MemoryCache线程安全，是否需要锁定?

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问题描述

对于初学者，让我把它扔在那里，我知道下面的代码不是线程安全的(更正:可能).我正在努力寻找的是一种实现，而我实际上可能会在测试中失败.我现在正在重构一个大型WCF项目，该项目需要一些(主要是)静态数据进行缓存，并从SQL数据库中进行填充.它需要至少每天一次过期并刷新"，这就是为什么我要使用MemoryCache.

For starters let me just throw it out there that I know the code below is not thread safe (correction: might be). What I am struggling with is finding an implementation that is and one that I can actually get to fail under test. I am refactoring a large WCF project right now that needs some (mostly) static data cached and its populated from a SQL database. It needs to expire and "refresh" at least once a day which is why I am using MemoryCache.

我知道下面的代码不应该是线程安全的，但是我不能让它在繁重的工作下失败，而且使Google搜索显示两种实现方式的问题变得复杂化(带锁和不带锁以及是否需要锁的辩论.)

I know that the code below should not be thread safe but I cannot get it to fail under heavy load and to complicate matters a google search shows implementations both ways (with and without locks combined with debates whether or not they are necessary.

能在多线程环境中拥有MemoryCache知识的人让我明确知道是否需要在适当的地方锁定，以便在检索过程中不会引发对remove的调用(很少调用，但这是必需的)重新填充.

Could someone with knowledge of MemoryCache in a multi threaded environment let me definitively know whether or not I need to lock where appropriate so that a call to remove (which will seldom be called but its a requirement) will not throw during retrieval/repopulation.

public class MemoryCacheService : IMemoryCacheService
{
    private const string PunctuationMapCacheKey = "punctuationMaps";
    private static readonly ObjectCache Cache;
    private readonly IAdoNet _adoNet;

    static MemoryCacheService()
    {
        Cache = MemoryCache.Default;
    }

    public MemoryCacheService(IAdoNet adoNet)
    {
        _adoNet = adoNet;
    }

    public void ClearPunctuationMaps()
    {
        Cache.Remove(PunctuationMapCacheKey);
    }

    public IEnumerable GetPunctuationMaps()
    {
        if (Cache.Contains(PunctuationMapCacheKey))
        {
            return (IEnumerable) Cache.Get(PunctuationMapCacheKey);
        }

        var punctuationMaps = GetPunctuationMappings();

        if (punctuationMaps == null)
        {
            throw new ApplicationException("Unable to retrieve punctuation mappings from the database.");
        }

        if (punctuationMaps.Cast<IPunctuationMapDto>().Any(p => p.UntaggedValue == null || p.TaggedValue == null))
        {
            throw new ApplicationException("Null values detected in Untagged or Tagged punctuation mappings.");
        }

        // Store data in the cache
        var cacheItemPolicy = new CacheItemPolicy
        {
            AbsoluteExpiration = DateTime.Now.AddDays(1.0)
        };

        Cache.AddOrGetExisting(PunctuationMapCacheKey, punctuationMaps, cacheItemPolicy);

        return punctuationMaps;
    }

    //Go oldschool ADO.NET to break the dependency on the entity framework and need to inject the database handler to populate cache
    private IEnumerable GetPunctuationMappings()
    {
        var table = _adoNet.ExecuteSelectCommand("SELECT [id], [TaggedValue],[UntaggedValue] FROM [dbo].[PunctuationMapper]", CommandType.Text);
        if (table != null && table.Rows.Count != 0)
        {
            return AutoMapper.Mapper.DynamicMap<IDataReader, IEnumerable<PunctuationMapDto>>(table.CreateDataReader());
        }

        return null;
    }
}

MemoryCache线程安全

MemoryCache线程安全，是否需要锁定?

问题描述

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