From 4ff409eee68689f265fccbcdebcf71a4aa85930f Mon Sep 17 00:00:00 2001
From: James H <james.harrison@mongodb.com>
Date: Tue, 21 Oct 2025 17:04:55 +0100
Subject: [PATCH] SERVER-112103: Record start time only on start (#42346)

GitOrigin-RevId: 9d290e656ae8b700fae52b5bdd1ce40e0e76a0d4
---
 src/mongo/db/traffic_recorder.cpp | 14 +++++++-------
 src/mongo/db/traffic_recorder.h   |  6 ++++--
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/src/mongo/db/traffic_recorder.cpp b/src/mongo/db/traffic_recorder.cpp
index 4358d1964c5..373390a855f 100644
--- a/src/mongo/db/traffic_recorder.cpp
+++ b/src/mongo/db/traffic_recorder.cpp
@@ -92,22 +92,22 @@ void appendPacketHeader(DataBuilder& db, const TrafficRecordingPacket& packet) {
 
 TrafficRecorder::Recording::Recording(const StartTrafficRecording& options, TickSource* tickSource)
     : _path(_getPath(std::string{options.getDestination()})),
-      _maxLogSize(options.getMaxFileSize()) {
+      _maxLogSize(options.getMaxFileSize()),
+      _tickSource(tickSource) {
 
     MultiProducerSingleConsumerQueue<TrafficRecordingPacket, CostFunction>::Options queueOptions;
     queueOptions.maxQueueDepth = options.getMaxMemUsage();
     _pcqPipe =
         MultiProducerSingleConsumerQueue<TrafficRecordingPacket, CostFunction>::Pipe(queueOptions);
 
-    _trafficStats.setRunning(true);
     _trafficStats.setBufferSize(options.getMaxMemUsage());
     _trafficStats.setRecordingDir(_path);
     _trafficStats.setMaxFileSize(_maxLogSize);
-
-    startTime.store(tickSource->ticksTo<Microseconds>(tickSource->getTicks()));
 }
 
-void TrafficRecorder::Recording::run() {
+void TrafficRecorder::Recording::start() {
+    _trafficStats.setRunning(true);
+    startTime.store(_tickSource->ticksTo<Microseconds>(_tickSource->getTicks()));
     _thread = stdx::thread([consumer = std::move(_pcqPipe.consumer), this] {
         if (!boost::filesystem::is_directory(boost::filesystem::absolute(_path))) {
             boost::filesystem::create_directory(boost::filesystem::absolute(_path));
@@ -302,7 +302,7 @@ void TrafficRecorder::start(const StartTrafficRecording& options, ServiceContext
         uassert(ErrorCodes::BadValue, "Traffic recording already active", !*rec);
         *rec = _makeRecording(options, svcCtx->getTickSource());
 
-        (*rec)->run();
+        (*rec)->start();
     }
 
     _shouldRecord.store(true);
@@ -436,7 +436,7 @@ TrafficRecorderForTest::RecordingForTest::getPcqPipe() {
     return _pcqPipe;
 }
 
-void TrafficRecorderForTest::RecordingForTest::run() {
+void TrafficRecorderForTest::RecordingForTest::start() {
     // No-op for tests
 }
 
diff --git a/src/mongo/db/traffic_recorder.h b/src/mongo/db/traffic_recorder.h
index 492db966f48..8bf0cb714aa 100644
--- a/src/mongo/db/traffic_recorder.h
+++ b/src/mongo/db/traffic_recorder.h
@@ -119,7 +119,7 @@ protected:
         Recording(const StartTrafficRecording& options, TickSource* tickSource);
         virtual ~Recording() = default;
 
-        virtual void run();
+        virtual void start();
         virtual Status shutdown();
 
         /**
@@ -154,6 +154,8 @@ protected:
         const std::string _path;
         const int64_t _maxLogSize;
 
+        TickSource* _tickSource;
+
         stdx::thread _thread;
 
         stdx::mutex _mutex;
@@ -189,7 +191,7 @@ public:
                                          TrafficRecorder::Recording::CostFunction>::Pipe&
         getPcqPipe();
 
-        void run() override;
+        void start() override;
 
         Status shutdown() override;
     };