private static void ProcessStartOfRequest <T>(ExecutionState <T> executionState, string startLogMessage, CancellationTokenSource timeoutTokenSource = null)
{
RESTCommand <T> cmd = executionState.RestCMD;
// 1. Build request and content
executionState.CurrentOperation = ExecutorOperation.BeginOperation;
// Content is re-created every retry, as HttpClient disposes it after a successful request
HttpContent content = cmd.BuildContent != null?cmd.BuildContent(cmd, executionState.OperationContext) : null;
// This is so the old auth header etc is cleared out, the content is where serialization occurs which is the major perf hit
Uri uri = cmd.StorageUri.GetUri(executionState.CurrentLocation);
Uri transformedUri = cmd.Credentials.TransformUri(uri);
Logger.LogInformational(executionState.OperationContext, SR.TraceStartRequestAsync, transformedUri);
UriQueryBuilder builder = new UriQueryBuilder(executionState.RestCMD.Builder);
executionState.Req = cmd.BuildRequest(cmd, transformedUri, builder, content, cmd.ServerTimeoutInSeconds, executionState.OperationContext);
// 2. Set Headers
Executor.ApplyUserHeaders(executionState);
// Let the user know we are ready to send
Executor.FireSendingRequest(executionState);
// 3. Sign Request is not needed, as HttpClient will call us
// 4. Set timeout (this is actually not honored by asynchronous requests)
if (executionState.OperationExpiryTime.HasValue)
{
// set the token to cancel after timing out, if the higher token hasn't already been cancelled
timeoutTokenSource?.CancelAfter(executionState.RemainingTimeout);
}
else
{
// effectively prevent timeout
timeoutTokenSource?.CancelAfter(int.MaxValue);
}
}
private async static Task <T> ExecuteAsyncInternal <T>(RESTCommand <T> cmd, IRetryPolicy policy, OperationContext operationContext, CancellationToken token)
{
// Note all code below will reference state, not params directly, this will allow common code with multiple executors (APM, Sync, Async)
using (ExecutionState <T> executionState = new ExecutionState <T>(cmd, policy, operationContext))
using (CancellationTokenSource timeoutTokenSource = CancellationTokenSource.CreateLinkedTokenSource(token))
{
bool shouldRetry = false;
TimeSpan delay = TimeSpan.Zero;
// Note - The service accepts both api-version and x-ms-version and therefore it is ok to add x-ms-version to all requests.
// Create a new client
HttpClient client = cmd.HttpClient ?? HttpClientFactory.Instance;
do
{
try
{
executionState.Init();
// 0. Begin Request
Executor.StartRequestAttempt(executionState);
// 1. Build request and content
executionState.CurrentOperation = ExecutorOperation.BeginOperation;
// Content is re-created every retry, as HttpClient disposes it after a successful request
HttpContent content = cmd.BuildContent != null?cmd.BuildContent(cmd, executionState.OperationContext) : null;
// This is so the old auth header etc is cleared out, the content is where serialization occurs which is the major perf hit
Uri uri = cmd.StorageUri.GetUri(executionState.CurrentLocation);
Uri transformedUri = cmd.Credentials.TransformUri(uri);
Logger.LogInformational(executionState.OperationContext, SR.TraceStartRequestAsync, transformedUri);
UriQueryBuilder builder = new UriQueryBuilder(executionState.RestCMD.Builder);
executionState.Req = cmd.BuildRequest(cmd, transformedUri, builder, content, cmd.ServerTimeoutInSeconds, executionState.OperationContext);
// 2. Set Headers
Executor.ApplyUserHeaders(executionState);
// Let the user know we are ready to send
Executor.FireSendingRequest(executionState);
// 3. Sign Request is not needed, as HttpClient will call us
// 4. Set timeout
if (executionState.OperationExpiryTime.HasValue)
{
// set the token to cancel after timing out, if the higher token hasn't already been cancelled
timeoutTokenSource.CancelAfter(executionState.RemainingTimeout);
}
else
{
// effectively prevent timeout
timeoutTokenSource.CancelAfter(int.MaxValue);
}
Executor.CheckTimeout <T>(executionState, true);
}
catch (Exception ex)
{
Logger.LogError(executionState.OperationContext, SR.TraceInitRequestError, ex.Message);
// Store exception and throw here. All operations in this try would be non-retryable by default
StorageException storageEx = await StorageException.TranslateExceptionAsync(ex, executionState.Cmd.CurrentResult, null, timeoutTokenSource.Token, executionState.Resp).ConfigureAwait(false);
storageEx.IsRetryable = false;
executionState.ExceptionRef = storageEx;
throw executionState.ExceptionRef;
}
// Enter Retryable Section of execution
try
{
// Send Request
executionState.CurrentOperation = ExecutorOperation.BeginGetResponse;
Logger.LogInformational(executionState.OperationContext, SR.TraceGetResponse);
executionState.Resp = await client.SendAsync(executionState.Req, HttpCompletionOption.ResponseHeadersRead, timeoutTokenSource.Token).ConfigureAwait(false);
executionState.CurrentOperation = ExecutorOperation.EndGetResponse;
// Check that echoed client ID matches the one we sent
var clientRequestId = HttpRequestParsers.GetHeader(executionState.Req, Constants.HeaderConstants.ClientRequestIdHeader);
var echoedClientRequestId = HttpResponseParsers.GetHeader(executionState.Resp, Constants.HeaderConstants.ClientRequestIdHeader);
if (echoedClientRequestId != null && echoedClientRequestId != clientRequestId)
{
var requestId = HttpResponseParsers.GetHeader(executionState.Resp, Constants.HeaderConstants.RequestIdHeader);
var storageEx = new StorageException($"Echoed client request ID: {echoedClientRequestId} does not match sent client request ID: {clientRequestId}. Service request ID: {requestId}")
{
IsRetryable = false
};
executionState.ExceptionRef = storageEx;
throw storageEx;
}
// Since HttpClient wont throw for non success, manually check and populate an exception
if (!executionState.Resp.IsSuccessStatusCode)
{
// At this point, don't try to read the stream to parse the error
executionState.ExceptionRef = await Exceptions.PopulateStorageExceptionFromHttpResponseMessage(executionState.Resp, executionState.Cmd.CurrentResult, executionState.Cmd.ParseError).ConfigureAwait(false);
}
Logger.LogInformational(executionState.OperationContext, SR.TraceResponse, executionState.Cmd.CurrentResult.HttpStatusCode, executionState.Cmd.CurrentResult.ServiceRequestID, executionState.Cmd.CurrentResult.ContentMd5, executionState.Cmd.CurrentResult.ContentCrc64, executionState.Cmd.CurrentResult.Etag);
Executor.FireResponseReceived(executionState);
// 7. Do Response parsing (headers etc, no stream available here)
if (cmd.PreProcessResponse != null)
{
executionState.CurrentOperation = ExecutorOperation.PreProcess;
try
{
executionState.Result = cmd.PreProcessResponse(cmd, executionState.Resp, executionState.ExceptionRef, executionState.OperationContext);
// clear exception
executionState.ExceptionRef = null;
}
catch (Exception ex)
{
executionState.ExceptionRef = ex;
}
Logger.LogInformational(executionState.OperationContext, SR.TracePreProcessDone);
}
// 8. (Potentially reads stream from server)
executionState.CurrentOperation = ExecutorOperation.GetResponseStream;
var responseStream = await executionState.Resp.Content.ReadAsStreamAsync().ConfigureAwait(false);
if (cmd.NetworkTimeout.HasValue)
{
responseStream = new TimeoutStream(responseStream, cmd.NetworkTimeout.Value);
}
cmd.ResponseStream = responseStream;
// The stream is now available in ResponseStream. Use the stream to parse out the response or error
if (executionState.ExceptionRef != null)
{
executionState.CurrentOperation = ExecutorOperation.BeginDownloadResponse;
Logger.LogInformational(executionState.OperationContext, SR.TraceDownloadError);
try
{
cmd.ErrorStream = new MemoryStream();
await cmd.ResponseStream.WriteToAsync(cmd.ErrorStream, default(IBufferManager), null /* copyLength */, null /* maxLength */, ChecksumRequested.None, executionState, new StreamDescriptor(), timeoutTokenSource.Token).ConfigureAwait(false);
cmd.ErrorStream.Seek(0, SeekOrigin.Begin);
executionState.ExceptionRef = StorageException.TranslateExceptionWithPreBufferedStream(executionState.ExceptionRef, executionState.Cmd.CurrentResult, stream => executionState.Cmd.ParseError(stream, executionState.Resp, null), cmd.ErrorStream, executionState.Resp);
throw executionState.ExceptionRef;
}
finally
{
cmd.ResponseStream.Dispose();
cmd.ResponseStream = null;
cmd.ErrorStream.Dispose();
cmd.ErrorStream = null;
}
}
else
{
if (!cmd.RetrieveResponseStream)
{
cmd.DestinationStream = Stream.Null;
}
if (cmd.DestinationStream != null)
{
if (cmd.StreamCopyState == null)
{
cmd.StreamCopyState = new StreamDescriptor();
}
try
{
executionState.CurrentOperation = ExecutorOperation.BeginDownloadResponse;
Logger.LogInformational(executionState.OperationContext, SR.TraceDownload);
await cmd.ResponseStream.WriteToAsync(cmd.DestinationStream, default(IBufferManager), null /* copyLength */, null /* maxLength */, cmd.ChecksumRequestedForResponseStream, executionState, cmd.StreamCopyState, timeoutTokenSource.Token).ConfigureAwait(false);
}
finally
{
cmd.ResponseStream.Dispose();
cmd.ResponseStream = null;
}
}
}
// 9. Evaluate Response & Parse Results, (Stream potentially available here)
if (cmd.PostProcessResponseAsync != null)
{
executionState.CurrentOperation = ExecutorOperation.PostProcess;
Logger.LogInformational(executionState.OperationContext, SR.TracePostProcess);
executionState.Result = await cmd.PostProcessResponseAsync(cmd, executionState.Resp, executionState.OperationContext, timeoutTokenSource.Token).ConfigureAwait(false);
}
executionState.CurrentOperation = ExecutorOperation.EndOperation;
Logger.LogInformational(executionState.OperationContext, SR.TraceSuccess);
Executor.FinishRequestAttempt(executionState);
return(executionState.Result);
}
catch (Exception e)
{
Logger.LogWarning(executionState.OperationContext, SR.TraceGenericError, e.Message);
Executor.FinishRequestAttempt(executionState);
if (e is TaskCanceledException && (executionState.OperationExpiryTime.HasValue && DateTime.Now.CompareTo(executionState.OperationExpiryTime.Value) > 0))
{
e = new TimeoutException(SR.TimeoutExceptionMessage, e);
}
#if NETCORE || WINDOWS_RT
StorageException translatedException = StorageException.TranslateException(e, executionState.Cmd.CurrentResult, stream => executionState.Cmd.ParseError(stream, executionState.Resp, null), executionState.Resp);
#else
StorageException translatedException = StorageException.TranslateException(e, executionState.Cmd.CurrentResult, stream => executionState.Cmd.ParseError(stream, executionState.Resp, null));
#endif
executionState.ExceptionRef = translatedException;
Logger.LogInformational(executionState.OperationContext, SR.TraceRetryCheck, executionState.RetryCount, executionState.Cmd.CurrentResult.HttpStatusCode, translatedException.IsRetryable ? "yes" : "no", translatedException.Message);
shouldRetry = false;
if (translatedException.IsRetryable && (executionState.RetryPolicy != null))
{
executionState.CurrentLocation = Executor.GetNextLocation(executionState.CurrentLocation, cmd.LocationMode);
Logger.LogInformational(executionState.OperationContext, SR.TraceNextLocation, executionState.CurrentLocation);
IExtendedRetryPolicy extendedRetryPolicy = executionState.RetryPolicy as IExtendedRetryPolicy;
if (extendedRetryPolicy != null)
{
RetryContext retryContext = new RetryContext(
executionState.RetryCount++,
cmd.CurrentResult,
executionState.CurrentLocation,
cmd.LocationMode);
RetryInfo retryInfo = extendedRetryPolicy.Evaluate(retryContext, executionState.OperationContext);
if (retryInfo != null)
{
Logger.LogInformational(executionState.OperationContext, SR.TraceRetryInfo, retryInfo.TargetLocation, retryInfo.UpdatedLocationMode);
shouldRetry = true;
executionState.CurrentLocation = retryInfo.TargetLocation;
cmd.LocationMode = retryInfo.UpdatedLocationMode;
delay = retryInfo.RetryInterval;
}
}
else
{
shouldRetry = executionState.RetryPolicy.ShouldRetry(
executionState.RetryCount++,
cmd.CurrentResult.HttpStatusCode,
executionState.ExceptionRef,
out delay,
executionState.OperationContext);
}
if ((delay < TimeSpan.Zero) || (delay > Constants.MaximumRetryBackoff))
{
delay = Constants.MaximumRetryBackoff;
}
}
}
finally
{
if (executionState.Resp != null)
{
executionState.Resp.Dispose();
executionState.Resp = null;
}
}
// potentially backoff
if (!shouldRetry || (executionState.OperationExpiryTime.HasValue && (DateTime.Now + delay).CompareTo(executionState.OperationExpiryTime.Value) > 0))
{
Logger.LogError(executionState.OperationContext, shouldRetry ? SR.TraceRetryDecisionTimeout : SR.TraceRetryDecisionPolicy, executionState.ExceptionRef.Message);
throw executionState.ExceptionRef;
}
else
{
if (cmd.RecoveryAction != null)
{
// I.E. Rewind stream etc.
cmd.RecoveryAction(cmd, executionState.Cmd.CurrentResult.Exception, executionState.OperationContext);
}
if (delay > TimeSpan.Zero)
{
await Task.Delay(delay, token).ConfigureAwait(false);
}
Logger.LogInformational(executionState.OperationContext, SR.TraceRetry);
}
Executor.FireRetrying(executionState);
}while (shouldRetry);
// should never get here
throw new NotImplementedException(SR.InternalStorageError);
}
}