I am calling WCF service in ASP.NET Core and everything is working fine, but whenever end of using gets executed, I get an error:
This OperationContextScope is being disposed out of order
I believe I am using wrong pattern to call WCF service using async/await but I am not sure what I am doing wrong.
Below is the code I am using to call a service.
[HttpPost]
public async Task<IActionResult> Runcase(IFormCollection formCollection)
{
if (ModelState.IsValid)
{
var runnumber = formCollection["Run number"];
await CallServiceasync();
return RedirectToAction("", "");
}
else
{
return View(formCollection);
}
}
public async Task CallServiceasync()
{
var product = p1.Value;
var a = product.first;
foreach (int Age in a.age)
{
foreach (int Gender in a.sex)
{
foreach (int Healthclass in a.uclass)
{
RequestData requestData = new RequestData()
{
ProductID = 534,
STATE = "CO",
AGE1 = Age,
SEX1 = Gender,
UND_CLASS1 = Healthclass,
};
RecieveResponseasync(requestData);
}
}
}
}
public async Task RecieveResponseasync(InputValues inputValues)
{
string reqedata = "";
string apikey = "001010iZno7001010L";
QuoteEngineService.MarketingSoftwareClient Service = new QuoteEngineService.MarketingSoftwareClient();
await Service.OpenAsync();
try
{
using (OperationContextScope scope = new OperationContextScope(Service.InnerChannel))
{
HttpRequestMessageProperty httpRequestMessage = new HttpRequestMessageProperty();
httpRequestMessage.Headers.Add("apikey", apikey);
OperationContext.Current.OutgoingMessageProperties[HttpRequestMessageProperty.Name] = httpRequestMessage;
reqedata = inputValues.XmlSerializetoString();
var result = await Service.ProcessRequestAsync(reqedata, "4fa2-ae27");
var outputvalues = new OutputvaluesViewModel();
outputvalues = result.DeserializeToObject();
List<OutputValue> outputs = new List<OutputValue>();
if (outputvalues.InitialPremium != null)
outputs.Add(new OutputValue { Name = "InitialPremium", Result = outputvalues.InitialPremium});
if (outputvalues.TargetPremium != null)
outputs.Add(new OutputValue { Name = "TargetPremium", Result = outputvalues.TargetPremium });
foreach (var output in outputs)
{
await _context.outputValues.AddAsync(output);
await _context.SaveChangesAsync();
}
await Task.Delay(500);
}
}// **At this point I am getting error**
catch (Exception ex)
{
throw;
}
finally
{
if (Service.State == System.ServiceModel.CommunicationState.Opened)
{
await Service.CloseAsync();
}
}
}
From the docs:
Warning
Do not use the asynchronous "await" pattern within a OperationContextScope block. When the continuation occurs, it may run on a different thread and OperationContextScope is thread specific. If you need to call "await" for an async call, use it outside of the OperationContextScope block.
Related
public async Task<JobViewModel> Handle(AddJobCommand command, CancellationToken cancellationToken)
{
if (command.JobViewModel == null) throw new InvalidOperationException("Empty request.");
var jobViewModel = command.JobViewModel;
try
{
var job = _mapper.Map<DataAccess.Domain.Lab.Job>(jobViewModel);
_context.Set<DataAccess.Domain.Lab.Job>().Add(job);
if (job.Notes!= null)
{
var newNote = job.Notes.FirstOrDefault(n => n.IsNew);
if (newNote != null)
{
newNote.JobId = job.Id;
_context.Set<DataAccess.Domain.Lab.JobNote>().Attach(newNote);
_context.Entry(newNote).State = EntityState.Added;
}
}
await OnBeforeAdd(job); // job.Name = await GenerateJobName();
await _context.SaveChangesAsync();
jobViewModel.Id = job.Id;
return jobViewModel;
}
catch (DbEntityValidationException e)
{
foreach (var eve in e.EntityValidationErrors)
{
Console.WriteLine("Entity of type \"{0}\" in state \"{1}\" has the following validation errors:",
eve.Entry.Entity.GetType().Name, eve.Entry.State);
foreach (var ve in eve.ValidationErrors)
{
Console.WriteLine("- Property: \"{0}\", Error: \"{1}\"",
ve.PropertyName, ve.ErrorMessage);
}
}
throw;
}
catch (DbUpdateException e)
{
Console.WriteLine(e.Message);
throw;
}
catch (Exception e)
{
Console.WriteLine(e.Message);
throw;
}
}
protected async Task OnBeforeAdd(DataAccess.Domain.Lab.Job job)
{
if (string.IsNullOrWhiteSpace(job.Name))
{
job.Name = await GenerateJobName();
}
}
private async Task<string> GenerateJobName()
{
Func<int, int, string> composeName = (year, number) => string.Format("S{0:D2}{1:D3}", year, number);
int currentYear = DateTime.UtcNow.Year % 100;
int newJobNumber = 501;
//if (_context.Jobs!= null)
// {
// string maxJobNumber = await _context.Jobs.MaxAsync(j => j.Name);
string maxJobNumber = await _context.Jobs.MaxAsync(j=>j.Name);
if (!string.IsNullOrWhiteSpace(maxJobNumber))
{
var matches = Regex.Matches(maxJobNumber, "S" + currentYear + "(?<num>[0-9]{3})");
if (matches.Count == 1)
{
newJobNumber = int.Parse(matches[0].Groups["num"].Value) + 1;
}
}
// }
string newName = composeName(currentYear, newJobNumber);
while (await _context.Jobs.AnyAsync(j => j.Name == newName))
{
newJobNumber++;
newName = composeName(currentYear, newJobNumber);
}
return newName;
}
}
}
Below line give error:
string maxJobNumber = await _context.Jobs.MaxAsync(j=>j.Name);
On running the code it throws below exception "A second operation started on this context before a previous asynchronous operation completed. Use 'await' to ensure that any asynchronous operations have completed before calling another method on this context. Any instance members are not guaranteed to be thread safe."
Also the same line "string maxJobNumber = await _context.Jobs.MaxAsync(j=>j.Name);" shows warning message as
converting null literal or possible null value to non-nullable type string error . Can this be an issue?
Some comments about the above code:
There's no need for these lines:
if (job.Notes!= null)
{
var newNote = job.Notes.FirstOrDefault(n => n.IsNew);
if (newNote != null)
{
newNote.JobId = job.Id;
_context.Set<DataAccess.Domain.Lab.JobNote>().Attach(newNote);
_context.Entry(newNote).State = EntityState.Added;
}
}
Once you've added the job to the DbSet, EF will automatically figure out that its JobNotes need to be added as well. And, it will determine there state appropriately.
This is the pattern I would use:
public async Task<JobViewModel> Handle(AddJobCommand command, CancellationToken cancellationToken)
{
var jobViewModel = command.JobViewModel;
var job = _mapper.Map<DataAccess.Domain.Lab.Job>(jobViewModel);
job.Name = await GenerateJobName(job.Name);
await _context.Set<DataAccess.Domain.Lab.Job>().AddAsync(job);
await _context.SaveChangesAsync();
jobViewModel.Id = job.Id;
return jobViewModel;
}
private async Task<string> GenerateJobName(DataAccess.Domain.Lab.Job job)
{
if (!string.IsNullOrWhiteSpace(job.Name)) return job.Name;
...
}
You may be overthinking all the try-catch stuff. It is more than half the code and is obscuring the real logic. I would move that out to a higher location and concentrate on making this do the one thing it's intended to do.
The reason the code performs differently in PROD is due to a race condition. There's no debugger in PROD, so your first calls are finishing with enough time to start the second calls.
We have a web API application which runs on .net4.6.1. We have tried several times to figure out the root cause where it is getting deadlock, but failed. Below is the code snippet. We are hitting this API endpoint every 1 minute. It will pick 300 transaction at a time for processing from the DB. We have observed that it get stuck when there are no files to process from the DB. Not sure though. It would be helpful if someone can help us.TIA
public class TaxEngineIntegratorController : ApiController
{
public async Task Get(int id)
{
try
{
await MainFileMethod();
}
catch (Exception Ex)
{
SerilogMethods.LogError(log, Ex, "Get");
}
}
public async Task MainFileMethod()
{
List<FileTransaction> lstFTtoLock = new List<FileTransaction>();
try
{
List<int> lstStatusIds = new List<int>();
lstStatusIds.Add(objStatusManager.GetStatusIdbyName(Status.ConversionToXmlSucceded));
lstStatusIds.Add(objStatusManager.GetStatusIdbyName(Status.Reprocess));
//Getting the serviceURL of TRTaxEngine
string seriviceURL = objConfigManager.GetConfigurationdbyKey(ConfigurationList.TRTaxEngineURL);
//Getting the output path for the file to be placed after processing
string outputfilePath = objConfigManager.GetConfigurationdbyKey(ConfigurationList.TRTaxOutputXMLFolder);
FileMasterManager objFileMasterManager = new FileMasterManager();
TRTaxXMLOperations objxmlresp = new TRTaxXMLOperations();
//Getting all the files list for proccessing from the DB
List<FileTransaction> lstFiletoProcess = await objTransManager.GetFileListforProcessingAsync(lstStatusIds, true);
lstFTtoLock = lstFiletoProcess;
if (lstFiletoProcess.Count == 0)
return;
if (lstFiletoProcess.Count > 0)
{
var tasks = new List<Task<string>>();
using (HttpClient httpClnt = new HttpClient())
{
httpClnt.Timeout = TimeSpan.FromMilliseconds(-1);
foreach (FileTransaction item in lstFiletoProcess)
{
TRXMLResponseModel objRespModel = new TRXMLResponseModel();
objRespModel.strxmlResponse = string.Empty;
string fullFileName = item.FilePath + item.ConvertedName;
objRespModel.outputFilename = outputfilePath + item.ConvertedName;
FileMaster fileMaster = objFileMasterManager.GetById(item.FileId);
//Proccessing the file and getting the output filedata
Task<string> t = objxmlresp.GetXMLResponse(seriviceURL, fullFileName, fileMaster.CountryId.GetValueOrDefault(), httpClnt, objFileOperation, objRespModel.outputFilename, item);
tasks.Add(t);
objRespModel.strxmlResponse = await t;
}
var result = await Task.WhenAll(tasks);
}
SerilogMethods.LogCustomException(log, "Http Client Destroyed in Tax Engine", "GetXMLResponse");
}
}
catch (Exception Ex)
{
if (lstFTtoLock != null && lstFTtoLock.Count > 0)
{
objTransManager.UpdateFileTransactionIsPickedtoFalse(lstFTtoLock);
}
throw Ex;
}
}
}
//Getting all the files list for proccessing from the DB
public async Task<List<FileTransaction>> GetFileListforProcessingAsync(List<int> lstStatusList, bool IsActive)
{
try
{
List<FileTransaction> lstFTList = new List<FileTransaction>();
using (SUTBACDEVContext db = new SUTBACDEVContext())
{
//DataTable dtFileTransactions = GetFileTransactionListAsync(lstStatusList, IsActive);
string connectionString = db.Database.GetDbConnection().ConnectionString;
var conn = new SqlConnection(connectionString);
string query = #"[SUTGITA].[GetFileListforProcessing]";
using (var sqlAdpt = new SqlDataAdapter(query, conn))
{
sqlAdpt.SelectCommand.CommandType = CommandType.StoredProcedure;
sqlAdpt.SelectCommand.Parameters.AddWithValue("#StatusId", string.Join(",", lstStatusList.Select(n => n.ToString()).ToArray()));
sqlAdpt.SelectCommand.Parameters.AddWithValue("#IsActive", IsActive);
sqlAdpt.SelectCommand.CommandTimeout = 60000;
DataTable dtFileTransactions = new DataTable();
sqlAdpt.Fill(dtFileTransactions);
if (dtFileTransactions != null && dtFileTransactions.Rows.Count > 0)
{
IEnumerable<long> ids = dtFileTransactions.AsEnumerable().ToList().Select(p => p["id"]).ToList().OfType<long>();
lstFTList = await db.FileTransaction.Include(x => x.File.Country).Where(x => ids.Contains(x.Id)).OrderBy(x => x.Id).ToListAsync();
}
}
}
return lstFTList;
}
catch (Exception ex)
{
throw ex;
}
}
public async Task<string> GetXMLResponse(string baseUrl, string fullFileName, int countryId, HttpClient client, FileOperations objFileOperation, string outputfilePath, FileTransaction item)
{
try
{
var fileData = new StringBuilder(objFileOperation.ReadFile(fullFileName));
using (HttpContent content = new StringContent(TransformToSOAPXml(fileData, countryId), Encoding.UTF8, "text/xml"))
{
using (HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, baseUrl))
{
request.Headers.Add("SOAPAction", "");
request.Content = content;
using (HttpResponseMessage response = await client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead))
{
response.EnsureSuccessStatusCode();
if (response.IsSuccessStatusCode)
{
using (Stream streamToReadFrom = await response.Content.ReadAsStreamAsync())
{
using (Stream streamToWriteTo = File.Open(outputfilePath, FileMode.Create))
{
await streamToReadFrom.CopyToAsync(streamToWriteTo);
}
}
var transactionEntry = new FileTransaction
{
FileId = item.FileId,
FilePath = outputfilePath,
ConvertedName = item.ConvertedName,
ActionedBy = Process.Process3,
TimeStamp = DateTime.UtcNow,
StatusId = objStatusManager.GetStatusIdbyName(Status.OutputXmlReceived),
IsActive = true,
CreatedBy = Others.Scheduler,
CreatedOn = DateTime.UtcNow,
ModifiedBy = Others.Scheduler,
ModifiedOn = DateTime.UtcNow
};
//Inserting the new record and Updating isActive filed of previous record in Tranasaction table(Calling updateDataonTRSuccess method of TRTaxXMLOperations class)
await updateDataonTRSuccessAsync(item, transactionEntry);
return "Success";
}
else
{
SerilogMethods.LogCustomException(log, "Error occured in Tax Engine", "GetXMLResponse");
//Log the SOAP response when the SOAP fails with an error message
if (response.Content != null)
{
throw new Exception(await response.Content.ReadAsStringAsync());
}
return null;
}
}
}
}
}
catch (Exception ex)
{
SerilogMethods.LogError(log, ex, "GetXMLResponse");
return null;
}
}
The following changes I have done to make it work to this specific method.
Removal of this line : objRespModel.strxmlResponse = await t;
and added configureawait(false) to this line :List lstFiletoProcess = await objTransManager.GetFileListforProcessingAsync(lstStatusIds, true).ConfigureAwait(false); Below is the working code
public async Task MainFileMethod()
{
List<FileTransaction> lstFTtoLock = new List<FileTransaction>();
try
{
List<int> lstStatusIds = new List<int>();
lstStatusIds.Add(objStatusManager.GetStatusIdbyName(Status.ConversionToXmlSucceded));
lstStatusIds.Add(objStatusManager.GetStatusIdbyName(Status.Reprocess));
//Getting the serviceURL of TRTaxEngine
string seriviceURL = objConfigManager.GetConfigurationdbyKey(ConfigurationList.TRTaxEngineURL);
//Getting the output path for the file to be placed after processing
string outputfilePath = objConfigManager.GetConfigurationdbyKey(ConfigurationList.TRTaxOutputXMLFolder);
FileMasterManager objFileMasterManager = new FileMasterManager();
TRTaxXMLOperations objxmlresp = new TRTaxXMLOperations();
//Getting all the files list for proccessing from the DB
List<FileTransaction> lstFiletoProcess = await objTransManager.GetFileListforProcessingAsync(lstStatusIds, true).ConfigureAwait(false);
lstFTtoLock = lstFiletoProcess;
if (lstFiletoProcess.Count == 0)
return;
if (lstFiletoProcess.Count > 0)
{
var tasks = new List<Task<string>>();
using (HttpClient httpClnt = new HttpClient())
{
httpClnt.Timeout = TimeSpan.FromMilliseconds(-1);
//Getting the files for processing
foreach (FileTransaction item in lstFiletoProcess)
{
TRXMLResponseModel objRespModel = new TRXMLResponseModel();
objRespModel.strxmlResponse = string.Empty;
string fullFileName = item.FilePath + item.ConvertedName;
objRespModel.outputFilename = outputfilePath + item.ConvertedName;
FileMaster fileMaster = objFileMasterManager.GetById(item.FileId);
//Proccessing the file and getting the output filedata
Task<string> t = objxmlresp.GetXMLResponse(seriviceURL, fullFileName, fileMaster.CountryId.GetValueOrDefault(), httpClnt, objFileOperation, objRespModel.outputFilename, item, objTransManager);
tasks.Add(t);
//objRespModel.strxmlResponse = await t;
}
var result = await Task.WhenAll(tasks);
}
}
}
catch (Exception Ex)
{
if (lstFTtoLock != null && lstFTtoLock.Count > 0)
{
objTransManager.UpdateFileTransactionIsPickedtoFalse(lstFTtoLock);
}
throw Ex;
}
}
My Recommendation:
The method "Get(int id)" is somewhat confusing. first, it takes "id" and does nothing with it. Also it return nothing so it is not a "Get" method. It is basically asking for all transactions with status "Status.ConversionToXmlSucceded" & "Status.Reprocess" and are active to be gotten and processed via the "objxmlresp.GetXMLResponse" method... You Dont Have To Await the "MainFileMethod();" in "Get(int id)" just return the task or return Ok(); and allow all the process to go on in the background. You can experiment with reducing the "sqlAdpt.SelectCommand.CommandTimeout = 60000;".
I am adding a new web API call to existing functionality. I want to make this API call async but looks like it is causing deadlock. I have to make a lot more changes if I want to make entire code channel async which is not possible.
Questions I have are:
Is it possible to call async method from regular method?
What am I missing here? OR What is the correct approach here?
Code:
// Exisitng Method
public Tuple<RestaurantDeliveryProvider, DeliveryHubResult, Task<DeliveryManagerQuoteResponse>> CreateDeliveryRequest(OrderContextDTO orderContextDto)
{
var provider = RestaurantBl.GetDeliveryProviderInformationByRestaurantId(orderContextDto.RestaurantId ?? 0);
var deliveryHubResult = RestaurantBl.GetDeliveryHubResult(orderContextDto.OrderId ?? 0);;
// New Call which always comes back with "Not Yet Computed" result
Task<DeliveryManagerQuoteResponse> deliveryManagerQuoteResponse = _deliveryManager.CreateQuoteRequestAsync(orderContextDto, orderInfo);
return Tuple.Create(provider, deliveryHubResult, deliveryManagerQuoteResponse);
}
Async Methods:
public async Task<DeliveryManagerQuoteResponse> CreateQuoteRequestAsync(OrderContextDTO orderContextDto, OrderInfoDTO orderInfo)
{
DeliveryManagerQuoteResponse deliveryManagerQuoteResponse = null;
try
{
var restaurantInfo = RestaurantApi.GetRestaurant(orderInfo.RestaurantId);
var quoteRequest = new DeliveryManagerQuoteRequest
{
DeliveryProvider = null,
Country = orderContextDto.DeliveryEstimateRequestDto.RequestedDeliveryAddress.Country,
Concept = "BK",
StoreName = "BK-TEST-US-4",
OrderId = orderInfo.OrderId.ToString(),
AllowCash = false,
PaymentType = OrderPaymentType.Prepaid_Credit,
Note = orderInfo.DeliveryInstructions,
};
deliveryManagerQuoteResponse = await Quote(quoteRequest);
}
catch (Exception ex)
{
Log.ErrorFormat("Get Delivery Manager Quote failed: Error: {0}, OrderId: {1}", ex.Message, orderContextDto.OrderId);
}
return deliveryManagerQuoteResponse;
}
public async Task<DeliveryManagerQuoteResponse> Quote(DeliveryManagerQuoteRequest quoteRequest)
{
DeliveryManagerQuoteResponse deliveryManagerQuoteResponse;
var client = HttpClientFactory.GetClient();
var content = HttpClientFactory.JsonContentFactory.CreateJsonContent(quoteRequest);
var response = await client.PostAsync("https://myUrl", content);
if (response.IsSuccessStatusCode)
{
var data = await response.Content.ReadAsStringAsync();
deliveryManagerQuoteResponse = JsonConvert.DeserializeObject<DeliveryManagerQuoteResponse>(data);
}
else
{
throw new Exception((int)response.StatusCode + "-" + response.StatusCode);
}
return deliveryManagerQuoteResponse;
}
I tried following as well but same result:
public async Task<DeliveryManagerQuoteResponse> Quote(DeliveryManagerQuoteRequest quoteRequest)
{
DeliveryManagerQuoteResponse deliveryManagerQuoteResponse;
using (var client = new HttpClient())
{
var content = HttpClientFactory.JsonContentFactory.CreateJsonContent(quoteRequest);
var response = await client.PostAsync("https://myUrl", content);
if (response.IsSuccessStatusCode)
{
var data = await response.Content.ReadAsStringAsync();
deliveryManagerQuoteResponse = JsonConvert.DeserializeObject<DeliveryManagerQuoteResponse>(data);
}
else
{
throw new Exception((int)response.StatusCode + "-" + response.StatusCode);
}
}
return deliveryManagerQuoteResponse;
}
Output (sorry for the blurry output, if you click on it, you will see clear result):
don't
don't
Basically, there is no good or workable way to call an async method from a sync method and wait for the answer. There's "sync over async", but that's an anti-pattern and should be aggressively avoided.
So either:
rewrite the caller to be async
implement a synchronous version of the API
I have a async task method which will be accessed on both foreground and background. In foreground, where user call this method via a button whereas in the background I have a timer triggering the method in some interval.
I tried put lock but it gives exception await can not be inside the lock statement.
public static async Task<CommonResult<IEnumerable<AttendanceDTO>>> DownloadAttendanceAsync(string selectedDate, int siteId)
{
try
{
if (new AttendanceBLL().IsLocalDataAvailable(siteId, DateTime.Parse(selectedDate)))
return new CommonResult<IEnumerable<AttendanceDTO>>() { IsSuccess = true, Data = null };
var queue = new EntityQueueBLL();
//var latestUpdatedOn = queue.GetMaxUpdated(siteId, EntityIDEnum.Attendance);
var url = string.Format(Constants.PathPullAttendance, selectedDate, siteId);
var result = await new HttpRequestClient().GetRequest<IEnumerable<AttendanceDTO>>(url);
if (!result.IsSuccess)
return new CommonResult<IEnumerable<AttendanceDTO>>() { IsSuccess = false, Data = null, ErrorMessage = result.ErrorMessage };
if (result.Data != null && result.Data.Count() > 0)
{
var maxUpdatedOn = result.Data.Max(x => DateTime.Parse(x.UpdatedOn));
queue.Add(siteId, result.Data, result.Data.Count(), EntityIDEnum.Attendance, EntityType.Attendance, maxUpdatedOn);
}
return new CommonResult<IEnumerable<AttendanceDTO>> { IsSuccess = true, Data = result.Data };
}
catch (Exception e)
{
return new CommonResult<IEnumerable<AttendanceDTO>> { IsSuccess = false, Data = null, ErrorMessage = "Download Error" };
}
}
I tried put lock but it gives exception await can not be inside the lock statement.
The await-compatible equivalent of lock is SemaphoreSlim:
private static SempahoreSlim _mutex = new SemaphoreSlim(1);
public static async Task<CommonResult<IEnumerable<AttendanceDTO>>> DownloadAttendanceAsync(string selectedDate, int siteId)
{
await _mutex.WaitAsync();
try
{
...
}
catch (Exception e)
{
return new CommonResult<IEnumerable<AttendanceDTO>> { IsSuccess = false, Data = null, ErrorMessage = "Download Error" };
}
finally
{
_mutex.Release();
}
}
I use
AsyncLazy
For my initialization, which can be called from different threads. The task is only called once and other callers wait for it.
try the below:
await Task.Delay(2000);
Yesterday I've found out how to create several async http requests without async/await. But today I need to do it in a loop: if some of responses don't satisfy some condition - I need to change a request for them and send these requests again. It may be repeated several times.
I've tried this code:
do
{
var loadingCoordinatesTasks = new List<Task<Terminal>>();
var totalCountOfTerminals = terminalPresetNode.ChildNodes.Count;
var uiTaskScheduler = TaskScheduler.FromCurrentSynchronizationContext();
foreach (var terminal in terminals.Except(_terminalsWithCoordinates))
{
var address = terminal.GetNextAddress();
var webRequest = (HttpWebRequest)WebRequest.Create(GeoCoder.GeoCodeUrl + address);
var webRequestTask = Task.Factory.FromAsync<WebResponse>(webRequest.BeginGetResponse,
webRequest.EndGetResponse,
terminal);
var parsingTask = webRequestTask.ContinueWith(antecedent =>
{
// Parse the response
});
loadingCoordinatesTasks.Add(parsingTask);
}
Task.Factory.ContinueWhenAll(loadingCoordinatesTasks.ToArray(), antecedents =>
{
foreach (var antecedent in antecedents)
{
var terminalWithCoordinates = antecedent.Result;
if (antecedent.Status == TaskStatus.RanToCompletion &&
!terminalWithCoordinates.Coordinates.AreUnknown)
{
_terminalsWithCoordinates.Add(terminalWithCoordinates);
_countOfProcessedTerminals++;
}
}
});
} while (_countOfProcessedTerminals < totalCountOfTerminals);
but is it possible to check the condition in while just after every single set of requests executed?
You can perform the check after increasing the count:
_countOfProcessedTerminals++;
if (_countOfProcessedTerminals >= totalCountOfTerminals)
{
break;
}
Is _countOfProcessedTerminals thread-safe though?
I manage to do it using recursion:
public void RunAgainFailedTasks(IEnumerable<Task<Terminal>> tasks)
{
Task.Factory.ContinueWhenAll(tasks.ToArray(), antecedents =>
{
var failedTasks = new List<Task<Terminal>>();
foreach (var antecedent in antecedents)
{
var terminal = antecedent.Result;
// Previous request was failed
if (terminal.Coordinates.AreUnknown)
{
string address;
try
{
address = terminal.GetNextAddress();
}
catch (FormatException) // No versions more
{
continue;
}
var getCoordinatesTask = CreateGetCoordinatesTask(terminal, address);
failedTasks.Add(getCoordinatesTask);
}
else
{
_terminalsWithCoordinates.Add(terminal);
}
}
if (failedTasks.Any())
{
RunAgainFailedTasks(failedTasks);
}
else
{
// Display a map
}
}, CancellationToken.None,
TaskContinuationOptions.None,
TaskScheduler.FromCurrentSynchronizationContext());
}
private Task<Terminal> CreateGetCoordinatesTask(Terminal terminal, string address)
{
var webRequest = (HttpWebRequest)WebRequest.Create(GeoCoder.GeoCodeUrl + address);
webRequest.KeepAlive = false;
webRequest.ProtocolVersion = HttpVersion.Version10;
var webRequestTask = Task.Factory.FromAsync<WebResponse>(webRequest.BeginGetResponse,
webRequest.EndGetResponse,
terminal);
var parsingTask = webRequestTask.ContinueWith(webReqTask =>
{
// Parse the response
});
return parsingTask;
}