原标题：使用Nito.AsyncEx实现异步锁
Lock是常用的同步锁，但是我们无法在Lock的内部实现异步调用，比如我们无法使用await.
以下面的代码为例，当你在lock内部使用await时，VS会报错提醒。
最简单的解决办法就是使用第三方的库Nito.AsyncEx。可以通过Nuget安装。
通过AsyncLock就可以在锁的内部实现异步操作了。
样例代码如下：
public class AsyncLockDemo
{
//private readonly object _mutex = new object();
private readonly AsyncLock _mutex = new AsyncLock();
private int i = 0;
public void Execute()
{
Console.WriteLine("before call foo1: "+ i);
Foo1().ContinueWith(new Action(t =>
{
Console.WriteLine("foo1 completed: " + i);
}));
Console.WriteLine("after call foo1: " + i);
Console.WriteLine("before call foo2: " + i);
Foo2().ContinueWith(new Action(t =>
{
Console.WriteLine("foo2 completed: " + i);
}));
Console.WriteLine("after call foo2: " + i);
}
public async Task Foo1()
{
using (await _mutex.LockAsync())
{
await Task.Delay(TimeSpan.FromSeconds(1));
Console.WriteLine("Foo1 start: " + i);
await DoSomethingAsync(1);
Console.WriteLine("Foo1 end: " + i);
}
}
public async Task Foo2()
{
using (await _mutex.LockAsync())
{
Console.WriteLine("Foo2 start: " + i);
//await Task.Delay(TimeSpan.FromSeconds(1));
await DoSomethingAsync(2);
Console.WriteLine("Foo2 end: " + i);
}
}
private Task DoSomethingAsync(int j)
{
return Task.Run(() =>
{
Thread.Sleep(2000);
i = j;
});
}
}
运行结果如下：
