PluralKit/PluralKit.Core/SchemaService.cs

62 lines
2.4 KiB
C#

using System;
using System.Data;
using System.IO;
using System.Threading.Tasks;
using Dapper;
using Npgsql;
using Serilog;
namespace PluralKit {
public class SchemaService
{
private const int TargetSchemaVersion = 1;
private DbConnectionFactory _conn;
private ILogger _logger;
public SchemaService(DbConnectionFactory conn, ILogger logger)
{
_conn = conn;
_logger = logger.ForContext<SchemaService>();
}
public async Task ApplyMigrations()
{
for (var version = 0; version <= TargetSchemaVersion; version++)
await ApplyMigration(version);
}
private async Task ApplyMigration(int migrationId)
{
// migrationId is the *target* version
using var conn = await _conn.Obtain();
using var tx = conn.BeginTransaction();
// See if we even have the info table... if not, we implicitly define the version as -1
// This means migration 0 will get executed, which ensures we're at a consistent state.
// *Technically* this also means schema version 0 will be identified as -1, but since we're only doing these
// checks in the above for loop, this doesn't matter.
var hasInfoTable = await conn.QuerySingleOrDefaultAsync<int>("select count(*) from information_schema.tables where table_name = 'info'") == 1;
int currentVersion;
if (hasInfoTable)
currentVersion = await conn.QuerySingleOrDefaultAsync<int>("select schema_version from info");
else currentVersion = -1;
if (currentVersion >= migrationId)
return; // Don't execute the migration if we're already at the target version.
using var stream = typeof(SchemaService).Assembly.GetManifestResourceStream($"PluralKit.Core.Migrations.{migrationId}.sql");
if (stream == null) throw new ArgumentException("Invalid migration ID");
using var reader = new StreamReader(stream);
var migrationQuery = await reader.ReadToEndAsync();
_logger.Information("Current schema version is {CurrentVersion}, applying migration {MigrationId}", currentVersion, migrationId);
await conn.ExecuteAsync(migrationQuery, transaction: tx);
tx.Commit();
}
}
}