private async Task <MutexOperationResult> ForceClearIfTimeoutExpired()
{
var result = new MutexOperationResult();
try
{
var file = await GetFile();
if (file != null)
{
var currentTime = DateTime.Now;
var fileTimeStamp = file.DateCreated;
if ((currentTime - fileTimeStamp).TotalMilliseconds > TIMEOUT_MSEC * 2)
{
var cleared = await ClearAsync();
result.Combine(cleared);
Debug.WriteLine("-------Force clear: " + cleared.ToString());
}
}
else
{
result.Result = MutexOperationResultEnum.Free;
}
}
catch
{
result.Result = MutexOperationResultEnum.ExceptionFileSystem | MutexOperationResultEnum.FailToClear;
}
return(result);
}
public async Task <MutexOperationResult> AcquireAsync(int milliseconds = 0)
{
var result = new MutexOperationResult();
StorageFile file = null;
try
{
file = await GetFile();
}
catch
{
result.Result = MutexOperationResultEnum.ExceptionFileSystem;
return(result);
}
if (file == null)
{
try
{
result.Result = MutexOperationResultEnum.Free;
var key = Guid.NewGuid().ToString();
file = await Folder.CreateFileAsync(FILE);
await FileIO.WriteTextAsync(file, key);
result.AcquisitionKey = key;
result.Result = MutexOperationResultEnum.Acquired;
SetDeferredMutexRelease(result); // Will launch task which release mutex when timeout
}
catch (Exception)
{
result.Result = MutexOperationResultEnum.ExceptionFileSystem;
}
}
else
{
// First attempt to intercept mutex: force clear if mutex Acquired longer then TIMEOUT
var forcedCleared = await ForceClearIfTimeoutExpired();
if (forcedCleared.ResultIs(MutexOperationResultEnum.Cleared))
{
var forcedAcquired = await AcquireAsync();
result.Combine(forcedCleared);
result.Combine(forcedAcquired);
return(result);
}
// Second attempt to intercept mutex: await specifyed delay
if (milliseconds >= 1000)
{
for (var i = 0; i < Math.Min(milliseconds, TIMEOUT_MSEC) / 1000; i++) // There is no need to wait longer then TIMEOUT,
// if mutex not released it indicates greater failure
{
await Task.Delay(1000);
var delayedAcquired = await AcquireAsync();
result.Combine(delayedAcquired);
if (delayedAcquired.ResultIs(MutexOperationResultEnum.Acquired))
{
return(result);
}
}
result.Result = MutexOperationResultEnum.FailToAcquire;
}
}
return(result);
}