Add option for database cache size

config-example.json

@@ -7,7 +7,8 @@
     "username": "syzoj",
     "password": "@DATABASE_PASSWORD@",
     "host": "127.0.0.1",
-    "migrated_to_typeorm": true
+    "migrated_to_typeorm": true,
+    "cache_size": 1000
   },
   "logo": {
     "url": null,

models/common.ts

@@ -2,6 +2,8 @@ import * as TypeORM from "typeorm";
 import * as LRUCache from "lru-cache";
 import * as DeepCopy from "deepcopy";
 
+declare var syzoj: any;
+
 interface Paginater {
   pageCnt: number;
   perPage: number;
@@ -23,7 +25,7 @@ const caches: Map<string, LRUCache<number, Model>> = new Map();
 function ensureCache(modelName) {
   if (!caches.has(modelName)) {
     caches.set(modelName, new LRUCache({
-      max: 500
+      max: syzoj.config.db.cache_size
     }));
   }
 

models/problem.ts

@@ -194,7 +194,9 @@ import * as util from "util";
 import * as LRUCache from "lru-cache";
 import * as DeepCopy from "deepcopy";
 
-const problemTagCache = new LRUCache<number, number[]>();
+const problemTagCache = new LRUCache<number, number[]>({
+  max: syzoj.config.db.cache_size
+});
 
 enum ProblemType {
   Traditional = "traditional",