Update sessions table for accuracy/efficiency

- changed id to case-sensitive ascii (some PHP configurations use letter
  casing to distinguish different sessions)
- added index on modified, for more efficient gc
- updated gc to make an index-compatible query

application/libraries/Omeka/Session/SaveHandler/DbTable.php

@@ -104,4 +104,20 @@ public function write($id, $data)
         // Discard parent's return value and return true (PHP 7 actually cares about this)
         return true;
     }
+
+    /**
+     * Garbage Collection
+     *
+     * Overrides Zend's gc to always use the same lifetime rather than the stored column
+     *
+     * @param int $maxlifetime
+     * @return true
+     */
+    public function gc($maxlifetime)
+    {
+        $this->delete($this->getAdapter()->quoteIdentifier($this->_modifiedColumn, true) . ' < '
+                    . $this->getAdapter()->quote(time() - $this->_lifetime));
+
+        return true;
+    }
 }

application/migrations/20240713211400_updateSessionsTable.php

@@ -0,0 +1,20 @@
+<?php
+/**
+ * Omeka
+ *
+ * @copyright Copyright 2007-2020 Roy Rosenzweig Center for History and New Media
+ * @license http://www.gnu.org/licenses/gpl-3.0.txt GNU GPLv3
+ */
+
+/**
+ * Change sessions table to case-sensitive ascii IDs and add index on modified column
+ *
+ * @package Omeka\Db\Migration
+ */
+class updateSessionsTable extends Omeka_Db_Migration_AbstractMigration
+{
+    public function up()
+    {
+        $this->db->query("ALTER TABLE {$this->db->Session} MODIFY `id` varchar(128) collate ascii_bin, ADD INDEX `modified` (`modified`)");
+    }
+}

application/schema/sessions.sql

@@ -1,7 +1,8 @@
 CREATE TABLE IF NOT EXISTS `%PREFIX%sessions` (
-`id` varchar(128),
+`id` varchar(128) collate ascii_bin,
 `modified` bigint,
 `lifetime` int,
 `data` blob,
-PRIMARY KEY (`id`)
+PRIMARY KEY (`id`),
+KEY `modified` (`modified`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

bootstrap.php

@@ -8,7 +8,7 @@
  */
 
 // Define the current version of Omeka.
-define('OMEKA_VERSION', '3.2-dev');
+define('OMEKA_VERSION', '3.2-dev2');
 
 // Define the application environment.
 if (!defined('APPLICATION_ENV')) {