fix(core): poll async ops eagerly (#12385)

Currently all async ops are polled lazily, which means that op
initialization code is postponed until control is yielded to the event
loop. This has some weird consequences, e.g.

```js
let listener = Deno.listen(...);
let conn_promise = listener.accept();
listener.close();
// `BadResource` is thrown. A reasonable error would be `Interrupted`.
let conn = await conn_promise;
```

JavaScript promises are expected to be eagerly evaluated. This patch
makes ops actually do that.

1 files changed, 4 insertions, 3 deletions

diff --git a/core/ops_json.rs b/core/ops_json.rs
index 0ca7e5ce4..dca9a9a77 100644
--- a/core/ops_json.rs
+++ b/core/ops_json.rs
@@ -1,6 +1,7 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
 
 use crate::error::AnyError;
+use crate::ops::OpCall;
 use crate::serialize_op_result;
 use crate::Op;
 use crate::OpFn;
@@ -35,7 +36,7 @@ pub fn void_op_async() -> Box<OpFn> {
     let op_id = payload.op_id;
     let pid = payload.promise_id;
     let op_result = serialize_op_result(Ok(()), state);
-    Op::Async(Box::pin(futures::future::ready((pid, op_id, op_result))))
+    Op::Async(OpCall::ready((pid, op_id, op_result)))
   })
 }
 
@@ -127,7 +128,7 @@ where
     use crate::futures::FutureExt;
     let fut = op_fn(state.clone(), a, b)
       .map(move |result| (pid, op_id, serialize_op_result(result, state)));
-    Op::Async(Box::pin(fut))
+    Op::Async(OpCall::eager(fut))
   })
 }
 
@@ -159,7 +160,7 @@ where
     use crate::futures::FutureExt;
     let fut = op_fn(state.clone(), a, b)
       .map(move |result| (pid, op_id, serialize_op_result(result, state)));
-    Op::AsyncUnref(Box::pin(fut))
+    Op::AsyncUnref(OpCall::eager(fut))
   })
 }