bench: Adds a benchmark for HexStr

Benchmarks conversion of a full binary block into hex, like it is done in rest.cpp.

src/Makefile.bench.include

@@ -44,6 +44,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/rollingbloom.cpp \
   bench/rpc_blockchain.cpp \
   bench/rpc_mempool.cpp \
+  bench/strencodings.cpp \
   bench/util_time.cpp \
   bench/verify_script.cpp
 

src/bench/strencodings.cpp

@@ -0,0 +1,18 @@
+// Copyright (c) 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 <bench/data.h>
+#include <util/strencodings.h>
+
+static void HexStrBench(benchmark::Bench& bench)
+{
+    auto const& data = benchmark::data::block413567;
+    bench.batch(data.size()).unit("byte").run([&] {
+        auto hex = HexStr(data);
+        ankerl::nanobench::doNotOptimizeAway(hex);
+    });
+}
+
+BENCHMARK(HexStrBench);