Align nextTick in decorate with other usages (#5184)

packages/api-derive/src/staking/query.ts

@@ -99,14 +99,14 @@ export const query = firstMemo(
 
 export function queryMulti (instanceId: string, api: DeriveApi): (accountIds: (Uint8Array | string)[], flags: StakingQueryFlags) => Observable<DeriveStakingQuery[]> {
   return memo(instanceId, (accountIds: (Uint8Array | string)[], flags: StakingQueryFlags): Observable<DeriveStakingQuery[]> =>
-    accountIds.length
-      ? api.derive.session.indexes().pipe(
-        switchMap(({ activeEra }): Observable<DeriveStakingQuery[]> => {
-          const stashIds = accountIds.map((accountId) => api.registry.createType('AccountId', accountId));
+    api.derive.session.indexes().pipe(
+      switchMap(({ activeEra }): Observable<DeriveStakingQuery[]> => {
+        const stashIds = accountIds.map((a) => api.registry.createType('AccountId', a));
 
-          return getBatch(api, activeEra, stashIds, flags);
-        })
-      )
-      : of([])
+        return stashIds.length
+          ? getBatch(api, activeEra, stashIds, flags)
+          : of([]);
+      })
+    )
   );
 }

packages/api/src/base/Decorate.ts

@@ -844,21 +844,29 @@ export abstract class Decorate<ApiType extends ApiTypes> extends Events {
     let valueIdx = 0;
     let valueObs: Observable<Codec[]>;
 
+    // if we don't have queue entries yet,
+    // or the current queue has fired (see from below),
+    // or the current queue has the max entries,
+    // then we create a new queue
     if (queueIdx === -1 || !queue[queueIdx] || queue[queueIdx][1].length === PAGE_SIZE_Q) {
       queueIdx++;
 
       valueObs = from(
-        // Defer to the next tick - this aligns with nextTick in @polkadot/util,
-        // however since we return a value here, we don't re-use what is there
-        Promise
-          .resolve()
-          .then((): [StorageEntry, unknown[]][] => {
+        // we delay the execution until the next tick, this allows
+        // any queries made in this timeframe to be added to the same
+        // queue for a single query
+        new Promise<[StorageEntry, unknown[]][]>((resolve): void => {
+          nextTick((): void => {
+            // get all the calls in this instance, resolve with it
+            // and then clear the queue so we don't add more
+            // (anyhting after this will be added to a new queue)
             const calls = queue[queueIdx][1];
 
             delete queue[queueIdx];
 
-            return calls;
-          })
+            resolve(calls);
+          });
+        })
       ).pipe(
         switchMap((calls) => query(calls))
       );
@@ -872,6 +880,7 @@ export abstract class Decorate<ApiType extends ApiTypes> extends Events {
     }
 
     return valueObs.pipe(
+      // return the single value at this index
       map((values) => values[valueIdx])
     );
   }