public class AsyncThrottle
{
    // 信号量控制并发数
    private readonly SemaphoreSlim _semaphore;

    public AsyncThrottle(int maxParallelism)
    {
        if (maxParallelism <= 0)
            throw new ArgumentOutOfRangeException(nameof(maxParallelism), "并行数必须大于0");
        _semaphore = new SemaphoreSlim(maxParallelism);
    }

    // 执行异步操作，支持取消
    public async Task ExecuteAsync(Func<Task> action, CancellationToken ct = default)
    {
        // 等待信号量，支持取消
        await _semaphore.WaitAsync(ct);
        try
        {
            // 执行异步操作
            await action();
        }
        finally
        {
            // 释放信号量，避免泄漏
            _semaphore.Release();
        }
    }

    // 重载：支持有返回值的异步操作
    public async Task<TResult> ExecuteAsync<TResult>(Func<Task<TResult>> action, CancellationToken ct = default)
    {
        await _semaphore.WaitAsync(ct);
        try
        {
            return await action();
        }
        finally
        {
            _semaphore.Release();
        }
    }
}