c# - 是否有必要处置每个 ManagementObject？

Question

我注意到 ManagementObject 是 IDisposable，但它也是从 ManagementClass.GetInstances() 和 ManagementObjectSearcher.Get() 返回的，这是否意味着我需要处置遇到的每个对象？

像这样:

ManagementObject ret;
foreach(ManagementObject mo in searcher.Get()) {
    if( IsWhatIWant(mo) ) ret = mo;
    else mo.Dispose();
}

进一步混淆这一点:ManagementBaseObject 中存在一个错误，它没有正确实现 IDisposable(参见 Using clause fails to call Dispose?)，因此您需要自己调用它，或者使用正确调用它的包装器。

这很烦人，因为我周围有太多 ManagementObjectCollections。

Answer 1

我创建了一个辅助对象来处理所有创建的管理对象:

public class ManagementObjectDisposer : IDisposable
{
    private List<IDisposable> disposables = new List<IDisposable>();

    /// <summary>
    /// Workaround to dispose ManagementBaseObject properly.
    /// See http://stackoverflow.com/questions/11896282
    /// </summary>
    /// <param name="disposable"></param>
    public static void DisposeOne(IDisposable disposable)
    {
        ManagementBaseObject mbo = disposable as ManagementBaseObject;
        if (mbo != null)
            mbo.Dispose();
        else
            disposable.Dispose();
    }

    public void Dispose()
    {
        Exception firstException = null;
        foreach (IDisposable d in Enumerable.Reverse(disposables))
        {
            try
            {
                DisposeOne(d);
            }
            catch (Exception ex)
            {
                if (firstException == null)
                    firstException = ex;
                else
                    cvtLogger.GetLogger(this).Error($"Swallowing exception when disposing: {d.GetType()}", ex);
            }
        }
        disposables.Clear();
        if (firstException != null)
            throw firstException;
    }

    public T Add<T>(T disposable) where T : IDisposable
    {
        disposables.Add(disposable);
        return disposable;
    }

    /// <summary>
    /// Helper for ManagementObjectSearcher with adding all objects to the disposables.
    /// </summary>
    /// <param name="query">The query string.</param>
    public IEnumerable<ManagementBaseObject> Search(string query)
    {
        ManagementObjectSearcher searcher = this.Add(new ManagementObjectSearcher(query));
        return EnumerateCollection(searcher.Get());
    }

    /// <summary>
    /// Helper for adding ManagementObjectCollection and enumerating it.
    /// </summary>
    public IEnumerable<ManagementBaseObject> EnumerateCollection(ManagementObjectCollection collection)
    {
        this.Add(collection);
        ManagementObjectCollection.ManagementObjectEnumerator enumerator = this.Add(collection.GetEnumerator());
        while (enumerator.MoveNext())
            yield return this.Add(enumerator.Current);
    }
}

就像这样使用它:

using (var moDisposer = new ManagementObjectDisposer())
{
    foreach (var mobj = moDisposer.Search("SELECT * FROM Win32_Processor")
        Console.WriteLine(mobj["DeviceID"]);
}

注意:ManagementClass.GetInstances() 也很容易添加到 ManagementObjectDisposer。