如何修復 Windows-API-Code-Pack 中的 ArgumentException？

Question

我創建了一個應用程序，該應用程序使用此包中的 Windows-API-Code-Pack 從文件中讀取屬性。 我在檢索屬性時遇到問題

var width = fileInfo.Properties.GetProperty(SystemProperties.System.Video.FrameWidth).ValueAsObject;

代碼在這里中斷給我

System.ArgumentException: An item with the same key has already been added.
   at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at Microsoft.WindowsAPICodePack.Shell.PropertySystem.ShellPropertyFactory.GenericCreateShellProperty[T](PropertyKey propKey, T thirdArg)
   at Microsoft.WindowsAPICodePack.Shell.PropertySystem.ShellProperties.GetProperty(PropertyKey key)

這主要發生在在 PLINQ 中調用這部分代碼時

.AsParallel().WithDegreeOfParallelism(_maxConcurrentThreads).ForAll(...)

即使度數設置為1。我該如何解決？

Answer 1

為了擴展您現有的答案，將 Dictionary 切換到 ConcurrentDictionary 也可以解決問題並消除對鎖的需要。

    private static ConcurrentDictionary<int, Func<PropertyKey, ShellPropertyDescription, object, IShellProperty>> _storeCache
        = new ConcurrentDictionary<int, Func<PropertyKey, ShellPropertyDescription, object, IShellProperty>>();
...

    private static IShellProperty GenericCreateShellProperty<T>(PropertyKey propKey, T thirdArg)
    {
       ...

        Func<PropertyKey, ShellPropertyDescription, object, IShellProperty> ctor;
        ctor = _storeCache.GetOrAdd((hash, (key, args) -> {
            Type[] argTypes = { typeof(PropertyKey), typeof(ShellPropertyDescription), args.thirdType };
            return ExpressConstructor(args.type, argTypes);
        }, {thirdType, type});

        return ctor(propKey, propDesc, thirdArg);
    }

Answer 2

按照stuartd 的建議，我能夠通過修改包的源代碼並在第 57 行和第 62 行的代碼中添加鎖來解決這個問題，就像這樣

lock (_storeCache)
{
    if (!_storeCache.TryGetValue(hash, out ctor))
    {
        Type[] argTypes = { typeof(PropertyKey), typeof(ShellPropertyDescription), thirdType };
        ctor = ExpressConstructor(type, argTypes);
        lock (_storeCache)
            _storeCache.Add(hash, ctor);
    }
}