Small perf wins inside MemoryCache

[ilmax]

Hi, I was looking at the caching code and I found some points which can be enhanced to avoid creating unnecessary objects. I'm referring to the class MemoryCache, the private field _entries can be a Dictionary<string, CacheEntry> instead of anIDictionary<string, CacheEntry> (since it's private and it's always initialized to a Dictionary<string, CacheEntry>) thus saving some unnecessary memory allocation when iterating over Keys and Values. Also the RemoveEntries method could be changed to accept a List instead of IEnumerable<CacheEntry> (since it's a private method always called with an instance of List<CacheEntry>) saving 1 object allocation when iterating over the list of entries. This change will also be consistent with the method ExpirePriorityBucket which already accept generic lists parameters.

It's not a huge improvement, but it's a fairly simple one at least IMHO.

Max.

[Eilon]

We generally do all our perf work based on specific measurements of various scenarios. Do you have an idea of what kind of realistic improvement there could be from this?

[justinvp]

FYI, I noticed these as well and went ahead and fixed them while making some other changes in #74.

[justinvp]

Fixed by #74. This can be closed.