Make flush optional.

Author: rkistner

packages/sqlite_async/lib/src/web/database.dart

@@ -113,7 +113,8 @@ class WebDatabase
   @override
   Future<T> writeTransaction<T>(
       Future<T> Function(SqliteWriteContext tx) callback,
-      {Duration? lockTimeout}) {
+      {Duration? lockTimeout,
+      bool? flush}) {
     return writeLock(
         (writeContext) =>
             internalWriteTransaction(writeContext, (context) async {
@@ -122,22 +123,25 @@ class WebDatabase
               return callback(_ExclusiveTransactionContext(this, writeContext));
             }),
         debugContext: 'writeTransaction()',
-        lockTimeout: lockTimeout);
+        lockTimeout: lockTimeout,
+        flush: flush);
   }
 
   @override
 
   /// Internal writeLock which intercepts transaction context's to verify auto commit is not active
   Future<T> writeLock<T>(Future<T> Function(SqliteWriteContext tx) callback,
-      {Duration? lockTimeout, String? debugContext}) async {
+      {Duration? lockTimeout, String? debugContext, bool? flush}) async {
     if (_mutex case var mutex?) {
       return await mutex.lock(() async {
         final context = _ExclusiveContext(this);
         try {
           return await callback(context);
         } finally {
           context.markClosed();
-          await _database.fileSystem.flush();
+          if (flush != false) {
+            await this.flush();
+          }
         }
       });
     } else {
@@ -149,12 +153,20 @@ class WebDatabase
         return await callback(context);
       } finally {
         context.markClosed();
-        await _database.fileSystem.flush();
+        if (flush != false) {
+          await this.flush();
+        }
         await _database.customRequest(
             CustomDatabaseMessage(CustomDatabaseMessageKind.releaseLock));
       }
     }
   }
+
+  @override
+  Future<void> flush() async {
+    await isInitialized;
+    return _database.fileSystem.flush();
+  }
 }
 
 class _SharedContext implements SqliteReadContext {

packages/sqlite_async/lib/src/web/database/web_sqlite_database.dart

@@ -131,24 +131,32 @@ class SqliteDatabaseImpl
 
   @override
   Future<T> writeLock<T>(Future<T> Function(SqliteWriteContext tx) callback,
-      {Duration? lockTimeout, String? debugContext}) async {
+      {Duration? lockTimeout, String? debugContext, bool? flush}) async {
     await isInitialized;
     return _runZoned(() {
       return _connection.writeLock(callback,
-          lockTimeout: lockTimeout, debugContext: debugContext);
+          lockTimeout: lockTimeout, debugContext: debugContext, flush: flush);
     }, debugContext: debugContext ?? 'execute()');
   }
 
   @override
   Future<T> writeTransaction<T>(
       Future<T> Function(SqliteWriteContext tx) callback,
-      {Duration? lockTimeout}) async {
+      {Duration? lockTimeout,
+      bool? flush}) async {
     await isInitialized;
     return _runZoned(
-        () => _connection.writeTransaction(callback, lockTimeout: lockTimeout),
+        () => _connection.writeTransaction(callback,
+            lockTimeout: lockTimeout, flush: flush),
         debugContext: 'writeTransaction()');
   }
 
+  @override
+  Future<void> flush() async {
+    await isInitialized;
+    return _connection.flush();
+  }
+
   @override
   Future<void> close() async {
     await isInitialized;

packages/sqlite_async/lib/web.dart

@@ -65,4 +65,34 @@ abstract class WebSqliteConnection implements SqliteConnection {
     );
     return database;
   }
+
+  /// Same as [SqliteConnection.writeLock].
+  ///
+  /// Has an additional [flush] (defaults to true). This can be set to false
+  /// to delay flushing changes to the database file, losing durability guarantees.
+  /// This only has an effect when IndexedDB storage is used.
+  ///
+  /// See [flush] for details.
+  Future<T> writeLock<T>(Future<T> Function(SqliteWriteContext tx) callback,
+      {Duration? lockTimeout, String? debugContext, bool? flush});
+
+  /// Same as [SqliteConnection.writeTransaction].
+  ///
+  /// Has an additional [flush] (defaults to true). This can be set to false
+  /// to delay flushing changes to the database file, losing durability guarantees.
+  /// This only has an effect when IndexedDB storage is used.
+  ///
+  /// See [flush] for details.
+  Future<T> writeTransaction<T>(
+      Future<T> Function(SqliteWriteContext tx) callback,
+      {Duration? lockTimeout,
+      bool? flush});
+
+  /// Flush changes to the underlying storage.
+  ///
+  /// When this returns, all changes previously written will be persisted
+  /// to storage.
+  ///
+  /// This only has an effect when IndexedDB storage is used.
+  Future<void> flush();
 }