In SQLBagOStuff: make it possible to change the purge period, or disable purging...

diff --git a/includes/objectcache/SqlBagOStuff.php b/includes/objectcache/SqlBagOStuff.php
index 7d87a24..10f42cd 100644 (file)
--- a/includes/objectcache/SqlBagOStuff.php
+++ b/includes/objectcache/SqlBagOStuff.php
@@ -18,17 +18,28 @@ class SqlBagOStuff extends BagOStuff {
        var $db;
        var $serverInfo;
        var $lastExpireAll = 0;
+       var $purgePeriod = 100;
 
        /**
         * Constructor. Parameters are:
         *   - server:   A server info structure in the format required by each 
         *               element in $wgDBServers.
+        *
+        *   - purgePeriod: The average number of object cache requests in between 
+        *                  garbage collection operations, where expired entries 
+        *                  are removed from the database. Or in other words, the 
+        *                  reciprocal of the probability of purging on any given 
+        *                  request. If this is set to zero, purging will never be 
+        *                  done.
         */
        public function __construct( $params ) {
                if ( isset( $params['server'] ) ) {
                        $this->serverInfo = $params['server'];
                        $this->serverInfo['load'] = 1;
                }
+               if ( isset( $params['purgePeriod'] ) ) {
+                       $this->purgePeriod = intval( $params['purgePeriod'] );
+               }
        }
 
        /**
@@ -213,14 +224,19 @@ class SqlBagOStuff extends BagOStuff {
        }
 
        protected function garbageCollect() {
-               /* Ignore 99% of requests */
-               if ( !mt_rand( 0, 100 ) ) {
-                       $now = time();
-                       /* Avoid repeating the delete within a few seconds */
-                       if ( $now > ( $this->lastExpireAll + 1 ) ) {
-                               $this->lastExpireAll = $now;
-                               $this->expireAll();
-                       }
+               if ( !$this->purgePeriod ) {
+                       // Disabled
+                       return;
+               }
+               // Only purge on one in every $this->purgePeriod requests.
+               if ( $this->purgePeriod !== 1 && mt_rand( 0, $this->purgePeriod - 1 ) ) {
+                       return;
+               }
+               $now = time();
+               // Avoid repeating the delete within a few seconds
+               if ( $now > ( $this->lastExpireAll + 1 ) ) {
+                       $this->lastExpireAll = $now;
+                       $this->expireAll();
                }
        }