From ab4f5bb674946ba3d85cf985e486909e7db00036 Mon Sep 17 00:00:00 2001
From: Pat Hickey <pat@moreproductive.org>
Date: Thu, 29 Apr 2021 16:23:36 -0700
Subject: [PATCH] move dummy executor out to wiggle:: for reuse

---
 crates/wiggle/src/lib.rs                | 37 ++++++++++++++++
 crates/wiggle/wasmtime/macro/src/lib.rs | 59 ++-----------------------
 2 files changed, 41 insertions(+), 55 deletions(-)

diff --git a/crates/wiggle/src/lib.rs b/crates/wiggle/src/lib.rs
index 7bcba7c065..602a8c9d17 100644
--- a/crates/wiggle/src/lib.rs
+++ b/crates/wiggle/src/lib.rs
@@ -953,3 +953,40 @@ impl From<GuestError> for Trap {
         Trap::String(err.to_string())
     }
 }
+
+pub unsafe fn run_in_dummy_executor<F: std::future::Future>(future: F) -> F::Output {
+    use std::pin::Pin;
+    use std::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
+
+    let mut f = Pin::from(Box::new(future));
+    let waker = dummy_waker();
+    let mut cx = Context::from_waker(&waker);
+    match f.as_mut().poll(&mut cx) {
+        Poll::Ready(val) => return val,
+        Poll::Pending => {
+            panic!("Cannot wait on pending future: must enable wiggle \"async\" future and execute on an async Store")
+        }
+    }
+
+    fn dummy_waker() -> Waker {
+        return unsafe { Waker::from_raw(clone(5 as *const _)) };
+
+        unsafe fn clone(ptr: *const ()) -> RawWaker {
+            assert_eq!(ptr as usize, 5);
+            const VTABLE: RawWakerVTable = RawWakerVTable::new(clone, wake, wake_by_ref, drop);
+            RawWaker::new(ptr, &VTABLE)
+        }
+
+        unsafe fn wake(ptr: *const ()) {
+            assert_eq!(ptr as usize, 5);
+        }
+
+        unsafe fn wake_by_ref(ptr: *const ()) {
+            assert_eq!(ptr as usize, 5);
+        }
+
+        unsafe fn drop(ptr: *const ()) {
+            assert_eq!(ptr as usize, 5);
+        }
+    }
+}
diff --git a/crates/wiggle/wasmtime/macro/src/lib.rs b/crates/wiggle/wasmtime/macro/src/lib.rs
index 4764d217c1..67c91817c5 100644
--- a/crates/wiggle/wasmtime/macro/src/lib.rs
+++ b/crates/wiggle/wasmtime/macro/src/lib.rs
@@ -101,12 +101,10 @@ fn generate_module(
     let mut ctor_externs = Vec::new();
     let mut host_funcs = Vec::new();
 
-    let mut requires_dummy_executor = false;
-
     for f in module.funcs() {
         let asyncness = async_conf.is_async(module.name.as_str(), f.name.as_str());
         match asyncness {
-            Asyncness::Blocking => requires_dummy_executor = true,
+            Asyncness::Blocking => {}
             Asyncness::Async => {
                 assert!(
                     cfg!(feature = "async"),
@@ -165,12 +163,6 @@ contained in the `cx` parameter.",
         }
     });
 
-    let dummy_executor = if requires_dummy_executor {
-        dummy_executor()
-    } else {
-        quote!()
-    };
-
     quote! {
         #type_docs
         pub struct #type_name {
@@ -233,8 +225,6 @@ contained in the `cx` parameter.",
             }
 
             #(#fns)*
-
-            #dummy_executor
         }
     }
 }
@@ -250,6 +240,7 @@ fn generate_func(
     ctors: &mut Vec<TokenStream2>,
     host_funcs: &mut Vec<(witx::Id, TokenStream2)>,
 ) {
+    let rt = names.runtime_mod();
     let name_ident = names.func(&func.name);
 
     let (params, results) = func.wasm_signature();
@@ -329,7 +320,7 @@ fn generate_func(
                 let #name_ident = wasmtime::Func::wrap(
                     store,
                     move |caller: wasmtime::Caller #(, #arg_decls)*| -> Result<#ret_ty, wasmtime::Trap> {
-                        Self::run_in_dummy_executor(Self::#fn_ident(&caller, &mut my_ctx.borrow_mut() #(, #arg_names)*))
+                        unsafe { #rt::run_in_dummy_executor(Self::#fn_ident(&caller, &mut my_ctx.borrow_mut() #(, #arg_names)*)) }
                     }
                 );
             });
@@ -381,7 +372,7 @@ fn generate_func(
                             .store()
                             .get::<std::rc::Rc<std::cell::RefCell<#ctx_type>>>()
                             .ok_or_else(|| wasmtime::Trap::new("context is missing in the store"))?;
-                        Self::run_in_dummy_executor(Self::#fn_ident(&caller, &mut ctx.borrow_mut()  #(, #arg_names)*))
+                        unsafe { #rt::run_in_dummy_executor(Self::#fn_ident(&caller, &mut ctx.borrow_mut()  #(, #arg_names)*)) }
                     },
                 );
             }
@@ -404,45 +395,3 @@ fn generate_func(
     };
     host_funcs.push((func.name.clone(), host_wrapper));
 }
-
-fn dummy_executor() -> TokenStream2 {
-    quote! {
-        fn run_in_dummy_executor<F: std::future::Future>(future: F) -> F::Output {
-            use std::pin::Pin;
-            use std::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
-
-            let mut f = Pin::from(Box::new(future));
-            let waker = dummy_waker();
-            let mut cx = Context::from_waker(&waker);
-            match f.as_mut().poll(&mut cx) {
-                Poll::Ready(val) => return val,
-                Poll::Pending => {
-                    panic!("Cannot wait on pending future: must enable wiggle \"async\" future and execute on an async Store")
-                }
-            }
-
-            fn dummy_waker() -> Waker {
-                return unsafe { Waker::from_raw(clone(5 as *const _)) };
-
-                unsafe fn clone(ptr: *const ()) -> RawWaker {
-                    assert_eq!(ptr as usize, 5);
-                    const VTABLE: RawWakerVTable = RawWakerVTable::new(clone, wake, wake_by_ref, drop);
-                    RawWaker::new(ptr, &VTABLE)
-                }
-
-                unsafe fn wake(ptr: *const ()) {
-                    assert_eq!(ptr as usize, 5);
-                }
-
-                unsafe fn wake_by_ref(ptr: *const ()) {
-                    assert_eq!(ptr as usize, 5);
-                }
-
-                unsafe fn drop(ptr: *const ()) {
-                    assert_eq!(ptr as usize, 5);
-                }
-            }
-
-        }
-    }
-}