♻️ Don't use api decorator for scope.destroy

We were installing an api decorator as the method for implementing the
destroy method on scope, but this required recomputing the middleware
stack for every scope creation which is totally unecessary work.

This just puts it on a prototype method of ScopeInternal. That way,
there is one version of the function, and the default api handle, just
invokes it straight away.

Author: cowboyd

lib/api.ts

@@ -28,7 +28,9 @@ export const api: Apis = {
     create() {
       throw new TypeError(`no handler for Scope.create()`);
     },
-    *destroy() {},
+    destroy(scope) {
+      return (scope as ScopeInternal).destroy();
+    },
     set(scope, context, value) {
       return (scope as ScopeInternal).contexts[context.name] = value;
     },

lib/scope-internal.ts

@@ -33,6 +33,10 @@ export function buildScopeInternal(
 ): [ScopeInternal, () => Operation<void>] {
   let destructors = new Set<() => Operation<void>>();
   let destruction = createFuture<void>();
+  let signaled = false;
+  let unbind = parent
+    ? (parent as ScopeInternal).ensure(() => destroy())
+    : () => {};
 
   let contexts: Record<string, unknown> = Object.create(
     parent ? (parent as ScopeInternal).contexts : null,
@@ -82,21 +86,12 @@ export function buildScopeInternal(
       destructors.add(op);
       return () => destructors.delete(op);
     },
-  });
-
-  scope.set(Priority, scope.expect(Priority) + 1);
-  scope.set(Children, new Set());
-  parent?.expect(Children).add(scope);
 
-  let destroy = () => api.invoke(scope, "destroy", [scope]);
-  let unbind = parent
-    ? (parent as ScopeInternal).ensure(() => destroy())
-    : () => {};
-
-  scope.around(api, {
     *destroy(): Operation<void> {
-      destroy = () => destruction.future;
-
+      if (signaled) {
+        return yield* destruction.future;
+      }
+      signaled = true;
       parent?.expect(Children).delete(scope);
       unbind();
       let outcome = Ok();
@@ -121,18 +116,20 @@ export function buildScopeInternal(
       }
 
       unbox(outcome);
-    },
-  }, { at: "min" });
+    }
+  });
+
+  scope.set(Priority, scope.expect(Priority) + 1);
+  scope.set(Children, new Set());
+  parent?.expect(Children).add(scope);
+
+  let destroy = () => api.invoke(scope, "destroy", [scope]);
 
-  return [scope, () => destroy()];
+  return [scope, destroy];
 }
 
 export interface ScopeInternal extends Scope, AsyncDisposable {
   contexts: Record<string, unknown>;
   ensure(op: () => Operation<void>): () => void;
-  reduce<T, TSum>(
-    context: Context<T>,
-    fn: (sum: TSum, item: T) => TSum,
-    initial: TSum,
-  ): TSum;
+  destroy(): Operation<void>;
 }