Async transactions

[artalar]

We need a way to handle optimistic UI easily. The idea is accumulate rollback during transaction and do not cleanup them up until async transaction end. To prevent state collision and for first simple version we could lock touched atoms for mutations and throw an error if somebody trying to change an atom during it lock. In this flow we allow the only simple isolated transactions but it will already better than nothing.

Example.

const reatomLike = (post) => {
  const like = reatomAsync((ctx) => api.toggleLike(ctx, post.id)).pipe(
    withDataAtom(post.like),
    withAbort(),
    asTransaction()
  );
  onUpdate(like, (ctx) => like.dataAtom(ctx, (state) => !state));
  // THIS will be done automatically by `asTransaction`
  // onUpdate(like.onReject, (ctx) => like.dataAtom(ctx, (state) => !state));

  return like;
};

const fetchFeed = reatomAsync((ctx, from) => api.getFeed(ctx, from)).pipe(
  withDataAtom([], (ctx, { data }, state) => [
    ...state,
    ...data.map((post) => ({ ...post, like: reatomLike(post) })),
  ])
);