feat: add SQLite3 config synchronous

app/Config/Database.php

@@ -65,6 +65,7 @@ class Database extends Config
     //        'failover'    => [],
     //        'foreignKeys' => true,
     //        'busyTimeout' => 1000,
+    //        'synchronous' => null,
     //        'dateFormat'  => [
     //            'date'     => 'Y-m-d',
     //            'datetime' => 'Y-m-d H:i:s',

system/Database/SQLite3/Connection.php

@@ -16,6 +16,7 @@
 use CodeIgniter\Database\BaseConnection;
 use CodeIgniter\Database\Exceptions\DatabaseException;
 use CodeIgniter\Database\TableName;
+use CodeIgniter\Exceptions\InvalidArgumentException;
 use Exception;
 use SQLite3;
 use SQLite3Result;
@@ -56,6 +57,15 @@ class Connection extends BaseConnection
      */
     protected $busyTimeout;
 
+    /**
+     * The setting of the "synchronous" flag
+     *
+     * @var int<0, 3>|null flag
+     *
+     * @see https://www.sqlite.org/pragma.html#pragma_synchronous
+     */
+    protected ?int $synchronous = null;
+
     /**
      * @return void
      */
@@ -70,6 +80,13 @@ public function initialize()
         if (is_int($this->busyTimeout)) {
             $this->connID->busyTimeout($this->busyTimeout);
         }
+
+        if (is_int($this->synchronous)) {
+            if (! in_array($this->synchronous, [0, 1, 2, 3], true)) {
+                throw new InvalidArgumentException('Invalid synchronous value.');
+            }
+            $this->connID->exec('PRAGMA synchronous = ' . $this->synchronous);
+        }
     }
 
     /**

tests/system/Database/Live/SQLite3/ConnectTest.php

@@ -0,0 +1,52 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <[email protected]>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Database\Live\SQLite3;
+
+use CodeIgniter\Exceptions\InvalidArgumentException;
+use CodeIgniter\Test\CIUnitTestCase;
+use Config\Database;
+use PHPUnit\Framework\Attributes\Group;
+
+/**
+ * @internal
+ */
+#[Group('DatabaseLive')]
+final class ConnectTest extends CIUnitTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->db = Database::connect($this->DBGroup);
+
+        if ($this->db->DBDriver !== 'SQLite3') {
+            $this->markTestSkipped('This test is only for SQLite3.');
+        }
+    }
+
+    public function testShowErrorMessageWhenSettingInvalidSynchronous(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('Invalid synchronous value.');
+
+        $config = config('Database');
+        $group  = $config->tests;
+        // Sets invalid synchronous.
+        $group['synchronous'] = 123;
+        $db                   = Database::connect($group);
+
+        // Actually connect to DB.
+        $db->initialize();
+    }
+}

user_guide_src/source/changelogs/v4.6.0.rst

@@ -208,6 +208,8 @@ Others
 - Added a new configuration ``foundRows`` for MySQLi to use ``MYSQLI_CLIENT_FOUND_ROWS``.
 - Added the ``BaseConnection::resetTransStatus()`` method to reset the transaction
   status. See :ref:`transactions-resetting-transaction-status` for details.
+- SQLite3 has a new Config item ``synchronous`` to adjust how strict SQLite is at flushing
+  to disk during transactions. Modifying this can be useful if we use journal mode set to ``WAL``.
 
 Model
 =====

user_guide_src/source/database/configuration.rst

@@ -178,6 +178,8 @@ Description of Values
                      See `SQLite documentation <https://www.sqlite.org/pragma.html#pragma_foreign_keys>`_.
                      To enforce Foreign Key constraint, set this config item to true.
 **busyTimeout**  (``SQLite3`` only) milliseconds (int) - Sleeps for a specified amount of time when a table is locked.
+**synchronous**  (``SQLite3`` only) flag (int) - How strict SQLite will be at flushing to disk during transactions.
+                 Use `null` to stay with the default setting. This can be used since v4.6.0.
 **numberNative** (``MySQLi`` only) true/false (boolean) - Whether to enable MYSQLI_OPT_INT_AND_FLOAT_NATIVE.
 **foundRows**    (``MySQLi`` only) true/false (boolean) - Whether to enable MYSQLI_CLIENT_FOUND_ROWS.
 **dateFormat**   The default date/time formats as PHP's `DateTime format`_.