/// <summary>
/// Sets all of the given switch points into the invalid state.
/// After this call executes, no thread will observe any of the
/// switch points to be in a valid state.
/// <para>
/// This operation is likely to be expensive and should be used sparingly.
/// If possible, it should be buffered for batch processing on sets of switch points.
/// </para>
/// <para>
/// If {@code switchPoints} contains a null element,
/// a {@code NullPointerException} will be raised.
/// In this case, some non-null elements in the array may be
/// processed before the method returns abnormally.
/// Which elements these are (if any) is implementation-dependent.
///
/// <p style="font-size:smaller;">
/// <em>Discussion:</em>
/// For performance reasons, {@code invalidateAll} is not a virtual method
/// on a single switch point, but rather applies to a set of switch points.
/// Some implementations may incur a large fixed overhead cost
/// for processing one or more invalidation operations,
/// but a small incremental cost for each additional invalidation.
/// In any case, this operation is likely to be costly, since
/// other threads may have to be somehow interrupted
/// in order to make them notice the updated switch point state.
/// However, it may be observed that a single call to invalidate
/// several switch points has the same formal effect as many calls,
/// each on just one of the switch points.
///
/// <p style="font-size:smaller;">
/// <em>Implementation Note:</em>
/// Simple implementations of {@code SwitchPoint} may use
/// a private <seealso cref="MutableCallSite"/> to publish the state of a switch point.
/// In such an implementation, the {@code invalidateAll} method can
/// simply change the call site's target, and issue one call to
/// <seealso cref="MutableCallSite#syncAll synchronize"/> all the
/// private call sites.
///
/// </para>
/// </summary>
/// <param name="switchPoints"> an array of call sites to be synchronized </param>
/// <exception cref="NullPointerException"> if the {@code switchPoints} array reference is null
/// or the array contains a null </exception>
public static void InvalidateAll(SwitchPoint[] switchPoints)
{
if (switchPoints.Length == 0)
{
return;
}
MutableCallSite[] sites = new MutableCallSite[switchPoints.Length];
for (int i = 0; i < switchPoints.Length; i++)
{
SwitchPoint spt = switchPoints[i];
if (spt == null) // MSC.syncAll will trigger a NPE
{
break;
}
sites[i] = spt.Mcs;
spt.Mcs.Target = K_false;
}
MutableCallSite.SyncAll(sites);
}
/// <summary>
/// Creates a new switch point.
/// </summary>
public SwitchPoint()
{
this.Mcs = new MutableCallSite(K_true);
this.McsInvoker = Mcs.DynamicInvoker();
}
