Changeset 27075 for trunk/src/wp-includes/wp-db.php

Timestamp:

02/02/2014 10:06:42 PM (11 years ago)

Author:

nacin

Message:

When the MySQL server has "gone away," attempt to reconnect and retry the query.

props pento.
see #5932.

File:

• trunk/src/wp-includes/wp-db.php (modified) (7 diffs)

trunk/src/wp-includes/wp-db.php

@@ -157 +157 @@
      */
     var $queries;
+
+    /**
+     * The number of times to retry reconnecting before dying.
+     *
+     * @since 3.9.0
+     * @access protected
+     * @see wpdb::check_connection()
+     * @var int
+     */
+    protected $reconnect_retries = 5;
 
     /**
@@ -1193 +1203 @@
 
     /**
-     * Connect to and select database
+     * Connect to and select database.
      *
      * @since 3.0.0
-     */
-    function db_connect() {
+     *
+     * @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 3.9.0.
+     *
+     * @return bool True with a successful connection, false on failure.
+     */
+    function db_connect( $allow_bail = true ) {
 
         $this->is_mysql = true;
@@ -1218 +1234 @@
         }
 
-        if ( !$this->dbh ) {
+        if ( ! $this->dbh && $allow_bail ) {
             wp_load_translations_early();
 
@@ -1238 +1254 @@
 " ), htmlspecialchars( $this->dbhost, ENT_QUOTES ) ), 'db_connect_fail' );
 
-            return;
-        }
-
-        $this->set_charset( $this->dbh );
-
-        $this->set_sql_mode();
-
-        $this->ready = true;
-
-        $this->select( $this->dbname, $this->dbh );
+            return false;
+        } else if ( $this->dbh ) {
+            $this->set_charset( $this->dbh );
+            $this->set_sql_mode();
+            $this->ready = true;
+            $this->select( $this->dbname, $this->dbh );
+
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Check that the connection to the database is still up. If not, try to reconnect.
+     *
+     * If this function is unable to reconnect, it will forcibly die.
+     *
+     * @since 3.9.0
+     *
+     * @return bool True if the connection is up.
+     */
+    function check_connection() {
+        if ( @mysql_ping( $this->dbh ) ) {
+            return true;
+        }
+
+        $error_reporting = false;
+
+        // Disable warnings, as we don't want to see a multitude of "unable to connect" messages
+        if ( WP_DEBUG ) {
+            $error_reporting = error_reporting();
+            error_reporting( $error_reporting & ~E_WARNING );
+        }
+
+        for ( $tries = 1; $tries <= $this->reconnect_retries; $tries++ ) {
+            // On the last try, re-enable warnings. We want to see a single instance of the
+            // "unable to connect" message on the bail() screen, if it appears.
+            if ( $this->reconnect_retries === $tries && WP_DEBUG ) {
+                error_reporting( $error_reporting );
+            }
+
+            if ( $this->db_connect( false ) ) {
+                if ( $error_reporting ) {
+                    error_reporting( $error_reporting );
+                }
+
+                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 contact with the database server at <code>%s</code>. This could mean your host's database server is 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' );
+
+        // Call dead_db() if bail didn't die, because this database is no more. It has ceased to be (at least temporarily).
+        dead_db();
     }
 
@@ -1263 +1335 @@
         if ( ! $this->ready )
             return false;
+
         /**
          * Filter the database query.
@@ -1282 +1355 @@
         $this->last_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() );
+        $this->_do_query( $query );
+
+        // MySQL server has gone away, try to reconnect
+        if ( empty( $this->dbh ) || 2006 == mysql_errno( $this->dbh ) ) {
+            if ( $this->check_connection() ) {
+                $this->_do_query( $query );
+            }
+        }
 
         // If there is an error then take note of it..
@@ -1325 +1398 @@
 
         return $return_val;
+    }
+
+    /**
+     * Internal function to perform the mysql_query call
+     *
+     * @since 3.9.0
+     *
+     * @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() );
+        }
     }