I am very new to akka and trying to model a solution for a problem.
Consider I have a DiskMonitorActor which looks like
public final class DiskMonitorActor extends UntypedActor {
private final File assetsDirectory;
private final long thresholdPercentage;
private final LoggingAdapter logging =
Logging.getLogger(getContext().system(), this);
public DiskMonitorActor(final File assetsDirectory, final long
thresholdPercentage) {
this.assetsDirectory = assetsDirectory;
this.thresholdPercentage = thresholdPercentage;
}
public static Props props(final File assetsDirectory, final long
thresholdPercentage) {
return Props.create(new Creator<DiskMonitorActor>(){
private static final long serialVersionUID = 1L;
public DiskMonitorActor create() throws Exception {
return new DiskMonitorActor(assetsDirectory, thresholdPercentage);
}
});
}
@Override
public void onReceive(final Object message) throws Exception {
if (message instanceof DiskMonitorMessage) {
logging.info("disk: {}, total space: {}, usable space: {}",
assetsDirectory.getAbsolutePath(),
assetsDirectory.getTotalSpace(),
assetsDirectory.getUsableSpace());
if (isThresholdExceeded()) {
logging.error("Disk full. Available Space {}",
assetsDirectory.getFreeSpace());
throw new DiskException("disk capacity reached threshold.");
}
} else {
unhandled(message);
}
}
private boolean isThresholdExceeded() {
final long usedBytes = assetsDirectory.getTotalSpace() -
assetsDirectory.getUsableSpace();
final long thresholdBytes = assetsDirectory.getTotalSpace() *
thresholdPercentage / 100;
return usedBytes >= thresholdBytes;
}
}
I am able to unit test this as
public class DiskMonitorActorTest {
@Mock
private File assetsDirectory;
@Rule
public TestName testName = new TestName();
@Rule
public ExpectedException expectedException = ExpectedException.none();
@Before
public void setUp() throws Exception {
MockitoAnnotations.initMocks(this);
}
@Test
public void testDiskMonitorWhenThresholdReached() throws Exception {
when(assetsDirectory.getAbsolutePath()).thenReturn("test/file/path");
when(assetsDirectory.getTotalSpace()).thenReturn(100L);
when(assetsDirectory.getUsableSpace()).thenReturn(10L);
final Props props = DiskMonitorActor.props(assetsDirectory, 10L);
final ActorSystem system = ActorSystem.create("system");
final TestActorRef<DiskMonitorActor> actorRef =
TestActorRef.create(system, props, testName.getMethodName());
final DiskMonitorActor diskMonitorActor = actorRef.underlyingActor();
expectedException.expect(DiskException.class);
expectedException.expectMessage("disk capacity reached threshold.");
diskMonitorActor.onReceive(new DiskMonitorMessage());
}
}
I have a TenantMonitor which is supposed to monitor DiskMonitor (for any
exception) and take preventive actions, if necessary. It looks like
public class TenantMonitorActor extends UntypedActor {
private static final String TENANT_MONITORING_CONF =
"tenant.monitoring.conf";
private final LoggingAdapter logging =
Logging.getLogger(getContext().system(), this);
private static final SupervisorStrategy strategy =
new OneForOneStrategy(1, Duration.create(1, TimeUnit.SECONDS),
new Function<Throwable, Directive>() {
public Directive apply(final Throwable param)
throws Exception {
if (param instanceof DiskException) {
return stop();
}
return restart();
}
});
@Override
public void onReceive(final Object message) throws Exception {
if (message instanceof TenantMonitorMessage) {
logging.info("Tenant Monitor Setup");
setUpMonitoring();
}
}
@Override
public SupervisorStrategy supervisorStrategy() {
return strategy;
}
private void setUpMonitoring() {
final Config monitoringConf =
ConfigFactory.load(TENANT_MONITORING_CONF);
setupDiskMonitoring(monitoringConf);
}
private void setupDiskMonitoring(final Config monitoringConf) {
final String diskLocationKey = "tenant.monitoring.disk.location";
final String thresholdPercentKey =
"tenant.monitoring.disk.error.threshold.percent";
final Props diskMonitorProps =
DiskMonitorActor.props(getAssetsDirectory(monitoringConf,
diskLocationKey),
monitoringConf.getLong(thresholdPercentKey));
final ActorRef diskMonitorActorRef =
getContext().actorOf(diskMonitorProps, "diskMonitor");
final FiniteDuration start = Duration.create(0, TimeUnit.SECONDS);
final String schedulerKey = "tenant.monitoring.disk.schedule.seconds";
final FiniteDuration recurring =
Duration.create(monitoringConf.getInt(schedulerKey),
TimeUnit.SECONDS);
final ActorSystem system = getContext().system();
system.scheduler()
.schedule(start, recurring, diskMonitorActorRef,
new DiskMonitorMessage(), system.dispatcher(), null);
}
protected File getAssetsDirectory(final Config monitoringConf, final
String diskLocationKey) {
return new File(monitoringConf.getString(diskLocationKey));
}
}
The part where I am stuck is how do I inject failures when testing it?
Specifically I am looking for help on
1. How do I test this Monitor for specific failures and make sure
correct action is called
2. How could I have written this code in a better way
Thanks a lot
+ Harit Himanshu
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