PluralKit/PluralKit.Core/Database/Schemas.cs

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C#
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using System;
using System.Data;
using System.IO;
using System.Threading.Tasks;
using Dapper;
using Npgsql;
using Serilog;
namespace PluralKit.Core
{
public class Schemas
{
private const string RootPath = "PluralKit.Core.Database"; // "resource path" root for SQL files
private const int TargetSchemaVersion = 7;
private Database _conn;
private ILogger _logger;
public Schemas(Database conn, ILogger logger)
{
_conn = conn;
_logger = logger.ForContext<Schemas>();
}
public static void Initialize()
{
// Without these it'll still *work* but break at the first launch + probably cause other small issues
NpgsqlConnection.GlobalTypeMapper.MapComposite<ProxyTag>("proxy_tag");
NpgsqlConnection.GlobalTypeMapper.MapEnum<PrivacyLevel>("privacy_level");
}
public async Task InitializeDatabase()
{
// Run everything in a transaction
await using var conn = await _conn.Obtain();
await using var tx = await conn.BeginTransactionAsync();
// Before applying migrations, clean out views/functions to prevent type errors
await ExecuteSqlFile($"{RootPath}.clean.sql", conn, tx);
// Apply all migrations between the current database version and the target version
await ApplyMigrations(conn, tx);
// Now, reapply views/functions (we deleted them above, no need to worry about conflicts)
await ExecuteSqlFile($"{RootPath}.views.sql", conn, tx);
await ExecuteSqlFile($"{RootPath}.Functions.functions.sql", conn, tx);
// Finally, commit tx
await tx.CommitAsync();
}
private async Task ApplyMigrations(IPKConnection conn, IDbTransaction tx)
{
var currentVersion = await GetCurrentDatabaseVersion(conn);
_logger.Information("Current schema version: {CurrentVersion}", currentVersion);
for (var migration = currentVersion + 1; migration <= TargetSchemaVersion; migration++)
{
_logger.Information("Applying schema migration {MigrationId}", migration);
await ExecuteSqlFile($"{RootPath}.Migrations.{migration}.sql", conn, tx);
}
}
private async Task ExecuteSqlFile(string resourceName, IPKConnection conn, IDbTransaction tx = null)
{
await using var stream = typeof(Schemas).Assembly.GetManifestResourceStream(resourceName);
if (stream == null) throw new ArgumentException($"Invalid resource name '{resourceName}'");
using var reader = new StreamReader(stream);
var query = await reader.ReadToEndAsync();
await conn.ExecuteAsync(query, transaction: tx);
// If the above creates new enum/composite types, we must tell Npgsql to reload the internal type caches
// This will propagate to every other connection as well, since it marks the global type mapper collection dirty.
// TODO: find a way to get around the cast to our internal tracker wrapper... this could break if that ever changes
conn.ReloadTypes();
}
private async Task<int> GetCurrentDatabaseVersion(IPKConnection conn)
{
// First, check if the "info" table exists (it may not, if this is a *really* old database)
var hasInfoTable =
await conn.QuerySingleOrDefaultAsync<int>(
"select count(*) from information_schema.tables where table_name = 'info'") == 1;
// If we have the table, read the schema version
if (hasInfoTable)
return await conn.QuerySingleOrDefaultAsync<int>("select schema_version from info");
// If not, we return version "-1"
// This means migration 0 will get executed, getting us into a consistent state
// Then, migration 1 gets executed, which creates the info table and sets version to 1
return -1;
}
}
}