BloombergLP::bdlcc::SingleConsumerQueue::tryPopFront

Attempt to remove the element from the front of this queue without blocking, and, if successful, load the specified value with the removed element. Return 0 on success, and a non-zero value otherwise. Specifically, return e_DISABLED if isPopFrontDisabled(), and e_EMPTY if !isPopFrontDisabled() and the queue was empty. On failure, value is not changed. The behavior is undefined unless the invoker of this method is the single consumer.