FileDistributedLock is not thread safe

In heavy multithreading scenario (>10 parallel threads) 84. line throws System.UnauthorizedAccessException which is not properly caught.

 lockFileStream = new FileStream(this.Name, FileMode.OpenOrCreate, FileAccess.Read, FileShare.None, bufferSize: 1, FileOptions.DeleteOnClose);

Stack trace:

System.UnauthorizedAccessException
  HResult=0x80070005
  Message=Access to the path 'C:\Users\adamp\AppData\Local\Temp\execute_workflow_definitionZDIA7GR5FQLVK2GQ6WQSLQLW3FV3XHCL.lock' is denied.
  Source=System.Private.CoreLib
  StackTrace:
   at System.IO.FileStream.ValidateFileHandle(SafeFileHandle fileHandle)
   at System.IO.FileStream.CreateFileOpenHandle(FileMode mode, FileShare share, FileOptions options)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options)
   at Medallion.Threading.FileSystem.FileDistributedLock.TryAcquire(CancellationToken cancellationToken) in C:\Users\mikea_000\Documents\Interests\CS\DistributedLock\DistributedLock.FileSystem\FileDistributedLock.cs:line 84
   at Medallion.Threading.FileSystem.FileDistributedLock.<>c.<Medallion.Threading.Internal.IInternalDistributedLock<Medallion.Threading.FileSystem.FileDistributedLockHandle>.InternalTryAcquireAsync>b__10_0(FileDistributedLock this, CancellationToken token) in C:\Users\mikea_000\Documents\Interests\CS\DistributedLock\DistributedLock.FileSystem\FileDistributedLock.cs:line 58
   at Medallion.Threading.Internal.BusyWaitHelper.<WaitAsync>d__0`2.MoveNext() in C:\Users\mikea_000\Documents\Interests\CS\DistributedLock\DistributedLock.Core\Internal\BusyWaitHelper.cs:line 54
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at System.Runtime.CompilerServices.ConfiguredValueTaskAwaitable`1.ConfiguredValueTaskAwaiter.GetResult()
   at Medallion.Threading.Internal.Helpers.<Convert>d__1`2.MoveNext() in C:\Users\mikea_000\Documents\Interests\CS\DistributedLock\DistributedLock.Core\Internal\Helpers.cs:line 24
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at System.Runtime.CompilerServices.ConfiguredValueTaskAwaitable`1.ConfiguredValueTaskAwaiter.GetResult()
 

The exception is later caught, but only if a directory with the same name as the file already exists. You also need to catch this exception without any condition and return null as the result. (Tested on Windows 10.)

[Invenisso]

I can confirm that the error is no longer present when I use the new package. Thanks for fixing. 😃

[Invenisso]

@madelson Thank you for taking care of the problem! I will check your fix as soon as I get back to work on monday, because now I don’t have access to my environment.