1 | package com.hammurapi.eventbus; |
2 | |
3 | /** |
4 | * Inference policy defines how new events (conclusions) posted by handlers are dispatched. |
5 | * Different policies provide different levels of serialization/concurrency of event processing. |
6 | * @author Pavel Vlasov |
7 | * |
8 | */ |
9 | public enum InferencePolicy { |
10 | |
11 | /** |
12 | * New events (conclusions) are dispatched immediately when they are posted. |
13 | * IMPORTANT: Use of this policy with join handlers may lead to ConcurrentModificationException if |
14 | * posted events match the same join handlers and inference commands are executed in |
15 | * the same thread. |
16 | */ |
17 | IMMEDIATELY, |
18 | |
19 | /** |
20 | * Conclusions are accumulated during handler execution and are posted to the |
21 | * bus after the handler successfully finishes execution (without exception). |
22 | */ |
23 | AFTER_HANDLER, |
24 | |
25 | /** |
26 | * Conclusions are accumulated during event dispatching and are posted to the |
27 | * bus after all handlers for the current event finish execution. |
28 | */ |
29 | AFTER_EVENT, |
30 | |
31 | /** |
32 | * "Root event" is an event which is posted to the bus by the client code (not by a handler) through |
33 | * EventBus.post() method. With this inference policy conclusions are accumulated and get posted |
34 | * to the bus after all handlers for the root event and previously posted conclusions finish execution. |
35 | */ |
36 | AFTER_ROOT_EVENT, |
37 | |
38 | /** |
39 | * Only one event at a time is dispatched by the bus. Handlers and predicates still execute in parallel by |
40 | * the executor service. |
41 | */ |
42 | EXCLUSIVE |
43 | |
44 | } |