WCF方法共享一本字典 [英] WCF methods sharing a dictionary

问题描述

我要创建一个WCF服务库和我有一个关于线程安全食用该库中的方法的问题，以下是完整的实现，我到现在为止。

I'm creating a WCF Service Library and I have a question regarding thread-safety consuming a method inside this library, here is the full implementation that I have until now.

namespace WCFConfiguration
{
    [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall, ConcurrencyMode = ConcurrencyMode.Single)]
    public class ConfigurationService : IConfigurationService
    {
        ConcurrentDictionary<Tuple<string,string>, string> configurationDictionary = new ConcurrentDictionary<Tuple<string,string>, string>();

        public void Configuration(IEnumerable<Configuration> configurationSet)
        {
            Tuple<string, string> lookupStrings;
            foreach (var config in configurationSet)
            {
                lookupStrings = new Tuple<string, string>(config.BoxType, config.Size);
                configurationDictionary.TryAdd(lookupStrings, config.RowNumber);
            }
        }

        public void ScanReceived(string boxType, string size, string packerId = null)
        {

        }
    }
}

想象一下，我有一个10价值观在我的configurationDictionary，很多人想查询该字典消费ScanReceived方法，是指那些10值来为每个请求ScanReceived客户共享？我需要改变我的ServiceBehavior？

Imagine that I have a 10 values in my configurationDictionary and many people want to query this dictionary consuming ScanReceived method, are those 10 values be shared for each of the clients that request ScanReceived? Do I need to change my ServiceBehavior?

的配置方法只消耗一个人的方式。

The Configuration method is only consumed by one person by the way.

推荐答案

随着 InstanceContextMode PerCall 你应该让每一个远程电话打进来时（这我假设将是要么配置（）或 ScanReceived您服务，你的字典的新实例（））。这不会分享 configurationDictionary 多个客户端之间。

With an InstanceContextMode of PerCall you should get a new instance of your service and your dictionary every time a remote call comes in (which I'm assuming will be either Configuration() or ScanReceived()). This won't share configurationDictionary between multiple clients.

随着 ConcurrencyMode 单你永远只能有跑路的code单线程任何一个时间。因此，并发的任何问题都没有实际意义。

With a ConcurrencyMode of Single you'll only ever have a single thread running your code at any one time. So any issues of concurrency are moot.

两种方式来分享 configurationDictionary ：

1. 请为静态：私人只读静态ConcurrentDictionary＆LT; ...＆GT; ...
2. 更改 InstanceContextMode ，可能你的 ConcurrencyMode 。

1. Make it static: private readonly static ConcurrentDictionary<...> ...
2. Change your InstanceContextMode, and possibly your ConcurrencyMode.

我建议第一个选项，如果你不希望数以千计的电话，以每秒为您服务。

I'd recommend the first option if you're not expecting thousands of calls to your service per second.

MSDN有关于 InstanceContextMode 和一些信息< A HREF =htt​​p://msdn.microsoft.com/en-us/library/ms752230.aspx相对=nofollow>服务类的实例化。

MSDN has some information about InstanceContextMode and instancing of service classes.

如果您更改为 InstanceContextMode.Single 和 ConcurrencyMode.Multiple 你可以得到许多线程同时执行，你将需要担心同步访问。

If you change to InstanceContextMode.Single and ConcurrencyMode.Multiple you can get many threads executing at once and you will need to worry about synchronised access.

最主要的是要注意的是，当你查询/迭代在你的字典里，别人可能会修改。拼抢字典的快照，然后查询快照应该解决这个问题：

The main thing to watch out for is that when you're querying / iterating over your dictionary, someone else might modify it. Grabbing a snapshot of the dictionary and then querying the snapshot should get around that problem:

foreach (var x in configurationDictionary.ToArray())
{
     ....
}

或者，如果你使用LINQ：

Or, if you're using LINQ:

var someResult = configurationDictionary.ToArray().Where(...).Select(...)

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