Fix waiting on a query that panicked

[Zoxc]

This fixes waiting on a query that panicked. The code now looks for QueryResult::Poisoned in the query state in addition to the query cache. This fixes #111528.

r? @cjgillot

[cjgillot]

The only possible course of action is unwinding. Should we replace the match by an assertion?

Suggested change

	// We didn't find the query result in the query cache. Check if it was
	// poisoned due to a panic instead.
	let lock = query.query_state(qcx).active.get_shard_by_value(&key).lock();
	match lock.get(&key) {
	// The query we waited on panicked. Continue unwinding here.
	Some(QueryResult::Poisoned) => FatalError.raise(),
	_ => panic!(
	"query result must in the cache or the query must be poisoned after a wait"
	),
	}
	// We didn't find the query result in the query cache. Check if it was
	// poisoned due to a panic instead.
	debug_assert!(
	matches!(
	query.query_state(qcx).active.get_shard_by_value(&key).lock().get(&key),
	Some(QueryResult::Poisoned),
	),
	"query result must in the cache or the query must be poisoned after a wait",
	);
	// The query we waited on panicked. Continue unwinding here.
	FatalError.raise()

[Zoxc]

I feel like the current version makes it more clear that we should only call FatalError.raise() once we observe the QueryResult::Poisoned case. I don't think I want to downgrade to a debug_assert without some more testing of the parallel compiler. This path is also not terribly hot.

[cjgillot]

@bors r+

[bors]

📌 Commit 3040d92 has been approved by cjgillot

It is now in the queue for this repository.

[bors]

⌛ Testing commit 3040d92 with merge 22d41ae...

[bors]

☀️ Test successful - checks-actions
Approved by: cjgillot
Pushing 22d41ae to master...

[rust-timer]

Finished benchmarking commit (22d41ae): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.8%	[2.8%, 2.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.2%	[-1.2%, -1.2%]	1
All ❌✅ (primary)	-	-	0

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 630.77s -> 631.198s (0.07%)
Artifact size: 316.08 MiB -> 316.03 MiB (-0.02%)