async_hooks: avoid unneeded AsyncResource creation

Inspired by the callstack at #34556 (comment) If the wanted store is equal to the active store it's not needed to create an AsyncResource. Refs: #34556 (comment) PR-URL: #34616 Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Stephen Belanger <[email protected]> Reviewed-By: Vladimir de Turckheim <[email protected]> Reviewed-By: Andrey Pechkurov <[email protected]>
nodejs · Sep 22, 2020 · 0a44017 · 0a44017
1 parent 07968ac
commit 0a44017
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Showing 2 changed files with 20 additions and 2 deletions.
diff --git a/lib/async_hooks.js b/lib/async_hooks.js
@@ -3,6 +3,7 @@
 const {
   NumberIsSafeInteger,
   ObjectDefineProperties,
+  ObjectIs,
   ReflectApply,
   Symbol,
 } = primordials;
@@ -285,6 +286,10 @@ class AsyncLocalStorage {
   }
 
   run(store, callback, ...args) {
+    // Avoid creation of an AsyncResource if store is already active
+    if (ObjectIs(store, this.getStore())) {
+      return callback(...args);
+    }
     const resource = new AsyncResource('AsyncLocalStorage');
     return resource.runInAsyncScope(() => {
       this.enterWith(store);

diff --git a/test/async-hooks/test-async-local-storage-run-resource.js b/test/async-hooks/test-async-local-storage-run-resource.js
@@ -10,8 +10,21 @@ const asyncLocalStorage = new AsyncLocalStorage();
 
 const outerResource = executionAsyncResource();
 
-asyncLocalStorage.run(new Map(), () => {
-  assert.notStrictEqual(executionAsyncResource(), outerResource);
+const store = new Map();
+asyncLocalStorage.run(store, () => {
+  assert.strictEqual(asyncLocalStorage.getStore(), store);
+  const innerResource = executionAsyncResource();
+  assert.notStrictEqual(innerResource, outerResource);
+  asyncLocalStorage.run(store, () => {
+    assert.strictEqual(asyncLocalStorage.getStore(), store);
+    assert.strictEqual(executionAsyncResource(), innerResource);
+    const otherStore = new Map();
+    asyncLocalStorage.run(otherStore, () => {
+      assert.strictEqual(asyncLocalStorage.getStore(), otherStore);
+      assert.notStrictEqual(executionAsyncResource(), innerResource);
+      assert.notStrictEqual(executionAsyncResource(), outerResource);
+    });
+  });
 });
 
 assert.strictEqual(executionAsyncResource(), outerResource);