Files
5d0dab5fc6 [turbopack] Enforce root attribute for strongly consistent reads and collectibles (#93114)
### What?

Replaces the silent "make root node" promotion in the turbo-tasks
backend with a panic that enforces tasks to already have the `root`
attribute before performing strongly consistent reads, reading task
collectibles, or removing collectibles.

### Why?

Previously, the backend would silently promote any non-root task to a
root node (aggregation number `u32::MAX`) when these operations were
requested. This masked incorrect task configuration — tasks that needed
root-level aggregation weren't explicitly declared as such, making it
harder to reason about the aggregation graph and hiding potential
performance issues from implicit promotions.

### How?

**Backend enforcement (3 locations):**
- **Strongly consistent read** (`backend/mod.rs`): Checks
`NativeFunction.is_root` on the target task. If it's a persistent task
without `root`, panics with both the target and reader task
descriptions.
- **Read task collectibles** (`backend/mod.rs`): Same check when reading
collectibles from a task.
- **Remove collectibles** (`operation/update_collectible.rs`): Same
check when removing collectibles (count < 0).

All three locations drop the task guard before panicking to avoid
deadlocking with `debug_get_task_description`.

**Macro support for `root` on methods:**
- `value_impl_macro.rs`: Now reads the `root` attribute from
`#[turbo_tasks::function(root)]` on inherent impl and trait impl methods
(previously hardcoded to `false`).
- `value_trait_macro.rs`: Same for trait default methods.

**`root` attribute additions:**
- All `#[turbo_tasks::function(operation)]` in test files, benchmarks,
and fuzz code
- Production operations in `crates/next-api/` that are read with strong
consistency
- Regular functions and methods in tests that use
`.strongly_consistent()`
- Trait methods in `value_impl` and `value_trait` blocks used with
strong consistency

**New test:**
- `non_root_task_panic.rs`: Verifies the panic fires when attempting a
strongly consistent read on a non-root operation task. Captures the
panic from the worker thread via a panic hook since the panic propagates
as a channel error to the test thread.

<!-- NEXT_JS_LLM_PR -->

---------

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>
2026-05-12 18:56:02 +00:00

55 lines
1.8 KiB
Rust

#![feature(arbitrary_self_types)]
use anyhow::Result;
use turbo_tasks::{TaskInput, TransientValue, Vc};
use turbo_tasks_testing::{Registration, register, run_without_cache_check};
static REGISTRATION: Registration = register!();
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_transient_vc() -> Result<()> {
run_without_cache_check(&REGISTRATION, async {
test_transient_operation(TransientValue::new(123))
.read_strongly_consistent()
.await?;
Ok(())
})
.await
}
#[turbo_tasks::function(operation, root)]
async fn test_transient_operation(transient_arg: TransientValue<i32>) -> Result<()> {
let called_with_transient = has_transient_arg(transient_arg);
let called_with_persistent = has_persistent_arg(123);
assert!(called_with_transient.is_transient());
assert!(!called_with_persistent.is_transient());
assert!(has_vc_arg(called_with_transient).is_transient());
assert!(!has_vc_arg(called_with_persistent).is_transient());
let called_with_transient_resolved = called_with_transient.to_resolved().await?;
let called_with_persistent_resolved = called_with_persistent.to_resolved().await?;
assert!(called_with_transient_resolved.is_transient());
assert!(!called_with_persistent_resolved.is_transient());
assert!(has_vc_arg(*called_with_transient_resolved).is_transient());
assert!(!has_vc_arg(*called_with_persistent_resolved).is_transient());
Ok(())
}
#[turbo_tasks::function]
fn has_transient_arg(arg: TransientValue<i32>) -> Vc<i32> {
Vc::cell(*arg)
}
#[turbo_tasks::function]
fn has_persistent_arg(arg: i32) -> Vc<i32> {
Vc::cell(arg)
}
#[turbo_tasks::function]
async fn has_vc_arg(arg: Vc<i32>) -> Result<Vc<i32>> {
Ok(Vc::cell(*arg.await?))
}