Dispose File stream and stream

Question

Hi,

Does I handle the dispose in correct way ?

Note: This line contentStream.CopyTo(fileStream); can take long time.

I got contentStream here from download file from our website.

var zipPathForFolderOrPathForFile = $"{innerFolderPath}\{fileNameResults}";

// Create the file from stream in destination

var fileStream = File.Create(zipPathForFolderOrPathForFile);

contentStream.CopyTo(fileStream);

fileStream.Dispose();

contentStream.Dispose();

Answer 1

Hi @Dani_S , Welcome to Microsoft Q&A,

The using statement ensures that resources are automatically closed and released after execution is complete, without the need to explicitly call the Dispose() method. This not only makes the code more concise, but also ensures that resources are properly released even in the event of an exception.

If contentStream.CopyTo(fileStream) may take a long time to run, consider using an asynchronous method to avoid blocking the thread.

Before creating the file, make sure the destination directory exists.

using System.IO;
using System.Threading.Tasks;

// Ensure the directory exists
Directory.CreateDirectory(innerFolderPath);

var zipPathForFolderOrPathForFile = $"{innerFolderPath}\\{fileNameResults}";

using (var fileStream = File.Create(zipPathForFolderOrPathForFile))
{
await contentStream.CopyToAsync(fileStream);
}

// Close and release contentStream
await contentStream.DisposeAsync();

Best Regards,

Jiale

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Answer 2

The better, easier and more safe way iis to use the "suing" directive for disposable objects, see

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/using-directive

Answer 3

No your code is not exception safe. Exception safe code means that anything that must run is guaranteed to run even if an exception occurs and, at any point in the code, it stops running the rest of the function. In your case explicit calls to Dispose may never execute if any earlier line happens to fail because of an exception.

While this can be resolved using a try-finally, for IDisposable implementations (such as Stream) you should use the using statement. The syntax depends on the version of .NET you're running. The full syntax that is always supported looks like this:

var zipPathForFolderOrPathForFile = $"{innerFolderPath}\{fileNameResults}";

using (var fileStream = File.Create(zipPathForFolderOrPathForFile))
{
   contentStream.CopyTo(fileStream);
};  //fileStream is automatically disposed at this point irrelevant of errors

Note that fileStream is scoped to the using block to make it clear when it gets cleaned up. If you're using NET 6+ then you can use a simpler syntax.

var zipPathForFolderOrPathForFile = $"{innerFolderPath}\{fileNameResults}";

using var fileStream = File.Create(zipPathForFolderOrPathForFile);

contentStream.CopyTo(fileStream);

//fileStream is automatically disposed when the current block goes away

They are functionally equivalent. Note that contentStream is not cleaned up here because it isn't clear how you got it. If it was passed to you as a parameter then the caller is responsible for cleaning up that stream. If you got it as the return value of a method you called inside this block of code then you need to wrap it in a using as well.

using (var contentStream = Whatever()) {
   var zipPathForFolderOrPathForFile = $"{innerFolderPath}\{fileNameResults}";

   using (var fileStream = File.Create(zipPathForFolderOrPathForFile))
   {
      contentStream.CopyTo(fileStream);
   };   //fileStream is automatically disposed at this point irrelevant of errors
};  //contentStream is automatically disposed at this point irrelevant of errors

Or in newer versions the simpler.

using var contentStream = Whatever();

var zipPathForFolderOrPathForFile = $"{innerFolderPath}\{fileNameResults}";

using var fileStream = File.Create(zipPathForFolderOrPathForFile);

contentStream.CopyTo(fileStream);

//fileStream and contentStream are automatically disposed when the current block goes away