Replace spinning_top with parking_lot when std is available

oak_functions_service/src/lookup.rs

@@ -65,6 +65,16 @@ impl DataBuilder {
     }
 }
 
+#[cfg(feature = "std")]
+mod mutexes {
+    pub use parking_lot::{Mutex, RwLock};
+}
+
+#[cfg(not(feature = "std"))]
+mod mutexes {
+    pub use spinning_top::{RwSpinlock as RwLock, Spinlock as Mutex};
+}
+
 /// Utility for managing lookup data.
 ///
 /// `LookupDataManager` can be used to create `LookupData` instances that share
@@ -82,33 +92,21 @@ impl DataBuilder {
 /// In the future we may replace both the mutex and the hash map with something
 /// like RCU.
 pub struct LookupDataManager {
-    #[cfg(feature = "std")]
-    data: parking_lot::RwLock<Arc<Data>>,
-    #[cfg(not(feature = "std"))]
-    data: spinning_top::RwSpinlock<Arc<Data>>,
+    data: mutexes::RwLock<Arc<Data>>,
     // Behind a lock, because we have multiple references to LookupDataManager and need to mutate
     // data builder.
-    #[cfg(feature = "std")]
-    data_builder: parking_lot::Mutex<DataBuilder>,
-    #[cfg(not(feature = "std"))]
-    data_builder: spinning_top::Spinlock<DataBuilder>,
+    data_builder: mutexes::Mutex<DataBuilder>,
     logger: Arc<dyn OakLogger>,
 }
 
 impl LookupDataManager {
     /// Creates a new instance with empty backing data.
     pub fn new_empty(logger: Arc<dyn OakLogger>) -> Self {
         Self {
-            #[cfg(feature = "std")]
-            data: parking_lot::RwLock::new(Arc::new(Data::default())),
-            #[cfg(not(feature = "std"))]
-            data: spinning_top::RwSpinlock::new(Arc::new(Data::default())),
+            data: mutexes::RwLock::new(Arc::new(Data::default())),
             // Incrementally builds the backing data that will be used by new `LookupData`
             // instances when finished.
-            #[cfg(feature = "std")]
-            data_builder: parking_lot::Mutex::new(DataBuilder::default()),
-            #[cfg(not(feature = "std"))]
-            data_builder: spinning_top::Spinlock::new(DataBuilder::default()),
+            data_builder: mutexes::Mutex::new(DataBuilder::default()),
             logger,
         }
     }