Retry on failure to flush to the API

Author: bmermet

src/Datadog.Tracer.Tests/ApiTests.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Net;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Datadog.Tracer.Tests
+{
+    public class SetResponseHandler : DelegatingHandler
+    {
+        private HttpResponseMessage _response;
+        public int RequestsCount { get; set; }
+
+        public SetResponseHandler(HttpResponseMessage response)
+        {
+            _response = response;
+        }
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            RequestsCount++;
+            return Task.FromResult(_response);
+        }
+    }
+
+    public class ApiTests
+    {
+        private const int _retries = 2;
+
+        [Fact]
+        public async Task SendServiceAsync_200OK_AllGood()
+        {
+            var response = new HttpResponseMessage
+            {
+                StatusCode = HttpStatusCode.OK
+            };
+            var handler = new SetResponseHandler(response);
+            var api = new Api(new Uri("http://localhost:1234"), handler);
+
+            await api.SendServiceAsync(new ServiceInfo());
+
+            Assert.Equal(1, handler.RequestsCount);
+        }
+
+        [Fact]
+        public async Task SendServiceAsync_500_Retry()
+        {
+            var response = new HttpResponseMessage
+            {
+                StatusCode = HttpStatusCode.InternalServerError
+            };
+            var handler = new SetResponseHandler(response);
+            var api = new Api(new Uri("http://localhost:1234"), handler);
+
+            await api.SendServiceAsync(new ServiceInfo());
+
+            Assert.Equal(1 + _retries, handler.RequestsCount);
+        }
+    }
+}

src/Datadog.Tracer/Api.cs

@@ -1,7 +1,7 @@
 using MsgPack.Serialization;
 using System;
 using System.Collections.Generic;
-using System.IO;
+using System.Net;
 using System.Net.Http;
 using System.Reflection;
 using System.Runtime.InteropServices;
@@ -54,32 +54,42 @@ public Api(Uri baseEndpoint, DelegatingHandler delegatingHandler = null)
             _client.DefaultRequestHeaders.Add("Datadog-Meta-Tracer-Version", Assembly.GetEntryAssembly().GetName().Version.ToString());
         }
 
-        public async Task SendTracesAsync(IList<List<Span>> traces)
+        private async Task SendAsync<T>(T value, Uri endpoint)
         {
-            try
-            {
-                var content = new MsgPackContent<IList<List<Span>>>(traces, _serializationContext);
-                var response = await _client.PostAsync(_tracesEndpoint, content);
-                response.EnsureSuccessStatusCode();
-            }
-            catch
+            const int retries = 2;
+            for (int i = 0; i < retries + 1; i++)
             {
-                //TODO:bertrand Log exception
+                try
+                {
+                    var content = new MsgPackContent<T>(value, _serializationContext);
+                    var response = await _client.PostAsync(endpoint, content);
+                    if(response.StatusCode == HttpStatusCode.OK)
+                    {
+                        return;
+                    }
+                    if((int)response.StatusCode >= 400 && (int)response.StatusCode < 500)
+                    {
+                        // TODO:bertrand log
+                        return;
+                    }
+                    throw new HttpRequestException($"The request to {endpoint} failed with status {response.StatusCode}");
+                }
+                catch
+                {
+                    // TODO:bertrand Log
+                }
+                await Task.Delay(TimeSpan.FromSeconds(1));
             }
         }
 
+        public async Task SendTracesAsync(IList<List<Span>> traces)
+        {
+            await SendAsync(traces, _tracesEndpoint);
+        }
+
         public async Task SendServiceAsync(ServiceInfo service)
         {
-            try
-            {
-                var content = new MsgPackContent<ServiceInfo>(service, _serializationContext);
-                var response = await _client.PostAsync(_servicesEndpoint, content);
-                response.EnsureSuccessStatusCode();
-            }
-            catch
-            {
-                // TODO:bertrand log exception 
-            }
+            await SendAsync(service, _servicesEndpoint);
         }
     }
 }