Limit redis cache size of renderer by using a LRU cache

config-example.json

@@ -126,5 +126,6 @@
   "no_cdn": false,
   "submissions_page_fast_pagination": false,
   "username_regex": "^[a-zA-Z0-9\\-\\_]+$",
-  "site_for_download": ""
+  "site_for_download": "",
+  "renderer_cache_size": "30000"
 }

libs/renderer.js

@@ -1,6 +1,6 @@
 const child_process = require('child_process');
 
-const rendererd = child_process.fork(__dirname + '/rendererd', [syzoj.config.redis]);
+const rendererd = child_process.fork(__dirname + '/rendererd', [syzoj.config.redis, parseInt(syzoj.config.renderer_cache_size)]);
 
 const resolver = {};
 let currentId = 0;

libs/rendererd.js

@@ -19,11 +19,13 @@ const xss = new XSS.FilterXSS({
 });
 
 const Redis = require('redis');
+const RedisLRU = require('redis-lru');
 const util = require('util');
 const redis = Redis.createClient(process.argv[2]);
+const redisLru = RedisLRU(redis, parseInt(process.argv[3]));
 const redisCache = {
-  get: util.promisify(redis.get).bind(redis),
-  set: util.promisify(redis.set).bind(redis)
+  get: redisLru.get.bind(redisLru),
+  set: redisLru.set.bind(redisLru)
 };
 
 async function highlight(code, lang) {

package.json

@@ -59,6 +59,7 @@
     "object-hash": "^1.3.1",
     "randomstring": "^1.1.5",
     "redis": "^2.8.0",
+    "redis-lru": "^0.6.0",
     "reflect-metadata": "^0.1.13",
     "request": "^2.74.0",
     "request-promise": "^4.2.4",

yarn.lock

@@ -2881,6 +2881,11 @@ redis-commands@^1.2.0:
   resolved "https://registry.yarnpkg.com/redis-commands/-/redis-commands-1.4.0.tgz#52f9cf99153efcce56a8f86af986bd04e988602f"
   integrity sha512-cu8EF+MtkwI4DLIT0x9P8qNTLFhQD4jLfxLR0cCNkeGzs87FN6879JOJwNQR/1zD7aSYNbU0hgsV9zGY71Itvw==
 
+redis-lru@^0.6.0:
+  version "0.6.0"
+  resolved "https://registry.yarnpkg.com/redis-lru/-/redis-lru-0.6.0.tgz#2a820a99011fe1a16a7ad2d67980def9d3336c7a"
+  integrity sha512-nDH+EHcUXp+cJdnkq8Hb+99kr82EDmAiFY40Bb02nB00A4N/dUqw3SCIJSgH8SUP2uee9EFijbMlf5WSul22uw==
+
 redis-parser@^2.6.0:
   version "2.6.0"
   resolved "https://registry.yarnpkg.com/redis-parser/-/redis-parser-2.6.0.tgz#52ed09dacac108f1a631c07e9b69941e7a19504b"