SERVER-67644 fix racy std::string metric

1 files changed, 95 insertions, 0 deletions

diff --git a/src/mongo/db/commands/server_status_metric_test.cpp b/src/mongo/db/commands/server_status_metric_test.cpp
new file mode 100644
index 00000000000..6de4042226b
--- /dev/null
+++ b/src/mongo/db/commands/server_status_metric_test.cpp
@@ -0,0 +1,95 @@
+/**
+ *    Copyright (C) 2022-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    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
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    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 Server Side 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/db/commands/server_status_metric.h"
+
+#include "mongo/bson/bsonelement.h"
+#include "mongo/bson/bsonobj.h"
+#include "mongo/bson/bsonobjbuilder.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo {
+namespace {
+
+class MetricTreeTest : public unittest::Test {
+protected:
+    MetricTree* tree() const {
+        return _tree.get();
+    }
+
+    BSONObj metrics() {
+        BSONObjBuilder builder;
+        tree()->appendTo(builder);
+        return builder.obj();
+    }
+
+    std::unique_ptr<MetricTree> _tree = std::make_unique<MetricTree>();
+};
+
+TEST_F(MetricTreeTest, ValidateCounterMetric) {
+    auto& counter =
+        addMetricToTree(std::make_unique<ServerStatusMetricField<Counter64>>("tree.counter"),
+                        tree())
+            .value();
+
+    counter.increment();
+    const auto firstMetrics = metrics();
+    BSONElement counterElement = firstMetrics["metrics"]["tree"]["counter"];
+    ASSERT(counterElement.isNumber());
+    ASSERT_EQ(counterElement.numberInt(), counter.get());
+
+    counter.increment(2);
+
+    const auto secondMetrics = metrics();
+    BSONElement anotherCounterElement = secondMetrics["metrics"]["tree"]["counter"];
+    ASSERT(anotherCounterElement.isNumber());
+    ASSERT_EQ(anotherCounterElement.numberInt(), counter.get());
+}
+
+TEST_F(MetricTreeTest, ValidateTextMetric) {
+    auto& text =
+        addMetricToTree(std::make_unique<ServerStatusMetricField<std::string>>("tree.text"), tree())
+            .value();
+
+    text = "hello";
+
+    auto firstMetrics = metrics();
+    BSONElement textElement = firstMetrics["metrics"]["tree"]["text"];
+    ASSERT_EQ(textElement.type(), BSONType::String);
+    ASSERT_EQ(textElement.String(), text);
+
+    text = "bye";
+
+    auto secondMetrics = metrics();
+    BSONElement anotherTextElement = secondMetrics["metrics"]["tree"]["text"];
+    ASSERT_EQ(anotherTextElement.type(), BSONType::String);
+    ASSERT_EQ(anotherTextElement.String(), text);
+}
+}  // namespace
+}  // namespace mongo