Create a SynapseDuration rust class

This makes it easier to create a `Duration` instance in Rust.

Author: erikjohnston

rust/src/duration.rs

@@ -0,0 +1,57 @@
+/*
+ * This file is licensed under the Affero General Public License (AGPL) version 3.
+ *
+ * Copyright (C) 2025 Element Creations, Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * See the GNU Affero General Public License for more details:
+ * <https://www.gnu.org/licenses/agpl-3.0.html>.
+ */
+
+use once_cell::sync::OnceCell;
+use pyo3::{
+    types::{IntoPyDict, PyAnyMethods},
+    Bound, BoundObject, IntoPyObject, Py, PyAny, PyResult, Python,
+};
+
+/// A reference to the `synapse.util.duration` module.
+static DURATION: OnceCell<Py<PyAny>> = OnceCell::new();
+
+/// Access to the `synapse.util.duration` module.
+fn duration_module(py: Python<'_>) -> PyResult<&Bound<'_, PyAny>> {
+    Ok(DURATION
+        .get_or_try_init(|| py.import("synapse.util.duration").map(Into::into))?
+        .bind(py))
+}
+
+/// Mirrors the `synapse.util.duration.Duration` Python class.
+pub struct SynapseDuration {
+    microseconds: u64,
+}
+
+impl SynapseDuration {
+    pub fn from_milliseconds(milliseconds: u64) -> Self {
+        Self {
+            microseconds: milliseconds * 1_000,
+        }
+    }
+}
+
+impl<'py> IntoPyObject<'py> for &SynapseDuration {
+    type Target = PyAny;
+    type Output = Bound<'py, Self::Target>;
+    type Error = anyhow::Error;
+
+    fn into_pyobject(self, py: Python<'py>) -> Result<Self::Output, Self::Error> {
+        let duration_module = duration_module(py)?;
+        let kwargs = [("microseconds", self.microseconds)].into_py_dict(py)?;
+        let duration_instance = duration_module
+            .call_method("Duration", (), Some(&kwargs))
+            .map_err(|e| anyhow::anyhow!("Failed to create Duration instance: {}", e))?;
+        Ok(duration_instance.into_bound())
+    }
+}