Make DynNum thread-safe

src/numbers/dynnum.rs

@@ -20,6 +20,7 @@ use super::{Assign, Fixed, GuardedFixed, NativeFloat64, Number, Rational};
 use num_traits::{Num, One, Zero};
 //use wasm_bindgen::prelude::wasm_bindgen;
 
+use std::cell::Cell;
 use std::cmp::{Ord, Ordering};
 use std::fmt;
 use std::mem::ManuallyDrop;
@@ -27,6 +28,7 @@ use std::ops::{self, Deref, DerefMut};
 
 /// Represents the underlying implementation for [DynNum]s
 //#[wasm_bindgen]
+#[derive(Copy, Clone)]
 pub enum NumKind {
 	/// See [crate::numbers::fixed]
 	Fixed,
@@ -38,15 +40,15 @@ pub enum NumKind {
 	Rational,
 }
 
-/// Determines which underlying implementation to use
-static mut KIND: NumKind = NumKind::Fixed;
+thread_local! {
+	/// Determines which underlying implementation to use
+	static KIND: Cell<NumKind> = Cell::new(NumKind::Fixed);
+}
 
 /// Returns which underlying implementation is in use
 #[inline]
-fn get_kind() -> &'static NumKind {
-	unsafe {
-		return &KIND;
-	}
+fn get_kind() -> NumKind {
+	return KIND.with(|kind_cell| kind_cell.get());
 }
 
 /// A wrapper for different numeric types using dynamic dispatch
@@ -60,9 +62,9 @@ pub union DynNum {
 impl DynNum {
 	/// Set which underlying implementation to use
 	pub fn set_kind(kind: NumKind) {
-		unsafe {
-			KIND = kind;
-		}
+		KIND.with(|kind_cell| {
+			kind_cell.set(kind);
+		});
 	}
 }