Add beforeOpen callback to native factories

packages/sqlite_async/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.14.4
+
+- Native: Add the `NativeSqliteOpenFactory.beforeOpen` method, which can be overridden to configure
+  SQLite asynchronously before opening databases.
+
 ## 0.14.3
 
 - Include identifier of mutexes when a navigator lock attempt is aborted.

packages/sqlite_async/lib/src/native/database/native_sqlite_database.dart

@@ -251,7 +251,9 @@ final class NativeSqliteDatabaseImpl extends SqliteDatabaseImpl {
 
   static Future<SqliteConnectionPool> _openNativePool(
     NativeSqliteOpenFactory openFactory,
-  ) {
+  ) async {
+    await openFactory.beforeOpen();
+
     // We want to open pools asynchronously since running pragma statements as
     // part of openFactory.open might do IO. openAsync spawn a temporary isolate
     // for that.

packages/sqlite_async/lib/src/native/native_sqlite_open_factory.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:sqlite3/sqlite3.dart' as sqlite;
 
 import '../common/abstract_open_factory.dart';
@@ -9,6 +11,17 @@ import '../common/abstract_open_factory.dart';
 base class NativeSqliteOpenFactory extends InternalOpenFactory {
   NativeSqliteOpenFactory({required super.path, super.sqliteOptions});
 
+  /// A (potentially asynchronous) hook to invoke before opening databases for
+  /// a pool.
+  ///
+  /// This does nothing by default, but can be overridden to apply global
+  /// SQLite configuration options before databases are opened, e.g. to set
+  /// [sqlite.CommonSqlite3.tempDirectory].
+  ///
+  /// This method is invoked in the main isolate, not the background isolate
+  /// responsible for opening connections.
+  FutureOr<void> beforeOpen() {}
+
   @override
   List<String> pragmaStatements(SqliteOpenOptions options) {
     List<String> statements = [];

packages/sqlite_async/test/native/basic_test.dart

@@ -362,6 +362,15 @@ void main() {
         ),
       );
     });
+
+    test('invokes beforeOpen callback on factories', () async {
+      final factoy = _BeforeSetupHook(path: path);
+      final db = SqliteDatabase.withFactory(factoy);
+      expect(factoy.didCallBeforeOpen, isFalse);
+      await db.initialize();
+
+      expect(factoy.didCallBeforeOpen, isTrue);
+    });
   });
 }
 
@@ -381,3 +390,14 @@ final class _InvalidPragmaOnOpenFactory extends NativeSqliteOpenFactory {
     ];
   }
 }
+
+final class _BeforeSetupHook extends NativeSqliteOpenFactory {
+  var didCallBeforeOpen = false;
+
+  _BeforeSetupHook({required super.path});
+
+  @override
+  void beforeOpen() {
+    didCallBeforeOpen = true;
+  }
+}