如何锁定具有相同ID的对象？ [英] How to lock objects withthe same ids?

问题描述

我有以下代码：

public void Update(Foo foo)
{
    lock(_locker) 
    {
        UpdateFirstPart(foo.First);
        UpdateSecondPart(foo.Second);
        UpdateThirdPart(foo.Third);
    }
} 

public class Foo 
{
    public int Id;

    public Some1 First;  

    public Some2 Second; 

    public Some3 Third; 
}

方法更新可以在两个或多个线程中执行，我使用 lock 来防止 foo 出现货币问题。但是我只想锁定具有 Id 相似的 Foo 。例如，如果一个线程使用Foo.Id = 1执行方法 Update ，而另一个线程使用Foo.Id =执行 Update 2然后不需要 lock ，并且如果两个线程使用两个实例 Foo 和相同的 Id ，锁是必需的。是否可以创建这样的锁？

Method Update can be performed in two or more threads and I use lock to prevent cuncurency problems with foo. But I would like to lock only those Foo that have similar Id. For instance if one thread executes method Update with Foo.Id = 1 and another thread executes Update with Foo.Id = 2 then lock is not needed and if two threads execute Update with two instances Foo with the same Id, lock is needed. Is it possible to create a such lock?

推荐答案

您可以使用此类为每个ID获取一个锁定对象：

You could use this class to get a lock object for every Id:

public class MultiLockObjects<TKey>
{
    private readonly ConcurrentDictionary<TKey, Object>  _multiLocker = new ConcurrentDictionary<TKey, Object>();

    public Object this[TKey key]
    {
        get
        {
            Object lockObj = _multiLocker.GetOrAdd(key, tKey => new Object());
            return lockObj;
        }
    }
}

然后持有它的一个实例

private MultiLockObjects<int> _idLocks = new MultiLockObjects<int>();

用法很简单：

public void Update(Foo foo)
{
    Object idLockObject = _idLocks[foo.Id];
    lock (idLockObject)
    {
        UpdateFirstPart(foo.First);
        UpdateSecondPart(foo.Second);
        UpdateThirdPart(foo.Third);
    }
}

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