apollo_mempool: same block logic

[ayeletstarkware]

Note

Medium Risk
Changes FIFO mempool batching semantics to depend on both timestamp and block_number, including emitting empty results on block gaps and realigning after rewinds; this affects block-building behavior and could impact liveness/ordering if edge cases are missed.

Overview
FIFO (Echonet) transaction batching is now block-aware. The FIFO queue replaces the single last_returned_timestamp gate with a CurrentProposalState that tracks the proposal timestamp, the expected_block_number, and whether an empty block should be emitted.

get_txs/has_ready_txs/iter_over_ready_txs now only return transactions matching the current proposal’s (timestamp, expected_block_number), advance expected_block_number once a block is drained, return an empty chunk once when a block-number gap is detected, and realign to earlier blocks when rewound transactions reappear at the head.

Adds targeted tests covering: same-block retrieval across multiple get_txs chunks, block-number gaps (single and long), resolving timestamps after the queue is emptied and after new txs arrive, and rewind scenarios that continue within the same block or realign to an earlier block.

^{Written by Cursor Bugbot for commit 4575a22. This will update automatically on new commits. Configure here.}

[reviewable-StarkWare]

This change is 

[ayeletstarkware]

• apollo_mempool: same block logic #13300 👈 (View in Graphite)
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[ron-starkware]

@ron-starkware reviewed 2 files and all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on ayeletstarkware).

[matanl-starkware]

@matanl-starkware reviewed 2 files and all commit messages, and made 4 comments.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on ayeletstarkware).

---

crates/apollo_mempool/src/fifo_transaction_queue.rs line 223 at r1 (raw file):

    fn pop_ready_chunk(&mut self, n_txs: usize) -> Vec<TransactionReference> {
        let Some(mut current_state) = self.current_proposal_state else {

Avoid unnecessary move, and then you don't need the last self.current_proposal_state = Some(current_state);

Suggestion:

let Some(current_state) = self.current_proposal_state.as_mut() else {

---

crates/apollo_mempool/src/fifo_transaction_queue.rs line 232 at r1 (raw file):

            // Queue is empty, nothing to return.
            return Vec::new();
        };

Check this before the non-None current_proposal_state panic

Code quote:

        let Some(front_tx) = self.queue.front() else {
            // Queue is empty, nothing to return.
            return Vec::new();
        };

---

crates/apollo_mempool/src/fifo_transaction_queue.rs line 307 at r1 (raw file):

            (Some(state), Some(front_tx)) => state.matches_tx(front_tx),
            _ => false,
        }

I like !

Code quote:

        match (self.current_proposal_state, self.queue.front()) {
            (Some(state), Some(front_tx)) => state.matches_tx(front_tx),
            _ => false,
        }

---

crates/apollo_mempool/src/fifo_transaction_queue.rs line 315 at r1 (raw file):

                .iter()
                .take_while(|tx| {
                    self.current_proposal_state.is_some_and(|state| state.matches_tx(tx))

Extract outside the for loop

Code quote:

self.current_proposal_state.is_some_and(|state| state

[ayeletstarkware]

@ayeletstarkware made 2 comments.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on matanl-starkware).

---

crates/apollo_mempool/src/fifo_transaction_queue.rs line 223 at r1 (raw file):

Previously, matanl-starkware (Matan Lior) wrote…

Avoid unnecessary move, and then you don't need the last self.current_proposal_state = Some(current_state);

Done.

---

crates/apollo_mempool/src/fifo_transaction_queue.rs line 315 at r1 (raw file):

Previously, matanl-starkware (Matan Lior) wrote…

Extract outside the for loop

Done.

[matanl-starkware]

@matanl-starkware reviewed 2 files and all commit messages, and resolved 2 discussions.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on ayeletstarkware).