protected function getCacheFile($key)
{
if ($this->directoryLevel > 0) {
$base = $this->cachePath;
for ($i = 0; $i < $this->directoryLevel; ++$i) {
if (($prefix = substr($key, $i + $i, 2)) !== false) {
$base .= DIRECTORY_SEPARATOR . $prefix;
}
}
return $base . DIRECTORY_SEPARATOR . $key . $this->cacheFileSuffix;
} else {
return $this->cachePath . DIRECTORY_SEPARATOR . $key . $this->cacheFileSuffix;
}
}