Implement new experimental SQLite integration module

admin/load.php

@@ -156,17 +156,48 @@ function perflab_render_modules_page_field( $module_slug, $module_data, $module_
 				<input type="checkbox" id="<?php echo esc_attr( "{$base_id}_enabled" ); ?>" aria-describedby="<?php echo esc_attr( "{$base_id}_description" ); ?>" disabled>
 				<input type="hidden" name="<?php echo esc_attr( "{$base_name}[enabled]" ); ?>" value="<?php echo $enabled ? '1' : '0'; ?>">
 				<?php
+				if ( 'database/sqlite' === $module_slug && file_exists( WP_CONTENT_DIR . '/db.php' ) && ! defined( 'PERFLAB_SQLITE_DB_DROPIN_VERSION' ) ) {
+					printf(
+						/* translators: %s: db.php drop-in path */
+						esc_html__( 'The SQLite module cannot be activated because a different %s drop-in already exists.', 'performance-lab' ),
+						'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
+					);
+				} elseif ( 'database/sqlite' === $module_slug && ! wp_is_writable( WP_CONTENT_DIR ) ) {
+					printf(
+						/* translators: %s: db.php drop-in path */
+						esc_html__( 'The SQLite module cannot be activated because the %s directory is not writable.', 'performance-lab' ),
+						'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '</code>'
+					);
+				} elseif ( 'database/sqlite' === $module_slug && ! class_exists( 'SQLite3' ) ) {
+					esc_html_e( 'The SQLite module cannot be activated because the SQLite extension is not loaded.', 'performance-lab' );
+				} else {
 					printf(
 						/* translators: %s: module name */
 						__( '%s is already part of your WordPress version and therefore cannot be loaded as part of the plugin.', 'performance-lab' ),
 						esc_html( $module_data['name'] )
 					);
+				}
 				?>
 			<?php } ?>
 		</label>
 		<p id="<?php echo esc_attr( "{$base_id}_description" ); ?>" class="description">
 			<?php echo esc_html( $module_data['description'] ); ?>
 		</p>
+		<?php if ( 'database/sqlite' === $module_slug ) : ?>
+			<?php if ( $enabled ) : ?>
+				<?php if ( defined( 'PERFLAB_SQLITE_DB_DROPIN_VERSION' ) ) : ?>
+					<?php // Don't use the WP notice classes here, as that makes them move to the top of the page. ?>
+					<p class="notice notice-warning" style="padding:1em;max-width:50em;">
+						<?php esc_html_e( 'Your site is currently using an SQLite database. You can disable this module to get back to your previous MySQL database, with all your previous data intact.', 'performance-lab' ); ?>
+					</p>
+				<?php endif; ?>
+			<?php else : ?>
+				<?php // Don't use the WP notice classes here, as that makes them move to the top of the page. ?>
+				<p class="notice notice-warning" style="padding:1em;max-width:50em;">
+					<?php esc_html_e( 'Enabling this module will switch to a separate database and install WordPress in it. You will need to reconfigure your site, and start with a fresh site. Disabling the module you will get back to your previous MySQL database, with all your previous data intact. Warning: Do not activate if your site is implemented in a multi-server environment.', 'performance-lab' ); ?>
+				</p>
+			<?php endif; ?>
+		<?php endif; ?>
 	</fieldset>
 	<?php
 }

load.php

@@ -260,3 +260,97 @@ function perflab_load_active_and_valid_modules() {
 if ( is_admin() ) {
 	require_once PERFLAB_PLUGIN_DIR_PATH . 'admin/load.php';
 }
+
+/**
+ * Trigger actions when a module gets activated or deactivated.
+ *
+ * @since n.e.x.t
+ *
+ * @param mixed $old_value Old value of the option.
+ * @param mixed $value     New value of the option.
+ */
+function perflab_run_module_activation_deactivation( $old_value, $value ) {
+	$old_value = (array) $old_value;
+	$value     = (array) $value;
+
+	// Get the list of modules that were activated, and load the activate.php files if they exist.
+	if ( ! empty( $value ) ) {
+		foreach ( $value as $module => $module_settings ) {
+			if ( ! empty( $module_settings['enabled'] ) && ( empty( $old_value[ $module ] ) || empty( $old_value[ $module ]['enabled'] ) ) ) {
+				perflab_activate_module( PERFLAB_PLUGIN_DIR_PATH . 'modules/' . $module );
+			}
+		}
+	}
+
+	// Get the list of modules that were deactivated, and load the deactivate.php files if they exist.
+	if ( ! empty( $old_value ) ) {
+		foreach ( $old_value as $module => $module_settings ) {
+			if ( ! empty( $module_settings['enabled'] ) && ( empty( $value[ $module ] ) || empty( $value[ $module ]['enabled'] ) ) ) {
+				perflab_deactivate_module( PERFLAB_PLUGIN_DIR_PATH . 'modules/' . $module );
+			}
+		}
+	}
+
+	return $value;
+}
+
+/**
+ * Activate a module.
+ *
+ * Runs the activate.php file if it exists.
+ *
+ * @since n.e.x.t
+ *
+ * @param string $module_dir_path The module's directory path.
+ */
+function perflab_activate_module( $module_dir_path ) {
+	$module_activation_file = $module_dir_path . '/activate.php';
+	if ( ! file_exists( $module_activation_file ) ) {
+		return;
+	}
+	$module = require $module_activation_file;
+	if ( ! is_callable( $module ) ) {
+		return;
+	}
+	$module();
+}
+
+/**
+ * Deactivate a module.
+ *
+ * Runs the deactivate.php file if it exists.
+ *
+ * @since n.e.x.t
+ *
+ * @param string $module_dir_path The module's directory path.
+ */
+function perflab_deactivate_module( $module_dir_path ) {
+	$module_deactivation_file = $module_dir_path . '/deactivate.php';
+	if ( ! file_exists( $module_deactivation_file ) ) {
+		return;
+	}
+	$module = require $module_deactivation_file;
+	if ( ! is_callable( $module ) ) {
+		return;
+	}
+	$module();
+}
+
+// Run the module activation & deactivation actions when the option is updated.
+add_action( 'update_option_' . PERFLAB_MODULES_SETTING, 'perflab_run_module_activation_deactivation', 10, 2 );
+
+// Run the module activation & deactivation actions when the option is added.
+add_action(
+	'add_option_' . PERFLAB_MODULES_SETTING,
+	/**
+	 * Fires after the option has been added.
+	 *
+	 * @param string $option Name of the option to add.
+	 * @param mixed  $value  Value of the option.
+	 */
+	function( $option, $value ) {
+		perflab_run_module_activation_deactivation( perflab_get_modules_setting_default(), $value );
+	},
+	10,
+	2
+);

modules/database/sqlite/activate.php

@@ -0,0 +1,169 @@
+<?php
+/**
+ * Actions to run when the module gets activated.
+ *
+ * @since n.e.x.t
+ * @package performance-lab
+ */
+
+/**
+ * Copies the db.php file in wp-content and reloads the page.
+ *
+ * @since n.e.x.t
+ */
+return function() {
+	// Bail early if the SQLite3 class does not exist.
+	if ( ! class_exists( 'SQLite3' ) ) {
+		return;
+	}
+
+	$destination = WP_CONTENT_DIR . '/db.php';
+
+	// Place database drop-in if not present yet, except in case there is
+	// another database drop-in present already.
+	if ( ! defined( 'PERFLAB_SQLITE_DB_DROPIN_VERSION' ) && ! file_exists( $destination ) ) {
+		// Init the filesystem to allow copying the file.
+		global $wp_filesystem;
+		if ( ! $wp_filesystem ) {
+			require_once ABSPATH . '/wp-admin/includes/file.php';
+			WP_Filesystem();
+		}
+
+		// Copy the file, replacing contents as needed.
+		if ( $wp_filesystem->touch( $destination ) ) {
+
+			// Get the db.copy.php file contents, replace placeholders and write it to the destination.
+			$file_contents = str_replace(
+				'{SQLITE_IMPLEMENTATION_FOLDER_PATH}',
+				__DIR__,
+				file_get_contents( __DIR__ . '/db.copy.php' )
+			);
+
+			$wp_filesystem->put_contents( $destination, $file_contents );
+		}
+	}
+
+	// As an extra safety check, bail if the current user cannot update
+	// (or install) WordPress core.
+	if ( ! current_user_can( 'update_core' ) ) {
+		return;
+	}
+
+	// Otherwise install WordPress in the SQLite database before the redirect,
+	// so that the user does not end up on the WordPress installation screen
+	// but rather remains in the Performance Lab modules screen.
+	add_filter(
+		'wp_redirect',
+		function( $redirect_location ) {
+			if ( ! defined( 'DATABASE_TYPE' ) ) {
+				define( 'DATABASE_TYPE', 'sqlite' );
+			}
+			require_once __DIR__ . '/constants.php';
+
+			// If the SQLite DB already exists, simply ensure the module is
+			// active there.
+			if ( file_exists( FQDB ) ) {
+				require_once __DIR__ . '/wp-includes/sqlite/db.php';
+				wp_set_wpdb_vars();
+				global $wpdb;
+				$row = $wpdb->get_row( $wpdb->prepare( "SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1", PERFLAB_MODULES_SETTING ) );
+				if ( is_object( $row ) ) {
+					$value = maybe_unserialize( $row->option_value );
+					if ( is_array( $value ) && ( ! isset( $value['database/sqlite'] ) || ! $value['database/sqlite']['enabled'] ) ) {
+						$value['database/sqlite'] = array( 'enabled' => true );
+						$wpdb->update( $wpdb->options, array( 'option_value' => maybe_serialize( $value ) ), array( 'option_name' => PERFLAB_MODULES_SETTING ) );
+					}
+				}
+				return $redirect_location;
+			}
+
+			// Get current basic setup data to install WordPress in the new DB.
+			$blog_title = get_bloginfo( 'name' );
+			$is_public  = (bool) get_option( 'blog_public' );
+			$language   = get_option( 'WPLANG' );
+			$user_email = get_option( 'admin_email' );
+			$admin_user = get_user_by( 'email', $user_email );
+			if ( ! $admin_user ) {
+				$admin_user = wp_get_current_user();
+			}
+
+			// If the current user is not the admin email user, look up the
+			// data for the current user. Additionally, attempt to keep them
+			// logged-in by retaining their current session. Depending on the
+			// site configuration, this is not 100% reliable as sites may store
+			// session tokens outside of user meta. However that does not lead
+			// to any problem, the user would simply be required to sign in
+			// again.
+			$current_user    = null;
+			$current_user_id = get_current_user_id();
+			if ( $current_user_id !== (int) $admin_user->ID ) {
+				$current_user = wp_get_current_user();
+			}
+			$user_sessions = get_user_meta( $current_user_id, 'session_tokens', true );
+
+			// Get current data to keep the Performance Lab plugin and relevant
+			// modules active in the new DB.
+			$active_plugins_option = array( plugin_basename( PERFLAB_MAIN_FILE ) );
+			$active_modules_option = get_option( PERFLAB_MODULES_SETTING, array() );
+
+			// Load and set up SQLite database.
+			require_once __DIR__ . '/wp-includes/sqlite/db.php';
+			wp_set_wpdb_vars();
+
+			// Load WordPress installation API functions.
+			require_once ABSPATH . 'wp-admin/includes/upgrade.php';
+
+			// Install WordPress in the SQLite database with the same base
+			// configuration as the MySQL database.
+			// Since $admin_user->user_pass is already hashed, add a filter to
+			// ensure it is inserted into the database like that, instead of
+			// being re-hashed.
+			$unhash_user_pass = function( $data, $update, $user_id, $userdata ) use ( $admin_user, $current_user ) {
+				// Double check this is actually the already hashed password,
+				// to prevent any chance of accidentally putting another
+				// password into the database which would then be plain text.
+				if (
+					! empty( $userdata['user_pass'] )
+					&& (
+						$userdata['user_pass'] === $admin_user->user_pass
+						|| $current_user && $userdata['user_pass'] === $current_user->user_pass
+					)
+				) {
+					$data['user_pass'] = $userdata['user_pass'];
+				}
+				return $data;
+			};
+			add_filter( 'wp_pre_insert_user_data', $unhash_user_pass, 10, 4 );
+			wp_install( $blog_title, $admin_user->user_login, $user_email, $is_public, '', $admin_user->user_pass, $language );
+			if ( $current_user ) { // Also "copy" current admin user if it's not the admin email owner.
+				wp_create_user( $current_user->user_login, $current_user->user_pass, $current_user->user_email );
+			}
+			remove_filter( 'wp_pre_insert_user_data', $unhash_user_pass );
+
+			// If user sessions are found, migrate them over so that the
+			// current user remains logged in.
+			if ( $user_sessions ) {
+				$session_user = get_user_by( 'login', $current_user ? $current_user->user_login : $admin_user->user_login );
+				if ( $session_user ) {
+					update_user_meta( $session_user->ID, 'session_tokens', $user_sessions );
+				}
+			}
+
+			// Activate the Performance Lab plugin and its modules.
+			// Use direct database query for Performance Lab modules to
+			// prevent module activation logic from firing again.
+			update_option( 'active_plugins', $active_plugins_option );
+			global $wpdb;
+			$wpdb->insert(
+				$wpdb->options,
+				array(
+					'option_name'  => PERFLAB_MODULES_SETTING,
+					'option_value' => maybe_serialize( $active_modules_option ),
+					'autoload'     => 'yes',
+				)
+			);
+
+			return $redirect_location;
+		}
+	);
+};

modules/database/sqlite/can-load.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * Can load function to determine if SQLite can be activated.
+ *
+ * @since n.e.x.t
+ * @package performance-lab
+ */
+
+/**
+ * Checks whether the given module can be activated.
+ *
+ * @since n.e.x.t
+ */
+return function() {
+
+	// If the PERFLAB_SQLITE_DB_DROPIN_VERSION constant is defined, then the module is already active.
+	if ( defined( 'PERFLAB_SQLITE_DB_DROPIN_VERSION' ) ) {
+		return true;
+	}
+
+	// If a db.php file already exists in the wp-content directory, then the module cannot be activated.
+	if ( file_exists( WP_CONTENT_DIR . '/db.php' ) ) {
+		return false;
+	}
+
+	// If the SQLite3 class does not exist, then the module cannot be activated.
+	if ( ! class_exists( 'SQLite3' ) ) {
+		return false;
+	}
+
+	// If the db.php file can't be written to the wp-content directory, then the module cannot be activated.
+	if ( ! wp_is_writable( WP_CONTENT_DIR ) ) {
+		return false;
+	}
+	return true;
+};