public async Task Invoke()

in src/Microsoft.ServiceFabric.AspNetCore/ServiceFabricMiddleware.cs [53:99]
32 lines of code
4 McCabe index (conditional complexity)

        public async Task Invoke(HttpContext context)
        {
            if (context == null)
            {
                throw new ArgumentNullException("context");
            }

            if (this.urlSuffix.Length == 0)
            {
                // when urlSuffix is empty string, just call the next middleware in pipeline.
                await this.next(context);
            }
            else
            {
                // If this middleware is enabled by specifying UseServiceFabricIntegration(), CommunicationListnerBehavior is:
                //   With ServiceFabricIntegrationOptions.UseUniqueServiceUrl (urlSuffix is /PartitionId/ReplicaOrInstanceId)
                //      - Url given to WebServer is http://+:port
                //      - Url given to Service Fabric Runtime is http://ip:port/PartitionId/ReplicaOrInstanceId

                // Since when registering with IWebHost, only http://+:port is provided:
                //    - HttpRequest.Path contains everything in url after http://+:port, and it must start with urlSuffix

                // So short circuit and return StatusCode 410 if (message isn't intended for this replica,):
                //    - HttpRequest.Path doesn't start with urlSuffix
                if (!context.Request.Path.StartsWithSegments(this.urlSuffix, out var matchedPath, out var remainingPath))
                {
                    context.Response.StatusCode = StatusCodes.Status410Gone;
                    return;
                }

                // All good, change Path, PathBase and call next middleware in the pipeline
                var originalPath = context.Request.Path;
                var originalPathBase = context.Request.PathBase;
                context.Request.Path = remainingPath;
                context.Request.PathBase = originalPathBase.Add(matchedPath);

                try
                {
                    await this.next(context);
                }
                finally
                {
                    context.Request.Path = originalPath;
                    context.Request.PathBase = originalPathBase;
                }
            }
        }