SERVER-42034 Optimize ItoA (~13% faster, remove the 1kLoC static table)

1 files changed, 36 insertions, 17 deletions

diff --git a/src/mongo/util/decimal_counter_bm.cpp b/src/mongo/util/decimal_counter_bm.cpp
index 8507622d1cd..fb0f0cc601e 100644
--- a/src/mongo/util/decimal_counter_bm.cpp
+++ b/src/mongo/util/decimal_counter_bm.cpp
@@ -37,41 +37,60 @@
 namespace mongo {
 
 void BM_decimalCounterPreInc(benchmark::State& state) {
-    DecimalCounter<uint32_t> count;
+    uint64_t items = 0;
     for (auto _ : state) {
-        benchmark::ClobberMemory();
-        benchmark::DoNotOptimize(StringData(++count));
+        DecimalCounter<uint32_t> count;
+        for (int i = state.range(0); i--;) {
+            benchmark::ClobberMemory();
+            benchmark::DoNotOptimize(StringData(++count));
+        }
+        items += state.range(0);
     }
+    state.SetItemsProcessed(items);
 }
 
 void BM_decimalCounterPostInc(benchmark::State& state) {
-    DecimalCounter<uint32_t> count;
+    uint64_t items = 0;
     for (auto _ : state) {
-        benchmark::ClobberMemory();
-        benchmark::DoNotOptimize(StringData(count++));
+        DecimalCounter<uint32_t> count;
+        for (int i = state.range(0); i--;) {
+            benchmark::ClobberMemory();
+            benchmark::DoNotOptimize(StringData(count++));
+        }
+        items += state.range(0);
     }
+    state.SetItemsProcessed(items);
 }
 
 void BM_ItoACounter(benchmark::State& state) {
-    uint32_t count = 0;
+    uint64_t items = 0;
     for (auto _ : state) {
-        benchmark::ClobberMemory();
-        benchmark::DoNotOptimize(StringData(ItoA(++count)));
+        uint32_t count = 0;
+        for (int i = state.range(0); i--;) {
+            benchmark::ClobberMemory();
+            benchmark::DoNotOptimize(StringData(ItoA(++count)));
+        }
+        items += state.range(0);
     }
+    state.SetItemsProcessed(items);
 }
 
 void BM_to_stringCounter(benchmark::State& state) {
-    uint32_t count = 0;
-    std::string str;
+    uint64_t items = 0;
     for (auto _ : state) {
-        benchmark::ClobberMemory();
-        benchmark::DoNotOptimize(std::to_string(++count));
+        uint32_t count = 0;
+        for (int i = state.range(0); i--;) {
+            benchmark::ClobberMemory();
+            benchmark::DoNotOptimize(std::to_string(++count));
+        }
+        items += state.range(0);
     }
+    state.SetItemsProcessed(items);
 }
 
-BENCHMARK(BM_decimalCounterPreInc);
-BENCHMARK(BM_decimalCounterPostInc);
-BENCHMARK(BM_ItoACounter);
-BENCHMARK(BM_to_stringCounter);
+BENCHMARK(BM_decimalCounterPreInc)->Arg(10000);
+BENCHMARK(BM_decimalCounterPostInc)->Arg(10000);
+BENCHMARK(BM_ItoACounter)->Arg(10000);
+BENCHMARK(BM_to_stringCounter)->Arg(10000);
 
 }  // namespace mongo