1 Commits (batch-branches-fix)

Author	SHA1	Message	Date
Simon H	9521b9f3dc	fix: don't rebase just-created batches (#18117) ... It's possible to rebase just-created batches. Case A: - batch A runs effects - one of these effects writes to a source. This creates a new batch B - an effect _after_ that (still part of "flush effects of batch A") executes a derived. This creates an entry in the `current` Map in batch B - batch A commits after processing batch B (`next_batch` etc logic), batch B is pending. Due to derived being part of batchB.current batch A can wrongfully think these are connected and try to rerun/add effects etc on batch B Case B: - like case A but with an additional await inside a pending snippet Case C: - batch A with source a and b, it flushes effects - one of these effects schedules batch B with b and c scheduling an async effect - batch B is deferred - batch A commits. Due to the a/b/c partial overlap it will needlessly rerun the just scheduled async effect All these cases are wrong. We fix it like this: 1. we call `this.#commit()` _before_ running the new batches, which may stick around due to having pending work, and we don't want to rebase these. This fixes case A and C 2. we capture derived values in `previous_batch` if it exists, because it means we're currently flushing effects, and derived writes belong to that batch and not a new one that might have been scheduled already. This fixes case B Discovered this while working on #18097 --------- Co-authored-by: Rich Harris <rich.harris@vercel.com>	4 months ago