faa2976a56 Remove mapRelay (MarcoFalke)
fccecd75fe net_processing: relay txs from m_most_recent_block (Anthony Towns)
Pull request description:
`mapRelay` (used to relay announced transactions that are no longer in the mempool) has issues:
* It doesn't have an absolute memory limit, only an implicit one based on the rate of transaction announcements
* <strike>It doesn't have a use-case</strike> EDIT: see below
Fix all issues by removing `mapRelay`.
For more context, on why a transaction may have been removed from the mempool, see c2f2abd0a4/src/txmempool.h (L228-L238)
For my rationale on why it is fine to not relay them:
Reason | | Rationale
-- | -- | --
`EXPIRY` | Expired from mempool | Mempool expiry is by default 2 weeks and can not be less than 1 hour, so a transaction can not be in `mapRelay` while expiring, unless a re-broadcast happened. This should be fine, because the transaction will be re-added to the mempool and potentially announced/relayed on the next re-broadcast.
`SIZELIMIT` | Removed in size limiting | A low fee transaction, which will be relayed by a different peer after `GETDATA_TX_INTERVAL` or after we sent a `notfound` message. Assuming it ever made it to another peer, otherwise it will happen on re-broadcast (same as with `EXPIRY` above).
`REORG` | Removed for reorganization | Block races are rare, so reorgs should be rarer. Also, the transaction is likely to be re-accepted via the `disconnectpool` later on. If not, it seems fine to let the originating wallet deal with rebroadcast in this case.
`BLOCK` | Removed for block | EDIT: Needed for compact block relay, see https://github.com/bitcoin/bitcoin/pull/27625#issuecomment-1544047433
`CONFLICT` | Removed for conflict with in-block transaction | The peer won't be able to add the tx to the mempool anyway, unless it is on a different block, in which case it seems fine to let the originating wallet take care of the rebroadcast (if needed).
`REPLACED` | Removed for replacement | EDIT: Also needed for compact block relay, see https://github.com/bitcoin/bitcoin/pull/27625#issuecomment-1544171255 ?
ACKs for top commit:
sdaftuar:
ACK faa2976a56
ajtowns:
ACK faa2976a56
glozow:
code review ACK faa2976a56
Tree-SHA512: 64ae3e387b001bf6bd5b6c938e7317f4361f9bc0b8cc5d8f63a16cda2408d2f634a22f8157dfcd8957502ef358208292ec91e7d70c9c2d8a8c47cc0114ecfebd
fbe48f97df