c# - 专注于性能的 ObservableDictionary 的替代方案

Question

我正在开发的 C# 应用程序使用 ObservableDictionary。其性能还不够快，无法满足其功能。 ObservableDictionary 的交互速度非常快(删除、添加和更新元素)，并且每次发生更改时都必须进行排序。我可以使用 ObservableDictionary 的替代方案来关注性能并且仍然能够快速排序吗？

Answer 1

编写自己的代码非常简单，不会在每次添加/更新或删除完成时重新绑定(bind)。正是因为这个原因，我们编写了自己的版本。本质上，我们所做的就是禁用已进行更改的通知，直到处理了集合中的所有对象，然后生成通知。它看起来像这样。正如您所看到的，我们使用 MvvmLight 作为我们的 MVVM 框架库。这将极大地提高性能。

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.Linq;
using FS.Mes.Client.Mvvm.MvvmTools.MvvmLight;

namespace FS.Mes.Client.Mvvm.MvvmTools
{
    /// <summary>
    /// Our implementation of ObservableCollection. This fixes one significant limitation in the .NET Framework implementation. When items
    /// are added or removed from an observable collection, the OnCollectionChanged event is fired for each item. Depending on how the collection
    /// is bound, this can cause significant performance issues. This implementation gets around this by suppressing the notification until all
    /// items are added or removed. This implementation is also thread safe. Operations against this collection are always done on the thread that
    /// owns the collection.
    /// </summary>
    /// <typeparam name="T">Collection type</typeparam>
    public class FsObservableCollection<T> : ObservableCollection<T>
    {
        #region [Constructor]
        /// <summary>
        /// Constructor
        /// </summary>
        public FsObservableCollection()
        {
            DispatcherHelper.Initialize();
        }
        #endregion

        #region [Public Properties]
        /// <summary>
        /// Gets or sets a property that determines if we are delaying notifications on updates.
        /// </summary>
        public bool DelayOnCollectionChangedNotification { get; set; }
        #endregion

        /// <summary>
        /// Add a range of IEnumerable items to the observable collection and optionally delay notification until the operation is complete.
        /// </summary>
        /// <param name="items"></param>
        /// <param name="delayCollectionChangedNotification">Value indicating whether delay notification will be turned on/off</param>
        public void AddRange(IEnumerable<T> items, bool delayCollectionChangedNotification = true)
        {
            if (items == null)
                throw new ArgumentNullException("items");

            DoDispatchedAction(() =>
            {
                DelayOnCollectionChangedNotification = delayCollectionChangedNotification;

                // Do we have any items to add?
                if (items.Any())
                {
                    try
                    {
                        foreach (var item in items)
                            this.Add(item);
                    }
                    finally
                    {
                        // We're done. Turn delay notification off and call the OnCollectionChanged() method and tell it we had a 'dramatic' change
                        // in the collection.
                        DelayOnCollectionChangedNotification = false;
                        this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
                    }
                }
            });
        }

        /// <summary>
        /// Clear the items in the ObservableCollection and optionally delay notification until the operation is complete.
        /// </summary>
        public void ClearItems(bool delayCollectionChangedNotification = true)
        {
            // Do we have anything to remove?
            if (!this.Any())
                return;

            DoDispatchedAction(() =>
            {
                try
                {
                    DelayOnCollectionChangedNotification = delayCollectionChangedNotification;

                    this.Clear();
                }
                finally
                {
                    // We're done. Turn delay notification off and call the OnCollectionChanged() method and tell it we had a 'dramatic' change
                    // in the collection.
                    DelayOnCollectionChangedNotification = false;
                    this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
                }
            });
        }

        /// <summary>
        /// Override the virtual OnCollectionChanged() method on the ObservableCollection class.
        /// </summary>
        /// <param name="e">Event arguments</param>
        protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
        {
            DoDispatchedAction(() =>
            {
                if (!DelayOnCollectionChangedNotification)
                    base.OnCollectionChanged(e);
            });
        }

        /// <summary>
        /// Makes sure 'action' is executed on the thread that owns the object. Otherwise, things will go boom.
        /// </summary>
        ///<param name="action">The action which should be executed</param>
        private static void DoDispatchedAction(Action action)
        {
            DispatcherHelper.CheckInvokeOnUI(action);
        }
    }
}