CHIA-3957 Improve requesting transactions advertised via NewTransaction

[AmineKhaldi]

Note

Medium Risk
Changes the transaction-fetch path to use synchronous request_transaction RPC responses and enqueue results into the per-peer TransactionQueue, which could affect mempool propagation and retry behavior under load. Test-only adjustments to expected_mempool_responses reduce flakiness but also change assumptions about connection counters.

Overview
Improves how a full node fetches transactions it learns about via peer advertisements by switching from fire-and-forget request_transaction + sleep polling to an awaited call_api(FullNodeAPI.request_transaction) flow, then enqueuing the received spend into the TransactionQueue (with fallback to alternate peers if a peer queue is full).

Adjusts mempool response expectation accounting by resetting expected_mempool_responses (including the old-peer mempool sync case) instead of incrementing it, and updates several tests to match this new semantics.

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[arvidn]

I don't understand how this can be backwards compatible. When you send a RequestMempoolTransactions to a peer, you will receive an unknown number of RespondTransaction messages in response. It looks like this change would just ban the peer.

Am I misunderstanding something?

[AmineKhaldi]

I don't understand how this can be backwards compatible. When you send a RequestMempoolTransactions to a peer, you will receive an unknown number of RespondTransaction messages in response. It looks like this change would just ban the peer.

Am I misunderstanding something?

This doesn't ban the peer, the connection stays and the message gets ignored.

[arvidn]

continue doesn't seem right here. If the queue is full, I would think it's very likely to be full after we request the transaction from another peer as well. Don't we have a queue or some kind of pacing that's meant to make sure we don't request more transactions when our processing queue is full?

[AmineKhaldi]

This is per peer, it's full for this peer.

[arvidn]

the exception would come from here, wouldn't it?
full_node.transaction_queue.put()

[AmineKhaldi]

That's what I mean by per peer.

if self._peers_transactions_queues[peer_id].priority_queue.qsize() >= self.peer_size_limit:
            self.log.warning(f"Transaction queue full for peer {peer_id}")
            raise TransactionQueueFull(f"Transaction queue full for peer {peer_id}")

[arvidn]

I don't see this code anywhere in this patch

[AmineKhaldi]

That's how full_node.transaction_queue.put() raises the exception in question.

[arvidn]

I think you can remove full_node.full_node_store.pending_tx_request entirely now. right? As you pointed out, we always clear the request in the finally block in tx_request_and_timeout(), so it doesn't really mean much here. The request is quite unlikely to be found in this set.

[AmineKhaldi]

Yes, done.

[arvidn]

with this change of using call_api(), all of these should probably be reviewed. It's not obvious that we need them anymore. especially pending_tx_request, I would expect to not be necessary

[AmineKhaldi]

We need pending_tx_request for new_transaction.

[cursor]

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

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[coveralls-official]

Pull Request Test Coverage Report for Build 23496106266

Details

• 17 of 21 (80.95%) changed or added relevant lines in 5 files are covered.
• 266 unchanged lines in 27 files lost coverage.
• Overall coverage decreased (-0.2%) to 91.136%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
chia/full_node/full_node_api.py	10	14	71.43%

Files with Coverage Reduction	New Missed Lines	%
chia/cmds/plotnft_funcs.py	1	85.42%
chia/full_node/block_store.py	1	96.88%
chia/rpc/rpc_server.py	1	90.94%
chia/server/chia_policy.py	1	94.52%
chia/_tests/core/mempool/test_mempool_manager.py	1	99.82%
chia/_tests/rpc/test_rpc_server.py	1	99.42%
chia/_tests/simulation/test_simulation.py	1	96.49%
chia/wallet/wallet_state_manager.py	1	94.46%
chia/wallet/wallet_user_store.py	1	98.18%
chia/data_layer/data_layer.py	2	85.78%

Totals
Change from base Build 23492166799:	-0.2%
Covered Lines:	105839
Relevant Lines:	115964

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💛 - Coveralls