cleanup: simplify precompile implementation with an iterator

Signed-off-by: Kate Goldenring <[email protected]>

containerd-shim-spin/src/engine.rs

@@ -357,31 +357,31 @@ impl Engine for SpinEngine {
 
     fn precompile(&self, layers: &[WasmLayer]) -> Result<Vec<Option<Vec<u8>>>> {
         // Runwasi expects layers to be returned in the same order, so wrap each layer in an option, setting non Wasm layers to None
-        let mut wasm_content_layers: Vec<Option<WasmLayer>> =
-            layers.iter().map(SpinEngine::is_wasm_content).collect();
-        for layer in &mut wasm_content_layers {
-            if let Some(wasm_layer) = layer.as_mut() {
-                log::info!(
-                    "Precompile called for wasm layer {:?}",
-                    wasm_layer.config.digest()
-                );
-                if self
-                    .wasmtime_engine
-                    .detect_precompiled(&wasm_layer.layer)
-                    .is_some()
-                {
-                    log::info!("Layer already precompiled {:?}", wasm_layer.config.digest());
-                    continue;
+        let precompiled_layers = layers
+            .iter()
+            .map(|layer| match SpinEngine::is_wasm_content(layer) {
+                Some(wasm_layer) => {
+                    log::info!(
+                        "Precompile called for wasm layer {:?}",
+                        wasm_layer.config.digest()
+                    );
+                    if self
+                        .wasmtime_engine
+                        .detect_precompiled(&wasm_layer.layer)
+                        .is_some()
+                    {
+                        log::info!("Layer already precompiled {:?}", wasm_layer.config.digest());
+                        Ok(None)
+                    } else {
+                        let component =
+                            spin_componentize::componentize_if_necessary(&wasm_layer.layer)?;
+                        let precompiled = self.wasmtime_engine.precompile_component(&component)?;
+                        Ok(Some(precompiled))
+                    }
                 }
-                let component = spin_componentize::componentize_if_necessary(&wasm_layer.layer)?;
-                let precompiled = self.wasmtime_engine.precompile_component(&component)?;
-                wasm_layer.layer = precompiled;
-            }
-        }
-        let precompiled_layers: Vec<Option<Vec<u8>>> = wasm_content_layers
-            .into_iter()
-            .map(|l| l.map(|l| l.layer))
-            .collect();
+                None => Ok(None),
+            })
+            .collect::<anyhow::Result<_>>()?;
         Ok(precompiled_layers)
     }