alternative solution

deferred grouped field sets are only initiated when the WrappedGraphQLResult in which they are contained are processed

Author: yaacovCR

src/execution/IncrementalGraph.ts

@@ -8,7 +8,6 @@ import type { GraphQLError } from '../error/GraphQLError.js';
 import type {
   DeferredFragmentRecord,
   DeferredGroupedFieldSetRecord,
-  DeferredGroupedFieldSetResult,
   IncrementalDataRecord,
   IncrementalDataRecordResult,
   ReconcilableDeferredGroupedFieldSetResult,
@@ -201,7 +200,6 @@ export class IncrementalGraph {
     for (const node of maybeEmptyNewRootNodes) {
       if (isDeferredFragmentRecord(node)) {
         if (node.deferredGroupedFieldSetRecords.size > 0) {
-          node.setAsPending();
           for (const deferredGroupedFieldSetRecord of node.deferredGroupedFieldSetRecords) {
             if (!this._completesRootNode(deferredGroupedFieldSetRecord)) {
               this._onDeferredGroupedFieldSet(deferredGroupedFieldSetRecord);
@@ -253,14 +251,16 @@ export class IncrementalGraph {
   private _onDeferredGroupedFieldSet(
     deferredGroupedFieldSetRecord: DeferredGroupedFieldSetRecord,
   ): void {
-    const result = (
-      deferredGroupedFieldSetRecord.result as BoxedPromiseOrValue<DeferredGroupedFieldSetResult>
-    ).value;
-    if (isPromise(result)) {
+    let deferredGroupedFieldSetResult = deferredGroupedFieldSetRecord.result;
+    if (!(deferredGroupedFieldSetResult instanceof BoxedPromiseOrValue)) {
+      deferredGroupedFieldSetResult = deferredGroupedFieldSetResult();
+    }
+    const value = deferredGroupedFieldSetResult.value;
+    if (isPromise(value)) {
       // eslint-disable-next-line @typescript-eslint/no-floating-promises
-      result.then((resolved) => this._enqueue(resolved));
+      value.then((resolved) => this._enqueue(resolved));
     } else {
-      this._enqueue(result);
+      this._enqueue(value);
     }
   }
 

src/execution/__tests__/defer-test.ts

@@ -986,7 +986,7 @@ describe('Execute: defer directive', () => {
     });
   });
 
-  it('Initiates all deferred grouped field sets immediately once they have been released as pending', async () => {
+  it('Initiates unique deferred grouped field sets after those that are common to sibling defers', async () => {
     const document = parse(`
       query {
         ... @defer {
@@ -1076,7 +1076,7 @@ describe('Execute: defer directive', () => {
     resolveC();
 
     expect(cResolverCalled).to.equal(true);
-    expect(eResolverCalled).to.equal(true);
+    expect(eResolverCalled).to.equal(false);
 
     const result3 = await iterator.next();
     expectJSON(result3).toDeepEqual({

src/execution/execute.ts

@@ -2123,15 +2123,6 @@ function executeDeferredGroupedFieldSets(
     } else {
       deferredGroupedFieldSetRecord.result = () =>
         new BoxedPromiseOrValue(executor());
-      const resolveThunk = () => {
-        const maybeThunk = deferredGroupedFieldSetRecord.result;
-        if (!(maybeThunk instanceof BoxedPromiseOrValue)) {
-          deferredGroupedFieldSetRecord.result = maybeThunk();
-        }
-      };
-      for (const deferredFragmentRecord of deferredFragmentRecords) {
-        deferredFragmentRecord.onPending(resolveThunk);
-      }
     }
 
     newDeferredGroupedFieldSetRecords.push(deferredGroupedFieldSetRecord);

src/execution/types.ts

@@ -224,9 +224,6 @@ export class DeferredFragmentRecord {
   reconcilableResults: Set<ReconcilableDeferredGroupedFieldSetResult>;
   children: Set<SubsequentResultRecord>;
 
-  private pending: boolean;
-  private fns: Array<() => void>;
-
   constructor(
     path: Path | undefined,
     label: string | undefined,
@@ -238,24 +235,6 @@ export class DeferredFragmentRecord {
     this.deferredGroupedFieldSetRecords = new Set();
     this.reconcilableResults = new Set();
     this.children = new Set();
-    this.pending = false;
-    this.fns = [];
-  }
-
-  onPending(fn: () => void): void {
-    if (this.pending) {
-      fn();
-    } else {
-      this.fns.push(fn);
-    }
-  }
-
-  setAsPending(): void {
-    this.pending = true;
-    let fn;
-    while ((fn = this.fns.shift()) !== undefined) {
-      fn();
-    }
   }
 }