Skip to content

Instantly share code, notes, and snippets.

@beeender
Created January 24, 2017 15:12
Show Gist options
  • Save beeender/9a37c81d56326f02be734a3087da0f84 to your computer and use it in GitHub Desktop.
Save beeender/9a37c81d56326f02be734a3087da0f84 to your computer and use it in GitHub Desktop.
Sequence changes related with https://github.com/realm/realm-java/pull/3834
@Test
public void breaking_changes() throws InterruptedException {
// # Global Realm listeners -- Both Realm & DynamicRealm#
// ## The global Realm change listener will be called immediately when commitTransaction() on the same thread ##
realm.addChangeListener(new RealmChangeListener<Realm>() {
@Override
public void onChange(Realm element) {
// Notice this will be called 3rd in the next event loop in the old implementaion.
RealmLog.info("This will be printed 2nd.");
}
});
realm.executeTransaction(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
RealmLog.info("This will be printed 1st.");
}
});
RealmLog.info("This will be printed 3rd."); // Notice in the old version, this will be called 2nd.
// ## The global Realm change listener may be called immediately when beginTransaction() on the same thread ##
final CountDownLatch bgCommitDone = new CountDownLatch(1);
realm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm realm) {
bgCommitDone.countDown();
}
});
bgCommitDone.await();
realm.addChangeListener(new RealmChangeListener<Realm>() {
@Override
public void onChange(Realm element) {
// Notice this will be called only once in the next event loop in the old implementation.
RealmLog.info("This will be printed 2 times.");
}
});
// beginTransaction will advance read the Realm to the latest version, and if it is different from current
// version, the change listener will be called.
realm.beginTransaction();
// Notice in the old version, this will be called 2nd.
RealmLog.info("This will be printed after first time listener called.");
realm.commitTransaction();
RealmLog.info("This will be printed at last."); // Notice in the old version, this will be called 2nd.
// ## The global listener won't be called if it is added later after commitTransaction on the same thread. ##
realm.beginTransaction();
realm.commitTransaction();
realm.addChangeListener(new RealmChangeListener<Realm>() {
@Override
public void onChange(Realm element) {
// Notice this will be called in the next event loop in the old implenmentation.
RealmLog.info("This won't be called.");
}
});
// # Listeners on RealmObject and DynamicRealmObject #
// ## All the changes for the global change listeners could be applied to the RealmObject listeners. ##
// ## Calling load on findFirstAsync()'s, and if it cannot find any results, the async query won't be rerun. ##
AllTypes allTypes = realm.where(AllTypes.class).findFirst();
assertTrue(allTypes.isValid() == false); // It cannot find any object match the query.
// In the old implementation, if calling load() and it cannot find any object, the query will rerun and return
// the results until it can find an object match the query. But it is a wrong behavior. Think about
// following code.
AllTypes allTypes1 = realm.where(AllTypes.class).findFirst();
assertTrue(allTypes1.isValid() == true); // It finds an object match the query.
realm.beginTransaction();
// In the old implementation, if the object gets deleted here and there is a pending COMPLETE_ASYNC_OBJECT event
// in the queue, the allTypes1 will become a different object which is a wrong behavior.
allTypes1.deleteFromRealm();
realm.commitTransaction();
// # RealmResults.distinct() will create a new RealmResults
RealmResults<AllTypes> results1 = realm.where(AllTypes.class).findAll();
RealmResults<AllTypes> results2 = results1.distinct(AllTypes.FIELD_DOUBLE);
// For the old implementation, the results2 will be the same with results1. But we have a bug tracking it, so
// this would be more like a bug fix than breaking change.
assertTrue(results1 != results2);
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment