From d3deaae99d900ff830952f8e75ef2eb61affe568 Mon Sep 17 00:00:00 2001
From: Pat Hickey <phickey@fastly.com>
Date: Thu, 21 Oct 2021 12:09:18 -0700
Subject: [PATCH] collapse some common code

---
 crates/wasmtime/src/instance.rs | 58 +++++++++++++--------------------
 1 file changed, 22 insertions(+), 36 deletions(-)

diff --git a/crates/wasmtime/src/instance.rs b/crates/wasmtime/src/instance.rs
index b2cf6affa5..bced7cfe4c 100644
--- a/crates/wasmtime/src/instance.rs
+++ b/crates/wasmtime/src/instance.rs
@@ -126,6 +126,11 @@ impl Instance {
             typecheck_externs(store.0, module, imports)?;
             Instantiator::new(store.0, module, ImportSource::Externs(imports))?
         };
+        assert!(
+            !store.0.async_support(),
+            "cannot use `new` when async support is enabled on the config"
+        );
+
         i.run(&mut store)
     }
 
@@ -162,7 +167,14 @@ impl Instance {
             typecheck_externs(store.0, module, imports)?;
             Instantiator::new(store.0, module, ImportSource::Externs(imports))?
         };
-        i.run_async(&mut store).await
+        let mut store = store.as_context_mut();
+        assert!(
+            store.0.async_support(),
+            "cannot use `new_async` without enabling async support on the config"
+        );
+        store
+            .on_fiber(|store| i.run(&mut store.as_context_mut()))
+            .await?
     }
 
     pub(crate) fn from_wasmtime(handle: InstanceData, store: &mut StoreOpaque) -> Instance {
@@ -472,13 +484,6 @@ impl<'a> Instantiator<'a> {
     }
 
     fn run<T>(&mut self, store: &mut StoreContextMut<'_, T>) -> Result<Instance, Error> {
-        assert!(
-            !store.0.async_support(),
-            "cannot use `new` when async support is enabled on the config"
-        );
-
-        // NB: this is the same code as `run_async`. It's intentionally
-        // small but should be kept in sync (modulo the async bits).
         loop {
             if let Some((instance, start, toplevel)) = self.step(store.0)? {
                 if let Some(start) = start {
@@ -491,33 +496,6 @@ impl<'a> Instantiator<'a> {
         }
     }
 
-    #[cfg(feature = "async")]
-    async fn run_async<T>(&mut self, store: &mut StoreContextMut<'_, T>) -> Result<Instance, Error>
-    where
-        T: Send,
-    {
-        assert!(
-            store.0.async_support(),
-            "cannot use `new_async` without enabling async support on the config"
-        );
-
-        // NB: this is the same code as `run`. It's intentionally
-        // small but should be kept in sync (modulo the async bits).
-        store
-            .on_fiber(|store| loop {
-                let step = self.step(store.0)?;
-                if let Some((instance, start, toplevel)) = step {
-                    if let Some(start) = start {
-                        Instantiator::start_raw(store, instance, start)?
-                    }
-                    if toplevel {
-                        break Ok(instance);
-                    }
-                }
-            })
-            .await?
-    }
-
     /// Processes the next initializer for the next instance being created
     /// without running any wasm code.
     ///
@@ -1002,7 +980,15 @@ impl<T> InstancePre<T> {
                 ImportSource::Definitions(&self.items),
             )?
         };
-        i.run_async(&mut store.as_context_mut()).await
+
+        let mut store = store.as_context_mut();
+        assert!(
+            store.0.async_support(),
+            "cannot use `new_async` without enabling async support on the config"
+        );
+        store
+            .on_fiber(|store| i.run(&mut store.as_context_mut()))
+            .await?
     }
 
     fn ensure_comes_from_same_store(&self, store: &StoreOpaque) -> Result<()> {