From 0eb3f31260232aa233c60ba58e7cd33734aa87cb Mon Sep 17 00:00:00 2001
From: Guillaume Binet <gbin@gootz.net>
Date: Sun, 26 May 2024 15:03:33 -0400
Subject: [PATCH] Adds a rudimentary clock

---
 Cargo.toml              |  2 +-
 copper_clock/Cargo.toml | 12 ++++++
 copper_clock/src/lib.rs | 82 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100644 copper_clock/Cargo.toml
 create mode 100644 copper_clock/src/lib.rs

diff --git a/Cargo.toml b/Cargo.toml
index dda192bd8..95f3afa77 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,3 +1,3 @@
 [workspace]
-members = ["copper", "copper_log_test", "copper_derive", "copper_derive_test", "copper_log", "examples/config_gen", "examples/pluginload", "examples/simplelogger", "examples/v4lsrc", "copper_log_runtime"]
+members = ["copper", "copper_log_test", "copper_derive", "copper_derive_test", "copper_log", "examples/config_gen", "examples/pluginload", "examples/simplelogger", "examples/v4lsrc", "copper_log_runtime", "copper_datalogger", "copper_clock"]
 resolver = "2"
diff --git a/copper_clock/Cargo.toml b/copper_clock/Cargo.toml
new file mode 100644
index 000000000..379806473
--- /dev/null
+++ b/copper_clock/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "copper_clock"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+quanta = "0.12.3"
+bincode = "2.0.0-rc.3"
+bincode_derive = "2.0.0-rc.3"
+
+[dev-dependencies]
+approx = "0.5.1"
diff --git a/copper_clock/src/lib.rs b/copper_clock/src/lib.rs
new file mode 100644
index 000000000..96fd7e6c0
--- /dev/null
+++ b/copper_clock/src/lib.rs
@@ -0,0 +1,82 @@
+pub use quanta::Instant;
+use quanta::{Clock, Mock};
+use std::sync::Arc;
+use std::time::Duration;
+
+#[cfg(test)]
+#[macro_use]
+extern crate approx;
+
+pub struct RobotClock {
+    inner: Clock,
+    ref_time: Instant,
+}
+
+impl RobotClock {
+    pub fn new() -> Self {
+        let clock = Clock::new();
+        let ref_time = clock.now();
+        RobotClock {
+            inner: clock,
+            ref_time,
+        }
+    }
+
+    // Builds a monotonic clock starting at the given reference time.
+    pub fn from_ref_time(ref_time_ns: u64) -> Self {
+        let clock = Clock::new();
+        let ref_time = clock.now() - Duration::from_nanos(ref_time_ns);
+        RobotClock {
+            inner: Clock::new(),
+            ref_time,
+        }
+    }
+
+    // Build a fake clock with a reference time of 0.
+    // The Mock interface enables you to increment and decrement the time.
+    pub fn mock() -> (Self, Arc<Mock>) {
+        let (clock, mock) = Clock::mock();
+        let ref_time = clock.now();
+        (
+            RobotClock {
+                inner: clock,
+                ref_time,
+            },
+            mock,
+        )
+    }
+
+    pub fn elapsed(&self) -> Duration {
+        self.inner.now() - self.ref_time
+    }
+}
+
+impl Default for RobotClock {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_mock() {
+        let (clock, mock) = RobotClock::mock();
+        assert_eq!(clock.elapsed(), Duration::from_secs(0));
+        mock.increment(Duration::from_secs(1));
+        assert_eq!(clock.elapsed(), Duration::from_secs(1));
+    }
+
+    #[test]
+    fn test_from_ref_time() {
+        let tolerance_ms = 10;
+        let clock = RobotClock::from_ref_time(1_000_000_000);
+        assert_relative_eq!(
+            clock.elapsed().as_millis() as f64,
+            Duration::from_secs(1).as_millis() as f64,
+            epsilon = tolerance_ms as f64
+        );
+    }
+}