net processing: Check if we are in ibd before processing block for txdownloadman

This avoids wasting work on calculating bloom filters that aren't
consumed during ibd and continuously re-calculated as now blocks get
validated.

Also update the functional test to document that transactions would now
be requested again once out of IBD.

Co-authored-by: Lőrinc <pap.lorinc@gmail.com>

src/net_processing.cpp

@@ -2054,12 +2054,12 @@ void PeerManagerImpl::BlockConnected(
     }
 
     // The following task can be skipped since we don't maintain a mempool for
-    // the historical chainstate.
+    // the historical chainstate, or during ibd since we don't receive incoming
-    if (role.historical) {
+    // transactions from peers into the mempool.
-        return;
+    if (!role.historical && !m_chainman.IsInitialBlockDownload()) {
+        LOCK(m_tx_download_mutex);
+        m_txdownloadman.BlockConnected(pblock);
     }
-    LOCK(m_tx_download_mutex);
-    m_txdownloadman.BlockConnected(pblock);
 }
 
 void PeerManagerImpl::BlockDisconnected(const std::shared_ptr<const CBlock> &block, const CBlockIndex* pindex)

test/functional/p2p_ibd_txrelay.py

@@ -89,13 +89,11 @@ class P2PIBDTxRelayTest(BitcoinTestFramework):
             assert not node.getblockchaininfo()['initialblockdownload']
             self.wait_until(lambda: all(peer['minfeefilter'] == NORMAL_FEE_FILTER for peer in node.getpeerinfo()))
 
-        self.log.info("Check that txs confirmed during IBD are in the recently-confirmed filter once out of ibd")
+        self.log.info("Check that txs confirmed during IBD are not in the recently-confirmed filter once out of ibd")
         peer_inver = self.nodes[0].add_p2p_connection(P2PDataStore())
         peer_inver.send_and_ping(msg_inv([CInv(t=MSG_WTX, h=ibd_wtxid)]))
         self.nodes[0].bumpmocktime(NONPREF_PEER_TX_DELAY)
-        peer_inver.sync_with_ping()
+        peer_inver.wait_for_getdata([ibd_wtxid])
-        with p2p_lock:
-            assert ibd_wtxid not in peer_inver.getdata_requests
         self.nodes[0].disconnect_p2ps()
 
         self.log.info("Check that nodes process the same transaction, even when unsolicited, when no longer in IBD")