C# 异步回调与等待机制全解

private TaskCompletionSource<string> _transTaskSource;
private TaskCompletionSource<bool> _transAviResultSource;
public bool TransResult{get;set;}
public string ImageFileName{get;set;}
private void OnAppMessageReceived(AppMessageEventArgs obj)
{
    if (obj.MessageId == "xxx")
    {
        Dictionary<string, object> dic = JsonHelper.Deserialize<Dictionary<string, object>>(obj.Value);
        if (dic["FileName"].ToString().Contains("avi"))
        {
            bool result = dic["Result"].ToString() == "1";
            _transAviResultSource?.TrySetResult(result);
        }
        else
        {
            string fileName = dic["FileName"].ToString();
            _transTaskSource?.TrySetResult(fileName);
        }
    }
}
protected virtual async Task<string> OnTransStandard(string fileFormat)
{
	switch (fileFormat)
    {
		case "avi":
			_transAviResultSource = new TaskCompletionSource<bool>();
			var result = _transService.Trans2Avi();
			var timeoutTask = Task.Delay(TimeSpan.FromSeconds(15));
			var completedTask = await Task.WhenAny(_transAviResultSource.Task, timeoutTask);
			if (completedTask == _transAviResultSource.Task)
			{
				TransResult = result;
			}
		break;
		default:
			_trasnTaskSource = new TaskCompletionSource<string>();
            _transService.Trans();
            var timeoutTask = Task.Delay(TimeSpan.FromSeconds(30), cancellationToken);
            var completedTask = await Task.WhenAny(_trasnTaskSource.Task, timeoutTask);
            if (completedTask == _trasnTaskSource.Task)
            {
                ImageFileName = await _trasnTaskSource.Task;
            }
            else
            {
                // TODO
            }
		break;
	}
}

using System.Collections.Concurrent;
// 使用字典支持并发，Key 为唯一标识（如文件名或请求ID）
private readonly ConcurrentDictionary<string, TaskCompletionSource<string>> _transTasks = new();
private readonly ConcurrentDictionary<string, TaskCompletionSource<bool>> _aviTasks = new();
private void OnAppMessageReceived(AppMessageEventArgs obj)
{
    if (obj.MessageId != "xxx") return;
    var dic = JsonHelper.Deserialize<Dictionary<string, object>>(obj.Value);
    string fileName = dic["FileName"]?.ToString() ?? string.Empty;
    if (fileName.Contains("avi"))
    {
        bool result = dic["Result"]?.ToString() == "1";
        // 尝试从字典中移除并设置结果，确保只处理一次
        if (_aviTasks.TryRemove(fileName, out var tcs))
        {
            tcs.TrySetResult(result);
        }
    }
    else
    {
        if (_transTasks.TryRemove(fileName, out var tcs))
        {
            tcs.TrySetResult(fileName);
        }
    }
}
protected virtual async Task<string> OnTransStandard(string fileFormat, string fileName)
{
    // 1. 设置超时取消令牌
    using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(fileFormat == "avi" ? 15 : 30));
    try
    {
        if (fileFormat == "avi")
        {
            var tcs = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
            _aviTasks[fileName] = tcs;
            _transService.Trans2Avi();
            // 使用 Register 绑定取消令牌到 TCS
            using (cts.Token.Register(() => tcs.TrySetCanceled()))
            {
                TransResult = await tcs.Task;
                return fileName;
            }
        }
        else
        {
            var tcs = new TaskCompletionSource<string>(TaskCreationOptions.RunContinuationsAsynchronously);
            _transTasks[fileName] = tcs;
            _transService.Trans();
            using (cts.Token.Register(() => tcs.TrySetCanceled()))
            {
                ImageFileName = await tcs.Task;
                return ImageFileName;
            }
        }
    }
    catch (OperationCanceledException)
    {
        // 统一处理超时逻辑
        HandleTimeout(fileName, fileFormat);
        return string.Empty;
    }
    finally
    {
        // 确保清理字典，防止内存泄漏
        _aviTasks.TryRemove(fileName, out _);
        _transTasks.TryRemove(fileName, out _);
    }
}

public bool TransResult { get; set; }
public string Filenames { get; set; }
private static readonly ManualResetEvent _event = new ManualResetEvent(false);
private void OnAppMessageReceived(AppMessageEventArgs obj)
{
    if (obj.MessageId == "xxx")
    {
        Dictionary<string, object> dic = JsonHelper.Deserialize<Dictionary<string, object>>(obj.Value);
        if (dic["FileName"].ToString().Contains("avi"))
        {
            TransResult = dic["Result"].ToString() == "1";
            _event.Set();
        }
        else
        {
            Filenames = dic["FileName"].ToString();
            _event.Set();
        }
    }
}
public virtual void OnDataTransformation()
{
	cancellationToken.ThrowIfCancellationRequested();
	_TranService.TransImage();
    _event.Reset();
    _event.WaitOne();
	cancellationToken.ThrowIfCancellationRequested();
}

// 这是一条死胡同，除非有人开门，否则车（线程）就停死在这里
_event.WaitOne();
// 只有开门后，才能跑这一行
DoNextStep();

// 这是一条路口，车（线程）发现红灯，就先掉头去干别的活了
await _tcs.Task;
// 绿灯亮了（SetResult），会有另一辆车（或原车）回来继续跑
DoNextStep();