SERVER-36108 speed up BSONArrayBuilder by counting in decimal

1 files changed, 52 insertions, 0 deletions

diff --git a/src/mongo/bson/bsonobjbuilder_bm.cpp b/src/mongo/bson/bsonobjbuilder_bm.cpp
new file mode 100644
index 00000000000..53410f72615
--- /dev/null
+++ b/src/mongo/bson/bsonobjbuilder_bm.cpp
@@ -0,0 +1,52 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include <benchmark/benchmark.h>
+
+#include "mongo/bson/bsonobjbuilder.h"
+
+namespace mongo {
+
+void BM_arrayBuilder(benchmark::State& state) {
+    size_t totalBytes = 0;
+    for (auto _ : state) {
+        benchmark::ClobberMemory();
+        BSONArrayBuilder array;
+        for (auto j = 0; j < state.range(0); j++)
+            array.append(j);
+        totalBytes += array.len();
+        benchmark::DoNotOptimize(array.done());
+    }
+    state.SetBytesProcessed(totalBytes);
+}
+
+BENCHMARK(BM_arrayBuilder)->Ranges({{{1}, {100'000}}});
+
+}  // namespace mongo