*/
public long getContentLength(CONFIG config, K key)
throws InterruptedException
{
HeadOperationResult result = headContent(config, key);
if (result.failed()) { // failed to contact any server
NodeFailure nodeFail = result.getFirstFail();
if (nodeFail != null) {
CallFailure callFail = nodeFail.getFirstCallFailure();
if (callFail != null) {
Throwable t = callFail.getCause();