next.js

bfce90ed - feat(turbo-tasks): Add `local_cells` argument to `turbo_tasks::function` macro, read it in `Vc::cell` (#68644)

feat(turbo-tasks): Add `local_cells` argument to `turbo_tasks::function` macro, read it in `Vc::cell` (#68644) Bigger picture: https://www.notion.so/vercel/Resolved-Vcs-Vc-Lifetimes-Local-Vcs-and-Vc-Refcounts-49d666d3f9594017b5b312b87ddc5bff ## What this PR does - Adds a `local_cells` argument to the `#[turbo_tasks::function(...)]` macro, which also implies `resolved` (#68422) - Stores that `local_cells` option in a `FunctionMeta` object on `CurrentTaskState`. - Reads that option when `Vc::cell` is called, and changes the behavior to construct a local cell instead of a normal, global one. ## What this PR does not do - Functions annotated with `local_cells` still create full tasks. Instead, they should inherit parts of `CurrentTaskState`, including their parent task's `TaskId` value, so that values resolved in a local task are resolved on their parent task. - Return values are not yet automatically resolved. This is shown in the tests, which must manually call `.resolve().await.unwrap()`. ## Naming: Why is it called "local_cells" and not just "local"? Right now, every turbo task is `tokio::spawn`ed. In the future, we'll probably want a way to run some tasks "locally" without the overhead of `tokio::spawn`. If I just called this flag `local` and not `local_cells`, it would then be hard later to name the concept of "local execution": - **Local Cells** *(what this PR is about)*: Will reduce long-term memory usage by avoiding caching functions that would otherwise have low hit rates. These tasks may still be `tokio::spawn`ed to take advantage of threads and the work-stealing executor. - **Local Execution** *(does not exist yet, lacks a formal proposal)*: Would improve CPU cache locality and would slightly decrease transient memory usage for short-running tasks by avoiding `tokio::spawn`. These tasks may still be cached. ## Test Plan ``` cargo nextest r -p turbo-tasks -p turbo-tasks-memory ```