/**
* Clean up tag id lists since as keys expire the ids remain in the tag id lists
*/
protected function _collectGarbage()
{
// Clean up expired keys from tag id set and global id set
$exists = array();
$tags = (array) $this->_redis->sMembers(self::SET_TAGS);
foreach ($tags as $tag) {
// Get list of expired ids for each tag
$tagMembers = $this->_redis->sMembers(self::PREFIX_TAG_IDS . $tag);
$numTagMembers = count($tagMembers);
$expired = array();
$numExpired = $numNotExpired = 0;
if ($numTagMembers) {
while ($id = array_pop($tagMembers)) {
if (!isset($exists[$id])) {
$exists[$id] = $this->_redis->exists(self::PREFIX_KEY . $id);
}
if ($exists[$id]) {
$numNotExpired++;
} else {
$numExpired++;
$expired[] = $id;
// Remove incrementally to reduce memory usage
if (count($expired) % 100 == 0 && $numNotExpired > 0) {
$this->_redis->sRem(self::PREFIX_TAG_IDS . $tag, $expired);
if ($this->_notMatchingTags) {
// Clean up expired ids from ids set
$this->_redis->sRem(self::SET_IDS, $expired);
}
$expired = array();
}
}
}
if (!count($expired)) {
continue;
}
}
// Remove empty tags or completely expired tags
if ($numExpired == $numTagMembers) {
$this->_redis->del(self::PREFIX_TAG_IDS . $tag);
$this->_redis->sRem(self::SET_TAGS, $tag);
} else {
if (count($expired)) {
$this->_redis->sRem(self::PREFIX_TAG_IDS . $tag, $expired);
if ($this->_notMatchingTags) {
// Clean up expired ids from ids set
$this->_redis->sRem(self::SET_IDS, $expired);
}
}
}
unset($expired);
}
// Clean up global list of ids for ids with no tag
if ($this->_notMatchingTags) {
// TODO
}
}