C# 如果在X分钟内没有新项目进入“通道”,如何读取小于批量大小的“通道”中的剩余项目

C# 如果在X分钟内没有新项目进入“通道”,如何读取小于批量大小的“通道”中的剩余项目,c#,asp.net-core,system.threading.channels,C#,Asp.net Core,System.threading.channels,我正在使用System.Threading.Channels中的Channel,希望批量读取项目(5项),我有如下方法 public class Batcher { private readonly Channel<MeasurementViewModel> _channel; public Batcher() { _channel = Channel.CreateUnbounded<MeasurementViewModel>();

我正在使用
System.Threading.Channels
中的
Channel
,希望批量读取项目(5项),我有如下方法

public class Batcher
{
    private readonly Channel<MeasurementViewModel> _channel;
    public Batcher()
    {
        _channel = Channel.CreateUnbounded<MeasurementViewModel>();
    }
    public async Task<MeasurementViewModel[]> ReadBatchAsync(int batchSize, CancellationToken stoppingToken)
    {
        var result = new MeasurementViewModel[batchSize];

        for (var i = 0; i < batchSize; i++)
        {
            result[i] = await _channel.Reader.ReadAsync(stoppingToken);
        }

        return result;
    }
}
public class WriterService : BackgroundService
{
    private readonly Batcher _batcher;
    public WriterService(Batcher batcher)
    {
        _batcher = batcher;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            var batchOfItems = await _batcher.ReadBatchAsync(5, stoppingToken);

            var range = string.Join(',', batchOfItems.Select(item => item.Value));

            var x = range;
        }
    }
}
这是有效的,每当
频道中有5个项目时,我就会得到
范围

问题是,当
频道中只剩下2个项目时,由于过去10分钟没有项目进入
频道,那么如何读取
频道中剩余的2个项目?

您可以创建一个
取消令牌源
,这样您就可以同时监视外部取消请求,以及内部引发的超时。下面是通过为类创建
ReadBatchAsync
扩展方法来使用此技术的示例:


先生,你让我高兴极了。非常好,非常感谢!!!!
public static async ValueTask<T[]> ReadBatchAsync<T>(
    this ChannelReader<T> channelReader,
    int batchSize, TimeSpan timeout, CancellationToken cancellationToken = default)
{
    // Arguments validation omitted
    var items = new List<T>(batchSize);
    using (var linkedCTS
        = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken))
    {
        linkedCTS.CancelAfter(timeout);
        while (true)
        {
            var token = items.Count == 0 ? cancellationToken : linkedCTS.Token;
            T item;
            try
            {
                item = await channelReader.ReadAsync(token).ConfigureAwait(false);
            }
            catch (OperationCanceledException)
            {
                cancellationToken.ThrowIfCancellationRequested();
                break; // The cancellation was induced by timeout (ignore it)
            }
            catch (ChannelClosedException)
            {
                if (items.Count == 0) throw;
                break;
            }
            items.Add(item);
            if (items.Count >= batchSize) break;
        }
    }
    return items.ToArray();
}
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
    while (true)
    {
        MeasurementViewModel[] batch;
        try
        {
            batch = await _channel.Reader.ReadBatchAsync(
                5, TimeSpan.FromMinutes(10), stoppingToken);
        }
        catch (OperationCanceledException) { return; }
        catch (ChannelClosedException) { break; }

        Console.WriteLine(String.Join(',', batch.Select(item => item.Value)));
    }
    await _channel.Reader.Completion; // Propagate possible failure
}