实体框架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在使用流程中进行了处理。

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，您应该将对象上下文视为您在需要时创建并在之后立即释放的短暂对象。

但我看不出这会泄漏内存的原因。您只处理托管资源，并且始终使用相同的密钥来访问 HttpContext，因此您不会创建新对象。