optimize migration class

Author: pfefferle

Diff for: includes/class-admin.php

@@ -267,8 +267,8 @@ public static function admin_menu() {
 	 * Load settings page
 	 */
 	public static function settings_page() {
-		require_once __DIR__ . '/class-db.php';
-		\Webmention\DB::update_database();
+		require_once __DIR__ . '/class-upgrade.php';
+		\Webmention\Upgrade::maybe_upgrade();
 		\Webmention\remove_semantic_linkbacks();
 
 		add_thickbox();

Diff for: includes/class-cli.php

@@ -315,9 +315,7 @@ public function generate( $args, $assoc_args ) {
 	 * @return void
 	 */
 	public function db_migration( $args, $assoc_args ) {
-		require_once __DIR__ . '/class-db.php';
-
-		DB::update_database();
+		Upgrade::maybe_upgrade();
 
 		WP_CLI::success( __( 'DB Migration finished', 'webmention' ) );
 	}

Diff for: includes/class-db.php

@@ -1,53 +1,107 @@
 <?php
 /**
- * Database Class
+ * Upgrade Class
  *
  * @package Webmention
  */
 namespace Webmention;
 
 /**
- * Database Class
+ * Upgrade Class
  *
  * @package Webmention
  */
-class DB {
+class Upgrade {
 	/**
-	 * Which internal datastructure version we are running on.
-	 *
-	 * @var int
+	 * Initialize the upgrade class.
 	 */
-	private static $target_version = '1.0.1';
-
-	public static function get_target_version() {
-		return self::$target_version;
+	public static function init() {
+		add_action( 'init', array( self::class, 'maybe_upgrade' ) );
 	}
 
+	/**
+	 * Get the current version.
+	 *
+	 * @return int
+	 */
 	public static function get_version() {
 		return get_option( 'webmention_db_version', 0 );
 	}
 
 	/**
 	 * Whether the database structure is up to date.
 	 *
-	 * @return bool
+	 * @return bool True if the database structure is up to date, false otherwise.
 	 */
 	public static function is_latest_version() {
-		return (bool) version_compare(
+		return (bool) \version_compare(
 			self::get_version(),
-			self::get_target_version(),
+			WEBMENTION_VERSION,
 			'=='
 		);
 	}
 
+	/**
+	 * Locks the database migration process to prevent simultaneous migrations.
+	 *
+	 * @return bool|int True if the lock was successful, timestamp of existing lock otherwise.
+	 */
+	public static function lock() {
+		global $wpdb;
+
+		// Try to lock.
+		$lock_result = (bool) $wpdb->query( $wpdb->prepare( "INSERT IGNORE INTO `$wpdb->options` ( `option_name`, `option_value`, `autoload` ) VALUES (%s, %s, 'no') /* LOCK */", 'webmention_migration_lock', \time() ) ); // phpcs:ignore WordPress.DB
+
+		if ( ! $lock_result ) {
+			$lock_result = \get_option( 'webmention_migration_lock' );
+		}
+
+		return $lock_result;
+	}
+
+	/**
+	 * Unlocks the database migration process.
+	 */
+	public static function unlock() {
+		\delete_option( 'webmention_migration_lock' );
+	}
+
+	/**
+	 * Whether the database migration process is locked.
+	 *
+	 * @return boolean
+	 */
+	public static function is_locked() {
+		$lock = \get_option( 'webmention_migration_lock' );
+
+		if ( ! $lock ) {
+			return false;
+		}
+
+		$lock = (int) $lock;
+
+		if ( $lock < \time() - 1800 ) {
+			self::unlock();
+			return false;
+		}
+
+		return true;
+	}
+
 	/**
 	 * Updates the database structure if necessary.
 	 */
-	public static function update_database() {
+	public static function maybe_upgrade() {
 		if ( self::is_latest_version() ) {
 			return;
 		}
 
+		if ( self::is_locked() ) {
+			return;
+		}
+
+		self::lock();
+
 		$version_from_db = self::get_version();
 
 		if ( version_compare( $version_from_db, '1.0.0', '<' ) ) {
@@ -57,7 +111,17 @@ public static function update_database() {
 			self::migrate_to_1_0_1();
 		}
 
-		update_option( 'webmention_db_version', self::$target_version );
+		/**
+		 * Fires when the system has to be migrated.
+		 *
+		 * @param string $version_from_db The version from which to migrate.
+		 * @param string $target_version  The target version to migrate to.
+		 */
+		\do_action( 'webmention_migrate', $version_from_db, WEBMENTION_VERSION );
+
+		\update_option( 'webmention_db_version', WEBMENTION_VERSION );
+
+		self::unlock();
 	}
 
 	/**

Diff for: includes/class-upgrade.php

@@ -24,11 +24,11 @@ public function test_update_database() {
 			)
 		);
 
-		$this->assertEquals( \Webmention\DB::get_version(), 0 );
+		$this->assertEquals( \Webmention\Upgrade::get_version(), 0 );
 
-		\Webmention\DB::update_database();
+		\Webmention\Upgrade::maybe_upgrade();
 
-		$this->assertEquals( \Webmention\DB::get_version(), '1.0.1' );
+		$this->assertEquals( \Webmention\Upgrade::get_version(), WEBMENTION_VERSION );
 
 		wp_cache_flush();