Finds a file by class name while caching lookups to Xcache.
string $class A class name to resolve to file:
string|null
public function findFile($class) {
if (xcache_isset($this->prefix . $class)) {
$file = xcache_get($this->prefix . $class);
}
else {
xcache_set($this->prefix . $class, $file = $this->classFinder
->findFile($class));
}
return $file;
}