From 33c61c7a831c6792b2de7bc0445fcbf1f24b4cf8 Mon Sep 17 00:00:00 2001
From: Menci <huanghaorui301@gmail.com>
Date: Sun, 21 Apr 2019 10:50:41 +0800
Subject: [PATCH] Optimize submissions pagination query

---
 models/common.ts      | 60 +++++++++++++++++++++++++++++++++++--------
 modules/submission.js | 15 +++++++----
 utility.js            | 13 ++++++++++
 views/submissions.ejs |  2 +-
 4 files changed, 74 insertions(+), 16 deletions(-)

diff --git a/models/common.ts b/models/common.ts
index 889fb9d..a19c911 100644
--- a/models/common.ts
+++ b/models/common.ts
@@ -33,14 +33,14 @@ export default class Model extends TypeORM.BaseEntity {
   static async queryPage(paginater: Paginater, where, order, largeData) {
     if (!paginater.pageCnt) return [];
 
-    let queryBuilder = where instanceof TypeORM.SelectQueryBuilder
-                     ? where
-                     : this.createQueryBuilder().where(where);
+    const queryBuilder = where instanceof TypeORM.SelectQueryBuilder
+                       ? where
+                       : this.createQueryBuilder().where(where);
 
     if (order) queryBuilder.orderBy(order);
 
-    queryBuilder = queryBuilder.skip((paginater.currPage - 1) * paginater.perPage)
-                               .take(paginater.perPage);
+    queryBuilder.skip((paginater.currPage - 1) * paginater.perPage)
+                .take(paginater.perPage);
 
     if (largeData) {
       const rawResult = await queryBuilder.select('id').getRawMany();
@@ -50,18 +50,58 @@ export default class Model extends TypeORM.BaseEntity {
     return queryBuilder.getMany();
   }
 
+  static async queryPageWithLargeData(queryBuilder, { currPageTop, currPageBottom, perPage }, type) {
+    const queryBuilderBak = queryBuilder.clone();
+
+    const result = {
+      meta: {
+        hasPrevPage: false,
+        hasNextPage: false,
+        top: 0,
+        bottom: 0
+      },
+      data: []
+    };
+
+    queryBuilder.take(perPage);
+    if (type === -1) {
+      if (currPageTop != null) queryBuilder.andWhere('id > :currPageTop', { currPageTop });
+    } else if (type === 1) {
+      if (currPageBottom != null) queryBuilder.andWhere('id < :currPageBottom', { currPageBottom });
+    }
+
+    result.data = await queryBuilder.getMany();
+
+    if (result.data.length === 0) return result;
+
+    const queryBuilderHasPrev = queryBuilderBak.clone(),
+          queryBuilderHasNext = queryBuilderBak;
+
+    result.meta.top = result.data[0].id;
+    result.meta.bottom = result.data[result.data.length - 1].id;
+
+    result.meta.hasPrevPage = !!(await queryBuilderHasPrev.andWhere('id > :id', {
+                                                            id: result.meta.top
+                                                          }).take(1).getOne());
+    result.meta.hasNextPage = !!(await queryBuilderHasNext.andWhere('id < :id', {
+                                                            id: result.meta.bottom
+                                                          }).take(1).getOne());
+
+    return result;
+  }
+
   static async queryRange(range: any[], where, order) {
     range[0] = parseInt(range[0]);
     range[1] = parseInt(range[1]);
 
-    let queryBuilder = where instanceof TypeORM.SelectQueryBuilder
-                     ? where
-                     : this.createQueryBuilder().where(where);
+    const queryBuilder = where instanceof TypeORM.SelectQueryBuilder
+                       ? where
+                       : this.createQueryBuilder().where(where);
 
     if (order) queryBuilder.orderBy(order);
 
-    queryBuilder = queryBuilder.skip(range[0] - 1)
-                               .take(range[1] - range[0] + 1);
+    queryBuilder.skip(range[0] - 1)
+                .take(range[1] - range[0] + 1);
 
     return queryBuilder.getMany();
   }
diff --git a/modules/submission.js b/modules/submission.js
index b4b923e..b4e1263 100644
--- a/modules/submission.js
+++ b/modules/submission.js
@@ -103,16 +103,21 @@ app.get('/submissions', async (req, res) => {
       isFiltered = true;
     }
 
-    let paginate = syzoj.utils.paginate(await JudgeState.countQuery(query), req.query.page, syzoj.config.page.judge_state);
-    let judge_state = await JudgeState.queryPage(paginate, query, { id: "DESC" }, true);
+    query.orderBy({
+      id: "DESC"
+    });
+
+    const queryResult = await JudgeState.queryPageWithLargeData(query, syzoj.utils.paginateLargeData(
+      req.query.currPageTop, req.query.currPageBottom, syzoj.config.page.judge_state
+    ), parseInt(req.query.page));
 
+    const judge_state = queryResult.data;
     await judge_state.forEachAsync(async obj => {
       await obj.loadRelationships();
       if (obj.problem.type !== 'submit-answer') obj.code_length = obj.code.length;
-    })
+    });
 
     res.render('submissions', {
-      // judge_state: judge_state,
       items: judge_state.map(x => ({
         info: getSubmissionInfo(x, displayConfig),
         token: (x.pending && x.task_id != null) ? jwt.sign({
@@ -123,7 +128,7 @@ app.get('/submissions', async (req, res) => {
         result: getRoughResult(x, displayConfig, true),
         running: false,
       })),
-      paginate: paginate,
+      paginate: queryResult.meta,
       pushType: 'rough',
       form: req.query,
       displayConfig: displayConfig,
diff --git a/utility.js b/utility.js
index d300cb9..68b04ad 100644
--- a/utility.js
+++ b/utility.js
@@ -245,6 +245,19 @@ module.exports = {
       }
     };
   },
+  paginateLargeData(currPageTop, currPageBottom, perPage) {
+    function parseIntOrNull(x) {
+      if (typeof x === 'string') x = parseInt(x);
+      if (typeof x !== 'number' || isNaN(x)) return null;
+      return x;
+    }
+
+    return {
+      currPageTop: parseIntOrNull(currPageTop),
+      currPageBottom: parseIntOrNull(currPageBottom),
+      perPage
+    };
+  },
   removeTitleTag(s) {
     return s.replace(/「[\S\s]+?」/, '');
   },
diff --git a/views/submissions.ejs b/views/submissions.ejs
index cc16b77..44ffa24 100644
--- a/views/submissions.ejs
+++ b/views/submissions.ejs
@@ -116,7 +116,7 @@
   </div>
   <% } else { %>
   <br>
-  <% include page %>
+  <% include page_largedata %>
   <% } %>
 </div>