/// <summary>
/// Signals the given item to the observer in a serialized fashion
/// allowing a concurrent OnError or OnCompleted emission to be delayed until
/// the observer.OnNext returns.
/// Do not call OnNext from multiple threads as it may lead to ignored items.
/// Use a full SerializedObserver wrapper for merging multiple sequences.
/// </summary>
/// <typeparam name="T">The element type of the observer.</typeparam>
/// <param name="sink">The observer to signal events in a serialized fashion.</param>
/// <param name="item">The item to signal.</param>
/// <param name="wip">Indicates there is an emission going on currently.</param>
/// <param name="error">The field containing an error or terminal indicator.</param>
public static void ForwardOnNext <T>(ISink <T> sink, T item, ref int wip, ref Exception?error)
{
if (Interlocked.CompareExchange(ref wip, 1, 0) == 0)
{
sink.ForwardOnNext(item);
if (Interlocked.Decrement(ref wip) != 0)
{
var ex = error !; // NB: A concurrent OnError or OnCompleted will either set Terminated or the original exception, so never null here.
if (ex != ExceptionHelper.Terminated)
{
error = ExceptionHelper.Terminated;
sink.ForwardOnError(ex);
}
else
{
sink.ForwardOnCompleted();
}
}
}
#if !NO_TRACE
else if (error == null)
{
Trace.TraceWarning("OnNext called while another OnNext call was in progress on the same Observer.");
}
#endif
}
/// <summary>
/// Signals the given item to the observer in a serialized fashion
/// allowing a concurrent OnError or OnCompleted emission to be delayed until
/// the observer.OnNext returns.
/// Do not call OnNext from multiple threads as it may lead to ignored items.
/// Use a full SerializedObserver wrapper for merging multiple sequences.
/// </summary>
/// <typeparam name="T">The element type of the observer.</typeparam>
/// <param name="sink">The observer to signal events in a serialized fashion.</param>
/// <param name="item">The item to signal.</param>
/// <param name="wip">Indicates there is an emission going on currently.</param>
/// <param name="error">The field containing an error or terminal indicator.</param>
public static void ForwardOnNext <T>(ISink <T> sink, T item, ref int wip, ref Exception error)
{
if (Interlocked.CompareExchange(ref wip, 1, 0) == 0)
{
sink.ForwardOnNext(item);
if (Interlocked.Decrement(ref wip) != 0)
{
var ex = error;
if (ex != ExceptionHelper.Terminated)
{
error = ExceptionHelper.Terminated;
sink.ForwardOnError(ex);
}
else
{
sink.ForwardOnCompleted();
}
}
}
#if (HAS_TRACE)
else if (error == null)
{
Trace.TraceWarning("OnNext called while another OnNext call was in progress on the same Observer.");
}
#endif
}
/// <summary>
/// Signals the given exception to the observer. If there is a concurrent
/// OnNext emission is happening, saves the exception into the given field
/// otherwise to be picked up by <see cref="ForwardOnNext{T}"/>.
/// This method can be called concurrently with itself and the other methods of this
/// helper class but only one terminal signal may actually win.
/// </summary>
/// <typeparam name="T">The element type of the observer.</typeparam>
/// <param name="sink">The observer to signal events in a serialized fashion.</param>
/// <param name="ex">The exception to signal sooner or later.</param>
/// <param name="wip">Indicates there is an emission going on currently.</param>
/// <param name="error">The field containing an error or terminal indicator.</param>
public static void ForwardOnError <T>(ISink <T> sink, Exception ex, ref int wip, ref Exception error)
{
if (ExceptionHelper.TrySetException(ref error, ex))
{
if (Interlocked.Increment(ref wip) == 1)
{
error = ExceptionHelper.Terminated;
sink.ForwardOnError(ex);
}
}
}
/// <summary>
/// Signals the given item to the observer in a serialized fashion
/// allowing a concurrent OnError or OnCompleted emission to be delayed until
/// the observer.OnNext returns.
/// Do not call OnNext from multiple threads as it may lead to ignored items.
/// Use a full SerializedObserver wrapper for merging multiple sequences.
/// </summary>
/// <typeparam name="T">The element type of the observer.</typeparam>
/// <param name="sink">The observer to signal events in a serialized fashion.</param>
/// <param name="item">The item to signal.</param>
/// <param name="wip">Indicates there is an emission going on currently.</param>
/// <param name="error">The field containing an error or terminal indicator.</param>
public static void ForwardOnNext <T>(ISink <T> sink, T item, ref int wip, ref Exception error)
{
if (Interlocked.CompareExchange(ref wip, 1, 0) == 0)
{
sink.ForwardOnNext(item);
if (Interlocked.Decrement(ref wip) != 0)
{
var ex = error;
if (ex != ExceptionHelper.Terminated)
{
error = ExceptionHelper.Terminated;
sink.ForwardOnError(ex);
}
else
{
sink.ForwardOnCompleted();
}
}
}
}