add bench for ShouldFanoutTo

src/Makefile.bench.include

@@ -51,6 +51,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/rpc_mempool.cpp \
   bench/streams_findbyte.cpp \
   bench/strencodings.cpp \
+  bench/txreconciliation.cpp \
   bench/util_time.cpp \
   bench/verify_script.cpp \
   bench/xor.cpp

src/bench/txreconciliation.cpp

@@ -0,0 +1,40 @@
+// Copyright (c) 2020-2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <bench/bench.h>
+
+#include <net.h>
+#include <node/txreconciliation.h>
+
+
+/* Benchmarks */
+
+static void ShouldFanoutTo(benchmark::Bench& bench)
+{
+    TxReconciliationTracker tracker(1);
+    // Register 120 inbound peers
+    int num_peers{120};
+    for(NodeId peer=0; peer < num_peers; peer++) {
+        tracker.PreRegisterPeer(peer);
+        tracker.RegisterPeer(peer, /*is_peer_inbound=*/true, 1, 1);
+    }
+    FastRandomContext rc{/*fDeterministic=*/true};
+    CSipHasher hasher(0x0706050403020100ULL, 0x0F0E0D0C0B0A0908ULL);
+
+    // The target function uses caching, so we want to mimic tx repetitions
+    // of the real-world behavior.
+    std::vector<Wtxid> txs;
+    for (size_t i = 0; i < 1000; i++) {
+        txs.push_back(Wtxid::FromUint256(rc.rand256()));
+    }
+
+    bench.run([&] {
+        size_t rand_i = rand() % txs.size();
+        for (NodeId peer = 0; peer < num_peers; ++peer) {
+            tracker.ShouldFanoutTo(txs[rand_i], CSipHasher(hasher), peer,/*inbounds_nonrcncl_tx_relay=*/0, /*outbounds_nonrcncl_tx_relay=*/0);
+        }
+    });
+}
+
+BENCHMARK(ShouldFanoutTo, benchmark::PriorityLevel::HIGH);