/** * Retrieves, but does not remove, the first allocated container on the specified host. * * @param host the host for which a container is needed. * @return the first {@link Container} allocated for the specified host or {@code null} if there * isn't one. */ protected Container peekAllocatedContainer(String host) { List<Container> allocatedContainers = containerRequestState.getContainersOnAHost(host); if (allocatedContainers == null || allocatedContainers.isEmpty()) { return null; } return allocatedContainers.get(0); }