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

85 lines
2.3 KiB
Rust

#![feature(arbitrary_self_types)]
#![feature(arbitrary_self_types_pointers)]
#![allow(clippy::needless_return)] // tokio macro-generated code doesn't respect this
use anyhow::Result;
use turbo_tasks::Vc;
use turbo_tasks_testing::{Registration, register, run_once};
static REGISTRATION: Registration = register!();
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_basic() {
let mut nonce = 0;
run_once(&REGISTRATION, move || {
// pass a nonce to re-run the test body on every turbo-tasks restart
nonce += 1;
async move { test_basic_operation(nonce).read_strongly_consistent().await }
})
.await
.unwrap()
}
#[turbo_tasks::function(operation, root)]
async fn test_basic_operation(nonce: u32) -> Result<Vc<()>> {
let _ = nonce; // ensure the nonce is part of our cache key
let output1 = func_without_args();
assert_eq!(output1.await?.value, 123);
let input = Value { value: 42 }.cell();
let output2 = func_transient(input);
assert_eq!(output2.await?.value, 42);
let output3 = func_persistent(output1);
assert_eq!(output3.await?.value, 123);
let output4 = nested_func_without_args_waiting();
assert_eq!(output4.await?.value, 123);
let output5 = nested_func_without_args_non_waiting();
assert_eq!(output5.await?.value, 123);
Ok(Vc::cell(()))
}
#[turbo_tasks::value]
#[derive(Clone, Debug)]
struct Value {
value: u32,
}
#[turbo_tasks::function]
async fn func_transient(input: Vc<Value>) -> Result<Vc<Value>> {
println!("func_transient");
let value = input.await?.value;
Ok(Value { value }.cell())
}
#[turbo_tasks::function]
async fn func_persistent(input: Vc<Value>) -> Result<Vc<Value>> {
println!("func_persistent");
let value = input.await?.value;
Ok(Value { value }.cell())
}
#[turbo_tasks::function]
fn func_without_args() -> Result<Vc<Value>> {
println!("func_without_args");
let value = 123;
Ok(Value { value }.cell())
}
#[turbo_tasks::function]
async fn nested_func_without_args_waiting() -> Result<Vc<Value>> {
println!("nested_func_without_args_waiting");
let value = func_without_args().owned().await?;
Ok(value.cell())
}
#[turbo_tasks::function]
fn nested_func_without_args_non_waiting() -> Result<Vc<Value>> {
println!("nested_func_without_args_non_waiting");
Ok(func_without_args())
}