Refactor mempool.rs to prevent from returning conflicting transaction during RBF

[romanz]

Currently, there seems to be a race when updating the mempool with RBF transactions - causing a concurrent API to return conflicting mempool transactions (i.e. spending the same inputs).

Also we need to add tests and simplify mempool.rs module.

[pedr0-fr]

Has this been solved? Maybe it could be normal behavior to show old RBF transactions that were replaced and flag the one that is currently in the mempool.

[romanz]

Has this been solved?

Not yet :)

Maybe it could be normal behavior to show old RBF transactions that were replaced and flag the one that is currently in the mempool.

Not sure - I prefer to keep the complexity at minimum...

[romanz]

Latest release's (0.9.0) mempool should always contain a subset of the bitcoind mempool.
In case of a RBF, the missing transaction will not be added to electrs mempool:

electrs/src/mempool.rs

Lines 102 to 113 in 239e465

	let entries: Vec<_> = to_add
	.par_iter()
	.filter_map(|txid| {
	match (
	daemon.get_transaction(txid, None),
	daemon.get_mempool_entry(txid),
	) {
	(Ok(tx), Ok(entry)) => Some((txid, tx, entry)),
	_ => None,
	}
	})
	.collect();