tari-project / tari / 36560855364

71%

Build Type

push

github

Committed by web-flow

Commit Message

fix(mempool): match sync inventory in linear time (#8057)

## Description

The mempool-sync responder (`start_responder_inner`) matched the peer's
`TransactionInventory` against its own mempool by running
`inventory.items.iter().position(..)` for every pooled transaction,
followed by a `Vec::contains` per item when building the missing-index
list. The cost was `|mempool| x |inventory|` per exchange, with the
inventory bounded only by the 3 MiB frame (~92k items).

This PR:

- builds a `HashMap<&[u8], usize>` from the inventory once (first index
wins, so a duplicated item is still reported missing at its later
positions, exactly as before) and records matches in a `HashSet<usize>`.
The keys come from the peer, so the map keeps std's randomly keyed
SipHash;
- rejects any inventory item that is not a 32-byte excess signature
scalar, before the mempool is snapshotted, with a new
`MempoolProtocolError::InvalidInventoryItem`.

Not in scope: an item-count cap and a responder concurrency limit. With
linear matching, a full-frame inventory costs a few ms.

## Motivation and Context

Keeps the responder's work linear in its inputs regardless of how full
the mempool is.

## How Has This Been Tested?

- New tests in `mempool/sync_protocol/test.rs`:
-
`responder_streams_unmatched_transactions_and_requests_missing_indexes`:
checks that matched transactions are not streamed, that the missing
indexes are correct, and that duplicate-item semantics are preserved.
- `responder_rejects_an_inventory_item_that_is_not_an_excess_signature`
- `cargo test -p tari_core --lib mempool::sync_protocol::`: 16 passed.
- `cargo ci-clippy -p tari_core` is clean.
- Release-mode measurement, 2,000-transaction mempool, one 92,521-item
inventory: first reply went from ~212 ms to ~30 ms (1-item baseline
~20-27 ms).

## Breaking Changes

- [x] None

🤖 Generated with [Claude Code](https://claude.com/claude-code)


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