apollo_propeller: add validation result handling

[sirandreww-starkware]

Note

Medium Risk
Touches async control flow and validator lifecycle management in MessageProcessor::run, so mistakes could stall validation or lose state; functionality added is minimal/log-only but affects runtime behavior.

Overview
The message processor now actively awaits completion of the background shard validation oneshot and clears pending_validation when results arrive.

Validation result handling has been extracted into handle_validation_result, which restores the moved UnitValidator and logs success/failure (with a TODO placeholder for processing validated units). A TODO was added noting an unhandled oneshot::RecvError case that could strand the validator if the rayon task panics.

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[reviewable-StarkWare]

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[sirandreww-starkware]

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• apollo_propeller: add channel closure handling #12011
• apollo_propeller: add PostReconstruction phase and threshold checking #12010
• apollo_propeller: add reconstruction result handling #12009
• apollo_propeller: add PreReconstruction phase and shard collection #12008
• apollo_propeller: add reconstruction types and spawn task #12007
• apollo_propeller: add validated unit handling and shard broadcasting #12006
• apollo_propeller: add validation result handling #12005 👈 (View in Graphite)
• apollo_propeller: add unit validation receiving and spawning #12004
• apollo_propeller: add MessageProcessor scaffolding #12003 : 1 other dependent PR (#12780 )
• apollo_propeller: added shard index utility functions to schedule manager #12002
• apollo_propeller: add sharding module with tests #11944 : 1 other dependent PR (#12001 )
• apollo_propeller: add message padding utilities #11943
• apollo_propeller: add behaviour public API stubs #11942
• apollo_propeller: add minimal config #11196 : 1 other dependent PR (#11197 )
• apollo_propeller: add behaviour skeleton #11195
• apollo_propeller: add Event enum to types #11194
• apollo_propeller: add dial upgrade error handling to handler #11074
• apollo_propeller: add rate-limited queue length warnings #11073
• apollo_propeller: add concurrent streams support to handler #11072
• apollo_propeller: implement outbound substream with message batching #11071
• apollo_propeller: add handler helper methods #11070
• main-v0.14.2

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

[guy-starkware]

Reviewable status: all files reviewed, 2 unresolved discussions (waiting on noamsp-starkware, ShahakShama, and sirandreww-starkware).

[sirandreww-starkware]

@sirandreww-starkware made 1 comment.
Reviewable status: 0 of 1 files reviewed, 1 unresolved discussion (waiting on guy-starkware, noamsp-starkware, and ShahakShama).

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crates/apollo_propeller/src/message_processor.rs line 138 at r1 (raw file):

Previously, guy-starkware wrote…

I don't know why this early return. It looks like two very similar branches. I would argue this would be more readable as a match or at least as if let {...} else {...}.

This changes in future PRs, this just prepares for that...

[guy-starkware]

@guy-starkware reviewed 1 file and all commit messages, and resolved 1 discussion.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on noamsp-starkware and ShahakShama).

[ShahakShama]

@ShahakShama reviewed all commit messages and made 2 comments.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on noamsp-starkware and sirandreww-starkware).

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crates/apollo_propeller/src/message_processor.rs line 124 at r2 (raw file):

    ) -> ControlFlow<()> {
        // Restore validator
        let (validation_result, validator_returned, unit) = result;

Use named struct instead of tuple

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crates/apollo_propeller/src/message_processor.rs line 127 at r2 (raw file):

        *validator = Some(validator_returned);

        // Early return for validation errors

remove early return (possibly as TODO)