feat(db): invert backup/restore logic

Do the migration on a temp copy of the db, then back up the original and move the temp into its file.

invokeai/app/api/dependencies.py

@@ -2,6 +2,7 @@
 
 from functools import partial
 from logging import Logger
+from pathlib import Path
 
 from invokeai.app.services.shared.sqlite.migrations.migration_1 import migration_1
 from invokeai.app.services.shared.sqlite.migrations.migration_2 import migration_2
@@ -75,12 +76,22 @@ class ApiDependencies:
         image_files = DiskImageFileStorage(f"{output_folder}/images")
 
         db = SqliteDatabase(config, logger)
-        migrator = SQLiteMigrator(database=db.database, lock=db.lock, logger=logger)
+
+        migrator = SQLiteMigrator(
+            db_path=db.database if isinstance(db.database, Path) else None,
+            conn=db.conn,
+            lock=db.lock,
+            logger=logger,
+            log_sql=config.log_sql,
+        )
         migration_2.register_post_callback(partial(migrate_embedded_workflows, logger=logger, image_files=image_files))
         migrator.register_migration(migration_1)
         migrator.register_migration(migration_2)
         migrator.run_migrations()
 
+        if not db.is_memory:
+            db.reinitialize()
+
         configuration = config
         logger = logger
 

invokeai/app/services/shared/sqlite/migrations/migration_1.py

@@ -6,6 +6,8 @@ from invokeai.app.services.shared.sqlite.sqlite_migrator import Migration
 def _migrate(cursor: sqlite3.Cursor) -> None:
     """Migration callback for database version 1."""
 
+    print("migration 1!!!")
+
     _create_board_images(cursor)
     _create_boards(cursor)
     _create_images(cursor)

invokeai/app/services/shared/sqlite/migrations/migration_2.py

@@ -6,6 +6,8 @@ from invokeai.app.services.shared.sqlite.sqlite_migrator import Migration
 def _migrate(cursor: sqlite3.Cursor) -> None:
     """Migration callback for database version 2."""
 
+    print("migration 2!!!")
+
     _add_images_has_workflow(cursor)
     _add_session_queue_workflow(cursor)
     _drop_old_workflow_tables(cursor)

invokeai/app/services/shared/sqlite/sqlite_database.py

@@ -10,18 +10,21 @@ from invokeai.app.services.shared.sqlite.sqlite_common import sqlite_memory
 class SqliteDatabase:
     database: Path | str  # Must declare this here to satisfy type checker
 
-    def __init__(self, config: InvokeAIAppConfig, logger: Logger):
+    def __init__(self, config: InvokeAIAppConfig, logger: Logger) -> None:
+        self.initialize(config, logger)
+
+    def initialize(self, config: InvokeAIAppConfig, logger: Logger) -> None:
         self._logger = logger
         self._config = config
         self.is_memory = False
         if self._config.use_memory_db:
             self.database = sqlite_memory
             self.is_memory = True
-            logger.info("Using in-memory database")
+            logger.info("Initializing in-memory database")
         else:
             self.database = self._config.db_path
             self.database.parent.mkdir(parents=True, exist_ok=True)
-            self._logger.info(f"Using database at {self.database}")
+            self._logger.info(f"Initializing database at {self.database}")
 
         self.conn = sqlite3.connect(database=self.database, check_same_thread=False)
         self.lock = threading.RLock()
@@ -32,6 +35,13 @@ class SqliteDatabase:
 
         self.conn.execute("PRAGMA foreign_keys = ON;")
 
+    def reinitialize(self) -> None:
+        """Reinitializes the database. Needed after migration."""
+        self.initialize(self._config, self._logger)
+
+    def close(self) -> None:
+        self.conn.close()
+
     def clean(self) -> None:
         with self.lock:
             try:

invokeai/app/services/shared/sqlite/sqlite_migrator.py

@@ -8,16 +8,14 @@ from typing import Callable, Optional, TypeAlias
 
 from pydantic import BaseModel, Field, model_validator
 
-from invokeai.app.services.shared.sqlite.sqlite_common import sqlite_memory
-
 MigrateCallback: TypeAlias = Callable[[sqlite3.Cursor], None]
 
 
-class MigrationError(Exception):
+class MigrationError(RuntimeError):
     """Raised when a migration fails."""
 
 
-class MigrationVersionError(ValueError, MigrationError):
+class MigrationVersionError(ValueError):
     """Raised when a migration version is invalid."""
 
 
@@ -25,8 +23,14 @@ class Migration(BaseModel):
     """
     Represents a migration for a SQLite database.
 
-    Migration callbacks will be provided an instance of SqliteDatabase.
-    Migration callbacks should not commit; the migrator will commit the transaction.
+    Migration callbacks will be provided an open cursor to the database. They should not commit their
+    transaction; this is handled by the migrator.
+
+    Pre- and post-migration callback may be registered with :meth:`register_pre_callback` or
+    :meth:`register_post_callback`.
+
+    If a migration has additional dependencies, it is recommended to use functools.partial to provide
+    the dependencies and register the partial as the migration callback.
     """
 
     from_version: int = Field(ge=0, strict=True, description="The database version on which this migration may be run")
@@ -77,6 +81,28 @@ class MigrationSet:
         # register() ensures that there is only one migration with a given from_version, so this is safe.
         return next((m for m in self._migrations if m.from_version == from_version), None)
 
+    def validate_migration_path(self) -> None:
+        """
+        Validates that the migrations form a single path of migrations from version 0 to the latest version.
+        Raises a MigrationError if there is a problem.
+        """
+        if self.count == 0:
+            return
+        if self.latest_version == 0:
+            return
+        current_version = 0
+        touched_count = 0
+        while current_version < self.latest_version:
+            migration = self.get(current_version)
+            if migration is None:
+                raise MigrationError(f"Missing migration from {current_version}")
+            current_version = migration.to_version
+            touched_count += 1
+        if current_version != self.latest_version:
+            raise MigrationError(f"Missing migration to {self.latest_version}")
+        if touched_count != self.count:
+            raise MigrationError("Migration path is not contiguous")
+
     @property
     def count(self) -> int:
         """The count of registered migrations."""
@@ -90,87 +116,112 @@ class MigrationSet:
         return sorted(self._migrations, key=lambda m: m.to_version)[-1].to_version
 
 
+def get_temp_db_path(original_db_path: Path) -> Path:
+    """Gets the path to the migrated database."""
+    return original_db_path.parent / original_db_path.name.replace(".db", ".db.temp")
+
+
 class SQLiteMigrator:
     """
     Manages migrations for a SQLite database.
 
-    :param db: The SqliteDatabase, representing the database on which to run migrations.
-    :param image_files: An instance of ImageFileStorageBase. Migrations may need to access image files.
+    :param db_path: The path to the database to migrate, or None if using an in-memory database.
+    :param conn: The connection to the database.
+    :param lock: A lock to use when running migrations.
+    :param logger: A logger to use for logging.
+    :param log_sql: Whether to log SQL statements. Only used when the log level is set to debug.
 
-    Migrations should be registered with :meth:`register_migration`. Migrations will be run in
-    order of their version number. If the database is already at the latest version, no migrations
-    will be run.
+    Migrations should be registered with :meth:`register_migration`.
+
+    During migration, a copy of the current database is made and the migrations are run on the copy. If the migration
+    is successful, the original database is backed up and the migrated database is moved to the original database's
+    path. If the migration fails, the original database is left untouched and the migrated database is deleted.
+
+    If the database is in-memory, no backup is made; the migration is run in-place.
     """
 
     backup_path: Optional[Path] = None
 
     def __init__(
         self,
-        database: Path | str,
+        db_path: Path | None,
+        conn: sqlite3.Connection,
         lock: threading.RLock,
         logger: Logger,
+        log_sql: bool = False,
     ) -> None:
         self._lock = lock
-        self._database = database
-        self._is_memory = database == sqlite_memory
+        self._db_path = db_path
         self._logger = logger
-        self._conn = sqlite3.connect(database)
+        self._conn = conn
+        self._log_sql = log_sql
         self._cursor = self._conn.cursor()
         self._migrations = MigrationSet()
 
-        # Use a lock file to indicate that a migration is in progress. Should only exist in the event of catastrophic failure.
-        self._migration_lock_file_path = (
-            self._database.parent / ".migration_in_progress" if isinstance(self._database, Path) else None
-        )
-
-        if self._unlink_lock_file():
+        # The presence of an temp database file indicates a catastrophic failure of a previous migration.
+        if self._db_path and get_temp_db_path(self._db_path).is_file():
             self._logger.warning("Previous migration failed! Trying again...")
+            get_temp_db_path(self._db_path).unlink()
 
     def register_migration(self, migration: Migration) -> None:
-        """
-        Registers a migration.
-        Migration callbacks should not commit any changes to the database; the migrator will commit the transaction.
-        """
+        """Registers a migration."""
         self._migrations.register(migration)
         self._logger.debug(f"Registered migration {migration.from_version} -> {migration.to_version}")
 
     def run_migrations(self) -> None:
         """Migrates the database to the latest version."""
         with self._lock:
-            self._create_version_table()
-            current_version = self._get_current_version()
+            # This throws if there is a problem.
+            self._migrations.validate_migration_path()
+            self._create_migrations_table(cursor=self._cursor)
 
             if self._migrations.count == 0:
                 self._logger.debug("No migrations registered")
                 return
 
-            latest_version = self._migrations.latest_version
-            if current_version == latest_version:
+            if self._get_current_version(self._cursor) == self._migrations.latest_version:
                 self._logger.debug("Database is up to date, no migrations to run")
                 return
 
             self._logger.info("Database update needed")
 
-            # Only make a backup if using a file database (not memory)
-            self._backup_db()
+            if self._db_path:
+                # We are using a file database. Create a copy of the database to run the migrations on.
+                temp_db_path = self._create_temp_db(self._db_path)
+                temp_db_conn = sqlite3.connect(temp_db_path)
+                # We have to re-set this because we just created a new connection.
+                if self._log_sql:
+                    temp_db_conn.set_trace_callback(self._logger.debug)
+                temp_db_cursor = temp_db_conn.cursor()
+                self._run_migrations(temp_db_cursor)
+                # Close the connections, copy the original database as a backup, and move the temp database to the
+                # original database's path.
+                self._finalize_migration(
+                    temp_db_conn=temp_db_conn,
+                    temp_db_path=temp_db_path,
+                    original_db_path=self._db_path,
+                )
+            else:
+                # We are using a memory database. No special backup or special handling needed.
+                self._run_migrations(self._cursor)
+                return
 
-            next_migration = self._migrations.get(from_version=current_version)
-            while next_migration is not None:
-                try:
-                    self._run_migration(next_migration)
-                    next_migration = self._migrations.get(self._get_current_version())
-                except MigrationError:
-                    self._restore_db()
-                    raise
             self._logger.info("Database updated successfully")
+            return
 
-    def _run_migration(self, migration: Migration) -> None:
+    def _run_migrations(self, temp_db_cursor: sqlite3.Cursor) -> None:
+        next_migration = self._migrations.get(from_version=self._get_current_version(temp_db_cursor))
+        while next_migration is not None:
+            self._run_migration(next_migration, temp_db_cursor)
+            next_migration = self._migrations.get(self._get_current_version(temp_db_cursor))
+
+    def _run_migration(self, migration: Migration, temp_db_cursor: sqlite3.Cursor) -> None:
         """Runs a single migration."""
         with self._lock:
             try:
-                if self._get_current_version() != migration.from_version:
+                if self._get_current_version(temp_db_cursor) != migration.from_version:
                     raise MigrationError(
-                        f"Database is at version {self._get_current_version()}, expected {migration.from_version}"
+                        f"Database is at version {self._get_current_version(temp_db_cursor)}, expected {migration.from_version}"
                     )
                 self._logger.debug(f"Running migration from {migration.from_version} to {migration.to_version}")
 
@@ -178,37 +229,37 @@ class SQLiteMigrator:
                 if migration.pre_migrate:
                     self._logger.debug(f"Running {len(migration.pre_migrate)} pre-migration callbacks")
                     for callback in migration.pre_migrate:
-                        callback(self._cursor)
+                        callback(temp_db_cursor)
 
                 # Run the actual migration
-                migration.migrate(self._cursor)
-                self._cursor.execute("INSERT INTO migrations (version) VALUES (?);", (migration.to_version,))
+                migration.migrate(temp_db_cursor)
+                temp_db_cursor.execute("INSERT INTO migrations (version) VALUES (?);", (migration.to_version,))
 
                 # Run post-migration callbacks
                 if migration.post_migrate:
                     self._logger.debug(f"Running {len(migration.post_migrate)} post-migration callbacks")
                     for callback in migration.post_migrate:
-                        callback(self._cursor)
+                        callback(temp_db_cursor)
 
                 # Migration callbacks only get a cursor. Commit this migration.
-                self._conn.commit()
+                temp_db_cursor.connection.commit()
                 self._logger.debug(
                     f"Successfully migrated database from {migration.from_version} to {migration.to_version}"
                 )
             except Exception as e:
                 msg = f"Error migrating database from {migration.from_version} to {migration.to_version}: {e}"
-                self._conn.rollback()
+                temp_db_cursor.connection.rollback()
                 self._logger.error(msg)
                 raise MigrationError(msg) from e
 
-    def _create_version_table(self) -> None:
-        """Creates a version table for the database, if one does not already exist."""
+    def _create_migrations_table(self, cursor: sqlite3.Cursor) -> None:
+        """Creates the migrations table for the database, if one does not already exist."""
         with self._lock:
             try:
-                self._cursor.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='migrations';")
-                if self._cursor.fetchone() is not None:
+                cursor.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='migrations';")
+                if cursor.fetchone() is not None:
                     return
-                self._cursor.execute(
+                cursor.execute(
                     """--sql
                     CREATE TABLE migrations (
                         version INTEGER PRIMARY KEY,
@@ -216,21 +267,21 @@ class SQLiteMigrator:
                     );
                     """
                 )
-                self._cursor.execute("INSERT INTO migrations (version) VALUES (0);")
-                self._conn.commit()
+                cursor.execute("INSERT INTO migrations (version) VALUES (0);")
+                cursor.connection.commit()
                 self._logger.debug("Created migrations table")
             except sqlite3.Error as e:
                 msg = f"Problem creating migrations table: {e}"
                 self._logger.error(msg)
-                self._conn.rollback()
+                cursor.connection.rollback()
                 raise MigrationError(msg) from e
 
-    def _get_current_version(self) -> int:
+    def _get_current_version(self, cursor: sqlite3.Cursor) -> int:
         """Gets the current version of the database, or 0 if the version table does not exist."""
         with self._lock:
             try:
-                self._cursor.execute("SELECT MAX(version) FROM migrations;")
-                version = self._cursor.fetchone()[0]
+                cursor.execute("SELECT MAX(version) FROM migrations;")
+                version = cursor.fetchone()[0]
                 if version is None:
                     return 0
                 return version
@@ -239,54 +290,19 @@ class SQLiteMigrator:
                     return 0
                 raise
 
-    def _backup_db(self) -> None:
-        """Backs up the databse, returning the path to the backup file."""
-        if self._is_memory:
-            self._logger.debug("Using memory database, skipping backup")
-        # Sanity check!
-        assert isinstance(self._database, Path)
-        with self._lock:
-            timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
-            backup_path = self._database.parent / f"{self._database.stem}_{timestamp}.db"
-            self._logger.info(f"Backing up database to {backup_path}")
+    def _create_temp_db(self, current_db_path: Path) -> Path:
+        """Copies the current database to a new file for migration."""
+        temp_db_path = get_temp_db_path(current_db_path)
+        shutil.copy2(current_db_path, temp_db_path)
+        self._logger.info(f"Copied database to {temp_db_path} for migration")
+        return temp_db_path
 
-            # Use SQLite's built in backup capabilities so we don't need to worry about locking and such.
-            backup_conn = sqlite3.connect(backup_path)
-            with backup_conn:
-                self._conn.backup(backup_conn)
-            backup_conn.close()
-
-            # Sanity check!
-            if not backup_path.is_file():
-                raise MigrationError("Unable to back up database")
-            self.backup_path = backup_path
-
-    def _restore_db(
-        self,
-    ) -> None:
-        """Restores the database from a backup file, unless the database is a memory database."""
-        if self._is_memory:
-            return
-
-        with self._lock:
-            self._logger.info(f"Restoring database from {self.backup_path}")
-            self._conn.close()
-            assert isinstance(self.backup_path, Path)
-            shutil.copy2(self.backup_path, self._database)
-
-    def _unlink_lock_file(self) -> bool:
-        """Unlinks the migration lock file, returning True if it existed."""
-        if self._is_memory or self._migration_lock_file_path is None:
-            return False
-        if self._migration_lock_file_path.is_file():
-            self._migration_lock_file_path.unlink()
-            return True
-        return False
-
-    def _write_migration_lock_file(self) -> None:
-        """Writes a file to indicate that a migration is in progress."""
-        if self._is_memory or self._migration_lock_file_path is None:
-            return
-        assert isinstance(self._database, Path)
-        with open(self._migration_lock_file_path, "w") as f:
-            f.write("1")
+    def _finalize_migration(self, temp_db_conn: sqlite3.Connection, temp_db_path: Path, original_db_path: Path) -> None:
+        """Closes connections, renames the original database as a backup and renames the migrated database to the original db path."""
+        self._conn.close()
+        temp_db_conn.close()
+        timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
+        backup_db_path = original_db_path.parent / f"{original_db_path.stem}_backup_{timestamp}.db"
+        original_db_path.rename(backup_db_path)
+        temp_db_path.rename(original_db_path)
+        self._logger.info(f"Migration successful. Original DB backed up to {backup_db_path}")