`fatxpool`: handling limits and priorities improvements (#6405)
This PR provides a number of improvements around handling limits and priorities in the fork-aware transaction pool. #### Notes to reviewers. #### Following are the notable changes: 1. #### [Better support](https://github.com/paritytech/polkadot-sdk/pull/6405/commits/414ec3cc) for `Usurped` transactions When any view reports an `Usurped` transaction (replaced by other with higher priority) it is removed from all the views (also inactive). Removal is implemented by simply submitting usurper transaction to all the views. It is also ensured that usurped tx will not sneak into the `view_store` in newly created view (this is why `ViewStore::pending_txs_replacements` was added). 1. #### [`TimedTransactionSource`](https://github.com/paritytech/polkadot-sdk/pull/6405/commits/f10590f3) introduced: Every view now has an information when the transaction entered the pool. Enforce limits (now only for future txs) uses this timestamp to find worst transactions. Having common timestamp ensures coherent assessment of the transaction's importance across different views. This also could later be used to select which ready transaction shall be dropped. 1. #### `DroppedWatcher`: [improved logic](https://github.com/paritytech/polkadot-sdk/pull/6405/commits/560db28c) for future transactions For future transaction - if the last referencing view is removed, the transaction will be dropped from the pool. This prevents future unincluded and un-promoted transactions from staying in the pool for long time. #### And some minor changes: 1. [simplified](https://github.com/paritytech/polkadot-sdk/pull/6405/commits/2d0bbf83) the flow in `update_view_with_mempool` (code duplication + minor bug fix). 2. `graph::BasePool`: [handling priorities](https://github.com/paritytech/polkadot-sdk/pull/6405/commits/c9f2d393) for future transaction improved (previously transaction with lower prio was reported as failed), 3. `graph::listener`: dedicated `limit_enforced`/`usurped`/`dropped` [calls added](https://github.com/paritytech/polkadot-sdk/pull/6405/commits/7b58a68c), 4. flaky test [fixed](https://github.com/paritytech/polkadot-sdk/pull/6405/commits/e0a7bc6c ) 5. new tests added, related to: #5809 --------- Co-authored-by:GitHub Action <[email protected]> Co-authored-by:
Iulian Barbu <[email protected]>