Refactor CircuitBreaker Pattern

Add Qos Config in ReRoute And Refactor CircuitBreakingDelegatingHandler

src/Ocelot/Configuration/Builder/ReRouteBuilder.cs

@@ -32,6 +32,9 @@ namespace Ocelot.Configuration.Builder
         private string _downstreamScheme;
         private string _downstreamHost;
         private int _dsPort;
+        private int _exceptionsAllowedBeforeBreaking;
+        private int _durationOfBreak;
+        private int _timeoutValue;
 
         public ReRouteBuilder()
         {
@@ -192,6 +195,24 @@ namespace Ocelot.Configuration.Builder
             return this;
         }
 
+        public ReRouteBuilder WithExceptionsAllowedBeforeBreaking(int exceptionsAllowedBeforeBreaking)
+        {
+            _exceptionsAllowedBeforeBreaking = exceptionsAllowedBeforeBreaking;
+            return this;
+        }
+
+        public ReRouteBuilder WithDurationOfBreak(int durationOfBreak)
+        {
+            _durationOfBreak = durationOfBreak;
+            return this;
+        }
+
+        public ReRouteBuilder WithTimeoutValue(int timeoutValue)
+        {
+            _timeoutValue = timeoutValue;
+            return this;
+        }
+
         public ReRoute Build()
         {
             Func<HostAndPort> downstreamHostFunc = () => new HostAndPort(_downstreamHost, _dsPort);
@@ -200,7 +221,8 @@ namespace Ocelot.Configuration.Builder
                 _isAuthenticated, new AuthenticationOptions(_authenticationProvider, _authenticationProviderUrl, _scopeName, 
                 _requireHttps, _additionalScopes, _scopeSecret), _configHeaderExtractorProperties, _claimToClaims, _routeClaimRequirement, 
                 _isAuthorised, _claimToQueries, _requestIdHeaderKey, _isCached, _fileCacheOptions, _serviceName, 
-                _useServiceDiscovery, _serviceDiscoveryAddress, _serviceDiscoveryProvider, downstreamHostFunc, _downstreamScheme);
+                _useServiceDiscovery, _serviceDiscoveryAddress, _serviceDiscoveryProvider, downstreamHostFunc, _downstreamScheme,
+                _exceptionsAllowedBeforeBreaking,_durationOfBreak, _timeoutValue);
         }
     }
 }

src/Ocelot/Configuration/Creator/FileOcelotConfigurationCreator.cs

@@ -96,7 +96,6 @@ namespace Ocelot.Configuration.Creator
                 && !string.IsNullOrEmpty(globalConfiguration?.ServiceDiscoveryProvider?.Address)
                 && !string.IsNullOrEmpty(globalConfiguration?.ServiceDiscoveryProvider?.Provider);
 
-
             Func<HostAndPort> downstreamHostAndPortFunc = () => new HostAndPort(reRoute.DownstreamHost.Trim('/'), reRoute.DownstreamPort);
 
             if (isAuthenticated)
@@ -116,7 +115,8 @@ namespace Ocelot.Configuration.Creator
                     reRoute.RouteClaimsRequirement, isAuthorised, claimsToQueries,
                     requestIdKey, isCached, new CacheOptions(reRoute.FileCacheOptions.TtlSeconds),
                     reRoute.ServiceName, useServiceDiscovery, globalConfiguration?.ServiceDiscoveryProvider?.Provider,
-                    globalConfiguration?.ServiceDiscoveryProvider?.Address, downstreamHostAndPortFunc, reRoute.DownstreamScheme);
+                    globalConfiguration?.ServiceDiscoveryProvider?.Address, downstreamHostAndPortFunc, reRoute.DownstreamScheme,
+                    reRoute.ExceptionsAllowedBeforeBreaking, reRoute.DurationOfBreak, reRoute.TimeoutValue);
             }
 
             return new ReRoute(new DownstreamPathTemplate(reRoute.DownstreamPathTemplate), reRoute.UpstreamTemplate, 
@@ -125,7 +125,8 @@ namespace Ocelot.Configuration.Creator
                 reRoute.RouteClaimsRequirement, isAuthorised, new List<ClaimToThing>(),
                     requestIdKey, isCached, new CacheOptions(reRoute.FileCacheOptions.TtlSeconds),
                     reRoute.ServiceName, useServiceDiscovery, globalConfiguration?.ServiceDiscoveryProvider?.Provider,
-                    globalConfiguration?.ServiceDiscoveryProvider?.Address, downstreamHostAndPortFunc, reRoute.DownstreamScheme);
+                    globalConfiguration?.ServiceDiscoveryProvider?.Address, downstreamHostAndPortFunc, reRoute.DownstreamScheme,
+                    reRoute.ExceptionsAllowedBeforeBreaking, reRoute.DurationOfBreak, reRoute.TimeoutValue);
         }
 
         private string BuildUpstreamTemplate(FileReRoute reRoute)

src/Ocelot/Configuration/File/FileReRoute.cs

@@ -29,5 +29,8 @@ namespace Ocelot.Configuration.File
         public string DownstreamScheme {get;set;}
         public string DownstreamHost {get;set;}
         public int DownstreamPort { get; set; }
+        public int ExceptionsAllowedBeforeBreaking { get; set; }
+        public int DurationOfBreak { get; set; }
+        public int TimeoutValue { get; set; }
     }
 }

src/Ocelot/Configuration/ReRoute.cs

@@ -10,7 +10,8 @@ namespace Ocelot.Configuration
             bool isAuthenticated, AuthenticationOptions authenticationOptions, List<ClaimToThing> configurationHeaderExtractorProperties, 
             List<ClaimToThing> claimsToClaims, Dictionary<string, string> routeClaimsRequirement, bool isAuthorised, List<ClaimToThing> claimsToQueries, 
             string requestIdKey, bool isCached, CacheOptions fileCacheOptions, string serviceName, bool useServiceDiscovery,
-            string serviceDiscoveryProvider, string serviceDiscoveryAddress, Func<HostAndPort> downstreamHostAndPort, string downstreamScheme)
+            string serviceDiscoveryProvider, string serviceDiscoveryAddress, Func<HostAndPort> downstreamHostAndPort, string downstreamScheme,
+            int exceptionsAllowedBeforeBreaking =3, int durationofBreak =8, int timeoutValue = 5000)
         {
             DownstreamPathTemplate = downstreamPathTemplate;
             UpstreamTemplate = upstreamTemplate;
@@ -35,6 +36,9 @@ namespace Ocelot.Configuration
                 ServiceDiscoveryAddress = serviceDiscoveryAddress;
                 DownstreamHostAndPort = downstreamHostAndPort;
                 DownstreamScheme = downstreamScheme;
+            ExceptionsAllowedBeforeBreaking = exceptionsAllowedBeforeBreaking;
+            DurationOfBreak = durationofBreak;
+            TimeoutValue = timeoutValue;
         }
 
         public DownstreamPathTemplate DownstreamPathTemplate { get; private set; }
@@ -57,5 +61,8 @@ namespace Ocelot.Configuration
         public string ServiceDiscoveryAddress { get; private set;}
         public Func<HostAndPort> DownstreamHostAndPort {get;private set;}
         public string DownstreamScheme {get;private set;}
+        public int ExceptionsAllowedBeforeBreaking { get; private set; }
+        public int DurationOfBreak { get; private set; }
+        public int TimeoutValue { get; private set; }
     }
 }

src/Ocelot/Request/Builder/HttpRequestCreator.cs

@@ -15,7 +15,8 @@ namespace Ocelot.Request.Builder
             IRequestCookieCollection cookies, 
             QueryString queryString, 
             string contentType, 
-            RequestId.RequestId requestId)
+            RequestId.RequestId requestId,
+            Values.QoS qos)
         {
             var request = await new RequestBuilder()
                 .WithHttpMethod(httpMethod)
@@ -26,6 +27,7 @@ namespace Ocelot.Request.Builder
                 .WithHeaders(headers)
                 .WithRequestId(requestId)
                 .WithCookies(cookies)
+                .WithQos(qos)
                 .Build();
 
             return new OkResponse<Request>(request);

src/Ocelot/Request/Builder/IRequestCreator.cs

@@ -14,6 +14,7 @@ namespace Ocelot.Request.Builder
             IRequestCookieCollection cookies,
             QueryString queryString,
             string contentType, 
-            RequestId.RequestId requestId);
+            RequestId.RequestId requestId,
+            Values.QoS qos);
     }
 }

src/Ocelot/Request/Builder/RequestBuilder.cs

@@ -22,6 +22,7 @@ namespace Ocelot.Request.Builder
         private RequestId.RequestId _requestId;
         private IRequestCookieCollection _cookies;
         private readonly string[] _unsupportedHeaders = {"host"};
+        private Values.QoS _qos;
 
         public RequestBuilder WithHttpMethod(string httpMethod)
         {
@@ -71,6 +72,12 @@ namespace Ocelot.Request.Builder
             return this;
         }
 
+        public RequestBuilder WithQos(Values.QoS qos)
+        {
+            _qos = qos;
+            return this;
+        }
+
         public async Task<Request> Build()
         {
             var uri = CreateUri();
@@ -90,7 +97,7 @@ namespace Ocelot.Request.Builder
 
             var cookieContainer = CreateCookieContainer(uri);
 
-            return new Request(httpRequestMessage, cookieContainer);
+            return new Request(httpRequestMessage, cookieContainer, _qos);
         }
 
         private Uri CreateUri()

src/Ocelot/Request/Middleware/HttpRequestBuilderMiddleware.cs

@@ -32,7 +32,8 @@ namespace Ocelot.Request.Middleware
             var buildResult = await _requestCreator
                 .Build(context.Request.Method, DownstreamUrl, context.Request.Body,
                     context.Request.Headers, context.Request.Cookies, context.Request.QueryString,
-                    context.Request.ContentType, new RequestId.RequestId(DownstreamRoute?.ReRoute?.RequestIdKey, context.TraceIdentifier));
+                    context.Request.ContentType, new RequestId.RequestId(DownstreamRoute?.ReRoute?.RequestIdKey, context.TraceIdentifier),
+                    new Values.QoS(DownstreamRoute.ReRoute.ExceptionsAllowedBeforeBreaking, DownstreamRoute.ReRoute.DurationOfBreak, DownstreamRoute.ReRoute.TimeoutValue));
 
             if (buildResult.IsError)
             {

src/Ocelot/Request/Request.cs

@@ -1,17 +1,20 @@
-using System.Net;
+using Ocelot.Values;
+using System.Net;
 using System.Net.Http;
 
 namespace Ocelot.Request
 {
     public class Request
     {
-        public Request(HttpRequestMessage httpRequestMessage, CookieContainer cookieContainer)
+        public Request(HttpRequestMessage httpRequestMessage, CookieContainer cookieContainer, QoS qos)
         {
             HttpRequestMessage = httpRequestMessage;
             CookieContainer = cookieContainer;
+            Qos = qos;
         }
 
         public HttpRequestMessage HttpRequestMessage { get; private set; }
         public CookieContainer CookieContainer { get; private set; }
+        public QoS Qos { get; private set; }
     }
 }

src/Ocelot/Requester/CircuitBreakingDelegatingHandler.cs

@@ -0,0 +1,74 @@
+using Ocelot.Logging;
+using Polly;
+using Polly.CircuitBreaker;
+using Polly.Timeout;
+using System;
+using System.Net;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Ocelot.Requester
+{
+    public class CircuitBreakingDelegatingHandler : DelegatingHandler
+    {
+        private readonly IOcelotLogger _logger;
+        private readonly int _exceptionsAllowedBeforeBreaking;
+        private readonly TimeSpan _durationOfBreak;
+        private readonly Policy _circuitBreakerPolicy;
+        private readonly TimeoutPolicy _timeoutPolicy;
+
+        public CircuitBreakingDelegatingHandler(int exceptionsAllowedBeforeBreaking, TimeSpan durationOfBreak,TimeSpan timeoutValue
+            ,TimeoutStrategy timeoutStrategy, IOcelotLogger logger, HttpMessageHandler innerHandler)
+            : base(innerHandler)
+        {
+            this._exceptionsAllowedBeforeBreaking = exceptionsAllowedBeforeBreaking;
+            this._durationOfBreak = durationOfBreak;
+
+            _circuitBreakerPolicy = Policy
+                .Handle<HttpRequestException>()
+                .Or<TimeoutRejectedException>()
+                .Or<TimeoutException>()
+                .CircuitBreakerAsync(
+                    exceptionsAllowedBeforeBreaking: exceptionsAllowedBeforeBreaking,
+                    durationOfBreak: durationOfBreak,
+                    onBreak: (ex, breakDelay) =>
+                    {
+                        _logger.LogError(".Breaker logging: Breaking the circuit for " + breakDelay.TotalMilliseconds + "ms!", ex);
+                    },
+                    onReset: () => _logger.LogDebug(".Breaker logging: Call ok! Closed the circuit again."),
+                    onHalfOpen: () => _logger.LogDebug(".Breaker logging: Half-open; next call is a trial.")
+                    );
+            _timeoutPolicy = Policy.TimeoutAsync(timeoutValue, timeoutStrategy);
+            _logger = logger;
+        }
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            Task<HttpResponseMessage> responseTask = null;
+
+            try
+            {
+                responseTask = Policy.WrapAsync(_circuitBreakerPolicy, _timeoutPolicy).ExecuteAsync<HttpResponseMessage>(() =>
+                {
+                    return  base.SendAsync(request,cancellationToken);
+                });
+                return responseTask;
+            }
+            catch (BrokenCircuitException ex)
+            {
+                _logger.LogError($"Reached to allowed number of exceptions. Circuit is open. AllowedExceptionCount: {_exceptionsAllowedBeforeBreaking}, DurationOfBreak: {_durationOfBreak}",ex);
+                throw;
+            }
+            catch (HttpRequestException)
+            {
+                return responseTask;
+            }
+        }
+
+        private static bool IsTransientFailure(HttpResponseMessage result)
+        {
+            return result.StatusCode >= HttpStatusCode.InternalServerError;
+        }
+    }
+}

src/Ocelot/Requester/HttpClientBuilder.cs

@@ -0,0 +1,41 @@
+using Ocelot.Logging;
+using Ocelot.Values;
+using Polly.Timeout;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Threading.Tasks;
+
+namespace Ocelot.Requester
+{
+    internal class HttpClientBuilder
+    {
+        private readonly Dictionary<int, Func<DelegatingHandler>> handlers = new Dictionary<int, Func<DelegatingHandler>>();
+
+        public HttpClientBuilder WithCircuitBreaker(QoS qos, IOcelotLogger logger, HttpMessageHandler innerHandler)
+        {
+            handlers.Add(5000, () => new CircuitBreakingDelegatingHandler(qos.ExceptionsAllowedBeforeBreaking, qos.DurationOfBreak, qos.TimeoutValue, qos.TimeoutStrategy, logger, innerHandler));
+            return this;
+        }
+
+        internal HttpClient Build()
+        {
+            return handlers.Any() ? new HttpClient(CreateHttpMessageHandler()) : new HttpClient();
+        }
+
+        private HttpMessageHandler CreateHttpMessageHandler()
+        {
+            HttpMessageHandler httpMessageHandler = new HttpClientHandler();
+
+            handlers.OrderByDescending(handler => handler.Key).Select(handler => handler.Value).Reverse().ToList().ForEach(handler =>
+            {
+                var delegatingHandler = handler();
+                delegatingHandler.InnerHandler = httpMessageHandler;
+                httpMessageHandler = delegatingHandler;
+            });
+
+            return httpMessageHandler;
+        }
+    }
+}

src/Ocelot/Requester/HttpClientHttpRequester.cs

@@ -4,9 +4,6 @@ using System.Net.Http;
 using System.Threading.Tasks;
 using Ocelot.Errors;
 using Ocelot.Responses;
-using Polly;
-using Polly.Timeout;
-using Polly.CircuitBreaker;
 using Ocelot.Logging;
 
 namespace Ocelot.Requester
@@ -14,7 +11,7 @@ namespace Ocelot.Requester
     public class HttpClientHttpRequester : IHttpRequester
     {
         private readonly IOcelotLogger _logger;
-
+ 
         public HttpClientHttpRequester(IOcelotLoggerFactory loggerFactory)
         {
             _logger = loggerFactory.CreateLogger<HttpClientHttpRequester>();
@@ -22,46 +19,26 @@ namespace Ocelot.Requester
 
         public async Task<Response<HttpResponseMessage>> GetResponse(Request.Request request)
         {
-            double timeoutvalue = 5000;
-            TimeoutStrategy timeoutStrategy = TimeoutStrategy.Pessimistic;
-
-            var timeoutPolicy = Policy
-            .TimeoutAsync(TimeSpan.FromMilliseconds(timeoutvalue), timeoutStrategy);
-
-            var circuitBreakerPolicy = Policy
-                .Handle<Exception>()
-                .Or<TimeoutRejectedException>()
-                .Or<TimeoutException>()
-                .CircuitBreakerAsync(
-                    exceptionsAllowedBeforeBreaking: 4,
-                    durationOfBreak: TimeSpan.FromSeconds(8),
-                    onBreak: (ex, breakDelay) =>
-                    {
-                        _logger.LogError(".Breaker logging: Breaking the circuit for " + breakDelay.TotalMilliseconds + "ms!", ex);
-                    },
-                    onReset: () => _logger.LogDebug(".Breaker logging: Call ok! Closed the circuit again."),
-                    onHalfOpen: () => _logger.LogDebug(".Breaker logging: Half-open; next call is a trial.")
-                    );
+            HttpClientBuilder builder = new HttpClientBuilder();    
 
             using (var handler = new HttpClientHandler { CookieContainer = request.CookieContainer })
-            using (var httpClient = new HttpClient(handler))
             {
-                try
+                builder.WithCircuitBreaker(request.Qos, _logger, handler);               
+                using (var httpClient = builder.Build())
                 {
-                    // Retry the following call according to the policy - 3 times.
-                    HttpResponseMessage response = await Policy.WrapAsync(circuitBreakerPolicy, timeoutPolicy).ExecuteAsync<HttpResponseMessage>(() =>
+                    try
                     {
-                        return httpClient.SendAsync(request.HttpRequestMessage);
-                    });
-                    return new OkResponse<HttpResponseMessage>(response);
-                }
-                catch (BrokenCircuitException exception)
-                {
-                    return
-                        new ErrorResponse<HttpResponseMessage>(new List<Error>
-                        {
-                            new UnableToCompleteRequestError(exception)
-                        });
+                        var response = await httpClient.SendAsync(request.HttpRequestMessage);
+                        return new OkResponse<HttpResponseMessage>(response);
+                    }
+                    catch (Exception exception)
+                    {
+                        return
+                            new ErrorResponse<HttpResponseMessage>(new List<Error>
+                            {
+                                new UnableToCompleteRequestError(exception)
+                            });
+                    }
                 }
             }
         }

src/Ocelot/Requester/IHttpRequester.cs

@@ -7,5 +7,7 @@ namespace Ocelot.Requester
     public interface IHttpRequester
     {
         Task<Response<HttpResponseMessage>> GetResponse(Request.Request request);
+
+
     }
 }

src/Ocelot/Values/QoS.cs

@@ -0,0 +1,27 @@
+using Polly.Timeout;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Ocelot.Values
+{
+    public class QoS
+    {
+        public QoS(int exceptionsAllowedBeforeBreaking, int durationofBreak, int timeoutValue, TimeoutStrategy timeoutStrategy = TimeoutStrategy.Pessimistic)
+        {
+            ExceptionsAllowedBeforeBreaking = exceptionsAllowedBeforeBreaking;
+            DurationOfBreak = TimeSpan.FromMilliseconds(durationofBreak);
+            TimeoutValue = TimeSpan.FromMilliseconds(timeoutValue);
+            TimeoutStrategy = timeoutStrategy;
+        }
+
+        public int ExceptionsAllowedBeforeBreaking { get; private set; }
+
+        public TimeSpan DurationOfBreak { get; private set; }
+
+        public TimeSpan TimeoutValue { get; private set; }
+
+        public TimeoutStrategy TimeoutStrategy { get; private set; }
+    }
+}