core: performance: userCache&scoreboard.pagination

packages/hydrooj/src/lib/paginate.ts

@@ -1,9 +1,9 @@
 import { Cursor } from 'mongodb';
 import { ValidationError } from '../error';
 
-async function paginate(
-    cursor: Cursor, page: number, pageSize: number,
-): Promise<[any[]/* docs */, number/* numPages */, number/* count */]> {
+async function paginate<T>(
+    cursor: Cursor<T>, page: number, pageSize: number,
+): Promise<[docs: T[], numPages: number, count: number]> {
     if (page <= 0) throw new ValidationError('page');
     const [count, pageDocs] = await Promise.all([
         cursor.count(),

packages/hydrooj/src/lib/rank.ts

@@ -1,16 +1,55 @@
-function ranked<T>(diter: T[], equ = (a: T, b: T) => a === b): [number, T][] {
+import { Cursor } from 'mongodb';
+import paginate from './paginate';
+
+type G<T> = Promise<[[number, T], () => G<T>] | []>;
+interface ranked {
+    <T>(cursor: Cursor<T>, equ: (a: T, b: T) => boolean, page: number): Promise<[number, T][]>;
+    iterate<T>(cursor: Cursor<T>, equ: (a: T, b: T) => boolean): G<T>;
+    all<T>(cursor: Cursor<T>, equ: (a: T, b: T) => boolean): Promise<[number, T][]>;
+}
+
+const ranked: ranked = async function rankedPage(cursor, equ = (a, b) => a === b, page) {
     let last = null;
-    let r = 0;
-    let count = 0;
-    const results: [number, T][] = [];
-    for (const doc of diter) {
+    let r = (page - 1) * 100;
+    let count = r;
+    const results = [];
+    const [docs] = await paginate(cursor, page, 100);
+    for (const doc of docs) {
         count++;
         if (count === 1 || !equ(last, doc)) r = count;
         last = doc;
         results.push([r, doc]);
     }
     return results;
-}
+};
+ranked.iterate = async function rankedIterate<T>(cursor: Cursor<T>, equ = (a, b) => a === b) {
+    let last = null;
+    let r = 0;
+    let count = 0;
+    async function getNext(): G<T> {
+        if (!await cursor.hasNext()) return [];
+        const doc = await cursor.next();
+        count++;
+        if (count === 1 || !equ(last, doc)) r = count;
+        last = doc;
+        return [[r, doc], getNext];
+    }
+    return await getNext();
+};
+ranked.all = async function rankedAll(cursor, equ = (a, b) => a === b) {
+    let last = null;
+    let r = 0;
+    let count = 0;
+    const results = [];
+    const docs = await cursor.toArray();
+    for (const doc of docs) {
+        count++;
+        if (count === 1 || !equ(last, doc)) r = count;
+        last = doc;
+        results.push([r, doc]);
+    }
+    return results;
+};
 
 global.Hydro.lib.rank = ranked;
 export = ranked;