Migrations lock.

src/FirebirdSql.EntityFrameworkCore.Firebird/Migrations/Internal/FbHistoryRepository.cs

@@ -16,42 +16,156 @@
 //$Authors = Jiri Cincura ([email protected]), Jean Ressouche, Rafael Almeida ([email protected])
 
 using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Migrations;
 using Microsoft.EntityFrameworkCore.Storage;
 
 namespace FirebirdSql.EntityFrameworkCore.Firebird.Migrations.Internal;
 
-public class FbHistoryRepository : HistoryRepository
+public class FbHistoryRepository(HistoryRepositoryDependencies dependencies) : HistoryRepository(dependencies)
 {
-	public FbHistoryRepository(HistoryRepositoryDependencies dependencies)
-		: base(dependencies)
-	{ }
+	static readonly TimeSpan RetryDelay = TimeSpan.FromSeconds(1);
 
 	protected override string ExistsSql
 	{
 		get
 		{
 			var escapedTableName = Dependencies.TypeMappingSource.GetMapping(typeof(string)).GenerateSqlLiteral(TableName);
-			return $@"SELECT COUNT(*) FROM rdb$relations WHERE COALESCE(rdb$system_flag, 0) = 0 AND rdb$view_blr IS NULL AND rdb$relation_name = {escapedTableName}";
+			return $"""
+				SELECT COUNT(*) FROM rdb$relations WHERE COALESCE(rdb$system_flag, 0) = 0 AND rdb$view_blr IS NULL AND rdb$relation_name = {escapedTableName}
+				""";
 		}
 	}
 
-	protected override bool InterpretExistsResult(object value) => Convert.ToInt64(value) != 0;
+	protected override bool InterpretExistsResult(object value)
+		=> Convert.ToInt64(value) != 0;
 
-	public override string GetCreateIfNotExistsScript() => GetCreateScript();
+	public override string GetCreateIfNotExistsScript()
+		=> GetCreateScript();
 
-	public override string GetBeginIfExistsScript(string migrationId)
+	protected virtual string LockTableName { get; } = "__EFMigrationsLock";
+
+	public override LockReleaseBehavior LockReleaseBehavior
+		=> LockReleaseBehavior.Explicit;
+
+	public override IMigrationsDatabaseLock AcquireDatabaseLock()
 	{
-		throw new NotSupportedException("Generating idempotent scripts is currently not supported.");
+		Dependencies.MigrationsLogger.AcquiringMigrationLock();
+
+		CreateLockTableCommand().ExecuteNonQuery(CreateRelationalCommandParameters());
+
+		var retryDelay = RetryDelay;
+		while (true)
+		{
+			var dbLock = CreateMigrationDatabaseLock();
+			var insertCount = CreateInsertLockCommand(DateTime.UtcNow)
+				.ExecuteScalar(CreateRelationalCommandParameters());
+			if ((int)insertCount == 1)
+			{
+				return dbLock;
+			}
+
+			Thread.Sleep(retryDelay);
+			if (retryDelay < TimeSpan.FromMinutes(1))
+			{
+				retryDelay = retryDelay.Add(retryDelay);
+			}
+		}
 	}
 
-	public override string GetBeginIfNotExistsScript(string migrationId)
+	public override async Task<IMigrationsDatabaseLock> AcquireDatabaseLockAsync(CancellationToken cancellationToken = default)
 	{
-		throw new NotSupportedException("Generating idempotent scripts is currently not supported.");
+		Dependencies.MigrationsLogger.AcquiringMigrationLock();
+
+		await CreateLockTableCommand().ExecuteNonQueryAsync(CreateRelationalCommandParameters(), cancellationToken).ConfigureAwait(false);
+
+		var retryDelay = RetryDelay;
+		while (true)
+		{
+			var dbLock = CreateMigrationDatabaseLock();
+			var insertCount = await CreateInsertLockCommand(DateTime.UtcNow)
+				.ExecuteScalarAsync(CreateRelationalCommandParameters(), cancellationToken)
+				.ConfigureAwait(false);
+			if ((int)insertCount == 1)
+			{
+				return dbLock;
+			}
+
+			await Task.Delay(RetryDelay, cancellationToken).ConfigureAwait(true);
+			if (retryDelay < TimeSpan.FromMinutes(1))
+			{
+				retryDelay = retryDelay.Add(retryDelay);
+			}
+		}
 	}
 
+	public override string GetBeginIfExistsScript(string migrationId)
+		=> throw new NotSupportedException("Generating idempotent scripts is currently not supported.");
+
+	public override string GetBeginIfNotExistsScript(string migrationId)
+		=> throw new NotSupportedException("Generating idempotent scripts is currently not supported.");
+
 	public override string GetEndIfScript()
+		=> throw new NotSupportedException("Generating idempotent scripts is currently not supported.");
+
+	IRelationalCommand CreateLockTableCommand()
 	{
-		throw new NotSupportedException("Generating idempotent scripts is currently not supported.");
+		return Dependencies.RawSqlCommandBuilder.Build($"""
+			EXECUTE BLOCK
+			AS
+			BEGIN
+				BEGIN
+					EXECUTE STATEMENT
+						'CREATE TABLE "{LockTableName}" (
+							"Id" INT NOT NULL CONSTRAINT "PK_{LockTableName}" PRIMARY KEY,
+							"Timestamp" TIMESTAMP NOT NULL
+						)';
+					WHEN SQLSTATE '42S01' DO
+					BEGIN
+					END
+				END
+			END
+			""");
 	}
+
+	IRelationalCommand CreateInsertLockCommand(DateTime timestamp)
+	{
+		var timestampLiteral = Dependencies.TypeMappingSource.GetMapping(typeof(DateTime)).GenerateSqlLiteral(timestamp);
+		return Dependencies.RawSqlCommandBuilder.Build($"""
+			EXECUTE BLOCK
+			RETURNS (ROWS_AFFECTED INT)
+			AS
+			BEGIN
+				ROWS_AFFECTED = 1;
+				BEGIN
+					INSERT INTO "{LockTableName}" ("Id", "Timestamp") VALUES (1, {timestampLiteral});
+					WHEN SQLSTATE '23000' DO
+					BEGIN
+						ROWS_AFFECTED = 0;
+					END
+				END
+				SUSPEND;
+			END
+			""");
+	}
+
+	IRelationalCommand CreateDeleteLockCommand()
+	{
+		return Dependencies.RawSqlCommandBuilder.Build($"""
+			DELETE FROM "{LockTableName}" WHERE "Id" = 1
+			""");
+	}
+
+	SqliteMigrationDatabaseLock CreateMigrationDatabaseLock()
+		=> new(CreateDeleteLockCommand(), CreateRelationalCommandParameters(), this);
+
+	RelationalCommandParameterObject CreateRelationalCommandParameters()
+		=> new(
+			Dependencies.Connection,
+			null,
+			null,
+			Dependencies.CurrentContext.Context,
+			Dependencies.CommandLogger, CommandSource.Migrations);
 }

src/FirebirdSql.EntityFrameworkCore.Firebird/Migrations/Internal/FbMigrationDatabaseLock.cs

@@ -0,0 +1,39 @@
+/*
+ *    The contents of this file are subject to the Initial
+ *    Developer's Public License Version 1.0 (the "License");
+ *    you may not use this file except in compliance with the
+ *    License. You may obtain a copy of the License at
+ *    https://github.com/FirebirdSQL/NETProvider/raw/master/license.txt.
+ *
+ *    Software distributed under the License is distributed on
+ *    an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either
+ *    express or implied. See the License for the specific
+ *    language governing rights and limitations under the License.
+ *
+ *    All Rights Reserved.
+ */
+
+//$Authors = Jiri Cincura ([email protected])
+
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage;
+
+namespace FirebirdSql.EntityFrameworkCore.Firebird.Migrations.Internal;
+
+public class SqliteMigrationDatabaseLock(
+	IRelationalCommand releaseLockCommand,
+	RelationalCommandParameterObject relationalCommandParameters,
+	IHistoryRepository historyRepository,
+	CancellationToken cancellationToken = default)
+	: IMigrationsDatabaseLock
+{
+	public virtual IHistoryRepository HistoryRepository => historyRepository;
+
+	public void Dispose()
+		=> releaseLockCommand.ExecuteScalar(relationalCommandParameters);
+
+	public async ValueTask DisposeAsync()
+		=> await releaseLockCommand.ExecuteScalarAsync(relationalCommandParameters, cancellationToken).ConfigureAwait(false);
+}