Ticket #5932: check-connection.2.diff

Index: wp-includes/wp-db.php
===================================================================
--- wp-includes/wp-db.php       (revision 21466)
+++ wp-includes/wp-db.php       (working copy)
@@ -147,6 +147,16 @@
         * @var array
         */
        var $queries;
+       
+       /**
+        * The number of times to retry reconnecting before dying.
+        *
+        * @since 3.5.0
+        * @access protected
+        * @see wpdb::check_connection()
+        * @var int
+        */
+       protected $reconnect_retries = 5;
 
        /**
         * WordPress table prefix
@@ -1066,6 +1076,50 @@
        }
 
        /**
+        * Check that the connection to the database is still up. If not, try to reconnect.
+        *
+        * @since 3.5.0
+        */
+       function check_connection() {
+               $tries = 1;
+               while ( ! mysql_ping( $this->dbh ) ) {
+                       if ( WP_DEBUG ) {
+                               $this->dbh = mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, true );
+                       } else {
+                               $this->dbh = @mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, true );
+                       }
+
+                       if ( $this->dbh ) {
+                               $this->set_charset( $this->dbh );
+                               $this->select( $this->dbname, $this->dbh );
+
+                               return true;
+                       }
+                               
+                       $tries++;
+                       
+                       if ( $tries >= $this->reconnect_retries ) {
+                               $this->bail( sprintf( __( "
+<h1>Error reconnecting to the database</h1>
+<p>This means that we lost our connection to the database server at <code>%s</code>, your host's database server may be down.</p>
+<ul>
+       <li>Are you sure that the database server is running?</li>
+       <li>Are you sure that the database server is not under particularly heavy load?</li>
+</ul>
+<p>If you're unsure what these terms mean you should probably contact your host. If you still need help you can always visit the <a href='http://wordpress.org/support/'>WordPress Support Forums</a>.</p>
+" ), htmlspecialchars( $this->dbhost, ENT_QUOTES ) ), 'db_connect_fail' );
+
+                               return false;
+                       }
+                       
+                       sleep( 1 );
+               }
+               
+               return true;
+       }
+
+
+       /**
         * Perform a MySQL database query, using current database connection.
         *
         * More information can be found on the codex page.
@@ -1091,15 +1145,16 @@
                // Keep track of the last query for debug..
                $this->last_query = $query;
 
-               if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
-                       $this->timer_start();
+               $this->_do_query( $query );
+               
+               // MySQL server has gone away, try to reconnect
+               if( mysql_errno == 2006 ) {
+                       if( ! $this->check_connection() )
+                               return false;
 
-               $this->result = @mysql_query( $query, $this->dbh );
-               $this->num_queries++;
+                       $this->_do_query( $query );
+               }
 
-               if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
-                       $this->queries[] = array( $query, $this->timer_stop(), $this->get_caller() );
-
                // If there is an error then take note of it..
                if ( $this->last_error = mysql_error( $this->dbh ) ) {
                        $this->print_error();
@@ -1140,6 +1195,27 @@
        }
 
        /**
+        * Internal function to perform the mysql_query call
+        *
+        * @since 3.5.0
+        *
+        * @access private
+        * @see wpdb::query()
+        *
+        * @param string $query The query to run
+        */
+       private function _do_query( $query ) {
+               if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
+                       $this->timer_start();
+
+               $this->result = @mysql_query( $query, $this->dbh );
+               $this->num_queries++;
+
+               if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
+                       $this->queries[] = array( $query, $this->timer_stop(), $this->get_caller() );
+       }
+
+       /**
         * Insert a row into a table.
         *
         * <code>