improve world.maintain() about sim-ecs

[vmwxiong]

Could maybe copy the whole world, then asynchronously work on it over time, a little bit each tick?

Not familiar with what maintain does though, just spitballing from what you said here.

[minecrawler]

Not familiar with what maintain does

This ECS works with the optimization, that each system carries a cache containing all entities it has to work on. This makes execution very fast, since you don't have to join or match anything, the dataSet is already available when system.run() executes.

There are only two hard things in Computer Science: cache invalidation and naming things.
-- Phil Karlton

So, you still have to make sure to keep the caches in sync with whatever happens in your world, and that's where world.maintain() comes into play. It syncs entities in the world with the systems' caches. This allows you to prepare changes to the world during one step and then sync them on the transition to the next step, which guarantees that all systems always work on the same entities per step. Having that work stretch out over several steps would mean that you unexpectedly have to wait for entities to hit your systems, instead of having them in there the next step guaranteed.

And that's also why I think that the only optimization for stretching out work would be to focus the syncing on systems which are actually in use (which is defined by the state - if you don't work with states, per default, all systems will run).

[minecrawler]

world.maintain was removed in favor of auto-syncing changes in cache at save points