+global\cache::updateCacheStatusFromLatestLog()

Complexity

Conditions	5
Paths	5

Size

Total Lines	61
Code Lines	25

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

<?php
    public function updateCacheStatusFromLatestLog($logId, $oldLogType, $newLogType)
    {
        if ($newLogType != $oldLogType) {
            // get new cache-status property of the new log type
            $cacheStatus = sql_value(
                "SELECT `cache_status` FROM `log_types` WHERE `id`='&1'",
                0,
                $newLogType
            );

            if ($cacheStatus != 0) {
                // If the new log type is a status-changing type, it's easy -
                // we can directly change the cache status:

                $this->setStatus($cacheStatus);
            } else {
                // If the new log type is not status-changing, but the old type was, the
                // cache status may need to be recalculated. To keep things simple, we will
                // always recalculate the cache status in this case.

                $cacheStatus = sql_value(
                    "SELECT `cache_status` FROM `log_types` WHERE `id`='&1'",
                    0,
                    $oldLogType
                );
                if ($cacheStatus != 0) {
                    // The only safe way to restore an old cache status is from table
                    // cache_status_modified. This is available since April 2013. As we
                    // do not allow status-changes by editing logs that are older than
                    // half a year, this is ok.

                    // The cache status is updated in a separate operation immediatly
                    // (usually within a millisecond or so) after saving a log, so we must
                    // apply some time lag to be on the safe side. It should be safe to
                    // assume that users will not edit the log type twice within <= 2 seconds:

                    $logCreated = sql_value(
                        "SELECT `date_created` FROM `cache_logs` WHERE `id`='&1'",
                        null,
                        $logId
                    );
                    $oldCacheStatus = sql_value(
                        "SELECT `old_state`
                         FROM `cache_status_modified`
                         WHERE `cache_id`='&1'
                         AND '&2' <= `date_modified`
                         AND TIMESTAMPDIFF(SECOND, '&2', `date_modified`) <= 2
                         ORDER BY `date_modified` DESC
                         LIMIT 1",
                        0,
                        $this->getCacheId(),
                        $logCreated
                    );

                    if ($oldCacheStatus > 0) {
                        $this->setStatus($oldCacheStatus);
                    }
                }
            }
        }
    }