I've got the following extension
Public Module CacheExtensions
Sub New()
End Sub
Private sync As New Object()
Public Const DefaultCacheExpiration As Integer = 1200 ''# 20 minutes
<Extension()>
Public Function GetOrStore(Of T)(ByVal cache As Cache, ByVal key As String, ByVal generator As Func(Of T)) As T
Return cache.GetOrStore(key, If(generator IsNot Nothing, generator(), Nothing), DefaultCacheExpiration)
End Function
<Extension()>
Public Function GetOrStore(Of T)(ByVal cache As Cache, ByVal key As String, ByVal generator As Func(Of T), ByVal expireInSeconds As Double) As T
Return cache.GetOrStore(key, If(generator IsNot Nothing, generator(), Nothing), expireInSeconds)
End Function
<Extension()>
Public Function GetOrStore(Of T)(ByVal cache As Cache, ByVal key As String, ByVal obj As T) As T
Return cache.GetOrStore(key, obj, DefaultCacheExpiration)
End Function
<Extension()>
Public Function GetOrStore(Of T)(ByVal cache As Cache, ByVal key As String, ByVal obj As T, ByVal expireInSeconds As Double) As T
Dim result = cache(key)
If result Is Nothing Then
SyncLock sync
If result Is Nothing Then
result = If(obj IsNot Nothing, obj, Nothing)
cache.Insert(key, result, Nothing, DateTime.Now.AddSeconds(expireInSeconds), cache.NoSlidingExpiration)
End If
End SyncLock
End If
Return DirectCast(result, T)
End Function
End Module
From here, I'm using the extension is a TagService to get a list of tags
Public Function GetTagNames() As List(Of String) Implements Domain.ITagService.GetTags
''# We're not using a dynamic Cache key because the list of TagNames
''# will persist across all users in all regions.
Return HttpRuntime.Cache.GetOrStore(Of List(Of String))("TagNamesOnly",
Function() _TagRepository.Read().Select(Function(t) t.Name).OrderBy(Function(t) t).ToList())
End Function
All of this is pretty much straight forward except when I put a breakpoint on _TagRepository.Read(). The problem is that it is getting called on every request, when I thought that it is only to be called when Result Is Nothing
Am I missing something here?
