feat: add SQLite3 config synchronous

Author: michalsn

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

@@ -56,6 +56,15 @@ class Connection extends BaseConnection
      */
     protected $busyTimeout;
 
+    /**
+     * The setting of the "synchronous" flag
+     *
+     * @var int|null flag
+     *
+     * @see https://www.sqlite.org/pragma.html#pragma_synchronous
+     */
+    protected $synchronous;
+
     /**
      * @return void
      */
@@ -70,6 +79,10 @@ public function initialize()
         if (is_int($this->busyTimeout)) {
             $this->connID->busyTimeout($this->busyTimeout);
         }
+
+        if (is_int($this->synchronous)) {
+            $this->connID->exec('PRAGMA synchronous = ' . $this->synchronous);
+        }
     }
 
     /**

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`_.