// Executes the asynchronous method with load balancing in case of virtual network
internal TResult ExecuteAndGetWithVirtualNetworkLoadBalancing <TResult>(Func <string, Task <TResult> > method)
{
if (_loadBalancer == null)
{
return(method.Invoke(null).Result);
}
else
{
TResult result = default(TResult);
int numRetries = _loadBalancer.GetNumAvailableEndpoints();
LoadBalancingHelper.Execute(() =>
{
var endpoint = _loadBalancer.GetEndpoint();
Contract.Assert(endpoint != null, "Load balancer failed to return a worker node endpoint!");
Trace.TraceInformation("\tIssuing request to endpoint " + endpoint);
try
{
result = method.Invoke(endpoint.ToString()).Result;
_loadBalancer.RecordSuccess(endpoint);
}
catch (Exception)
{
_loadBalancer.RecordFailure(endpoint);
throw;
}
},
new RetryOnAllExceptionsPolicy(),
new NoOpBackOffScheme(), numRetries: numRetries);
return(result);
}
}
/// <summary>
/// Issues the web request asynchronous.
/// </summary>
/// <param name="endpoint">The endpoint.</param>
/// <param name="method">The method.</param>
/// <param name="input">The input.</param>
/// <param name="options">request options</param>
/// <returns></returns>
public async Task <Response> IssueWebRequestAsync(string endpoint, string query, string method, Stream input,
RequestOptions options)
{
options.Validate();
var watch = Stopwatch.StartNew();
Trace.CorrelationManager.ActivityId = Guid.NewGuid();
var balancedEndpoint = _balancer.GetEndpoint();
// Grab the host. Use the alternative host if one is specified
var host = options.AlternativeHost != null ? options.AlternativeHost : balancedEndpoint.Host;
var builder = new UriBuilder(
balancedEndpoint.Scheme,
host,
options.Port,
options.AlternativeEndpoint + endpoint);
if (query != null)
{
builder.Query = query;
}
var target = builder.Uri;
try
{
Debug.WriteLine("Issuing request {0} to endpoint {1}", Trace.CorrelationManager.ActivityId, target);
var httpWebRequest = WebRequest.CreateHttp(target);
//httpWebRequest.ServicePoint.ReceiveBufferSize = options.ReceiveBufferSize;
//httpWebRequest.ServicePoint.UseNagleAlgorithm = options.UseNagle;
httpWebRequest.Timeout = options.TimeoutMillis; // This has no influence for calls that are made Async
httpWebRequest.KeepAlive = options.KeepAlive;
httpWebRequest.Credentials = _credentialCache;
httpWebRequest.PreAuthenticate = true;
httpWebRequest.Method = method;
httpWebRequest.Accept = _contentType;
httpWebRequest.ContentType = _contentType;
// This allows 304 (NotModified) requests to catch
//https://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.allowautoredirect(v=vs.110).aspx
httpWebRequest.AllowAutoRedirect = false;
if (options.AdditionalHeaders != null)
{
foreach (var kv in options.AdditionalHeaders)
{
httpWebRequest.Headers.Add(kv.Key, kv.Value);
}
}
long remainingTime = options.TimeoutMillis;
if (input != null)
{
// expecting the caller to seek to the beginning or to the location where it needs to be copied from
Stream req = null;
try
{
req = await httpWebRequest.GetRequestStreamAsync().WithTimeout(
TimeSpan.FromMilliseconds(remainingTime),
"Waiting for RequestStream");
remainingTime = options.TimeoutMillis - watch.ElapsedMilliseconds;
if (remainingTime <= 0)
{
remainingTime = 0;
}
await input.CopyToAsync(req).WithTimeout(
TimeSpan.FromMilliseconds(remainingTime),
"Waiting for CopyToAsync",
CancellationToken.None);
}
catch (TimeoutException)
{
httpWebRequest.Abort();
throw;
}
finally
{
if (req != null)
{
req.Close();
}
}
}
try
{
remainingTime = options.TimeoutMillis - watch.ElapsedMilliseconds;
if (remainingTime <= 0)
{
remainingTime = 0;
}
Debug.WriteLine("Waiting for response for request {0} to endpoint {1}",
Trace.CorrelationManager.ActivityId, target);
var response = (HttpWebResponse)await httpWebRequest.GetResponseAsync().WithTimeout(
TimeSpan.FromMilliseconds(remainingTime),
"Waiting for GetResponseAsync");
Debug.WriteLine("Web request {0} to endpoint {1} successful!", Trace.CorrelationManager.ActivityId,
target);
return(new Response
{
WebResponse = response,
RequestLatency = watch.Elapsed,
PostRequestAction = r =>
{
if (r.WebResponse.StatusCode == HttpStatusCode.OK ||
r.WebResponse.StatusCode == HttpStatusCode.Created ||
r.WebResponse.StatusCode == HttpStatusCode.NotModified)
{
_balancer.RecordSuccess(balancedEndpoint);
}
else
{
_balancer.RecordFailure(balancedEndpoint);
}
}
});
}
catch (TimeoutException)
{
httpWebRequest.Abort();
throw;
}
}
catch (WebException we)
{
// 404 is valid response
var resp = we.Response as HttpWebResponse;
if (resp.StatusCode == HttpStatusCode.NotFound)
{
_balancer.RecordSuccess(balancedEndpoint);
Debug.WriteLine("Web request {0} to endpoint {1} successful!", Trace.CorrelationManager.ActivityId,
target);
}
else
{
_balancer.RecordFailure(balancedEndpoint);
Debug.WriteLine("Web request {0} to endpoint {1} failed!", Trace.CorrelationManager.ActivityId,
target);
}
throw we;
}
catch (Exception e)
{
_balancer.RecordFailure(balancedEndpoint);
Debug.WriteLine("Web request {0} to endpoint {1} failed!", Trace.CorrelationManager.ActivityId, target);
throw e;
}
}
