Custom HighRepJobPolicy in Google App Engine development server - google-app-engine

Question

I am using a custom HighRepJobPolicy in the App Engine development server. The same class works fine when I use it in my unit tests:
LocalDatastoreServiceTestConfig datastoreConfig = new LocalDatastoreServiceTestConfig();
datastoreConfig.setAlternateHighRepJobPolicyClass(CustomHighRepJobPolicy.class);
But when I try to use this class in the Java development server by adding the JVM tag
-Ddatastore.high_replication_job_policy_class=foo.bar.CustomHighRepJobPolicy
I get a ClassNotFoundException:
Caused by: java.lang.ClassNotFoundException: foo.bar.CustomHighRepJobPolicy
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at com.google.appengine.tools.development.DevAppServerClassLoader.loadClass(DevAppServerClassLoader.java:87)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:186)
at com.google.appengine.api.datastore.dev.LocalDatastoreService.initHighRepJobPolicy(LocalDatastoreService.java:426)
... 66 more
Is this expected to work, or has anyone else tried this before? I ask because I could not find any information about this via Google, and the App Engine docs only mention the DefaultHighRepJobPolicy.

Answer 1

Looks like you were early to the party :
public class LocalCustomPolicyHighRepDatastoreTest {
private static final class CustomHighRepJobPolicy implements HighRepJobPolicy {
static int count = 0;
#Override
public boolean shouldApplyNewJob(Key entityGroup) {
// every other new job fails to apply
return count++ % 2 == 0;
}
#Override
public boolean shouldRollForwardExistingJob(Key entityGroup) {
// every other existing job fails to apply
return count++ % 2 == 0;
}
}
private final LocalServiceTestHelper helper =
new LocalServiceTestHelper(new LocalDatastoreServiceTestConfig()
.setAlternateHighRepJobPolicyClass(CustomHighRepJobPolicy.class));
#Before
public void setUp() {
helper.setUp();
}
#After
public void tearDown() {
helper.tearDown();
}
#Test
public void testEventuallyConsistentGlobalQueryResult() {
DatastoreService ds = DatastoreServiceFactory.getDatastoreService();
ds.put(new Entity("yam")); // applies
ds.put(new Entity("yam")); // does not apply
// first global query only sees the first Entity
assertEquals(1, ds.prepare(new Query("yam")).countEntities(withLimit(10)));
// second global query sees both Entities because we "groom" (attempt to
// apply unapplied jobs) after every query
assertEquals(2, ds.prepare(new Query("yam")).countEntities(withLimit(10)));
}
}