Ticket #5932: check-connection.5.diff

wp-includes/wp-db.php

@@ -147 +147 @@
          * @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
@@ -1031 +1041 @@
          * Connect to and select database
          *
          * @since 3.0.0
+         *
+         * @param bool $allow_bail Optional. Allows the function to bail, default true. If this is set to false, you will need to handle the lack of database connection manually. Available since 3.5.0
+         *
+         * @return bool true on successful connection, false on unsuccessful connection
          */
-        function db_connect() {
+        function db_connect( $allow_bail = true ) {
 
                 $this->is_mysql = true;
 
@@ -1042 +1056 @@
                         $this->dbh = @mysql_connect( $this->dbhost, $this->dbuser, $this->dbpassword, true );
                 }
 
-                if ( !$this->dbh ) {
+                if ( !$this->dbh && $allow_bail ) {
                         wp_load_translations_early();
                         $this->bail( sprintf( __( "
 <h1>Error establishing a database connection</h1>
@@ -1055 +1069 @@
 <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;
+                        return false;
                 }
+                else if ( $this->dbh ) {
+                        $this->set_charset( $this->dbh );
+                        $this->ready = true;
+                        $this->select( $this->dbname, $this->dbh );
 
-                $this->set_charset( $this->dbh );
+                        return true;
+                }
 
-                $this->ready = true;
+                return false;
+        }
 
-                $this->select( $this->dbname, $this->dbh );
+        /**
+         * Check that the connection to the database is still up. If not, try to reconnect.
+         *
+         * @since 3.5.0
+         *
+         * @return bool true if the connection is up, false if it's down and we were unable to reconnect
+         */
+        function check_connection() {
+                if ( mysql_ping( $this->dbh ) )
+                        return true;
+
+                for ( $tries = 1; $tries <= $this->reconnect_retries; $tries++ ) {
+                        if ( $this->db_connect() )
+                                return true;
+
+                        sleep( 1 );
+                }
+
+                // We weren't able to reconnect, so we better bail
+                $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;
         }
 
         /**
@@ -1091 +1140 @@
                 // Keep track of the last query for debug..
                 $this->last_query = $query;
 
-                if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
-                        $this->timer_start();
+                $this->_do_query( $query );
 
-                $this->result = @mysql_query( $query, $this->dbh );
-                $this->num_queries++;
+                // MySQL server has gone away, try to reconnect
+                if( mysql_errno( $this->dbh ) == 2006 ) {
+                        if( ! $this->check_connection() )
+                                return false;
 
-                if ( defined( 'SAVEQUERIES' ) && SAVEQUERIES )
-                        $this->queries[] = array( $query, $this->timer_stop(), $this->get_caller() );
+                        $this->_do_query( $query );
+                }
 
                 // If there is an error then take note of it..
                 if ( $this->last_error = mysql_error( $this->dbh ) ) {
@@ -1140 +1190 @@
         }
 
         /**
+         * 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>