private async Task <HttpSourceResult> GetAsync(
Uri uri,
bool ignoreNotFounds,
ILogger log,
CancellationToken token)
{
Func <Task <HttpResponseMessage> > request = () => SendWithCredentialSupportAsync(
() => new HttpRequestMessage(HttpMethod.Get, uri),
log,
token);
var response = await request();
try
{
if (ignoreNotFounds && response.StatusCode == HttpStatusCode.NotFound)
{
response.Dispose();
return(new HttpSourceResult(HttpSourceResultStatus.NotFound));
}
if (response.StatusCode == HttpStatusCode.NoContent)
{
response.Dispose();
// Ignore reading and caching the empty stream.
return(new HttpSourceResult(HttpSourceResultStatus.NoContent));
}
response.EnsureSuccessStatusCode();
var networkStream = await response.Content.ReadAsStreamAsync();
var timeoutStream = new DownloadTimeoutStream(uri.ToString(), networkStream, DownloadTimeout);
return(new HttpSourceResult(
HttpSourceResultStatus.OpenedFromNetwork,
null,
timeoutStream));
}
catch
{
try
{
response.Dispose();
}
catch
{
// Nothing we can do here.
}
throw;
}
}
internal async Task <XDocument> LoadXmlAsync(
string uri,
bool ignoreNotFounds,
ILogger log,
CancellationToken token)
{
return(await _httpSource.ProcessResponseAsync(
() =>
{
var request = new HttpRequestMessage(HttpMethod.Get, uri);
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/atom+xml"));
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/xml"));
return request;
},
async response =>
{
if (response.StatusCode == HttpStatusCode.OK)
{
var networkStream = await response.Content.ReadAsStreamAsync();
var timeoutStream = new DownloadTimeoutStream(uri, networkStream, _httpSource.DownloadTimeout);
return LoadXml(timeoutStream);
}
else if (ignoreNotFounds && response.StatusCode == HttpStatusCode.NotFound)
{
// Treat "404 Not Found" as an empty response.
return null;
}
else if (response.StatusCode == HttpStatusCode.NoContent)
{
// Always treat "204 No Content" as exactly that.
return null;
}
else
{
throw new FatalProtocolException(string.Format(
CultureInfo.CurrentCulture,
Strings.Log_FailedToFetchV2Feed,
uri,
(int)response.StatusCode,
response.ReasonPhrase));
}
},
log,
token));
}
/// <summary>
/// Make an HTTP request while retrying after failed attempts or timeouts.
/// </summary>
/// <remarks>
/// This method accepts a factory to create instances of the <see cref="HttpRequestMessage"/> because
/// requests cannot always be used. For example, suppose the request is a POST and contains content
/// of a stream that can only be consumed once.
/// </remarks>
public async Task <HttpResponseMessage> SendAsync(
HttpRetryHandlerRequest request,
string source,
ILogger log,
CancellationToken cancellationToken)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
// If specified via environment, override the default retry delay with the values provided
if (_enhancedHttpRetryHelper.IsEnabled)
{
request.RetryDelay = TimeSpan.FromMilliseconds(_enhancedHttpRetryHelper.DelayInMilliseconds);
}
var tries = 0;
HttpResponseMessage response = null;
var success = false;
while (tries < request.MaxTries && !success)
{
// There are many places where another variable named "MaxTries" is set to 1,
// so the Delay() never actually occurs.
// When opted in to "enhanced retry", do the delay and have it increase exponentially where applicable
// (i.e. when "tries" is allowed to be > 1)
if (tries > 0 || (_enhancedHttpRetryHelper.IsEnabled && request.IsRetry))
{
// "Enhanced" retry: In the case where this is actually a 2nd-Nth try, back off exponentially with some random.
// In many cases due to the external retry loop, this will be always be 1 * request.RetryDelay.TotalMilliseconds + 0-200 ms
if (_enhancedHttpRetryHelper.IsEnabled)
{
if (tries >= 3 || (tries == 0 && request.IsRetry))
{
log.LogVerbose("Enhanced retry: HttpRetryHandler is in a state that retry would have been abandoned or not waited if it were not enabled.");
}
await Task.Delay(TimeSpan.FromMilliseconds((Math.Pow(2, tries) * request.RetryDelay.TotalMilliseconds) + new Random().Next(200)), cancellationToken);
}
// Old behavior; always delay a constant amount
else
{
await Task.Delay(request.RetryDelay, cancellationToken);
}
}
tries++;
success = true;
using (var requestMessage = request.RequestFactory())
{
var stopwatches = new List <Stopwatch>(2);
var bodyStopwatch = new Stopwatch();
stopwatches.Add(bodyStopwatch);
Stopwatch headerStopwatch = null;
if (request.CompletionOption == HttpCompletionOption.ResponseHeadersRead)
{
headerStopwatch = new Stopwatch();
stopwatches.Add(headerStopwatch);
}
#if NET5_0
requestMessage.Options.Set(new HttpRequestOptionsKey <List <Stopwatch> >(StopwatchPropertyName), stopwatches);
#else
requestMessage.Properties[StopwatchPropertyName] = stopwatches;
#endif
var requestUri = requestMessage.RequestUri;
try
{
// The only time that we will be disposing this existing response is if we have
// successfully fetched an HTTP response but the response has an status code indicating
// failure (i.e. HTTP status code >= 500).
//
// If we don't even get an HTTP response message because an exception is thrown, then there
// is no response instance to dispose. Additionally, we cannot use a finally here because
// the caller needs the response instance returned in a non-disposed state.
//
// Also, remember that if an HTTP server continuously returns a failure status code (like
// 500 Internal Server Error), we will retry some number of times but eventually return the
// response as-is, expecting the caller to check the status code as well. This results in the
// success variable being set to false but the response being returned to the caller without
// disposing it.
response?.Dispose();
// Add common headers to the request after it is created by the factory. This includes
// X-NuGet-Session-Id which is added to all nuget requests.
foreach (var header in request.AddHeaders)
{
requestMessage.Headers.TryAddWithoutValidation(header.Key, header.Value);
}
log.LogInformation(" " + string.Format(
CultureInfo.InvariantCulture,
Strings.Http_RequestLog,
requestMessage.Method,
requestUri));
// Issue the request.
var timeoutMessage = string.Format(
CultureInfo.CurrentCulture,
Strings.Http_Timeout,
requestMessage.Method,
requestUri,
(int)request.RequestTimeout.TotalMilliseconds);
response = await TimeoutUtility.StartWithTimeout(
async timeoutToken =>
{
bodyStopwatch.Start();
headerStopwatch?.Start();
var responseMessage = await request.HttpClient.SendAsync(requestMessage, request.CompletionOption, timeoutToken);
headerStopwatch?.Stop();
return(responseMessage);
},
request.RequestTimeout,
timeoutMessage,
cancellationToken);
// Wrap the response stream so that the download can timeout.
if (response.Content != null)
{
var networkStream = await response.Content.ReadAsStreamAsync();
var timeoutStream = new DownloadTimeoutStream(requestUri.ToString(), networkStream, request.DownloadTimeout);
var inProgressEvent = new ProtocolDiagnosticInProgressHttpEvent(
source,
requestUri,
headerStopwatch?.Elapsed,
(int)response.StatusCode,
isRetry: request.IsRetry || tries > 1,
isCancelled: false,
isLastAttempt: tries == request.MaxTries && request.IsLastAttempt);
var diagnosticsStream = new ProtocolDiagnosticsStream(timeoutStream, inProgressEvent, bodyStopwatch, ProtocolDiagnostics.RaiseEvent);
var newContent = new StreamContent(diagnosticsStream);
// Copy over the content headers since we are replacing the HttpContent instance associated
// with the response message.
foreach (var header in response.Content.Headers)
{
newContent.Headers.TryAddWithoutValidation(header.Key, header.Value);
}
response.Content = newContent;
}
log.LogInformation(" " + string.Format(
CultureInfo.InvariantCulture,
Strings.Http_ResponseLog,
response.StatusCode,
requestUri,
bodyStopwatch.ElapsedMilliseconds));
if ((int)response.StatusCode >= 500)
{
success = false;
}
}
catch (OperationCanceledException)
{
response?.Dispose();
ProtocolDiagnostics.RaiseEvent(new ProtocolDiagnosticHttpEvent(
timestamp: DateTime.UtcNow,
source,
requestUri,
headerDuration: null,
eventDuration: bodyStopwatch.Elapsed,
httpStatusCode: null,
bytes: 0,
isSuccess: false,
isRetry: request.IsRetry || tries > 1,
isCancelled: true,
isLastAttempt: tries == request.MaxTries && request.IsLastAttempt));
throw;
}
catch (Exception e)
{
success = false;
response?.Dispose();
ProtocolDiagnostics.RaiseEvent(new ProtocolDiagnosticHttpEvent(
timestamp: DateTime.UtcNow,
source,
requestUri,
headerDuration: null,
eventDuration: bodyStopwatch.Elapsed,
httpStatusCode: null,
bytes: 0,
isSuccess: false,
isRetry: request.IsRetry || tries > 1,
isCancelled: false,
isLastAttempt: tries == request.MaxTries && request.IsLastAttempt));
if (tries >= request.MaxTries)
{
throw;
}
log.LogInformation(string.Format(
CultureInfo.CurrentCulture,
Strings.Log_RetryingHttp,
requestMessage.Method,
requestUri,
requestMessage)
+ Environment.NewLine
+ ExceptionUtilities.DisplayMessage(e));
}
}
}
return(response);
}
/// <summary>
/// Make an HTTP request while retrying after failed attempts or timeouts.
/// </summary>
/// <remarks>
/// This method accepts a factory to create instances of the <see cref="HttpRequestMessage"/> because
/// requests cannot always be used. For example, suppose the request is a POST and contains content
/// of a stream that can only be consumed once.
/// </remarks>
public async Task <HttpResponseMessage> SendAsync(
HttpRetryHandlerRequest request,
string source,
ILogger log,
CancellationToken cancellationToken)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
var tries = 0;
HttpResponseMessage response = null;
var success = false;
while (tries < request.MaxTries && !success)
{
if (tries > 0)
{
await Task.Delay(request.RetryDelay, cancellationToken);
}
tries++;
success = true;
using (var requestMessage = request.RequestFactory())
{
var stopwatches = new List <Stopwatch>(2);
var bodyStopwatch = new Stopwatch();
stopwatches.Add(bodyStopwatch);
Stopwatch headerStopwatch = null;
if (request.CompletionOption == HttpCompletionOption.ResponseHeadersRead)
{
headerStopwatch = new Stopwatch();
stopwatches.Add(headerStopwatch);
}
requestMessage.Properties[StopwatchPropertyName] = stopwatches;
var requestUri = requestMessage.RequestUri;
try
{
// The only time that we will be disposing this existing response is if we have
// successfully fetched an HTTP response but the response has an status code indicating
// failure (i.e. HTTP status code >= 500).
//
// If we don't even get an HTTP response message because an exception is thrown, then there
// is no response instance to dispose. Additionally, we cannot use a finally here because
// the caller needs the response instance returned in a non-disposed state.
//
// Also, remember that if an HTTP server continuously returns a failure status code (like
// 500 Internal Server Error), we will retry some number of times but eventually return the
// response as-is, expecting the caller to check the status code as well. This results in the
// success variable being set to false but the response being returned to the caller without
// disposing it.
response?.Dispose();
// Add common headers to the request after it is created by the factory. This includes
// X-NuGet-Session-Id which is added to all nuget requests.
foreach (var header in request.AddHeaders)
{
requestMessage.Headers.TryAddWithoutValidation(header.Key, header.Value);
}
log.LogInformation(" " + string.Format(
CultureInfo.InvariantCulture,
Strings.Http_RequestLog,
requestMessage.Method,
requestUri));
// Issue the request.
var timeoutMessage = string.Format(
CultureInfo.CurrentCulture,
Strings.Http_Timeout,
requestMessage.Method,
requestUri,
(int)request.RequestTimeout.TotalMilliseconds);
response = await TimeoutUtility.StartWithTimeout(
async timeoutToken =>
{
bodyStopwatch.Start();
headerStopwatch?.Start();
var responseMessage = await request.HttpClient.SendAsync(requestMessage, request.CompletionOption, timeoutToken);
headerStopwatch?.Stop();
return(responseMessage);
},
request.RequestTimeout,
timeoutMessage,
cancellationToken);
// Wrap the response stream so that the download can timeout.
if (response.Content != null)
{
var networkStream = await response.Content.ReadAsStreamAsync();
var timeoutStream = new DownloadTimeoutStream(requestUri.ToString(), networkStream, request.DownloadTimeout);
var inProgressEvent = new ProtocolDiagnosticInProgressHttpEvent(
source,
requestUri,
headerStopwatch?.Elapsed,
(int)response.StatusCode,
isRetry: request.IsRetry || tries > 1,
isCancelled: false,
isLastAttempt: tries == request.MaxTries && request.IsLastAttempt);
var diagnosticsStream = new ProtocolDiagnosticsStream(timeoutStream, inProgressEvent, bodyStopwatch, ProtocolDiagnostics.RaiseEvent);
var newContent = new StreamContent(diagnosticsStream);
// Copy over the content headers since we are replacing the HttpContent instance associated
// with the response message.
foreach (var header in response.Content.Headers)
{
newContent.Headers.TryAddWithoutValidation(header.Key, header.Value);
}
response.Content = newContent;
}
log.LogInformation(" " + string.Format(
CultureInfo.InvariantCulture,
Strings.Http_ResponseLog,
response.StatusCode,
requestUri,
bodyStopwatch.ElapsedMilliseconds));
if ((int)response.StatusCode >= 500)
{
success = false;
}
}
catch (OperationCanceledException)
{
response?.Dispose();
ProtocolDiagnostics.RaiseEvent(new ProtocolDiagnosticHttpEvent(
timestamp: DateTime.UtcNow,
source,
requestUri,
headerDuration: null,
eventDuration: bodyStopwatch.Elapsed,
httpStatusCode: null,
bytes: 0,
isSuccess: false,
isRetry: request.IsRetry || tries > 1,
isCancelled: true,
isLastAttempt: tries == request.MaxTries && request.IsLastAttempt));
throw;
}
catch (Exception e)
{
success = false;
response?.Dispose();
ProtocolDiagnostics.RaiseEvent(new ProtocolDiagnosticHttpEvent(
timestamp: DateTime.UtcNow,
source,
requestUri,
headerDuration: null,
eventDuration: bodyStopwatch.Elapsed,
httpStatusCode: null,
bytes: 0,
isSuccess: false,
isRetry: request.IsRetry || tries > 1,
isCancelled: false,
isLastAttempt: tries == request.MaxTries && request.IsLastAttempt));
if (tries >= request.MaxTries)
{
throw;
}
log.LogInformation(string.Format(
CultureInfo.CurrentCulture,
Strings.Log_RetryingHttp,
requestMessage.Method,
requestUri,
requestMessage)
+ Environment.NewLine
+ ExceptionUtilities.DisplayMessage(e));
}
}
}
return(response);
}
private async Task CreateCacheFileAsync(
HttpCacheResult result,
string uri,
HttpResponseMessage response,
HttpSourceCacheContext context,
Action <Stream> ensureValidContents,
CancellationToken cancellationToken)
{
// The update of a cached file is divided into two steps:
// 1) Delete the old file.
// 2) Create a new file with the same name.
using (var fileStream = new FileStream(
result.NewCacheFile,
FileMode.Create,
FileAccess.ReadWrite,
FileShare.None,
BufferSize,
useAsync: true))
{
using (var networkStream = await response.Content.ReadAsStreamAsync())
using (var timeoutStream = new DownloadTimeoutStream(uri, networkStream, DownloadTimeout))
{
await timeoutStream.CopyToAsync(fileStream, 8192, cancellationToken);
}
// Validate the content before putting it into the cache.
fileStream.Seek(0, SeekOrigin.Begin);
ensureValidContents?.Invoke(fileStream);
}
if (File.Exists(result.CacheFile))
{
// Process B can perform deletion on an opened file if the file is opened by process A
// with FileShare.Delete flag. However, the file won't be actually deleted until A close it.
// This special feature can cause race condition, so we never delete an opened file.
if (!IsFileAlreadyOpen(result.CacheFile))
{
File.Delete(result.CacheFile);
}
}
// If the destination file doesn't exist, we can safely perform moving operation.
// Otherwise, moving operation will fail.
if (!File.Exists(result.CacheFile))
{
File.Move(
result.NewCacheFile,
result.CacheFile);
}
// Even the file deletion operation above succeeds but the file is not actually deleted,
// we can still safely read it because it means that some other process just updated it
// and we don't need to update it with the same content again.
result.Stream = new FileStream(
result.CacheFile,
FileMode.Open,
FileAccess.Read,
FileShare.Read | FileShare.Delete,
BufferSize,
useAsync: true);
}