WPDB: Add a `close()` method to `wpdb`, for when the connection needs to be manually closed.

In the event that it was closed prematurely, `wpdb::query()` will re-open the connection automatically.

Fixes #34903.


Built from https://develop.svn.wordpress.org/trunk@36433


git-svn-id: http://core.svn.wordpress.org/trunk@36400 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.5-alpha-36432';
+$wp_version = '4.5-alpha-36433';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.

wp-includes/wp-db.php

@@ -3093,6 +3093,32 @@ class wpdb {
 		wp_die($message);
 	}
 
+
+	/**
+	 * Closes the current database connection.
+	 *
+	 * @since 4.5.0
+	 *
+	 * @return bool True if the connection was succesfully closed, false if it wasn't, or the connection doesn't exist.
+	 */
+	public function close() {
+		if ( ! $this->dbh ) {
+			return false;
+		}
+
+		if ( $this->use_mysqli ) {
+			$closed = mysqli_close( $this->dbh );
+		} else {
+			$closed = mysql_close( $this->dbh );
+		}
+
+		if ( $closed ) {
+			$this->dbh = null;
+		}
+
+		return $closed;
+	}
+
 	/**
 	 * Whether MySQL database is at least the required minimum version.
 	 *