benchmark: add micro-benchmarks for TraceID hex formatting and parsing

benchmark/CMakeLists.txt

@@ -6,6 +6,7 @@
 add_executable(dd_trace_cpp-benchmark
     benchmark.cpp
     hasher.cpp
+    trace_id_bench.cpp
 )
 
 # Google Benchmark is included as a git submodule.

benchmark/trace_id_bench.cpp

@@ -0,0 +1,54 @@
+#include <benchmark/benchmark.h>
+#include <datadog/trace_id.h>
+
+#include "datadog/hex.h"
+
+namespace {
+namespace dd = datadog::tracing;
+
+void BM_TraceID_HexPadded(benchmark::State& state) {
+  const dd::TraceID id{0xDEADBEEFCAFEBABEULL, 0x0102030405060708ULL};
+  for (auto _ : state) {
+    auto result = id.hex_padded();
+    benchmark::DoNotOptimize(result);
+  }
+}
+BENCHMARK(BM_TraceID_HexPadded);
+
+void BM_TraceID_ParseHex_128bit(benchmark::State& state) {
+  const std::string input{"0102030405060708deadbeefcafebabe"};
+  for (auto _ : state) {
+    auto result = dd::TraceID::parse_hex(input);
+    benchmark::DoNotOptimize(result);
+  }
+}
+BENCHMARK(BM_TraceID_ParseHex_128bit);
+
+void BM_TraceID_ParseHex_64bit(benchmark::State& state) {
+  const std::string input{"deadbeefcafebabe"};
+  for (auto _ : state) {
+    auto result = dd::TraceID::parse_hex(input);
+    benchmark::DoNotOptimize(result);
+  }
+}
+BENCHMARK(BM_TraceID_ParseHex_64bit);
+
+void BM_HexPadded_uint64(benchmark::State& state) {
+  const std::uint64_t value = 0xDEADBEEFCAFEBABEULL;
+  for (auto _ : state) {
+    auto result = dd::hex_padded(value);
+    benchmark::DoNotOptimize(result);
+  }
+}
+BENCHMARK(BM_HexPadded_uint64);
+
+void BM_Hex_uint64(benchmark::State& state) {
+  const std::uint64_t value = 0xDEADBEEFCAFEBABEULL;
+  for (auto _ : state) {
+    auto result = dd::hex(value);
+    benchmark::DoNotOptimize(result);
+  }
+}
+BENCHMARK(BM_Hex_uint64);
+
+}  // namespace