1 files changed, 66 insertions, 31 deletions
diff --git a/core/01_core.js b/core/01_core.js
index 6a6696bf8..bea9c4290 100644
--- a/core/01_core.js
+++ b/core/01_core.js
@@ -326,41 +326,76 @@
   }
   const InterruptedPrototype = Interrupted.prototype;
 
-  const promiseHooks = {
-    init: [],
-    before: [],
-    after: [],
-    resolve: [],
-    hasBeenSet: false,
-  };
+  const promiseHooks = [
+    [], // init
+    [], // before
+    [], // after
+    [], // resolve
+  ];
 
   function setPromiseHooks(init, before, after, resolve) {
-    if (init) ArrayPrototypePush(promiseHooks.init, init);
-    if (before) ArrayPrototypePush(promiseHooks.before, before);
-    if (after) ArrayPrototypePush(promiseHooks.after, after);
-    if (resolve) ArrayPrototypePush(promiseHooks.resolve, resolve);
+    const hooks = [init, before, after, resolve];
+    for (let i = 0; i < hooks.length; i++) {
+      const hook = hooks[i];
+      // Skip if no callback was provided for this hook type.
+      if (hook == null) {
+        continue;
+      }
+      // Verify that the type of `hook` is a function.
+      if (typeof hook !== "function") {
+        throw new TypeError(`Expected function at position ${i}`);
+      }
+      // Add the hook to the list.
+      ArrayPrototypePush(promiseHooks[i], hook);
+    }
 
-    if (!promiseHooks.hasBeenSet) {
-      promiseHooks.hasBeenSet = true;
+    const wrappedHooks = ArrayPrototypeMap(promiseHooks, (hooks) => {
+      switch (hooks.length) {
+        case 0:
+          return undefined;
+        case 1:
+          return hooks[0];
+        case 2:
+          return create2xHookWrapper(hooks[0], hooks[1]);
+        case 3:
+          return create3xHookWrapper(hooks[0], hooks[1], hooks[2]);
+        default:
+          return createHookListWrapper(hooks);
+      }
 
-      ops.op_set_promise_hooks((promise, parentPromise) => {
-        for (let i = 0; i < promiseHooks.init.length; ++i) {
-          promiseHooks.init[i](promise, parentPromise);
-        }
-      }, (promise) => {
-        for (let i = 0; i < promiseHooks.before.length; ++i) {
-          promiseHooks.before[i](promise);
-        }
-      }, (promise) => {
-        for (let i = 0; i < promiseHooks.after.length; ++i) {
-          promiseHooks.after[i](promise);
-        }
-      }, (promise) => {
-        for (let i = 0; i < promiseHooks.resolve.length; ++i) {
-          promiseHooks.resolve[i](promise);
-        }
-      });
-    }
+      // The following functions are used to create wrapper functions that call
+      // all the hooks in a list of a certain length. The reason to use a
+      // function that creates a wrapper is to minimize the number of objects
+      // captured in the closure.
+      function create2xHookWrapper(hook1, hook2) {
+        return function (promise, parent) {
+          hook1(promise, parent);
+          hook2(promise, parent);
+        };
+      }
+      function create3xHookWrapper(hook1, hook2, hook3) {
+        return function (promise, parent) {
+          hook1(promise, parent);
+          hook2(promise, parent);
+          hook3(promise, parent);
+        };
+      }
+      function createHookListWrapper(hooks) {
+        return function (promise, parent) {
+          for (let i = 0; i < hooks.length; i++) {
+            const hook = hooks[i];
+            hook(promise, parent);
+          }
+        };
+      }
+    });
+
+    ops.op_set_promise_hooks(
+      wrappedHooks[0],
+      wrappedHooks[1],
+      wrappedHooks[2],
+      wrappedHooks[3],
+    );
   }
 
   // Extra Deno.core.* exports