Make OpenAITelemetryPlugin record report metrics only if 'recording' is on

DevProxy.Abstractions/Plugins/BasePlugin.cs

@@ -55,6 +55,11 @@ public virtual Task AfterRequestLogAsync(RequestLogArgs e, CancellationToken can
         return Task.CompletedTask;
     }
 
+    public virtual Task AfterRecordingStartAsync(EventArgs e, CancellationToken cancellationToken)
+    {
+        return Task.CompletedTask;
+    }
+
     public virtual Task AfterRecordingStopAsync(RecordingArgs e, CancellationToken cancellationToken)
     {
         return Task.CompletedTask;

DevProxy.Abstractions/Plugins/IPlugin.cs

@@ -22,6 +22,7 @@ public interface IPlugin
     Task BeforeResponseAsync(ProxyResponseArgs e, CancellationToken cancellationToken);
     Task AfterResponseAsync(ProxyResponseArgs e, CancellationToken cancellationToken);
     Task AfterRequestLogAsync(RequestLogArgs e, CancellationToken cancellationToken);
+    Task AfterRecordingStartAsync(EventArgs e, CancellationToken cancellationToken);
     Task AfterRecordingStopAsync(RecordingArgs e, CancellationToken cancellationToken);
     Task MockRequestAsync(EventArgs e, CancellationToken cancellationToken);
 }

DevProxy.Plugins/Inspection/OpenAITelemetryPlugin.cs

@@ -67,7 +67,9 @@ public sealed class OpenAITelemetryPlugin(
     private LanguageModelPricesLoader? _loader;
     private MeterProvider? _meterProvider;
     private TracerProvider? _tracerProvider;
+
     private readonly ConcurrentDictionary<string, List<OpenAITelemetryPluginReportModelUsageInformation>> _modelUsage = [];
+    private bool _isRecording;
 
     public override string Name => nameof(OpenAITelemetryPlugin);
 
@@ -192,6 +194,16 @@ public override Task AfterResponseAsync(ProxyResponseArgs e, CancellationToken c
         return Task.CompletedTask;
     }
 
+    public override Task AfterRecordingStartAsync(EventArgs e, CancellationToken cancellationToken)
+    {
+        Logger.LogTrace("{Method} called", nameof(AfterRecordingStartAsync));
+
+        _isRecording = true;
+
+        Logger.LogTrace("Left {Name}", nameof(AfterRecordingStartAsync));
+        return Task.CompletedTask;
+    }
+
     public override Task AfterRecordingStopAsync(RecordingArgs e, CancellationToken cancellationToken)
     {
         Logger.LogTrace("{Method} called", nameof(AfterRecordingStopAsync));
@@ -206,6 +218,7 @@ public override Task AfterRecordingStopAsync(RecordingArgs e, CancellationToken
         };
 
         StoreReport(report, e);
+        _isRecording = false;
         _modelUsage.Clear();
 
         Logger.LogTrace("Left {Name}", nameof(AfterRecordingStopAsync));
@@ -856,8 +869,12 @@ private void RecordUsageMetrics(Activity activity, OpenAIRequest request, OpenAI
             CompletionTokens = usage.CompletionTokens,
             CachedTokens = usage.PromptTokensDetails?.CachedTokens ?? 0L
         };
-        var usagePerModel = _modelUsage.GetOrAdd(response.Model, model => []);
-        usagePerModel.Add(reportModelUsageInformation);
+
+        if (_isRecording)
+        {
+            var usagePerModel = _modelUsage.GetOrAdd(response.Model, model => []);
+            usagePerModel.Add(reportModelUsageInformation);
+        }
 
         if (!Configuration.IncludeCosts || Configuration.Prices is null)
         {

DevProxy/ApiControllers/ProxyController.cs

@@ -42,7 +42,7 @@ public async Task<IActionResult> SetAsync([FromBody] ProxyInfo proxyInfo, Cancel
         {
             if (proxyInfo.Recording.Value)
             {
-                _proxyStateController.StartRecording();
+                await _proxyStateController.StartRecordingAsync(cancellationToken);
             }
             else
             {

DevProxy/Proxy/IProxyStateController.cs

@@ -9,7 +9,7 @@ public interface IProxyStateController
 #pragma warning restore CA1515
 {
     IProxyState ProxyState { get; }
-    void StartRecording();
+    Task StartRecordingAsync(CancellationToken cancellationToken);
     Task StopRecordingAsync(CancellationToken cancellationToken);
     Task MockRequestAsync(CancellationToken cancellationToken);
     void StopProxy();

DevProxy/Proxy/ProxyEngine.cs

@@ -147,7 +147,7 @@ protected override async Task ExecuteAsync(CancellationToken stoppingToken)
 
         if (_config.Record)
         {
-            StartRecording();
+            await StartRecordingAsync(stoppingToken);
         }
 
         if (_config.TimeoutSeconds.HasValue)
@@ -210,7 +210,7 @@ private async Task ReadKeysAsync(CancellationToken cancellationToken)
 #pragma warning restore IDE0010
         {
             case ConsoleKey.R:
-                StartRecording();
+                await StartRecordingAsync(cancellationToken);
                 break;
             case ConsoleKey.S:
                 await StopRecordingAsync(cancellationToken);
@@ -225,14 +225,14 @@ private async Task ReadKeysAsync(CancellationToken cancellationToken)
         }
     }
 
-    private void StartRecording()
+    private async Task StartRecordingAsync(CancellationToken cancellationToken)
     {
         if (_proxyController.ProxyState.IsRecording)
         {
             return;
         }
 
-        _proxyController.StartRecording();
+        await _proxyController.StartRecordingAsync(cancellationToken);
     }
 
     private async Task StopRecordingAsync(CancellationToken cancellationToken)

DevProxy/Proxy/ProxyStateController.cs

@@ -23,7 +23,7 @@ sealed class ProxyStateController(
     private readonly ILogger _logger = logger;
     private ExceptionHandler ExceptionHandler => ex => _logger.LogError(ex, "An error occurred in a plugin");
 
-    public void StartRecording()
+    public async Task StartRecordingAsync(CancellationToken cancellationToken)
     {
         if (ProxyState.IsRecording)
         {
@@ -32,6 +32,19 @@ public void StartRecording()
 
         ProxyState.IsRecording = true;
         PrintRecordingIndicator(ProxyState.IsRecording);
+
+        var eventArgs = EventArgs.Empty;
+        foreach (var plugin in _plugins.Where(p => p.Enabled))
+        {
+            try
+            {
+                await plugin.AfterRecordingStartAsync(eventArgs, cancellationToken);
+            }
+            catch (Exception ex)
+            {
+                ExceptionHandler(ex);
+            }
+        }
     }
 
     public async Task StopRecordingAsync(CancellationToken cancellationToken)
@@ -69,7 +82,7 @@ public async Task StopRecordingAsync(CancellationToken cancellationToken)
 
     public async Task MockRequestAsync(CancellationToken cancellationToken)
     {
-        var eventArgs = new EventArgs();
+        var eventArgs = EventArgs.Empty;
 
         foreach (var plugin in _plugins.Where(p => p.Enabled))
         {