async_hooks: add thisArg to AsyncResource.bind

Semver-major Support setting the `thisArg` for AsyncResource.bind and AsyncResource.prototype.bind. If `thisArg` is not set, then `this` will be set to the `AsyncResource` instance. Fixes: #36051 Signed-off-by: James M Snell <jasnell@gmail.com>
nodejs · jasnell · Jan 4, 2021 · Jan 6, 2021 · 25d1319895f29d7381e7209f89ad753b1bf50158
commit 25d1319895f29d7381e7209f89ad753b1bf50158
diff --git a/doc/api/async_hooks.md b/doc/api/async_hooks.md
@@ -730,30 +730,40 @@ class DBQuery extends AsyncResource {
 }
 ```
 
-#### Static method: `AsyncResource.bind(fn[, type])`
+#### Static method: `AsyncResource.bind(fn[, type, [thisArg]])`
 <!-- YAML
 added:
   - v14.8.0
   - v12.19.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/36782
+    description: Added optional thisArg.
 -->
 
 * `fn` {Function} The function to bind to the current execution context.
 * `type` {string} An optional name to associate with the underlying
   `AsyncResource`.
+* `thisArg` {any}
 
 Binds the given function to the current execution context.
 
 The returned function will have an `asyncResource` property referencing
 the `AsyncResource` to which the function is bound.
 
-#### `asyncResource.bind(fn)`
+#### `asyncResource.bind(fn[, thisArg])`
 <!-- YAML
 added:
   - v14.8.0
   - v12.19.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/36782
+    description: Added optional thisArg.
 -->
 
 * `fn` {Function} The function to bind to the current `AsyncResource`.
+* `thisArg` {any}
 
 Binds the given function to execute to this `AsyncResource`'s scope.
 

diff --git a/lib/async_hooks.js b/lib/async_hooks.js
@@ -220,10 +220,15 @@ class AsyncResource {
     return this[trigger_async_id_symbol];
   }
 
-  bind(fn) {
+  bind(fn, thisArg = this) {
     if (typeof fn !== 'function')
       throw new ERR_INVALID_ARG_TYPE('fn', 'Function', fn);
-    const ret = FunctionPrototypeBind(this.runInAsyncScope, this, fn);
+    const ret =
+      FunctionPrototypeBind(
+        this.runInAsyncScope,
+        this,
+        fn,
+        thisArg);
     ObjectDefineProperties(ret, {
       'length': {
         configurable: true,
@@ -241,9 +246,9 @@ class AsyncResource {
     return ret;
   }
 
-  static bind(fn, type) {
+  static bind(fn, type, thisArg) {
     type = type || fn.name;
-    return (new AsyncResource(type || 'bound-anonymous-fn')).bind(fn);
+    return (new AsyncResource(type || 'bound-anonymous-fn')).bind(fn, thisArg);
   }
 }
 

diff --git a/test/parallel/test-asyncresource-bind.js b/test/parallel/test-asyncresource-bind.js
@@ -33,3 +33,19 @@ setImmediate(() => {
   assert.strictEqual(asyncResource.asyncId(), fn2());
   assert.notStrictEqual(asyncId, fn2());
 });
+
+const foo = {};
+const fn3 = asyncResource.bind(common.mustCall(function() {
+  assert.strictEqual(this, foo);
+}), foo);
+fn3();
+
+const fn4 = asyncResource.bind(common.mustCall(function() {
+  assert.strictEqual(this, asyncResource);
+}));
+fn4();
+
+const fn5 = asyncResource.bind(common.mustCall(function() {
+  assert.strictEqual(this, false);
+}), false);
+fn5();