Microsoft Enterprise Library Caching Application Block not thread safe?!
- by AlanR
Good aftenoon,
I created a super simple console app to test out the Enterprise Library Caching Application Block, and the behavior is blaffling. I'm hoping I screwed something that's easy to fix in the setup. Have each item expire after 5 seconds for testing purposes.
Basic setup -- "every second pick a number between 0 and 2. if the cache doesn't already have it, put it in there -- otherwise just grab it from the cache. Do this inside a LOCK statement to ensure thread safety.
APP.CONFIG:
<configuration>
<configSections>
<section name="cachingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Caching.Configuration.CacheManagerSettings, Microsoft.Practices.EnterpriseLibrary.Caching, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
</configSections>
<cachingConfiguration defaultCacheManager="Cache Manager">
<cacheManagers>
<add expirationPollFrequencyInSeconds="1" maximumElementsInCacheBeforeScavenging="1000"
numberToRemoveWhenScavenging="10" backingStoreName="Null Storage"
type="Microsoft.Practices.EnterpriseLibrary.Caching.CacheManager, Microsoft.Practices.EnterpriseLibrary.Caching, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
name="Cache Manager" />
</cacheManagers>
<backingStores>
<add encryptionProviderName="" type="Microsoft.Practices.EnterpriseLibrary.Caching.BackingStoreImplementations.NullBackingStore, Microsoft.Practices.EnterpriseLibrary.Caching, Version=4.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
name="Null Storage" />
</backingStores>
</cachingConfiguration>
</configuration>
C#:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Practices.EnterpriseLibrary.Common;
using Microsoft.Practices.EnterpriseLibrary.Caching;
using Microsoft.Practices.EnterpriseLibrary.Caching.Expirations;
namespace ConsoleApplication1
{
class Program
{
public static ICacheManager cache = CacheFactory.GetCacheManager("Cache Manager");
static void Main(string[] args)
{
while (true)
{
System.Threading.Thread.Sleep(1000); // sleep for one second.
var key = new Random().Next(3).ToString();
string value;
lock (cache)
{
if (!cache.Contains(key))
{
cache.Add(key, key, CacheItemPriority.Normal, null, new SlidingTime(TimeSpan.FromSeconds(5)));
}
value = (string)cache.GetData(key);
}
Console.WriteLine("{0} --> '{1}'", key, value);
//if (null == value) throw new Exception();
}
}
}
}
OUPUT -- How can I prevent the cache to returning nulls?
2 --> '2'
1 --> '1'
2 --> '2'
0 --> '0'
2 --> '2'
0 --> '0'
1 --> ''
0 --> '0'
1 --> '1'
2 --> ''
0 --> '0'
2 --> '2'
0 --> '0'
1 --> ''
2 --> '2'
1 --> '1'
Press any key to continue . . .
Thanks in advance,
-Alan.
