1 files changed, 69 insertions, 0 deletions
diff --git a/crates/tor-memquota/src/utils.rs b/crates/tor-memquota/src/utils.rs
new file mode 100644
index 000000000..4540df03d
--- /dev/null
+++ b/crates/tor-memquota/src/utils.rs
@@ -0,0 +1,69 @@
+//! Miscellanous internal utilities
+
+use crate::internal_prelude::*;
+
+/// Quantity of memory used, measured in bytes.
+///
+/// Like `usize` but `Display`s in a more friendly and less precise way
+#[derive(Debug, Clone, Copy, Hash, Default, Eq, PartialEq, Ord, PartialOrd)] //
+#[derive(From, Into, Deref, DerefMut, Serialize, Deserialize)]
+#[serde(transparent)]
+pub(crate) struct Qty(pub(crate) usize);
+
+impl Qty {
+    /// Maximum for the type
+    pub(crate) const MAX: Qty = Qty(usize::MAX);
+
+    /// Return the value as a plain number, a `usize`
+    ///
+    /// Provided so call sites don't need to write an opaque `.0` everywhere,
+    /// even though that would be fine.
+    pub(crate) const fn as_usize(self) -> usize {
+        self.0
+    }
+}
+
+impl Display for Qty {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mb = self.0 as f32 / (1024. * 1024.);
+        write!(f, "{:.2}MiB", mb)
+    }
+}
+
+/// Convenience extension trait to provide `.take()`
+///
+/// Convenient way to provide `.take()` on some of our types.
+pub(crate) trait DefaultExtTake: Default {
+    /// Returns `*self`, replacing it with the default value.
+    fn take(&mut self) -> Self {
+        mem::take(self)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    // @@ begin test lint list maintained by maint/add_warning @@
+    #![allow(clippy::bool_assert_comparison)]
+    #![allow(clippy::clone_on_copy)]
+    #![allow(clippy::dbg_macro)]
+    #![allow(clippy::mixed_attributes_style)]
+    #![allow(clippy::print_stderr)]
+    #![allow(clippy::print_stdout)]
+    #![allow(clippy::single_char_pattern)]
+    #![allow(clippy::unwrap_used)]
+    #![allow(clippy::unchecked_duration_subtraction)]
+    #![allow(clippy::useless_vec)]
+    #![allow(clippy::needless_pass_by_value)]
+    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->
+
+    use super::*;
+
+    #[test]
+    fn display_qty() {
+        let chk = |by, s| assert_eq!(Qty(by).to_string(), s);
+
+        chk(10 * 1024, "0.01MiB");
+        chk(1024 * 1024, "1.00MiB");
+        chk(1000 * 1024 * 1024, "1000.00MiB");
+    }
+}