Method cancellation by user input or no response
The website I work on allows users to generate reports between two dates selected by the user. The problem I'm running into is that if a user accidentally requests a report between a huge difference between dates, i.e. one year, the server is under a lot of pressure and can sometimes crash for all users. What I should do is have some kind of progress bar showing the user how long it will take from the report, and a cancel button or button to check if they are all there. I have searched for using an assignment undo token but not sure if this is what I want. also thought of a globally linked list with random numbers associated with true false as a user can open many reports at the same time. I've included some of the relevant code below.I would appreciate any help or point in the right direction, thanks
// java script which is passed from and dated and calls genonereport method
window.open('genonereport?idd=' + idd + '&fromm=' +
fromm + '&too=' + too + '&filetype=' + outputValue ,
'_blank');
// genonereport passes the values to the class below, which contains the corresponding method --- report.render, which is the method I want to cancel if the user cancels the report or leaves
public byte[] genReportBytes(int id, string fromm, string too, string filetype)
{
reportDetails repD = new reportDetails();
repD = getOneReport(id);
LocalReport report = new LocalReport();
if (fromm != null)
repD.ParametersCommandLine = "@startdate=" + fromm;
if (too != null)
repD.ParametersCommandLine += " @enddate=" + too;
string RDLCPath = ConfigurationManager.AppSettings["RDLCPath"];
string ReportOutputPath = ConfigurationManager.AppSettings["ReportOutputPath"];
string RDLCName = repD.RDLCName;
RDLCPath += @"\" + RDLCName;
report.ReportPath = RDLCPath;
string sqlGet = repD.SQLOfReport;
report.DataSources.Add(new ReportDataSource(repD.DatasetName, getReportData(sqlGet, repD.ParametersCommandLine)));
// export to byte array
Warning[] warnings;
string[] streamids;
string mimeType;
string encoding;
string filenameExtension;
string deviceInf = "";
byte[] bytes = new byte[64];
byte[] empty = null;
string extension;
bool Completed;
if (filetype == "pdf")
{
deviceInf = "<DeviceInfo><PageHeight>8.5in</PageHeight><PageWidth>11in</PageWidth><MarginLeft>0in</MarginLeft><MarginRight>0in</MarginRight></DeviceInfo>";
//fileName = ReportOutputPath + @"\" + repD.NameOfOutputPDF + ".PDF";
//Completed = ExecuteWithTimeLimit(TimeSpan.FromMilliseconds(5000), () =>
//{
bytes = report.Render("pdf", deviceInf, out mimeType, out encoding, out filenameExtension,
out streamids, out warnings);
//});
}
else
{
//fileName = ReportOutputPath + @"\" + repD.NameOfOutputPDF + ".XLS";
//Completed = ExecuteWithTimeLimit(TimeSpan.FromMilliseconds(5000), () =>
//{
bytes = report.Render(
"Excel");
//});
}
//if (Completed == true)
//{
return bytes;
//}
//else
//return empty;
}
// I got this far, but it only gets canceled after a certain amount of time, which is not good for me.
public static bool ExecuteWithTimeLimit(TimeSpan timeSpan, Action codeBlock)
{
try
{
Task task = Task.Factory.StartNew(() => codeBlock());
task.Wait(timeSpan);
return task.IsCompleted;
}
catch (AggregateException ae)
{
throw ae.InnerExceptions[0];
}
}
Sorry for the long term question, thanks again
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You will need at least three web endpoints:
- one to generate a report and return results
- one that your Javascript can periodically request to check progress.
- which your browser may request to cancel the task.
You will need to store the descriptor of each task in a dictionary with some kind of ID, so you can pass the ID to requests 2 and 3.
This article gives you an example on how to do this.
It's not easy, so limiting the report size that users can generate may be preferable.
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