Log plugin does not work on hooks, only on moves

[gabrielecastellano]

Hello everyone!

I use the ctx.log object to show a game log client-side. It works fine for moves, as I can add metadata before the move ends.

However, what if I want to log something outside of a move? Let's say, on some event? For instance, I have a 'onBegin' method in one of my phases, and I want to log something from that method. The ctx.log object is visible there, but If I try to append any metadata there, nothing arrives client-side as that happens outside of a move.

However, the event itself (without any metadata) has its own entry in the log client-side.

Am I doing anything wrong or this is a known limitation? Any way to work around this?

Thanks

[fladrif]

Looking at the documentation and code, plugins should be executing in both game events and moves. Do you have an example of it not working?

[gabrielecastellano]

My codebase is quite big. I can try to reproduce it on the tic-tac-toe example.
Meanwhile, I assume you are able to log during events handlers?

Gabriele

[gabrielecastellano]

Please check out this example.

I have modified the tic-tac-toe app introducing two phases. In the first phase, you can only click a button that ends the phase, while the second phase has the usual clickCell move.

I have tried to log.setMetadata() both at onEnd of the first phase, and at onBegin of the second phase. You can verify from the debug sidebar that those log entries are not reported (there is only the entry for the endPhase event, and it doesn't have any metadata). On the other end, all the metadata set during moves are correctly attached to their log entries.

[fladrif]

Thanks, yea I see the issue, it's with hooks and plugins. Plugins work correctly for moves and events, but hooks don't persist their data in execution to state here https://github.com/boardgameio/boardgame.io/blob/main/src/core/flow.ts#L332. All the wrapped hooks will probably need to return all state and not just { G }. I can create an MR, but it doesn't look like @benbot has been active to merge. @nicolodavis @delucis Can I be an interim maintainer?

note: hooks are the onEnd or onBegin functions you're writing. Events in the context of bgio are specifically the ones called from { events } = FnContext.

[gabrielecastellano]

Thank you for the clarification, I see the difference between events and hooks now. And I understand that even if events are logged, these will always come with no metadata I assume.

If log could be extended to hooks, it would be amazing. In my game logic there are some pieces of information that I would like to record that are not known during moves, but only during the hooks execution.

[fladrif]

Scratch my earlier comment, I misunderstood what was going on. The hook isn't where the issue lies, it's with the reducer and how it handles GAME_EVENT states https://github.com/boardgameio/boardgame.io/blob/main/src/core/reducer.ts#L295. In MOVE actions, the metadata gets appended to the deltaLog in the reducer fn, but the deltaLog generation for GAME_EVENTs happens in the actual event fn handler. That delta log generation in the event fn does not handle metadata. https://github.com/boardgameio/boardgame.io/blob/main/src/core/flow.ts#L522

[gabrielecastellano]

I see the problem, although I don't get if there is any particular reason why the log is initialized internally on the event handlers. Would calling initializeDeltalog() before processEvent() (along with removing those const deltalog = [...(state.deltalog || []), logEntry]; from within the event handlers, make the job?

I don't have much knowledge of the internal functioning of the framework, but I foresee a possible problem with the fact that an event might trigger multiple hooks (e.g., onEnd and onBegin of two consecutive phases).

[fladrif]

Yea, I'm not sure why they made that design decision. I think paradoxically initializeDeltalog() should be called at the end of the process since it takes the metadata in state.plugins.log.data and adds it to state.deltalog. I'm using the case Action.MAKE_MOVE: in src/core/reducer.ts as the pattern. In this case where the log is persisted within the individual events, it needs to be called there.