added user caching

src/BirdsiteLive.Twitter/CachedTwitterService.cs

@@ -0,0 +1,52 @@
+using System;
+using BirdsiteLive.Twitter.Models;
+using Microsoft.Extensions.Caching.Memory;
+
+namespace BirdsiteLive.Twitter
+{
+    public class CachedTwitterService : ITwitterService
+    {
+        private readonly ITwitterService _twitterService;
+
+        private MemoryCache _userCache = new MemoryCache(new MemoryCacheOptions()
+        {
+            SizeLimit = 5000
+        });
+        private MemoryCacheEntryOptions _cacheEntryOptions = new MemoryCacheEntryOptions()
+            .SetSize(1)//Size amount
+            //Priority on removing when reaching size limit (memory pressure)
+            .SetPriority(CacheItemPriority.High)
+            // Keep in cache for this time, reset time if accessed.
+            .SetSlidingExpiration(TimeSpan.FromHours(24))
+            // Remove from cache after this time, regardless of sliding expiration
+            .SetAbsoluteExpiration(TimeSpan.FromDays(30));
+
+        #region Ctor
+        public CachedTwitterService(ITwitterService twitterService)
+        {
+            _twitterService = twitterService;
+        }
+        #endregion
+
+        public TwitterUser GetUser(string username)
+        {
+            if (!_userCache.TryGetValue(username, out TwitterUser user))
+            {
+                user = _twitterService.GetUser(username);
+                _userCache.Set(username, user, _cacheEntryOptions);
+            }
+
+            return user;
+        }
+
+        public ExtractedTweet GetTweet(long statusId)
+        {
+            return _twitterService.GetTweet(statusId);
+        }
+
+        public ExtractedTweet[] GetTimeline(string username, int nberTweets, long fromTweetId = -1)
+        {
+            return _twitterService.GetTimeline(username, nberTweets, fromTweetId);
+        }
+    }
+}