Question

在.Net 4.5项目中，我使用一种简单的实用工具方法以线程安全的方式记忆结果（实际上是一个Web应用程序）：

public static class FuncUtilities
{
    public static Func<TArg, TResult> ThreadsafeMemoize<TArg, TResult>(Func<TArg, TResult> f)
    {
        var cache = new ConcurrentDictionary<TArg, TResult>();

        return arg => cache.GetOrAdd(arg, f);
    }

    public static Func<TArg, TArg2, TResult> ThreadsafeMemoize<TArg, TArg2, TResult>(Func<TArg, TArg2, TResult> f)
    {
        var cache = new ConcurrentDictionary<Tuple<TArg, TArg2>, TResult>();
        return (arg, arg2) =>
        {
            var key = new Tuple<TArg, TArg2>(arg, arg2);
            return cache.GetOrAdd(key, f(arg, arg2));
        };
    }

    public static Func<TArg, TArg2, TArg3, TResult> ThreadsafeMemoize<TArg, TArg2, TArg3, TResult>(Func<TArg, TArg2, TArg3, TResult> f)
    {
        var cache = new ConcurrentDictionary<Tuple<TArg, TArg2, TArg3>, TResult>();
        return (arg, arg2, arg3) =>
        {
            var key = new Tuple<TArg, TArg2, TArg3>(arg, arg2, arg3);
            return cache.GetOrAdd(key, f(arg, arg2, arg3));
        };
    }
}

在另一个项目中，必须以3.5运行，我有相同的记忆结果的要求。

如何将我的代码移植到.Net 3.5？

我found partial port of the class，但它缺少GetOrAdd方法，所以我尝试自己实现它：

public class ConcurrentDictionary<TKey, TValue>
{
    private readonly object _Padlock = new object();

    private readonly Dictionary<TKey, TValue> _Dictionary = new Dictionary<TKey, TValue>();

    public TValue this[TKey key]
    {
        get { lock (_Padlock) { return _Dictionary[key]; } }
        set { lock (_Padlock) { _Dictionary[key] = value; } }
    }

    public bool TryGetValue(TKey key, out TValue value)
    {
        lock (_Padlock)
        {
            return _Dictionary.TryGetValue(key, out value);
        }
    }

    public TValue GetOrAdd(TKey key, Func<TKey, TValue> factory)
    {
        lock (_Padlock)
        {
            if (!_Dictionary.ContainsKey(key))
            {
                _Dictionary.Add(key, factory(key));
            }
            return _Dictionary[key];
        }
    }
}

我还必须＆＃34;模拟＆＃34;嵌套Tuple

的KeyValuePair课程

public static class FuncUtilities
{
    public static Func<TArg, TResult> ThreadsafeMemoize<TArg, TResult>(Func<TArg, TResult> f)
    {
        var cache = new ConcurrentDictionary<TArg, TResult>();

        return arg => cache.GetOrAdd(arg, f);
    }

    public static Func<TArg, TArg2, TResult> ThreadsafeMemoize<TArg, TArg2, TResult>(Func<TArg, TArg2, TResult> f)
    {
        var cache = new ConcurrentDictionary<KeyValuePair<TArg, TArg2>, TResult>();
        return (arg, arg2) =>
        {
            var key = new KeyValuePair<TArg, TArg2>(arg, arg2);
            return cache.GetOrAdd(key, f(arg, arg2));
        };
    }

    public static Func<TArg, TArg2, TArg3, TResult> ThreadsafeMemoize<TArg, TArg2, TArg3, TResult>(Func<TArg, TArg2, TArg3, TResult> f)
    {
        var cache = new ConcurrentDictionary<KeyValuePair<KeyValuePair<TArg, TArg2>, TArg3>, TResult>();
        return (arg, arg2, arg3) =>
        {
            var key = new KeyValuePair<KeyValuePair<TArg, TArg2>, TArg3>(new KeyValuePair<TArg, TArg2>(arg, arg2), arg3);
            return cache.GetOrAdd(key, f(arg, arg2, arg3));
        };
    }
}

不幸的是，这不会编译：

1＆GT; C：\一些\ FuncUtilities.cs（29,24,29,57）：错误CS1502：最佳重载方法匹配＆＃39; some.ConcurrentDictionary，TResult＆GT; .GetOrAdd（System.Collections.Generic.KeyValuePair， System.Func，TResult＆GT;）＆＃39; 有一些无效的论点 1 GT; C：\一些\ FuncUtilities.cs（29,44,29,56）：错误CS1503：参数2：无法转换为＆＃39; TResult＆＃39;至＆＃39; System.Func，TResult＆GT;＆＃39; 1 GT; C：\一些\ FuncUtilities.cs（39,24,39,63）：错误CS1502：最佳重载方法匹配＆＃39; some.ConcurrentDictionary，TArg3＆GT;，＆TResult GT; .GetOrAdd（System.Collections.Generic.KeyValuePair，TArg3＆gt;中 System.Func，TArg3＆GT;，＆TResult GT;）＆＃39; 有一些无效的论点 1 GT; C：\一些\ FuncUtilities.cs（39,44,39,62）：错误CS1503：参数2：无法转换为＆＃39; TResult＆＃39;至＆＃39; System.Func，TArg3＆GT;，＆TResult GT;＆＃39;

试图在3.5项目中实现ConcurrentDictionary.GetOrAdd

0 个答案: