Awesome.
-----Original Message-----
From: Discussion of advanced .NET topics.
[mailto:[EMAIL PROTECTED] On Behalf Of Stoyan Damov
Sent: Monday, July 09, 2007 2:51 AM
To: [email protected]
Subject: Re: [ADVANCED-DOTNET] C# Singleton; foot in mouth
> protected static I Provider
> {
> if (_provider == null)
> {
> lock (_syncLock)
> {
> if (provder = null)
> provider =
> Activator.createfromconfig(...);
> }
> }
> return _provider;
> }
>
> But, that is a double-check lock, and I would need to document that at
least
> the BaseManager.Provider property is thread safe.
>
Yes, but your DCL is broken. However, if you rewrite it like this:
if (provider_ == null)
{
lock (syncLock_)
{
if (provider_ == null)
{
I instance = Activator....
Thread.MemoryBarrier(); // so that any out-of-order writes
complete[1]
provider_ = instance;
}
}
}
it will become thread-safe.
Cheers,
Stoyan
[1] I think I've read this a couple of years ago in Brad Abrams blog.
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