Add some logging for weird redirected POSTs

[lhc/web/wiklou.git] / includes / db / ChronologyProtector.php

diff --git a/includes/db/ChronologyProtector.php b/includes/db/ChronologyProtector.php
index 447b238..de5e72c 100644 (file)
--- a/includes/db/ChronologyProtector.php
+++ b/includes/db/ChronologyProtector.php
@@ -26,30 +26,40 @@
  * Kind of like Hawking's [[Chronology Protection Agency]].
  */
 class ChronologyProtector {
-       var $startupPos;
-       var $shutdownPos = array();
+       /** @var Array (DB master name => position) */
+       protected $startupPositions = array();
+       /** @var Array (DB master name => position) */
+       protected $shutdownPositions = array();
+
+       protected $initialized = false; // bool; whether the session data was loaded
 
        /**
         * Initialise a LoadBalancer to give it appropriate chronology protection.
         *
+        * If the session has a previous master position recorded, this will try to
+        * make sure that the next query to a slave of that master will see changes up
+        * to that position by delaying execution. The delay may timeout and allow stale
+        * data if no non-lagged slaves are available.
+        *
         * @param $lb LoadBalancer
+        * @return void
         */
-       function initLB( $lb ) {
-               if ( $this->startupPos === null ) {
-                       if ( !empty( $_SESSION[__CLASS__] ) ) {
-                               $this->startupPos = $_SESSION[__CLASS__];
-                       }
+       public function initLB( LoadBalancer $lb ) {
+               if ( $lb->getServerCount() <= 1 ) {
+                       return; // non-replicated setup
                }
-               if ( !$this->startupPos ) {
-                       return;
+               if ( !$this->initialized ) {
+                       $this->initialized = true;
+                       if ( isset( $_SESSION[__CLASS__] ) && is_array( $_SESSION[__CLASS__] ) ) {
+                               $this->startupPositions = $_SESSION[__CLASS__];
+                       }
                }
                $masterName = $lb->getServerName( 0 );
-
-               if ( $lb->getServerCount() > 1 && !empty( $this->startupPos[$masterName] ) ) {
+               if ( !empty( $this->startupPositions[$masterName] ) ) {
                        $info = $lb->parentInfo();
-                       $pos = $this->startupPos[$masterName];
+                       $pos = $this->startupPositions[$masterName];
                        wfDebug( __METHOD__ . ": LB " . $info['id'] . " waiting for master pos $pos\n" );
-                       $lb->waitFor( $this->startupPos[$masterName] );
+                       $lb->waitFor( $pos );
                }
        }
 
@@ -58,16 +68,15 @@ class ChronologyProtector {
         * down. Saves replication positions.
         *
         * @param $lb LoadBalancer
+        * @return void
         */
-       function shutdownLB( $lb ) {
-               // Don't start a session, don't bother with non-replicated setups
-               if ( strval( session_id() ) == '' || $lb->getServerCount() <= 1 ) {
-                       return;
+       public function shutdownLB( LoadBalancer $lb ) {
+               if ( session_id() == '' || $lb->getServerCount() <= 1 ) {
+                       return; // don't start a session; don't bother with non-replicated setups
                }
                $masterName = $lb->getServerName( 0 );
-               if ( isset( $this->shutdownPos[$masterName] ) ) {
-                       // Already done
-                       return;
+               if ( isset( $this->shutdownPositions[$masterName] ) ) {
+                       return; // already done
                }
                // Only save the position if writes have been done on the connection
                $db = $lb->getAnyOpenConnection( 0 );
@@ -78,18 +87,20 @@ class ChronologyProtector {
                }
                $pos = $db->getMasterPos();
                wfDebug( __METHOD__ . ": LB {$info['id']} has master pos $pos\n" );
-               $this->shutdownPos[$masterName] = $pos;
+               $this->shutdownPositions[$masterName] = $pos;
        }
 
        /**
         * Notify the ChronologyProtector that the LBFactory is done calling shutdownLB() for now.
         * May commit chronology data to persistent storage.
+        *
+        * @return void
         */
-       function shutdown() {
-               if ( session_id() != '' && count( $this->shutdownPos ) ) {
+       public function shutdown() {
+               if ( session_id() != '' && count( $this->shutdownPositions ) ) {
                        wfDebug( __METHOD__ . ": saving master pos for " .
-                               count( $this->shutdownPos ) . " master(s)\n" );
-                       $_SESSION[__CLASS__] = $this->shutdownPos;
+                               count( $this->shutdownPositions ) . " master(s)\n" );
+                       $_SESSION[__CLASS__] = $this->shutdownPositions;
                }
        }
 }