fix: enhance safety documentation for OwnedJsValue and implement Send/Sync traits

Author: Icemic

src/value/value.rs

@@ -28,12 +28,22 @@ use super::OwnedJsObject;
 /// OwnedJsValue wraps a Javascript value owned by the QuickJs runtime.
 ///
 /// Guarantees cleanup of resources by dropping the value from the runtime.
+/// 
+/// **Safety**:
+/// 
+/// This type is `Send` and `Sync` only for convenience, since [OwnedJsValue](crate::OwnedJsValue)
+/// itself is just a wrapper around a raw pointer. But any operation on the underlying raw pointer is unsafe.
+/// Make sure using it in a same thread.
+/// 
 pub struct OwnedJsValue {
     context: *mut q::JSContext,
     // FIXME: make private again, just for testing
     pub(crate) value: q::JSValue,
 }
 
+unsafe impl Send for OwnedJsValue {}
+unsafe impl Sync for OwnedJsValue {}
+
 impl PartialEq for OwnedJsValue {
     fn eq(&self, other: &Self) -> bool {
         unsafe { q::JS_VALUE_GET_PTR(self.value) == q::JS_VALUE_GET_PTR(other.value) }