GenericQueues.h

// http://opensource.apple.com/source/CF/CF-1153.18/CFInternal.h

// Returns a generic dispatch queue for when you want to just throw some work
// into the concurrent pile to execute, and don't care about specifics except
// to match the QOS of the main thread.
CF_INLINE dispatch_queue_t __CFDispatchQueueGetGenericMatchingMain(void) {
    return dispatch_get_global_queue(qos_class_main(), DISPATCH_QUEUE_OVERCOMMIT);
}

// Returns a generic dispatch queue for when you want to just throw some work
// into the concurrent pile to execute, and don't care about specifics except
// to match the QOS of the current thread.
CF_INLINE dispatch_queue_t __CFDispatchQueueGetGenericMatchingCurrent(void) {
    return dispatch_get_global_queue(qos_class_self(), 0); // DISPATCH_QUEUE_OVERCOMMIT left out intentionally at this point
}

// Returns a generic dispatch queue for when you want to just throw some work
// into the concurrent pile to execute, and don't care about specifics except
// that it should be in background QOS.
CF_INLINE dispatch_queue_t __CFDispatchQueueGetGenericBackground(void) {
    // Don't ACTUALLY use BACKGROUND, because of unknowable and unfavorable interactions like (<rdar://problem/16319229>)
    return dispatch_get_global_queue(QOS_CLASS_UTILITY, DISPATCH_QUEUE_OVERCOMMIT);
}