collapsed nested defers due to empty parents should be published last

also reduces code duplication

Author: yaacovCR

src/execution/IncrementalPublisher.ts

@@ -301,16 +301,7 @@ export class IncrementalPublisher {
     initialResultRecord: InitialResultRecord,
     data: ObjMap<unknown> | null,
   ): ExecutionResult | ExperimentalIncrementalExecutionResults {
-    const pendingSources = new Set<DeferredFragmentRecord | StreamRecord>();
-    for (const child of initialResultRecord.children) {
-      if (child.filtered) {
-        continue;
-      }
-      const maybePendingSources = this._publish(child);
-      for (const maybePendingSource of maybePendingSources) {
-        pendingSources.add(maybePendingSource);
-      }
-    }
+    const pendingSources = this._publish(initialResultRecord.children);
 
     const errors = initialResultRecord.errors;
     const initialResult = errors.length === 0 ? { data } : { errors, data };
@@ -533,15 +524,7 @@ export class IncrementalPublisher {
     const incrementalResults: Array<IncrementalResult> = [];
     const completedResults: Array<CompletedResult> = [];
     for (const subsequentResultRecord of completedRecords) {
-      for (const child of subsequentResultRecord.children) {
-        if (child.filtered) {
-          continue;
-        }
-        const maybePendingSources = this._publish(child);
-        for (const maybePendingSource of maybePendingSources) {
-          newPendingSources.add(maybePendingSource);
-        }
-      }
+      this._publish(subsequentResultRecord.children, newPendingSources);
       if (isStreamItemsRecord(subsequentResultRecord)) {
         if (subsequentResultRecord.isFinalRecord) {
           newPendingSources.delete(subsequentResultRecord.streamRecord);
@@ -648,42 +631,50 @@ export class IncrementalPublisher {
   }
 
   private _publish(
-    subsequentResultRecord: SubsequentResultRecord,
-  ): ReadonlyArray<DeferredFragmentRecord | StreamRecord> {
-    if (isStreamItemsRecord(subsequentResultRecord)) {
-      if (subsequentResultRecord.isCompleted) {
-        this._push(subsequentResultRecord);
-      } else {
-        this._introduce(subsequentResultRecord);
+    subsequentResultRecords: ReadonlySet<SubsequentResultRecord>,
+    pendingSources = new Set<DeferredFragmentRecord | StreamRecord>(),
+  ): Set<DeferredFragmentRecord | StreamRecord> {
+    const emptyRecords: Array<SubsequentResultRecord> = [];
+
+    for (const subsequentResultRecord of subsequentResultRecords) {
+      if (subsequentResultRecord.filtered) {
+        continue;
       }
+      if (isStreamItemsRecord(subsequentResultRecord)) {
+        if (subsequentResultRecord.isCompleted) {
+          this._push(subsequentResultRecord);
+        } else {
+          this._introduce(subsequentResultRecord);
+        }
 
-      const stream = subsequentResultRecord.streamRecord;
-      if (!stream.pendingSent) {
-        return [stream];
+        const stream = subsequentResultRecord.streamRecord;
+        if (!stream.pendingSent) {
+          pendingSources.add(stream);
+        }
+        continue;
       }
-      return [];
-    }
 
-    if (subsequentResultRecord._pending.size > 0) {
-      this._introduce(subsequentResultRecord);
-    } else if (
-      subsequentResultRecord.deferredGroupedFieldSetRecords.size === 0
-    ) {
-      const newPendingSources = [];
-      for (const child of subsequentResultRecord.children) {
-        const maybeNewPendingSources = this._publish(child);
-        newPendingSources.push(...maybeNewPendingSources);
+      if (subsequentResultRecord._pending.size > 0) {
+        this._introduce(subsequentResultRecord);
+      } else if (
+        subsequentResultRecord.deferredGroupedFieldSetRecords.size === 0
+      ) {
+        emptyRecords.push(subsequentResultRecord);
+        continue;
+      } else {
+        this._push(subsequentResultRecord);
+      }
+
+      if (!subsequentResultRecord.pendingSent) {
+        pendingSources.add(subsequentResultRecord);
       }
-      return newPendingSources;
-    } else {
-      this._push(subsequentResultRecord);
     }
 
-    if (!subsequentResultRecord.pendingSent) {
-      return [subsequentResultRecord];
+    for (const emptyRecord of emptyRecords) {
+      this._publish(emptyRecord.children, pendingSources);
     }
 
-    return [];
+    return pendingSources;
   }
 
   private _getChildren(

src/execution/__tests__/defer-test.ts

@@ -1088,16 +1088,16 @@ describe('Execute: defer directive', () => {
             data: {
               foo: 'foo',
             },
-            id: '1',
+            id: '0',
           },
           {
             data: {
               bar: 'bar',
             },
-            id: '0',
+            id: '1',
           },
         ],
-        completed: [{ id: '1' }, { id: '0' }],
+        completed: [{ id: '0' }, { id: '1' }],
         hasNext: false,
       },
     ]);