add micro-benchmarks for TraceID hex formatting and parsing (#311)

Author: AneesPatel

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 +1,47 @@
+#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, dd::TraceID id) {
+  for (auto _ : state) {
+    auto result = id.hex_padded();
+    benchmark::DoNotOptimize(result);
+  }
+}
+BENCHMARK_CAPTURE(BM_TraceID_HexPadded, NoPadding,
+                  dd::TraceID{0xDEADBEEFCAFEBABEULL, 0x0102030405060708ULL});
+BENCHMARK_CAPTURE(BM_TraceID_HexPadded, WithPadding, dd::TraceID{1, 0});
+
+void BM_TraceID_ParseHex(benchmark::State& state, std::string input) {
+  for (auto _ : state) {
+    auto result = dd::TraceID::parse_hex(input);
+    benchmark::DoNotOptimize(result);
+  }
+}
+BENCHMARK_CAPTURE(BM_TraceID_ParseHex, 64bit, std::string{"deadbeefcafebabe"});
+BENCHMARK_CAPTURE(BM_TraceID_ParseHex, 128bit,
+                  std::string{"0102030405060708deadbeefcafebabe"});
+
+void BM_HexPadded_uint64(benchmark::State& state, std::uint64_t value) {
+  for (auto _ : state) {
+    auto result = dd::hex_padded(value);
+    benchmark::DoNotOptimize(result);
+  }
+}
+BENCHMARK_CAPTURE(BM_HexPadded_uint64, NoPadding, 0xDEADBEEFCAFEBABEULL);
+BENCHMARK_CAPTURE(BM_HexPadded_uint64, WorstCasePadding, 0x1ULL);
+
+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