/// <summary>
/// Increments lock counter on a lock flag and returns <see cref="IDisposable"/> object.
/// </summary>
/// <param name="lockHolder">Reference to a field of type <see cref="DisposableLock"/> containing a flag to lock. If it is null, it will be initialized with new instance of DisposableLock.</param>
/// <param name="unlockAction">Optional action, that will be called when returned <see cref="IDisposable"/> object is disposed, and lock is unlocked. This action will not be called if lock is still locked.</param>
/// <returns>Instance of <see cref="IDisposable"/>, disposing of which will decrease lock counter on <see cref="lockHolder"/> and call <see cref="unlockAction"/> if lock is unlocked.</returns>
public static IDisposable Lock(ref DisposableLock lockHolder, Action unlockAction = null)
{
if (lockHolder == null)
{
lockHolder = new DisposableLock();
}
lockHolder.Counter++;
var lockHolderLocalReference = lockHolder; // ref variables cannot be passed to anonymous methods.
return(new DisposableAction(() =>
{
if (--lockHolderLocalReference.Counter == 0)
{
unlockAction?.Invoke();
}
}));
}
/// <summary>
/// Checks if lock holder is locked.
/// </summary>
/// <param name="disposableLock"><see cref="DisposableLock"/> object, can be null.</param>
/// <returns>True if <see cref="disposableLock"/> is not null and <see cref="DisposableLock.Counter"/> is more then 0. Otherwise returns False.</returns>
public static bool IsLocked(this DisposableLock disposableLock)
{
return(DisposableLock.IsLockedInternal(disposableLock));
}
/// <summary>
/// Checks if lock holder is locked.
/// </summary>
/// <param name="lockHolder"><see cref="DisposableLock"/> object, can be null.</param>
/// <returns>True if <see cref="lockHolder"/> is not null and <see cref="Counter"/> is more then 0. Otherwise returns False.</returns>
internal static bool IsLockedInternal(DisposableLock lockHolder)
{
return(lockHolder?.Counter > 0);
}
