/src/time/mod.rs
+++ b/src/time/mod.rs
@@ -13,7 +13,7 @@ use std::pin::Pin;
 use std::task::{Context, Poll};
 use wasip2::clocks::{
     monotonic_clock::{subscribe_duration, subscribe_instant},
-    wall_clock,
+    wall_clock::{self, Datetime},
 };
 
 use crate::{
@@ -28,11 +28,30 @@ use crate::{
 pub struct SystemTime(wall_clock::Datetime);
 
 impl SystemTime {
+    pub const UNIX_EPOCH: SystemTime = SystemTime(Datetime {
+        seconds: 0,
+        nanoseconds: 0,
+    });
+
     pub fn now() -> Self {
         Self(wall_clock::now())
     }
+
+    pub fn duration_since(&self, earlier: &SystemTime) -> Result<Duration, SystemTimeError> {
+        if self.0.seconds >= earlier.0.seconds {
+            if self.0.nanoseconds >= earlier.0.nanoseconds {
+                return Ok(Duration::new(
+                    self.0.seconds - earlier.0.seconds,
+                    self.0.nanoseconds - earlier.0.nanoseconds,
+                ));
+            }
+        }
+        Err(SystemTimeError())
+    }
 }
 
+pub struct SystemTimeError();
+
 /// An async iterator representing notifications at fixed interval.
 pub fn interval(duration: Duration) -> Interval {
     Interval { duration }
@@ -113,6 +132,18 @@ mod test {
         println!("{what} awaited for {} s", d.as_secs_f32());
     }
 
+    #[test]
+    fn systemtime() {
+        crate::runtime::block_on(async {
+            let earlier = SystemTime::UNIX_EPOCH;
+            let now = SystemTime::now();
+
+            assert!(now.duration_since(&earlier).is_ok());
+            assert!(now.duration_since(&now).is_ok_and(|x| x.as_secs() == 0));
+            assert!(earlier.duration_since(&now).is_err());
+        });
+    }
+
     #[test]
     fn timer_now() {
         crate::runtime::block_on(debug_duration("timer_now", async {

From bad5750fae6a59abcd355da33772cf4f41167286 Mon Sep 17 00:00:00 2001
From: Ryan P <r.pridgeon@f5.com>
Date: Mon, 22 Dec 2025 16:07:33 -0500
Subject: [PATCH 2/3] clippy: collapse nested if

---
 src/time/mod.rs | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/src/time/mod.rs b/src/time/mod.rs
index 2b94f9b..f4b4bf5 100644
--- a/src/time/mod.rs
+++ b/src/time/mod.rs
@@ -38,19 +38,18 @@ impl SystemTime {
     }
 
     pub fn duration_since(&self, earlier: &SystemTime) -> Result<Duration, SystemTimeError> {
-        if self.0.seconds >= earlier.0.seconds {
-            if self.0.nanoseconds >= earlier.0.nanoseconds {
-                return Ok(Duration::new(
-                    self.0.seconds - earlier.0.seconds,
-                    self.0.nanoseconds - earlier.0.nanoseconds,
-                ));
-            }
+        if self.0.seconds >= earlier.0.seconds && self.0.nanoseconds >= earlier.0.nanoseconds {
+            return Ok(Duration::new(
+                self.0.seconds - earlier.0.seconds,
+                self.0.nanoseconds - earlier.0.nanoseconds,
+            ));
         }
-        Err(SystemTimeError())
+
+        Err(SystemTimeError)
     }
 }
 
-pub struct SystemTimeError();
+pub struct SystemTimeError;
 
 /// An async iterator representing notifications at fixed interval.
 pub fn interval(duration: Duration) -> Interval {
@@ -133,7 +132,7 @@ mod test {
     }
 
     #[test]
-    fn systemtime() {
+    fn systemtime_duration_since() {
         crate::runtime::block_on(async {
             let earlier = SystemTime::UNIX_EPOCH;
             let now = SystemTime::now();

From b42b1a84ce575455c08b1caa509a780b21274f2a Mon Sep 17 00:00:00 2001
From: Ryan P <r.pridgeon@f5.com>
Date: Mon, 22 Dec 2025 16:23:38 -0500
Subject: [PATCH 3/3] SystemTimeError should implement debug, copy earlier

---
 src/time/mod.rs | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/time/mod.rs b/src/time/mod.rs
index f4b4bf5..a309900 100644
--- a/src/time/mod.rs
+++ b/src/time/mod.rs
@@ -37,7 +37,7 @@ impl SystemTime {
         Self(wall_clock::now())
     }
 
-    pub fn duration_since(&self, earlier: &SystemTime) -> Result<Duration, SystemTimeError> {
+    pub fn duration_since(&self, earlier: SystemTime) -> Result<Duration, SystemTimeError> {
         if self.0.seconds >= earlier.0.seconds && self.0.nanoseconds >= earlier.0.nanoseconds {
             return Ok(Duration::new(
                 self.0.seconds - earlier.0.seconds,
@@ -49,6 +49,7 @@ impl SystemTime {
     }
 }
 
+#[derive(Debug, Clone, Copy)]
 pub struct SystemTimeError;
 
 /// An async iterator representing notifications at fixed interval.
@@ -137,9 +138,9 @@ mod test {
             let earlier = SystemTime::UNIX_EPOCH;
             let now = SystemTime::now();
 
-            assert!(now.duration_since(&earlier).is_ok());
-            assert!(now.duration_since(&now).is_ok_and(|x| x.as_secs() == 0));
-            assert!(earlier.duration_since(&now).is_err());
+            assert!(now.duration_since(earlier).is_ok());
+            assert!(now.duration_since(now).is_ok_and(|x| x.as_secs() == 0));
+            assert!(earlier.duration_since(now).is_err());
         });
     }