Entity Framework的这种实现是否会泄漏内存？

Question

当在web应用程序或控制台应用程序中的using语句中使用实体上下文时，我无法确定实体上下文是否被放置在使用流中。

谢谢!

using System;
using System.Web;

namespace Foo.Model
{
    public partial class FooEntities : ObjectContext
    {
        private const string CurrentContextKey = "FooEntities.Current";

        [ThreadStatic]
        private static FooEntities _currentOnThreadStatic;
        private FooEntities _previousContext;

        /// <summary>
        /// Gets the current <see cref="FooEntities"/> instance, if an instance can be shared in the current context.
        /// </summary>
        /// <remarks>
        /// The current context is stored in the HTTP context, if it is available (otherwise it is stored in a thread-static instance).
        /// Multiple contexts can be stacked.
        /// </remarks>
        public static FooEntities Current
        {
            get
            {
                if (HttpContext.Current != null)
                {
                    return HttpContext.Current.Items[CurrentContextKey] as FooEntities;
                }
                else
                {
                    return _currentOnThreadStatic;
                }
            }

            private set
            {
                if (HttpContext.Current != null)
                {
                    HttpContext.Current.Items[CurrentContextKey] = value;
                }
                else
                {
                    _currentOnThreadStatic = value;
                }
            }
        }

        /// <summary>
        /// Returns a repository instance bound to this object context.
        /// </summary>
        /// <typeparam name="TRepository">The type of repository to instantiate.</typeparam>
        /// <returns>The repository instance.</returns>
        public TRepository GetRepository<TRepository>()
            where TRepository: BaseRepository
        {
            return (TRepository) Activator.CreateInstance(typeof(TRepository), this);
        }

        /// <summary>
        /// Ensures that an ambient context is available through <see cref="Current"/>, throwing an exception otherwise.
        /// </summary>
        /// <exception type="InvalidOperationException)">
        /// Thrown if <see cref="Current"/> is null.
        /// </exception>
        public static void EnsureContext()
        {
            if (Current == null)
            {
                throw new InvalidOperationException("An ambient FooEntities context is expected.");
            }
        }

        /// <summary>
        /// Releases the context instance.
        /// </summary>
        /// <param name="disposing"></param>
        protected override void Dispose(bool disposing)
        {
            Current = _previousContext;
            base.Dispose(disposing);
        }

        /// <summary>
        /// Is called by all constructors.
        /// </summary>
        partial void OnContextCreated()
        {
            _previousContext = Current;
            Current = this;
        }
    }
}

Answer 1

这是一个奇怪的设计。正如@Joel C在他的评论中指出的那样，你应该将对象上下文视为一个短暂的对象，当你需要它时创建它，然后立即释放它。

但我看不出这会泄漏内存的原因。您只需处理托管资源，并且始终对HttpContext使用相同的密钥，因此不会从头到尾创建新对象。