From a40f200c0aaf530a2a240c3d71f6c6c13df7fdcc Mon Sep 17 00:00:00 2001
From: Olivier Bellone <ob@stripe.com>
Date: Thu, 29 Aug 2019 11:25:06 -0700
Subject: [PATCH] Add EnableTelemetry flag

---
 .../Public/StripeConfiguration.cs             | 23 ++++++++++++++-
 .../Public/SystemNetHttpClient.cs             | 19 +++++++++++--
 src/StripeTests/Functional/TelemetryTest.cs   | 28 +++++++++++++++++++
 3 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/src/Stripe.net/Infrastructure/Public/StripeConfiguration.cs b/src/Stripe.net/Infrastructure/Public/StripeConfiguration.cs
index 7f426b85fa..ffd6b5d44f 100644
--- a/src/Stripe.net/Infrastructure/Public/StripeConfiguration.cs
+++ b/src/Stripe.net/Infrastructure/Public/StripeConfiguration.cs
@@ -20,6 +20,8 @@ public static class StripeConfiguration
 
         private static string clientId;
 
+        private static bool enableTelemetry = true;
+
         private static int maxNetworkRetries;
 
         private static IStripeClient stripeClient;
@@ -129,6 +131,24 @@ public static int MaxNetworkRetries
             }
         }
 
+        /// <summary>
+        /// Gets or sets the flag enabling request latency telemetry. Enabled by default.
+        /// </summary>
+        public static bool EnableTelemetry
+        {
+            get => enableTelemetry;
+
+            set
+            {
+                if (value != enableTelemetry)
+                {
+                    StripeClient = null;
+                }
+
+                enableTelemetry = value;
+            }
+        }
+
         /// <summary>
         /// Gets or sets a custom <see cref="StripeClient"/> for sending requests to Stripe's
         /// API. You can use this to use a custom message handler, set proxy parameters, etc.
@@ -239,7 +259,8 @@ private static StripeClient BuildDefaultStripeClient()
             var httpClient = new SystemNetHttpClient(
                 httpClient: null,
                 maxNetworkRetries: MaxNetworkRetries,
-                appInfo: AppInfo);
+                appInfo: AppInfo,
+                enableTelemetry: EnableTelemetry);
             return new StripeClient(ApiKey, ClientId, httpClient: httpClient);
         }
     }
diff --git a/src/Stripe.net/Infrastructure/Public/SystemNetHttpClient.cs b/src/Stripe.net/Infrastructure/Public/SystemNetHttpClient.cs
index 4d97042a90..2afba60213 100644
--- a/src/Stripe.net/Infrastructure/Public/SystemNetHttpClient.cs
+++ b/src/Stripe.net/Infrastructure/Public/SystemNetHttpClient.cs
@@ -25,6 +25,8 @@ public class SystemNetHttpClient : IHttpClient
 
         private readonly AppInfo appInfo;
 
+        private readonly bool enableTelemetry;
+
         private readonly RequestTelemetry requestTelemetry = new RequestTelemetry();
 
         private readonly object randLock = new object();
@@ -50,10 +52,14 @@ public class SystemNetHttpClient : IHttpClient
         /// Information about the "app" which this integration belongs to. This should be reserved
         /// for plugins that wish to identify themselves with Stripe.
         /// </param>
+        /// <param name="enableTelemetry">
+        /// Whether to enable request latency telemetry or not.
+        /// </param>
         public SystemNetHttpClient(
             System.Net.Http.HttpClient httpClient = null,
             int maxNetworkRetries = 0,
-            AppInfo appInfo = null)
+            AppInfo appInfo = null,
+            bool enableTelemetry = true)
         {
 #if NET45
             // With .NET Framework 4.5, it's necessary to manually enable support for TLS 1.2.
@@ -64,6 +70,7 @@ public SystemNetHttpClient(
             this.httpClient = httpClient ?? BuildDefaultSystemNetHttpClient();
             this.maxNetworkRetries = maxNetworkRetries;
             this.appInfo = appInfo;
+            this.enableTelemetry = enableTelemetry;
 
             this.stripeClientUserAgentString = this.BuildStripeClientUserAgentString();
             this.userAgentString = this.BuildUserAgentString();
@@ -118,7 +125,10 @@ public async Task<StripeResponse> MakeRequestAsync(
             HttpResponseMessage response = null;
             int retry = 0;
 
-            this.requestTelemetry.MaybeAddTelemetryHeader(request.StripeHeaders);
+            if (this.enableTelemetry)
+            {
+                this.requestTelemetry.MaybeAddTelemetryHeader(request.StripeHeaders);
+            }
 
             while (true)
             {
@@ -165,7 +175,10 @@ public async Task<StripeResponse> MakeRequestAsync(
                 throw requestException;
             }
 
-            this.requestTelemetry.MaybeEnqueueMetrics(response, duration);
+            if (this.enableTelemetry)
+            {
+                this.requestTelemetry.MaybeEnqueueMetrics(response, duration);
+            }
 
             var reader = new StreamReader(
                 await response.Content.ReadAsStreamAsync().ConfigureAwait(false));
diff --git a/src/StripeTests/Functional/TelemetryTest.cs b/src/StripeTests/Functional/TelemetryTest.cs
index 1920430490..d1775d0070 100644
--- a/src/StripeTests/Functional/TelemetryTest.cs
+++ b/src/StripeTests/Functional/TelemetryTest.cs
@@ -111,6 +111,34 @@ public async Task TelemetryWorksWithConcurrentRequests()
                     ItExpr.IsAny<CancellationToken>());
         }
 
+        [Fact]
+        public void NoTelemetryWhenDisabled()
+        {
+            var mockHandler = new Mock<HttpClientHandler> { CallBase = true };
+            var httpClient = new SystemNetHttpClient(
+                new System.Net.Http.HttpClient(mockHandler.Object),
+                enableTelemetry: false);
+            var stripeClient = new StripeClient("sk_test_123", httpClient: httpClient);
+
+            mockHandler.Reset();
+            var fakeServer = FakeServer.ForMockHandler(mockHandler);
+            fakeServer.Delay = TimeSpan.FromMilliseconds(20);
+
+            var service = new BalanceService(stripeClient);
+            service.Get();
+            fakeServer.Delay = TimeSpan.FromMilliseconds(40);
+            service.Get();
+            service.Get();
+
+            mockHandler.Protected()
+                .Verify(
+                    "SendAsync",
+                    Times.Exactly(3),
+                    ItExpr.Is<HttpRequestMessage>(m =>
+                        !m.Headers.Contains("X-Stripe-Client-Telemetry")),
+                    ItExpr.IsAny<CancellationToken>());
+        }
+
         private static bool TelemetryHeaderMatcher(
             HttpHeaders headers,
             Func<string, bool> requestIdMatcher,