SERVER-117685 Create an RAII type to track action duration and report metrics in server status (#46846)

Co-authored-by: Ruby Chen <ruby.chen@mongodb.com>
GitOrigin-RevId: b043b27169fad80917105a98f10fd2ebbe734796

.github/CODEOWNERS

@@ -1962,6 +1962,7 @@ WORKSPACE.bazel @10gen/devprod-build @svc-auto-approve-bot
 /src/mongo/db/**/compact_structured* @10gen/server-catalog-and-routing-ddl @10gen/server-security @svc-auto-approve-bot
 /src/mongo/db/**/partitioned* @10gen/server-programmability @svc-auto-approve-bot
 /src/mongo/db/**/logical_session_cache_factory_mongod* @10gen/server-transactions @svc-auto-approve-bot
+/src/mongo/db/**/action_duration_metrics* @10gen/server-storage-engine-integration @svc-auto-approve-bot
 
 # The following patterns are parsed from ./src/mongo/db/admission/OWNERS.yml
 /src/mongo/db/admission/**/* @10gen/server-workload-resilience @svc-auto-approve-bot

modules_poc/modules.yaml

@@ -851,6 +851,7 @@ storage_engine_integration:
     fully_marked: true
   files:
     - src/mongo/db/storage # excluding ./key_string, ./wiredtiger, ./devnull, some of ./kv
+    - src/mongo/db/action_duration_metrics*
     - src/mongo/db/record_id*
     - src/mongo/db/server_recovery*
     - src/mongo/db/mongod_options_storage*

src/mongo/db/BUILD.bazel

@@ -3545,3 +3545,26 @@ mongo_cc_library(
         "//src/mongo/db/validate:validate_state",
     ],
 )
+
+mongo_cc_library(
+    name = "action_duration_metrics",
+    srcs = [
+        "action_duration_metrics.cpp",
+    ],
+    deps = [
+        "//src/mongo/db/commands/server_status:server_status_core",
+    ],
+)
+
+mongo_cc_unit_test(
+    name = "action_duration_metrics_test",
+    srcs = [
+        "action_duration_metrics_test.cpp",
+    ],
+    tags = ["mongo_unittest_fourth_group"],
+    deps = [
+        "action_duration_metrics",
+        "//src/mongo/db:service_context_test_fixture",
+        "//src/mongo/unittest",
+    ],
+)

src/mongo/db/OWNERS.yml

@@ -346,3 +346,6 @@ filters:
   - "logical_session_cache_factory_mongod*":
     approvers:
       - 10gen/server-transactions
+  - "action_duration_metrics*":
+    approvers:
+      - 10gen/server-storage-engine-integration

src/mongo/db/action_duration_metrics.cpp

@@ -0,0 +1,92 @@
+/**
+ *    Copyright (C) 2026-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/action_duration_metrics.h"
+
+#include "mongo/db/commands/server_status/server_status.h"
+
+namespace mongo {
+
+namespace {
+
+const auto getActionDurationMetrics = ServiceContext::declareDecoration<ActionDurationMetrics>();
+
+class ActionDurationServerStatus : public ServerStatusSection {
+public:
+    using ServerStatusSection::ServerStatusSection;
+
+    bool includeByDefault() const final {
+        return true;
+    }
+
+    BSONObj generateSection(OperationContext* opCtx, const BSONElement& configElement) const final {
+        BSONObjBuilder b;
+        getActionDurationMetrics(opCtx->getServiceContext()).report(&b);
+        return b.obj();
+    }
+};
+
+auto& actionDurationServerStatus =
+    *ServerStatusSectionBuilder<ActionDurationServerStatus>("actionDuration")
+         .forShard()
+         .forRouter();
+
+}  // namespace
+
+const ActionDurationMetrics& ActionDurationMetrics::getDecoration(ServiceContext* serviceContext) {
+    return getActionDurationMetrics(serviceContext);
+}
+
+void ActionDurationMetrics::record(const std::string& action, Milliseconds millis) {
+    stdx::lock_guard lk(_mutex);
+    auto& entry = _entries[action];
+    entry.last = millis;
+    entry.total += millis;
+    entry.count++;
+}
+
+void ActionDurationMetrics::report(BSONObjBuilder* builder) const {
+    stdx::lock_guard lk(_mutex);
+    for (const auto& [action, entry] : _entries) {
+        BSONObjBuilder sub(builder->subobjStart(action));
+        sub.append("lastDurationMillis", durationCount<Milliseconds>(entry.last));
+        sub.append("totalDurationMillis", durationCount<Milliseconds>(entry.total));
+        sub.append("count", entry.count);
+    }
+}
+
+ActionDurationTimer::ActionDurationTimer(OperationContext* opCtx, std::string action)
+    : _opCtx(opCtx), _action(std::move(action)), _start(opCtx->fastClockSource().now()) {}
+
+ActionDurationTimer::~ActionDurationTimer() {
+    Milliseconds duration = _opCtx->fastClockSource().now() - _start;
+    getActionDurationMetrics(_opCtx->getServiceContext()).record(_action, duration);
+}
+
+}  // namespace mongo

src/mongo/db/action_duration_metrics.h

@@ -0,0 +1,91 @@
+/**
+ *    Copyright (C) 2026-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.
+ */
+
+#pragma once
+
+#include "mongo/bson/bsonobjbuilder.h"
+#include "mongo/db/service_context.h"
+#include "mongo/stdx/mutex.h"
+#include "mongo/util/time_support.h"
+
+#include <cstdint>
+#include <map>
+#include <string>
+
+namespace mongo {
+
+/**
+ * Tracks per-action duration metrics.
+ *
+ * This is a ServiceContext decoration.
+ */
+class ActionDurationMetrics {
+public:
+    struct Entry {
+        Milliseconds last{0};
+        Milliseconds total{0};
+        int64_t count{0};
+    };
+
+    static const ActionDurationMetrics& getDecoration(ServiceContext* serviceContext);
+
+    void record(const std::string& action, Milliseconds millis);
+
+    void report(BSONObjBuilder* builder) const;
+
+private:
+    mutable stdx::mutex _mutex;
+
+    // Use an ordered map to prevent schema changes in FTDC.
+    std::map<std::string, Entry> _entries;
+};
+
+/**
+ * RAII helper that measures the duration of a named action and records it into the
+ * ActionDurationMetrics decoration.
+ */
+class ActionDurationTimer {
+public:
+    ActionDurationTimer(const ActionDurationTimer&) = delete;
+    ActionDurationTimer& operator=(const ActionDurationTimer&) = delete;
+    ActionDurationTimer(ActionDurationTimer&&) = delete;
+    ActionDurationTimer& operator=(ActionDurationTimer&&) = delete;
+
+    // Caller is responsible for using the RAII within the OperationContext lifetime.
+    ActionDurationTimer(OperationContext* opCtx, std::string action);
+
+    ~ActionDurationTimer();
+
+private:
+    OperationContext* _opCtx;
+    std::string _action;
+    Date_t _start;
+};
+
+}  // namespace mongo

src/mongo/db/action_duration_metrics_test.cpp

@@ -0,0 +1,92 @@
+/**
+ *    Copyright (C) 2026-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/action_duration_metrics.h"
+
+#include "mongo/db/service_context_test_fixture.h"
+#include "mongo/util/clock_source_mock.h"
+
+
+namespace mongo {
+namespace {
+
+class ActionDurationMetricsTest : public ClockSourceMockServiceContextTest {
+public:
+    void advanceTime(Milliseconds m) {
+        static_cast<ClockSourceMock*>(getServiceContext()->getFastClockSource())->advance(m);
+    }
+
+    void assertCounts(const ActionDurationMetrics& metrics,
+                      const std::string& action,
+                      Milliseconds lastDuration,
+                      Milliseconds totalDuration,
+                      int64_t count) {
+        BSONObjBuilder builder;
+        metrics.report(&builder);
+
+        BSONObj obj = builder.obj();
+        BSONObj actionObj = obj.getObjectField(action);
+
+        ASSERT_EQ(lastDuration.count(), actionObj.getField("lastDurationMillis").numberLong());
+        ASSERT_EQ(totalDuration.count(), actionObj.getField("totalDurationMillis").numberLong());
+        ASSERT_EQ(count, actionObj.getField("count").numberLong());
+    }
+};
+
+TEST_F(ActionDurationMetricsTest, ActionDurationTimer) {
+    auto opCtx = makeOperationContext();
+    const ActionDurationMetrics& metrics =
+        ActionDurationMetrics::getDecoration(opCtx->getServiceContext());
+    const std::string action = "TimerTest";
+
+    {
+        ActionDurationTimer actionTimer(opCtx.get(), action);
+        advanceTime(Milliseconds(10));
+
+        // Metrics are only advanced when the RAII type is destructed.
+        assertCounts(metrics, action, Milliseconds(0), Milliseconds(0), 0);
+    }
+
+    assertCounts(metrics, action, Milliseconds(10), Milliseconds(10), 1);
+
+    // Advancing time while there's no RAII type in scope has no effect.
+    advanceTime(Milliseconds(1000));
+    assertCounts(metrics, action, Milliseconds(10), Milliseconds(10), 1);
+
+    {
+        ActionDurationTimer actionTimer(opCtx.get(), action);
+        advanceTime(Milliseconds(25));
+        assertCounts(metrics, action, Milliseconds(10), Milliseconds(10), 1);
+    }
+
+    assertCounts(metrics, action, Milliseconds(25), Milliseconds(35), 2);
+}
+
+}  // namespace
+}  // namespace mongo