Merge pull request #1427 from exogee-technology/fix/race-condition-on…

…-database-connection

Fix / Race condition on database connection

src/examples/databases/src/backend/database.ts

@@ -11,6 +11,7 @@ export const pgConnection = {
 		dbName: process.env.POSTGRES_DB_NAME ?? 'todo_app',
 		user: process.env.POSTGRES_DB_USER ?? 'postgres',
 		password: process.env.POSTGRES_DB_PASSWORD ?? '',
+		host: process.env.POSTGRES_DB_HOST ?? 'localhost',
 		port: parseInt(process.env.POSTGRES_DB_PORT ?? '5432'),
 	},
 };
@@ -23,6 +24,7 @@ export const myConnection = {
 		dbName: process.env.MYSQL_DB_NAME ?? 'todo_app',
 		user: process.env.MYSQL_DB_USER ?? 'root',
 		password: process.env.MYSQL_DB_PASSWORD ?? '',
+		host: process.env.MYSQL_DB_HOST ?? 'localhost',
 		port: parseInt(process.env.MYSQL_DB_PORT ?? '3306'),
 	},
 };

src/packages/mikroorm/src/database.ts

@@ -281,11 +281,8 @@ class DatabaseImplementation {
 }
 
 class ConnectionsManager {
-	private connections: Map<string, DatabaseImplementation>;
-
-	constructor() {
-		this.connections = new Map<string, DatabaseImplementation>();
-	}
+	private connections = new Map<string, DatabaseImplementation>();
+	private connectionPromises = new Map<string, Promise<DatabaseImplementation>>();
 
 	getConnections() {
 		return Array.from(this.connections.values());
@@ -301,21 +298,35 @@ class ConnectionsManager {
 		return databaseConnection;
 	}
 
-	public connect = async (id?: string, connectionOptions?: ConnectionOptions) => {
-		if (!id) throw new Error('Error: No id attached to connection.');
-
+	public connect = (id: string, connectionOptions: ConnectionOptions) => {
 		if (this.connections.has(id)) return this.connections.get(id);
-		const database = new DatabaseImplementation();
-		if (connectionOptions) await database.connect(connectionOptions);
-		logger.trace(`Saving database connection with id "${id}".`);
-		this.connections.set(id, database);
+
+		const connect = new Promise<DatabaseImplementation>((resolve, reject) => {
+			const database = new DatabaseImplementation();
+			database
+				.connect(connectionOptions)
+				.then(() => {
+					logger.trace(`Saving database connection with id "${id}".`);
+					this.connections.set(id, database);
+					resolve(database);
+				})
+				.catch(reject);
+		});
+
+		this.connectionPromises.set(id, connect);
+
+		return connect;
 	};
 
 	public database(id: string) {
 		logger.trace(`Finding database connection for id "${id}"`);
 		return this.connections.get(id);
 	}
 
+	public awaitableDatabase(id: string) {
+		return this.connectionPromises.get(id);
+	}
+
 	public async close(id: string) {
 		const database = this.database(id);
 		await database?.close();

src/packages/mikroorm/src/provider/provider.ts

@@ -157,11 +157,16 @@ export class MikroBackendProvider<D> implements BackendProvider<D> {
 		const connectionPlugin = {
 			name: connectionManagerId,
 			event: GraphweaverRequestEvent.OnRequest,
-			next: (_: GraphweaverRequestEvent, _next: GraphweaverPluginNextFunction) => {
+			next: async (_: GraphweaverRequestEvent, _next: GraphweaverPluginNextFunction) => {
 				logger.trace(`Graphweaver OnRequest plugin called`);
 
-				const connection = ConnectionManager.database(connectionManagerId);
-				if (!connection) throw new Error('No database connection found');
+				const connection = await ConnectionManager.awaitableDatabase(connectionManagerId);
+
+				if (!connection) {
+					throw new Error(
+						`No database connection found for connectionManagerId: ${connectionManagerId} after waiting for connection. This should not happen.`
+					);
+				}
 
 				return RequestContext.create(connection.orm.em, _next, {});
 			},