Serve large file async and then delete it - async-await

Question

Using Web API 2, I have a process that generates a temporary file for the purpose of writing it to the output stream for client consumption. The process can be somewhat long running, taking a few minutes to complete.
What I'd like to do is serve the file asynchronously and then delete it upon completion or cancellation (connection timeout).
Would something like this be close? I haven't tested yet, but I'm wondering of the continue will delete the file before it's served entirely.
public class FileCreationResult
{
public String FilePathOut { get; set; }
}
public class MyFileCreationProcess{
const string NaiveDefaultTempFilePath = #"c:\temp\mytempfile.bin";
public FileCreationResult Execute(){
// do stuff that makes a file
File.WriteAllBytes(NaiveDefaultTempFilePath, NaiveDefaultTempFilePath);
return new FileCreationResult{
FilePathOut = NaiveDefaultTempFilePath
};
}
}
public class Controller : ApiController
{
private readonly MyFileCreationProcess process;
public Controller(MyFileCreationProcess process)
{
this.process = process;
}
public async Task<HttpResponse> GetFile(CancellationToken cancellationToken){
return await Task.Run(()=>{
var fileCreationResult = process.Execute();
using( var stream = File.OpenRead(fileCreationResult.FilePathOut)){
var response = Request.CreateResponse();
response.Content = new StreamContent( stream);
return response;
//
// I would like to delete the file at path fileCreationResult.FilePathOut
// after it has been written to the output stream..
// how would I do this ?
}
});
}
}

Answer 1

You can probably just get away with a try finally block
public async Task<HttpResponse> GetFile(CancellationToken cancellationToken){
return await Task.Run(()=>{
var fileCreationResult = process.Execute();
try{
using( var stream = File.OpenRead(fileCreationResult.FilePathOut)){
var response = Request.CreateResponse();
response.Content = new StreamContent( stream);
return response;
}
}finally{
if(File.Exists(fileCreationResult.FilePathOut))
{
File.Delete(fileCreationResult.FilePathOut);
}
}
});
}
or if you want to use continueWith:
public Task<HttpResponse> GetFile(CancellationToken cancellationToken){
string path;
return Task.Run(()=>{
var fileCreationResult = process.Execute();
path = fileCreationResult.FilePathOut;
using( var stream = File.OpenRead(path)){
var response = Request.CreateResponse();
response.Content = new StreamContent( stream);
return response;
}
}).ContinueWith(x=>{
if(File.Exists(fileCreationResult.FilePathOut))
{
File.Delete(fileCreationResult.FilePathOut);
}
});
}
I should note I don't have a C# compiler handy so it may not compile but I think you get the point.