Realm, short look inside - Volodymyr Ischak

Realm, short look inside - Volodymyr Ischak

Transcript

1. Realm Short look inside
2. History
3. History
4. History
5. -> SQL SELECT owner.name, dog.name, city.name FROM owner INNER JOIN dog ON owner.dog_id = dog.id INNER JOIN city ON owner.city_id = city.id WHERE owner.name = 'Frank'
6. -> Java String query = "SELECT " + Owner.NAME + ", " + Dog.NAME + ", " + City.NAME + " FROM " + Owner.TABLE_NAME + " INNER JOIN " + Dog.TABLE_NAME + " ON " + Owner.DOG_ID + " = " + Dog.ID + " INNER JOIN " + City.TABLE_NAME + " ON " + Owner.CITY_ID + " = " + City.ID + " WHERE " + Owner.NAME = "'" + escape(queryName) + "'";
7. Solution ORM* *can save the world
8. Common ORM Copy into memory Deserialization PROCESSING Serialization Persist copy
9. //SKIP SLIDE JAVA RealmResults<Dog> puppies = realm.where(Dog.class).lessThan("age", 2).findAll(); puppies.size(); // => 0 realm.beginTransaction(); Dog dog = realm.createObject(Dog.class); dog.setAge(1); realm.commitTransaction(); puppies.size(); // => 1 // Change the dog from another query realm.beginTransaction(); Dog theDog = realm.where(Dog.class).equals("age", 1).findFirst(); theDog.setAge(3); realm.commitTransaction(); // Original dog is auto-updated dog.getAge(); // => 3 puppies.size(); // => 0
10. //SKIP SLIDE SWIFT let puppies = realm.objects(Dog).filter("age < 2") puppies.count // => 0 because no dogs have been added to the Realm yet let myDog = Dog() myDog.name = “Rex” myDog.age = 1 try! realm.write { realm.add(myDog) } puppies.count // => 1 updated in real-time // Access the Dog in a separate query let puppy = realm.objects(Dog).filter("age == 1").first try! realm.write { puppy.age = 3 } // Original Dog object is auto-updated myDog.age // => 3 puppies.count // => 0
11. Aim of realm • ResultSet (java) / CursorAdapter (Android) replacement • Flatbuffers
12. Object store Realm.getA().getB().getF() A B E F C D
13. Zero-copy in Realm User -name -title -book { -name -author } User -name -title -book User -name -title -book { -name -author } User -name -title -book User -name -title -book { -name -author } User -name -title -book { -name -author } ORM SQLite Realm Realm
14. Zero-copy in Realm User jUser = new User(); // Standard Java POJO User proxyUser = realm.copyToRealm(jUser); // Convert POJO to Proxy User proxyUser = realm.createObject(User.class); // Proxy // Query results are lazy RealmResults< User > queryResults = realm.allObjects(User .class); queryResults.get(0) != queryResults.get(0); // Different Java objects queryResults.get(0).equals(queryResults.get(0)); // Same data
15. Flatbuffers public long id() { int o = __offset(4); return o != 0 ? bb.getLong(o + bb_pos) : 0; } public String name() { int o = __offset(6); return o != 0 ? __string(o + bb_pos) : null; } ByteBuffer bb = ByteBuffer.wrap(bytes); MyObject obj = MyObject.getRootAsMyObject(bb); long id = obj.id(); String name = obj.name(); https://google.github.io/flatbuffers/
16. UI Consistency Fragment 1 Fragment 2 Fragment 1 Fragment 2
17. UI Consistency Fragment 1 Fragment 2 • Loader • Content URI • ContentObserver • ContentProvider
18. UI Consistency 1 2 2 3 Fragment 1 ContentProvider
19. MVCC A B E F C D A B E F C D A’ B` F’ A` B` E F` C D A B F GARBAGE
20. Consistency in Realm UI thread Background thread queue.next() queue.next() thread.start()
21. Consistency in Realm UI thread Background thread queue.next() queue.next() thread.start() Realm.getDefaultInstance() Realm.getDefaultInstance()
22. Consistency in Realm UI thread Background thread queue.next() queue.next() thread.start() realm.commitTransaction()
23. Consistency in Realm UI thread Background thread queue.next() queue.next() thread.start() realm.commitTransaction()
24. Consistency in Realm UI thread Background thread queue.next() queue.next() thread.start() handler.sendEmptyMessage(REALM_CHANGED);
25. UI Consistency Fragment 2 Fragment 1 Fragment 2 Fragment 1 new RealmChangeListener() { @Override public void onChange() { invalidateViews(); } }
26. beep-beep