/// <summary>
/// Wrap all IO operations on setting files with this function to avoid file-in-use errors
/// </summary>
private void ExecuteSynchronized(Action ioOperation)
{
var fileName = _fileSystem.GetFullPath(_fileName);
// Global: ensure mutex is honored across TS sessions
using (var mutex = new Mutex(false, "Global\\" + MutexNamingHelper.GenerateUniqueToken(fileName)))
{
var owner = false;
try
{
// operations on NuGet.config should be very short lived
owner = mutex.WaitOne(TimeSpan.FromMinutes(1));
// decision here is to proceed even if we were not able to get mutex ownership
// and let the potential IO errors bubble up. Reasoning is that failure to get
// ownership probably means faulty hardware and in this case it's better to report
// back than hang
ioOperation();
}
finally
{
if (owner)
{
mutex.ReleaseMutex();
}
}
}
}
/// <remarks>
/// We use this method instead of the "safe" methods in FileSystem because it attempts to retry multiple times with delays.
/// In our case, if we are unable to perform IO over the machine cache, we want to quit trying immediately.
/// </remarks>
private bool TryAct(Func <bool> action, string path)
{
try
{
// Global: machine cache is per user across TS sessions
var mutexName = "Global\\" + MutexNamingHelper.GenerateUniqueToken(FileSystem.GetFullPath(path) ?? path);
using (var mutex = new Mutex(false, mutexName))
{
bool owner = false;
try
{
try
{
owner = mutex.WaitOne(TimeSpan.FromMinutes(3));
// ideally we should throw an exception here if !owner such as
// throw new TimeoutException(string.Format("Timeout waiting for Machine Cache mutex for {0}", fullPath));
// we decided against it: machine cache operations being "best effort" basis.
// this may cause "File in use" exceptions for long lasting operations such as downloading a large package on
// a slow network connection
}
catch (AbandonedMutexException)
{
// TODO: consider logging a warning; abandonning a mutex is an indication something wrong is going on
owner = true; // now mine
}
return(action());
}
finally
{
if (owner)
{
mutex.ReleaseMutex();
}
}
}
}
catch (IOException)
{
}
catch (UnauthorizedAccessException)
{
// Do nothing if this fails.
}
return(false);
}