C#实现单线程异步互斥锁的示例代码

bool _lock = false;

_lock=true;

_lock=false;

var tcs = new TaskCompletionSource();

return tcs.Task;

tcs.SetResult();

Queue<TaskCompletionSource> _queue = new Queue<TaskCompletionSource>();

_queue.Enqueue(tcs);

_queue.Dequeue().SetResult();

/// <summary>
/// 异步锁，非线程锁，只能用于单线程异步环境中。
/// </summary>
class AsyncMutex
{
    Queue<TaskCompletionSource> _queue = new Queue<TaskCompletionSource>();
    bool _lock = false;
    /// <summary>
    /// 获取锁
    /// </summary>
    /// <returns>返回Task，await后即进入了锁</returns>
    public Task Acquire()
    {
        if (_lock)
        {
            var tcs = new TaskCompletionSource();
            _queue.Enqueue(tcs);
            return tcs.Task;
        }
        _lock = true;
        return Task.CompletedTask;
    }
    /// <summary>
    /// 尝试获取锁
    /// 因为是单线程环境，重复调用需要切换上下文，否则是无法成功的。
    /// 比如可以await Task.Delay(30);
    /// </summary>
    /// <returns>是否成功</returns>
    public bool TryAcquire()
    {
        if (_lock) return false;
        return _lock = true;
    }
    /// <summary>
    /// 释放锁
    /// </summary>
    public void Release()
    {
        if (_queue.Count > 0)
        {
            _queue.Dequeue().SetResult();
        }
        else
        {
            _lock = false;
        }
    }
}

AsyncMutex _mtx = new AsyncMutex();
async void test()
{
    await _mtx.Acquire();
    //custom code
    _mtx.Release();
}

AsyncMutex _mtx = new AsyncMutex();
void test()
{
    if (_mtx.TryAcquire())
    {
        //custom code
        _mtx.Release();
    }
}

AsyncMutex _mtx = new AsyncMutex();
async void test()
{
    //超时等待300ms
    bool isLock = false;
    for (int i = 0; i < 10; i++)
    {
        if (isLock = _mtx.TryAcquire()) break;
        await Task.Delay(30);
    }
    if (isLock)
    {
        //custom code
        _mtx.Release();
    }
}

async void test(int num)
{
    Console.WriteLine("enter " + num);
    //模拟异步操作
    await Task.Delay(10);
    Console.WriteLine("exit " + num);
}
//.net 6.0
test(1);
test(2);
test(3);

AsyncMutex _mtx = new AsyncMutex();
async void test(int num)
{
    await _mtx.Acquire();
    Console.WriteLine("enter " + num);
    //模拟异步操作
    await Task.Delay(10);
    Console.WriteLine("exit " + num);
    _mtx.Release();
}
//.net 6.0
test(1);
test(2);
test(3);