Fix statement arguments not being freed (#225)

Author: simolus3

sqlite3/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 2.4.2
+
+- Fix string and blob arguments to prepared statements never being
+  deallocated ([#225](https://github.com/simolus3/sqlite3.dart/issues/225)).
+
 ## 2.4.1+1
 
 - Allow version `0.7.x` of the `js` package.

sqlite3/lib/src/ffi/bindings.dart

@@ -3,6 +3,8 @@ import 'dart:convert';
 import 'dart:ffi';
 import 'dart:typed_data';
 
+import 'package:meta/meta.dart';
+
 import '../constants.dart';
 import '../functions.dart';
 import '../implementation/bindings.dart';
@@ -378,6 +380,9 @@ final class FfiStatement extends RawSqliteStatement {
   FfiStatement(this.database, this.stmt)
       : bindings = database.bindings.bindings;
 
+  @visibleForTesting
+  List<Pointer> get allocatedArguments => _allocatedArguments;
+
   @override
   void deallocateArguments() {
     for (final arg in _allocatedArguments) {

sqlite3/lib/src/implementation/statement.dart

@@ -11,7 +11,6 @@ final class FinalizableStatement extends FinalizablePart {
   final RawSqliteStatement statement;
 
   bool _inResetState = true;
-  bool _hasAllocatedArguments = false;
   bool _closed = false;
 
   FinalizableStatement(this.statement);
@@ -34,10 +33,7 @@ final class FinalizableStatement extends FinalizablePart {
   }
 
   void _deallocateArguments() {
-    if (_hasAllocatedArguments) {
-      _hasAllocatedArguments = false;
-      statement.deallocateArguments();
-    }
+    statement.deallocateArguments();
   }
 }
 

sqlite3/pubspec.yaml

@@ -1,6 +1,6 @@
 name: sqlite3
 description: Provides lightweight yet convenient bindings to SQLite by using dart:ffi
-version: 2.4.1+1
+version: 2.4.2
 homepage: https://github.com/simolus3/sqlite3.dart/tree/main/sqlite3
 issue_tracker: https://github.com/simolus3/sqlite3.dart/issues
 

sqlite3/test/ffi/prepared_statement_test.dart

@@ -1,5 +1,6 @@
 @Tags(['ffi'])
 import 'package:sqlite3/sqlite3.dart';
+import 'package:sqlite3/src/ffi/implementation.dart';
 import 'package:test/test.dart';
 
 import '../common/prepared_statement.dart';
@@ -9,4 +10,33 @@ void main() {
   final hasReturning = version.versionNumber > 3035000;
 
   testPreparedStatements(() => sqlite3, supportsReturning: hasReturning);
+
+  group('deallocates statement arguments', () {
+    late Database database;
+
+    setUp(() => database = sqlite3.openInMemory());
+    tearDown(() => database.dispose());
+
+    test('after binding different args', () {
+      final stmt = database.prepare('SELECT ?;');
+      stmt.execute(['this needs to be allocated and copied into ffi buffer']);
+      expect(
+          (stmt as FfiStatementImplementation).ffiStatement.allocatedArguments,
+          isNotEmpty);
+
+      stmt.execute([3]);
+      expect(stmt.ffiStatement.allocatedArguments, isEmpty);
+    });
+
+    test('after disposing statement', () {
+      final stmt = database.prepare('SELECT ?;');
+      stmt.execute(['this needs to be allocated and copied into ffi buffer']);
+      expect(
+          (stmt as FfiStatementImplementation).ffiStatement.allocatedArguments,
+          isNotEmpty);
+
+      stmt.dispose();
+      expect(stmt.ffiStatement.allocatedArguments, isEmpty);
+    });
+  });
 }