From 5f1f06fecf978b3d05e7da10fb0023e1ba9443ad Mon Sep 17 00:00:00 2001
From: softsimon <softsimon@protonmail.com>
Date: Wed, 27 Jan 2021 01:49:11 +0700
Subject: [PATCH] Don't save disk cache on exit. Handle corrupted mempool disk
 cache. fixes #304

---
 backend/src/api/disk-cache.ts | 74 ++++++++++-------------------------
 1 file changed, 20 insertions(+), 54 deletions(-)

diff --git a/backend/src/api/disk-cache.ts b/backend/src/api/disk-cache.ts
index 201391d84..4400cc79a 100644
--- a/backend/src/api/disk-cache.ts
+++ b/backend/src/api/disk-cache.ts
@@ -1,6 +1,5 @@
 import * as fs from 'fs';
 const fsPromises = fs.promises;
-import * as process from 'process';
 import * as cluster from 'cluster';
 import memPool from './mempool';
 import blocks from './blocks';
@@ -10,19 +9,7 @@ class DiskCache {
   private static FILE_NAME = './cache.json';
   private static FILE_NAMES = './cache{number}.json';
   private static CHUNK_SIZE = 10000;
-  constructor() {
-    if (!cluster.isMaster) {
-      return;
-    }
-    process.on('SIGINT', () => {
-      this.saveCacheToDiskSync();
-      process.exit(2);
-    });
-    process.on('SIGTERM', () => {
-      this.saveCacheToDiskSync();
-      process.exit(2);
-    });
-  }
+  constructor() { }
 
   async $saveCacheToDisk(): Promise<void> {
     if (!cluster.isMaster) {
@@ -51,52 +38,31 @@ class DiskCache {
     }
   }
 
-  saveCacheToDiskSync(): void {
-    try {
-      logger.debug('Writing mempool and blocks data to disk cache...');
-      const mempoolChunk_1 = Object.fromEntries(Object.entries(memPool.getMempool()).slice(0, DiskCache.CHUNK_SIZE));
-      fs.writeFileSync(DiskCache.FILE_NAME, JSON.stringify({
-        blocks: blocks.getBlocks(),
-        mempool: mempoolChunk_1
-      }), {flag: 'w'});
-      for (let i = 1; i < 10; i++) {
-        const mempoolChunk = Object.fromEntries(
-          Object.entries(memPool.getMempool()).slice(
-            DiskCache.CHUNK_SIZE * i, i === 9 ? undefined : DiskCache.CHUNK_SIZE * i + DiskCache.CHUNK_SIZE
-          )
-        );
-        fs.writeFileSync(DiskCache.FILE_NAMES.replace('{number}', i.toString()), JSON.stringify({
-          mempool: mempoolChunk
-        }), {flag: 'w'});
-      }
-
-      logger.debug('Mempool and blocks data saved to disk cache');
-    } catch (e) {
-      logger.warn('Error writing to cache file: ' + e.message || e);
-    }
-  }
-
   loadMempoolCache() {
     if (!fs.existsSync(DiskCache.FILE_NAME)) {
       return;
     }
-    let data: any = {};
-    const cacheData = fs.readFileSync(DiskCache.FILE_NAME, 'utf8');
-    if (cacheData) {
-      logger.info('Restoring mempool and blocks data from disk cache');
-      data = JSON.parse(cacheData);
-    }
-
-    for (let i = 1; i < 10; i++) {
-      const fileName = DiskCache.FILE_NAMES.replace('{number}', i.toString());
-      if (fs.existsSync(fileName)) {
-        const cacheData2 = JSON.parse(fs.readFileSync(fileName, 'utf8'));
-        Object.assign(data.mempool, cacheData2.mempool);
+    try {
+      let data: any = {};
+      const cacheData = fs.readFileSync(DiskCache.FILE_NAME, 'utf8');
+      if (cacheData) {
+        logger.info('Restoring mempool and blocks data from disk cache');
+        data = JSON.parse(cacheData);
       }
-    }
 
-    memPool.setMempool(data.mempool);
-    blocks.setBlocks(data.blocks);
+      for (let i = 1; i < 10; i++) {
+        const fileName = DiskCache.FILE_NAMES.replace('{number}', i.toString());
+        if (fs.existsSync(fileName)) {
+          const cacheData2 = JSON.parse(fs.readFileSync(fileName, 'utf8'));
+          Object.assign(data.mempool, cacheData2.mempool);
+        }
+      }
+
+      memPool.setMempool(data.mempool);
+      blocks.setBlocks(data.blocks);
+    } catch (e) {
+      logger.warn('Failed to parse mempoool and blocks cache. Skipping...');
+    }
   }
 }