Fixed potential torn reads in EventCounters (#26630)

Author: gfoidl

src/Hosting/Hosting/src/Internal/HostingEventSource.cs

@@ -87,23 +87,23 @@ protected override void OnEventCommand(EventCommandEventArgs command)
                 // This is the convention for initializing counters in the RuntimeEventSource (lazily on the first enable command).
                 // They aren't disabled afterwards...
 
-                _requestsPerSecondCounter ??= new IncrementingPollingCounter("requests-per-second", this, () => _totalRequests)
+                _requestsPerSecondCounter ??= new IncrementingPollingCounter("requests-per-second", this, () => Volatile.Read(ref _totalRequests))
                 {
                     DisplayName = "Request Rate",
                     DisplayRateTimeScale = TimeSpan.FromSeconds(1)
                 };
 
-                _totalRequestsCounter ??= new PollingCounter("total-requests", this, () => _totalRequests)
+                _totalRequestsCounter ??= new PollingCounter("total-requests", this, () => Volatile.Read(ref _totalRequests))
                 {
                     DisplayName = "Total Requests",
                 };
 
-                _currentRequestsCounter ??= new PollingCounter("current-requests", this, () => _currentRequests)
+                _currentRequestsCounter ??= new PollingCounter("current-requests", this, () => Volatile.Read(ref _currentRequests))
                 {
                     DisplayName = "Current Requests"
                 };
 
-                _failedRequestsCounter ??= new PollingCounter("failed-requests", this, () => _failedRequests)
+                _failedRequestsCounter ??= new PollingCounter("failed-requests", this, () => Volatile.Read(ref _failedRequests))
                 {
                     DisplayName = "Failed Requests"
                 };

src/Middleware/ConcurrencyLimiter/src/ConcurrencyLimiterEventSource.cs

@@ -87,12 +87,12 @@ protected override void OnEventCommand(EventCommandEventArgs command)
         {
             if (command.Command == EventCommand.Enable)
             {
-                _rejectedRequestsCounter ??= new PollingCounter("requests-rejected", this, () => _rejectedRequests)
+                _rejectedRequestsCounter ??= new PollingCounter("requests-rejected", this, () => Volatile.Read(ref _rejectedRequests))
                 {
                     DisplayName = "Rejected Requests",
                 };
 
-                _queueLengthCounter ??= new PollingCounter("queue-length", this, () => _queueLength)
+                _queueLengthCounter ??= new PollingCounter("queue-length", this, () => Volatile.Read(ref _queueLength))
                 {
                     DisplayName = "Queue Length",
                 };

src/Servers/Kestrel/Core/src/Internal/Infrastructure/KestrelEventSource.cs

@@ -318,54 +318,54 @@ protected override void OnEventCommand(EventCommandEventArgs command)
                 // This is the convention for initializing counters in the RuntimeEventSource (lazily on the first enable command).
                 // They aren't disabled afterwards...
 
-                _connectionsPerSecondCounter ??= new IncrementingPollingCounter("connections-per-second", this, () => _totalConnections)
+                _connectionsPerSecondCounter ??= new IncrementingPollingCounter("connections-per-second", this, () => Volatile.Read(ref _totalConnections))
                 {
                     DisplayName = "Connection Rate",
                     DisplayRateTimeScale = TimeSpan.FromSeconds(1)
                 };
 
-                _totalConnectionsCounter ??= new PollingCounter("total-connections", this, () => _totalConnections)
+                _totalConnectionsCounter ??= new PollingCounter("total-connections", this, () => Volatile.Read(ref _totalConnections))
                 {
                     DisplayName = "Total Connections",
                 };
 
-                _tlsHandshakesPerSecondCounter ??= new IncrementingPollingCounter("tls-handshakes-per-second", this, () => _totalTlsHandshakes)
+                _tlsHandshakesPerSecondCounter ??= new IncrementingPollingCounter("tls-handshakes-per-second", this, () => Volatile.Read(ref _totalTlsHandshakes))
                 {
                     DisplayName = "TLS Handshake Rate",
                     DisplayRateTimeScale = TimeSpan.FromSeconds(1)
                 };
 
-                _totalTlsHandshakesCounter ??= new PollingCounter("total-tls-handshakes", this, () => _totalTlsHandshakes)
+                _totalTlsHandshakesCounter ??= new PollingCounter("total-tls-handshakes", this, () => Volatile.Read(ref _totalTlsHandshakes))
                 {
                     DisplayName = "Total TLS Handshakes",
                 };
 
-                _currentTlsHandshakesCounter ??= new PollingCounter("current-tls-handshakes", this, () => _currentTlsHandshakes)
+                _currentTlsHandshakesCounter ??= new PollingCounter("current-tls-handshakes", this, () => Volatile.Read(ref _currentTlsHandshakes))
                 {
                     DisplayName = "Current TLS Handshakes"
                 };
 
-                _failedTlsHandshakesCounter ??= new PollingCounter("failed-tls-handshakes", this, () => _failedTlsHandshakes)
+                _failedTlsHandshakesCounter ??= new PollingCounter("failed-tls-handshakes", this, () => Volatile.Read(ref _failedTlsHandshakes))
                 {
                     DisplayName = "Failed TLS Handshakes"
                 };
 
-                _currentConnectionsCounter ??= new PollingCounter("current-connections", this, () => _currentConnections)
+                _currentConnectionsCounter ??= new PollingCounter("current-connections", this, () => Volatile.Read(ref _currentConnections))
                 {
                     DisplayName = "Current Connections"
                 };
 
-                _connectionQueueLengthCounter ??= new PollingCounter("connection-queue-length", this, () => _connectionQueueLength)
+                _connectionQueueLengthCounter ??= new PollingCounter("connection-queue-length", this, () => Volatile.Read(ref _connectionQueueLength))
                 {
                     DisplayName = "Connection Queue Length"
                 };
 
-                _httpRequestQueueLengthCounter ??= new PollingCounter("request-queue-length", this, () => _httpRequestQueueLength)
+                _httpRequestQueueLengthCounter ??= new PollingCounter("request-queue-length", this, () => Volatile.Read(ref _httpRequestQueueLength))
                 {
                     DisplayName = "Request Queue Length"
                 };
 
-                _currrentUpgradedHttpRequestsCounter ??= new PollingCounter("current-upgraded-requests", this, () => _currentUpgradedHttpRequests)
+                _currrentUpgradedHttpRequestsCounter ??= new PollingCounter("current-upgraded-requests", this, () => Volatile.Read(ref _currentUpgradedHttpRequests))
                 {
                     DisplayName = "Current Upgraded Requests (WebSockets)"
                 };

src/SignalR/common/Http.Connections/src/Internal/HttpConnectionsEventSource.cs

@@ -90,19 +90,19 @@ protected override void OnEventCommand(EventCommandEventArgs command)
                 // This is the convention for initializing counters in the RuntimeEventSource (lazily on the first enable command).
                 // They aren't disabled afterwards...
 
-                _connectionsStartedCounter ??= new PollingCounter("connections-started", this, () => _connectionsStarted)
+                _connectionsStartedCounter ??= new PollingCounter("connections-started", this, () => Volatile.Read(ref _connectionsStarted))
                 {
                     DisplayName = "Total Connections Started",
                 };
-                _connectionsStoppedCounter ??= new PollingCounter("connections-stopped", this, () => _connectionsStopped)
+                _connectionsStoppedCounter ??= new PollingCounter("connections-stopped", this, () => Volatile.Read(ref _connectionsStopped))
                 {
                     DisplayName = "Total Connections Stopped",
                 };
-                _connectionsTimedOutCounter ??= new PollingCounter("connections-timed-out", this, () => _connectionsTimedOut)
+                _connectionsTimedOutCounter ??= new PollingCounter("connections-timed-out", this, () => Volatile.Read(ref _connectionsTimedOut))
                 {
                     DisplayName = "Total Connections Timed Out",
                 };
-                _currentConnectionsCounter ??= new PollingCounter("current-connections", this, () => _currentConnections)
+                _currentConnectionsCounter ??= new PollingCounter("current-connections", this, () => Volatile.Read(ref _currentConnections))
                 {
                     DisplayName = "Current Connections",
                 };