Does this implementation of the Entity Framework l

问题:

I just can't make out if the entity context is disposed in the usage flow when used in a using statement in a web application or a console application.

Thanks!

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;
        }
    }
}

回答1:

It is an odd design. As @Joel C points out in his comment you should regard the object context as a shortlived object that you create when you need it and release right afterwards.

But I see no reason that this would leak memory. You are only dealing with managed resources and you are using the same key all the time to the HttpContext so you won't create new objects all over.