From 2d8fdc27d20ea25bed4fd2a0e66bef7da40bd0b5 Mon Sep 17 00:00:00 2001
From: Laura Hausmann <laura@hausmann.dev>
Date: Wed, 9 Feb 2022 18:26:27 +0100
Subject: [PATCH] Make migrations atomic and error-proof

---
 Migrations.cs | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/Migrations.cs b/Migrations.cs
index b6622b4..31ef739 100644
--- a/Migrations.cs
+++ b/Migrations.cs
@@ -55,7 +55,6 @@ public static class Migrations {
 			Console.Write("has been created with the password ");
 			Console.ForegroundColor = ConsoleColor.DarkMagenta;
 			Console.WriteLine(password);
-			Console.WriteLine();
 		}
 		else if (db.DataProvider.GetSchemaProvider().GetSchema(db).Tables.All(t => t.TableName != "DbInfo")) {
 			db.CreateTable<DbInfo>();
@@ -71,7 +70,20 @@ public static class Migrations {
 			Console.WriteLine("No migrations to run.");
 		}
 		else {
-			migrationsToRun.ForEach(RunMigration);
+			new Migration(0, "BEGIN TRANSACTION").Run(db);
+			try {
+				migrationsToRun.ForEach(p => p.Run(db));
+			}
+			catch {
+				Console.ForegroundColor = ConsoleColor.DarkRed;
+				Console.WriteLine($"Migrating to database version {DbVer} failed.");
+				new Migration(0, "ROLLBACK TRANSACTION").Run(db);
+				Console.ForegroundColor = ConsoleColor.DarkYellow;
+				Console.WriteLine("Rolled back migrations.");
+				Environment.Exit(1);
+			}
+
+			new Migration(0, "COMMIT TRANSACTION").Run(db);
 
 			var newdb  = new AppDb.DbConn();
 			var dbinfo = newdb.DbInfo.First();
@@ -87,8 +99,6 @@ public static class Migrations {
 		Console.ForegroundColor = ccolor;
 	}
 
-	private static void RunMigration(Migration mig) => mig.Run();
-
 	private class Migration {
 		private readonly string _sql;
 		public readonly  int    IntroducedWithDbVer;
@@ -98,9 +108,7 @@ public static class Migrations {
 			_sql                = sql;
 		}
 
-		public void Run() {
-			using var db = new AppDb.DbConn();
-
+		public void Run(DataConnection db) {
 			Console.ForegroundColor = ConsoleColor.DarkCyan;
 			Console.Write("Running migration: ");
 			Console.ForegroundColor = ConsoleColor.Yellow;