Default SQLite connections to WAL

packages/mysql-on-sqlite/src/sqlite/class-wp-sqlite-connection.php

@@ -19,6 +19,16 @@ class WP_SQLite_Connection {
 	 */
 	const DEFAULT_SQLITE_TIMEOUT = 10;
 
+	/**
+	 * The default SQLite journal mode.
+	 */
+	const DEFAULT_SQLITE_JOURNAL_MODE = 'WAL';
+
+	/**
+	 * The default SQLite synchronous setting for WAL mode.
+	 */
+	const DEFAULT_SQLITE_WAL_SYNCHRONOUS = 'NORMAL';
+
 	/**
 	 * The supported SQLite journal modes.
 	 *
@@ -33,6 +43,18 @@ class WP_SQLite_Connection {
 		'OFF',
 	);
 
+	/**
+	 * The supported SQLite synchronous settings.
+	 *
+	 * See: https://www.sqlite.org/pragma.html#pragma_synchronous
+	 */
+	const SQLITE_SYNCHRONOUS_SETTINGS = array(
+		'OFF',
+		'NORMAL',
+		'FULL',
+		'EXTRA',
+	);
+
 	/**
 	 * The PDO connection for SQLite.
 	 *
@@ -63,6 +85,7 @@ class WP_SQLite_Connection {
 	 *     @type int|null    $timeout      Optional. SQLite timeout in seconds.
 	 *                                     The time to wait for a writable lock.
 	 *     @type string|null $journal_mode Optional. SQLite journal mode.
+	 *     @type string|null $synchronous  Optional. SQLite synchronous setting.
 	 * }
 	 *
 	 * @throws InvalidArgumentException When some connection options are invalid.
@@ -92,9 +115,28 @@ public function __construct( array $options ) {
 		$this->pdo->setAttribute( PDO::ATTR_TIMEOUT, $timeout );
 
 		// Configure SQLite journal mode.
-		$journal_mode = $options['journal_mode'] ?? null;
+		$effective_journal_mode = null;
+		$journal_mode           = $options['journal_mode'] ?? self::DEFAULT_SQLITE_JOURNAL_MODE;
+		if ( is_string( $journal_mode ) ) {
+			$journal_mode = strtoupper( $journal_mode );
+		}
 		if ( $journal_mode && in_array( $journal_mode, self::SQLITE_JOURNAL_MODES, true ) ) {
-			$this->query( 'PRAGMA journal_mode = ' . $journal_mode );
+			$effective_journal_mode = strtoupper(
+				(string) $this->query( 'PRAGMA journal_mode = ' . $journal_mode )->fetchColumn()
+			);
+		}
+
+		// Configure SQLite synchronous setting.
+		$synchronous = $options['synchronous'] ?? null;
+		if ( null === $synchronous && 'WAL' === $effective_journal_mode ) {
+			// Keep rollback journal modes on SQLite's default durability unless explicitly configured.
+			$synchronous = self::DEFAULT_SQLITE_WAL_SYNCHRONOUS;
+		}
+		if ( is_string( $synchronous ) ) {
+			$synchronous = strtoupper( $synchronous );
+		}
+		if ( $synchronous && in_array( $synchronous, self::SQLITE_SYNCHRONOUS_SETTINGS, true ) ) {
+			$this->query( 'PRAGMA synchronous = ' . $synchronous );
 		}
 	}
 

packages/mysql-on-sqlite/tests/WP_SQLite_Connection_Tests.php

@@ -0,0 +1,75 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests for the SQLite connection setup.
+ */
+class WP_SQLite_Connection_Tests extends TestCase {
+	/**
+	 * Path to the temporary SQLite database file used in file-based tests.
+	 *
+	 * @var string|null
+	 */
+	private $db_path;
+
+	public function setUp(): void {
+		$this->db_path = tempnam( sys_get_temp_dir(), 'wp_sqlite_' );
+		unlink( $this->db_path );
+	}
+
+	public function tearDown(): void {
+		foreach ( array(
+			$this->db_path,
+			$this->db_path . '-wal',
+			$this->db_path . '-shm',
+			$this->db_path . '-journal',
+		) as $path ) {
+			if ( is_string( $path ) && file_exists( $path ) ) {
+				unlink( $path );
+			}
+		}
+		$this->db_path = null;
+	}
+
+	public function testDefaultJournalModeUsesWal(): void {
+		$connection = new WP_SQLite_Connection( array( 'path' => $this->db_path ) );
+
+		$this->assertSame(
+			'wal',
+			strtolower( (string) $connection->query( 'PRAGMA journal_mode' )->fetchColumn() )
+		);
+		$this->assertSame(
+			'1',
+			(string) $connection->query( 'PRAGMA synchronous' )->fetchColumn()
+		);
+	}
+
+	public function testJournalModeCanBeOverridden(): void {
+		$connection = new WP_SQLite_Connection(
+			array(
+				'path'         => $this->db_path,
+				'journal_mode' => 'DELETE',
+			)
+		);
+
+		$this->assertSame(
+			'delete',
+			strtolower( (string) $connection->query( 'PRAGMA journal_mode' )->fetchColumn() )
+		);
+	}
+
+	public function testSynchronousCanBeOverridden(): void {
+		$connection = new WP_SQLite_Connection(
+			array(
+				'path'        => $this->db_path,
+				'synchronous' => 'FULL',
+			)
+		);
+
+		$this->assertSame(
+			'2',
+			(string) $connection->query( 'PRAGMA synchronous' )->fetchColumn()
+		);
+	}
+}

packages/plugin-sqlite-database-integration/wp-includes/sqlite/class-wp-sqlite-db.php

@@ -316,6 +316,7 @@ public function db_connect( $allow_bail = true ) {
 					'pdo'          => $pdo,
 					'path'         => FQDB,
 					'journal_mode' => defined( 'SQLITE_JOURNAL_MODE' ) ? SQLITE_JOURNAL_MODE : null,
+					'synchronous'  => defined( 'SQLITE_SYNCHRONOUS' ) ? SQLITE_SYNCHRONOUS : null,
 				)
 			);
 			$this->dbh       = new WP_SQLite_Driver( $connection, $this->dbname );

packages/plugin-sqlite-database-integration/wp-includes/sqlite/install-functions.php

@@ -35,7 +35,13 @@ function sqlite_make_db_sqlite() {
 	}
 
 	$translator = new WP_SQLite_Driver(
-		new WP_SQLite_Connection( array( 'pdo' => $pdo ) ),
+		new WP_SQLite_Connection(
+			array(
+				'pdo'          => $pdo,
+				'journal_mode' => defined( 'SQLITE_JOURNAL_MODE' ) ? SQLITE_JOURNAL_MODE : null,
+				'synchronous'  => defined( 'SQLITE_SYNCHRONOUS' ) ? SQLITE_SYNCHRONOUS : null,
+			)
+		),
 		$wpdb->dbname
 	);
 	$query      = null;