chore: modernize connections handling in sqlite (#10894)

lib/dialects/sqlite/connection-manager.js

@@ -17,14 +17,16 @@ class ConnectionManager extends AbstractConnectionManager {
       delete this.sequelize.options.host;
     }
 
-    this.connections = {};
+    this.connections = new Map();
     this.lib = this._loadDialectModule('sqlite3').verbose();
     this.refreshTypeParser(dataTypes);
   }
 
   _onProcessExit() {
-    const promises = Object.getOwnPropertyNames(this.connections)
-      .map(connection => Promise.fromCallback(callback => this.connections[connection].close(callback)));
+    const promises = [];
+    for (const conn of this.connections.values()) {
+      promises.push(Promise.fromCallback(callback => conn.close(callback)));
+    }
 
     return Promise
       .all(promises)
@@ -38,20 +40,20 @@ class ConnectionManager extends AbstractConnectionManager {
     const dialectOptions = this.sequelize.options.dialectOptions;
     options.readWriteMode = dialectOptions && dialectOptions.mode;
 
-    if (this.connections[options.inMemory || options.uuid]) {
-      return Promise.resolve(this.connections[options.inMemory || options.uuid]);
+    if (this.connections.has(options.inMemory || options.uuid)) {
+      return Promise.resolve(this.connections.get(options.inMemory || options.uuid));
     }
 
     return new Promise((resolve, reject) => {
-      this.connections[options.inMemory || options.uuid] = new this.lib.Database(
+      this.connections.set(options.inMemory || options.uuid, new this.lib.Database(
         this.sequelize.options.storage || this.sequelize.options.host || ':memory:',
         options.readWriteMode || this.lib.OPEN_READWRITE | this.lib.OPEN_CREATE, // default mode
         err => {
           if (err) return reject(new sequelizeErrors.ConnectionError(err));
           debug(`connection acquired ${options.uuid}`);
-          resolve(this.connections[options.inMemory || options.uuid]);
+          resolve(this.connections.get(options.inMemory || options.uuid));
         }
-      );
+      ));
     }).tap(connection => {
       if (this.sequelize.config.password) {
         // Make it possible to define and use password for sqlite encryption plugin like sqlcipher
@@ -71,7 +73,7 @@ class ConnectionManager extends AbstractConnectionManager {
     if (connection.uuid) {
       connection.close();
       debug(`connection released ${connection.uuid}`);
-      delete this.connections[connection.uuid];
+      this.connections.delete(connection.uuid);
     }
   }
 }