private List<BlockDeviceMapping> getNewEphemeralDeviceMapping() {
final List<BlockDeviceMapping> oldDeviceMapping = getAmiBlockDeviceMappings();
final Set<String> occupiedDevices = new HashSet<String>();
for (final BlockDeviceMapping mapping : oldDeviceMapping) {
occupiedDevices.add(mapping.getDeviceName());
}
final List<String> available =
new ArrayList<String>(
Arrays.asList("ephemeral0", "ephemeral1", "ephemeral2", "ephemeral3"));
final List<BlockDeviceMapping> newDeviceMapping = new ArrayList<BlockDeviceMapping>(4);
for (char suffix = 'b'; suffix <= 'z' && !available.isEmpty(); suffix++) {
final String deviceName = String.format("/dev/xvd%s", suffix);
if (occupiedDevices.contains(deviceName)) continue;
final BlockDeviceMapping newMapping =
new BlockDeviceMapping().withDeviceName(deviceName).withVirtualName(available.get(0));
newDeviceMapping.add(newMapping);
available.remove(0);
}
return newDeviceMapping;
}
