Await promises in parallel

models/common.ts

@@ -173,12 +173,15 @@ export default class Model extends TypeORM.BaseEntity {
     result.meta.top = result.data[0].id;
     result.meta.bottom = result.data[result.data.length - 1].id;
 
-    result.meta.hasPrevPage = !!(await queryBuilderHasPrev.andWhere(`id ${idOrder === PaginationIDOrder.DESC ? '>' : '<'} :id`, {
+    // Run two queries in parallel.
+    await Promise.all(([
+      async () => result.meta.hasPrevPage = !!(await queryBuilderHasPrev.andWhere(`id ${idOrder === PaginationIDOrder.DESC ? '>' : '<'} :id`, {
                                                                           id: result.meta.top
-                                                          }).take(1).getOne());
+                                                                        }).take(1).getOne()),
-    result.meta.hasNextPage = !!(await queryBuilderHasNext.andWhere(`id ${idOrder === PaginationIDOrder.DESC ? '<' : '>'} :id`, {
+      async () => result.meta.hasNextPage = !!(await queryBuilderHasNext.andWhere(`id ${idOrder === PaginationIDOrder.DESC ? '<' : '>'} :id`, {
                                                                           id: result.meta.bottom
-                                                          }).take(1).getOne());
+                                                                        }).take(1).getOne())
+    ]).map(f => f()));
 
     return result;
   }

models/judge_state.ts

@@ -133,13 +133,15 @@ export default class JudgeState extends Model {
     if (this.type === 0) {
       await this.loadRelationships();
 
-      // No need to await them.
+      const promises = [];
-      this.user.refreshSubmitInfo();
+      promises.push(this.user.refreshSubmitInfo());
-      this.problem.resetSubmissionCount();
+      promises.push(this.problem.resetSubmissionCount());
 
       if (!newSubmission) {
-        this.problem.updateStatistics(this.user_id);
+        promises.push(this.problem.updateStatistics(this.user_id));
       }
+
+      await Promise.all(promises);
     } else if (this.type === 1) {
       let contest = await Contest.findById(this.type_info);
       await contest.newSubmission(this);