/// <summary>
/// Tries to propagate completion from the reader to the writer.
/// </summary>
/// <typeparam name="T">The type of the items in the reader and writer.</typeparam>
/// <param name="reader">The reader.</param>
/// <param name="writer">The writer.</param>
/// <param name="passthroughError"><see langword="true"/> - passthrough error, <see langword="false"/> - mute error.</param>
/// <returns>true, if completion was propagated, false otherwise.</returns>
public static bool TryPropagateCompletion <T>(
this IChannelReader <T> reader,
IChannelWriter <T> writer,
bool passthroughError = true)
{
VxArgs.NotNull(reader, nameof(reader));
VxArgs.NotNull(writer, nameof(writer));
if (reader.Completion.IsCompleted)
{
Exception error = null;
try
{
reader.Completion.GetAwaiter().GetResult();
}
catch (Exception ex)
{
if (passthroughError)
{
error = ex;
}
}
return(writer.TryComplete(error));
}
return(false);
}
/// <summary>
/// Performs copy processing from the reader to the writer.
/// </summary>
/// <typeparam name="T">The type of the items to copy.</typeparam>
/// <param name="reader">The source.</param>
/// <param name="writer">The target.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>Async execution TPL task.</returns>
public static async Task Copy <T>(
this IChannelReader <T> reader,
IChannelWriter <T> writer,
CancellationToken cancellationToken = default,
ChannelCompletionPassthroughProc producerCompletionPassthroughProc = null,
ChannelCompletionPassthroughProc consumerCompletionPassthroughProc = null,
Func <T, ValueTask> handleLostItemsProc = null)
{
VxArgs.NotNull(reader, nameof(reader));
VxArgs.NotNull(writer, nameof(writer));
CancellationToken readCancellationToken = cancellationToken;
if (producerCompletionPassthroughProc == null)
{
producerCompletionPassthroughProc = (error, isFromChannel) =>
{
writer.TryComplete(error);
return(new ValueTask());
};
}
if (consumerCompletionPassthroughProc == null)
{
consumerCompletionPassthroughProc = (error, isFromChannel) =>
{
reader.TryComplete(error);
return(new ValueTask());
};
}
Exception handlersError = null;
try
{
while (true)
{
T item;
try
{
if (!reader.TryRead(out item))
{
if (!await reader.WaitToReadAsync(readCancellationToken))
{
Exception error = null;
try
{
await reader.Completion;
}
catch (Exception ex)
{
error = ex;
}
finally
{
try
{
await producerCompletionPassthroughProc(error);
}
catch (Exception ex)
{
handlersError = ex;
}
}
return;
}
else
{
continue;
}
}
}
catch (Exception error)
{
try
{
await producerCompletionPassthroughProc(error, false);
}
catch (Exception ex)
{
handlersError = ex;
}
return;
}
// Trying to write, until target closed, or cancellation raised.
while (true)
{
try
{
if (writer.TryWrite(item))
{
break;
}
if (!await writer.WaitToWriteAsync(readCancellationToken))
{
if (handleLostItemsProc != null)
{
try
{
await handleLostItemsProc(item);
}
catch (Exception ex)
{
handlersError = ex;
}
}
Exception error = null;
try
{
await writer.Completion;
}
catch (Exception ex)
{
error = ex;
}
finally
{
try
{
await consumerCompletionPassthroughProc(error);
}
catch (Exception ex)
{
handlersError = ex;
}
}
return;
}
}
catch (Exception error)
{
try
{
if (handleLostItemsProc != null)
{
try
{
await handleLostItemsProc(item);
}
catch (Exception ex)
{
handlersError = ex;
}
}
}
finally
{
try
{
await consumerCompletionPassthroughProc(error, false);
}
catch (Exception ex)
{
handlersError = ex;
}
}
return;
}
}
}
}
finally
{
if (handlersError != null)
{
throw handlersError;
}
}
}
