Рефакторинг, преобразование классов в синглтоны

server/db/ConnManager.js

@@ -0,0 +1,60 @@
+const fs = require('fs-extra');
+
+const SqliteConnectionPool = require('./SqliteConnectionPool');
+const log = new (require('../core/AppLogger'))().log;//singleton
+
+const migrations = {
+    'app': require('./migrations/app'),
+    'readerStorage': require('./migrations/readerStorage'),
+};
+
+let instance = null;
+
+//singleton
+class ConnManager {
+    constructor() {
+        if (!instance) {
+            this.inited = false;
+
+            instance = this;
+        }
+
+        return instance;
+    }
+
+    async init(config) {
+        this.config = config;
+        this._pool = {};
+
+        const force = null;//(config.branch == 'development' ? 'last' : null);
+
+        for (const poolConfig of this.config.db) {
+            const dbFileName = this.config.dataDir + '/' + poolConfig.fileName;
+
+            //бэкап
+            if (await fs.pathExists(dbFileName))
+                await fs.copy(dbFileName, `${dbFileName}.bak`);
+
+            const connPool = new SqliteConnectionPool();
+            await connPool.open(poolConfig.connCount, dbFileName);
+
+            log(`Opened database "${poolConfig.poolName}"`);
+            //миграции
+            const migs = migrations[poolConfig.poolName];
+            if (migs && migs.data.length) {
+                const applied = await connPool.migrate(migs.data, migs.table, force);
+                if (applied.length)
+                    log(`${applied.length} migrations applied to "${poolConfig.poolName}"`);
+            }
+
+            this._pool[poolConfig.poolName] = connPool;
+        }
+        this.inited = true;
+    }
+
+    get pool() {
+        return this._pool;
+    }
+}
+
+module.exports = ConnManager;