Summary ● Introduction ● Why is it hard? ● Why deterministic simulation? ● What is rollback? ● Implementation details ● Debugging ● ImprovementsElias Farhan ● Head Instructor of Games Programming and BeyondWe still need to wait for all the player inputs to process the confirm frame…What is a rollback system?Input predictionMispredictionDoing a rollbackRollback Implementation DetailsPhysics vs Graphics Fixed TickRollback Manager InputsRollbackGame System Architecture Game systems need a function to rollback (revert to a previous state). Typically a simple copy of data.Naïve OOP architecture ● Hard to

TransactionException; void commit(TransactionStatus status) throws TransactionException; void rollback(TransactionStatus status) throws TransactionException; } This is primarily a service provider interface Mono commit(ReactiveTransaction status) throws TransactionException; Mono rollback(ReactiveTransaction status) throws TransactionException; } The reactive transaction manager is EJBs. • The Spring Framework offers declarative rollback rules, a feature with no EJB equivalent. Both programmatic and declarative support for rollback rules is provided. • The Spring Framework lets

RETURNING ROWS UPDATE OR INSERT 8. Управление транзакциями RELEASE SAVEPOINT ROLLBACK ROLLBACK RETAIN ROLLBACK TO SAVEPOINT SAVEPOINT Внутренние точки сохранения Точки сохранения и PSQL DELETE db_event ::= CONNECT | DISCONNECT | TRANSACTION START | TRANSACTION COMMIT | TRANSACTION ROLLBACK number ::= 0..32767 (по умолчанию 0) ::= См. PSQL::DECLARE для информации о полном соединения (CONNECT, DISCONNECT) и транзакции (TRANSACTION START, TRANSACTION COMMIT и TRANSACTION ROLLBACK). Только SYSDBA или владелец базы данных могут создавать, изменять или удалять такие триггера.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 @Rollback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Transaction Rollback and Commit Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . @DynamicPropertySource • @DirtiesContext 9 • @TestExecutionListeners • @RecordApplicationEvents • @Commit • @Rollback • @BeforeTransaction • @AfterTransaction • @Sql • @SqlConfig • @SqlMergeMode • @SqlGroup

Safety Guarantee Invariants are preserved No resources are leaked No state change (commit-or-rollback) Not always possible (e.g. sockets, streams, etc.) No-Throw Guarantee The operation cannot Safety Guarantee Invariants are preserved No resources are leaked No state change (commit-or-rollback) Not always possible No-Throw Guarantee The operation cannot fail 1 2 3 4 5 6 7 8 Safety Guarantee Invariants are preserved No resources are leaked No state change (commit-or-rollback) Not always possible No-Throw Guarantee The operation cannot fail 1 2 3 4 5 6 7 8

a block wrapped by the atomic() context manager, you can explicitly rollback or commit at any point by calling Transaction.rollback() or Transaction.commit(). When you do this inside a wrapped block of a # new transaction will begin automatically after the call # to rollback(). transaction.rollback() error_saving = True create_report(error_saving=error_saving) # Note: create(username='huey') # This will roll back the above create() query. nested_txn.rollback() User.create(username='mickey') # When the block ends, the transaction is committed (assuming

a block wrapped by the atomic() context manager, you can explicitly rollback or commit at any point by calling Transaction.rollback() or Transaction.commit(). When you do this inside a wrapped block of a # new transaction will begin automatically after the call # to rollback(). transaction.rollback() error_saving = True create_report(error_saving=error_saving) # Note: create(username='huey') # This will roll back the above create() query. nested_txn.rollback() User.create(username='mickey') # When the block ends, the transaction is committed (assuming

a block wrapped by the atomic() context manager, you can explicitly rollback or commit at any point by calling Transaction.rollback() or Transaction.commit(). When you do this inside a wrapped block of a # new transaction will begin automatically after the call # to rollback(). transaction.rollback() error_saving = True create_report(error_saving=error_saving) # Note: create(username='huey') # This will roll back the above create() query. nested_txn.rollback() User.create(username='mickey') # When the block ends, the transaction is committed (assuming

a block wrapped by the atomic() context manager, you can explicitly rollback or commit at any point by calling Transaction.rollback() or Transaction.commit(). When you do this inside a wrapped block of wrapped with "atomic", a # new transaction will begin automatically after the call # to rollback(). transaction.rollback() error_saving = True create_report(error_saving=error_saving) # Note: no need to call savepoint. User.create(username='huey') # This will roll back the above create() query. nested_txn.rollback() User.create(username='mickey') # When the block ends, the transaction is committed (assuming

a block wrapped by the atomic() context manager, you can explicitly rollback or commit at any point by calling Transaction.rollback() or Transaction.commit(). When you do this inside a wrapped block of wrapped with "atomic", a # new transaction will begin automatically after the call # to rollback(). transaction.rollback() error_saving = True create_report(error_saving=error_saving) # Note: no need to call 6. Database 57 peewee Documentation, Release 3.4.0 (continued from previous page) nested_txn.rollback() User.create(username='mickey') # When the block ends, the transaction is committed (assuming