1 files changed, 41 insertions, 0 deletions
diff --git a/toolkit/crashreporter/client/app/src/thread_bound.rs b/toolkit/crashreporter/client/app/src/thread_bound.rs
new file mode 100644
index 0000000000..28095f42f4
--- /dev/null
+++ b/toolkit/crashreporter/client/app/src/thread_bound.rs
@@ -0,0 +1,41 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Encapsulate thread-bound values in a safe manner.
+//!
+//! This allows non-`Send`/`Sync` values to be transferred across thread boundaries, checking at
+//! runtime at access sites whether it is safe to use them.
+
+pub struct ThreadBound<T> {
+    data: T,
+    origin: std::thread::ThreadId,
+}
+
+impl<T: Default> Default for ThreadBound<T> {
+    fn default() -> Self {
+        ThreadBound::new(Default::default())
+    }
+}
+
+impl<T> ThreadBound<T> {
+    pub fn new(data: T) -> Self {
+        ThreadBound {
+            data,
+            origin: std::thread::current().id(),
+        }
+    }
+
+    pub fn borrow(&self) -> &T {
+        assert!(
+            std::thread::current().id() == self.origin,
+            "unsafe access to thread-bound value"
+        );
+        &self.data
+    }
+}
+
+// # Safety
+// Access to the inner value is only permitted on the originating thread.
+unsafe impl<T> Send for ThreadBound<T> {}
+unsafe impl<T> Sync for ThreadBound<T> {}