From dc83309db79d3998ab706dc6f1f9f064c83c0451 Mon Sep 17 00:00:00 2001
From: Oliver Booth <me@olivr.me>
Date: Sun, 13 Aug 2023 18:03:08 +0100
Subject: [PATCH] perf(blog): cache users

---
 OliverBooth/Services/BlogUserService.cs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/OliverBooth/Services/BlogUserService.cs b/OliverBooth/Services/BlogUserService.cs
index 09ed3ef..9b797eb 100644
--- a/OliverBooth/Services/BlogUserService.cs
+++ b/OliverBooth/Services/BlogUserService.cs
@@ -1,3 +1,4 @@
+using System.Collections.Concurrent;
 using System.Diagnostics.CodeAnalysis;
 using Microsoft.EntityFrameworkCore;
 using OliverBooth.Data.Blog;
@@ -10,6 +11,7 @@ namespace OliverBooth.Services;
 internal sealed class BlogUserService : IBlogUserService
 {
     private readonly IDbContextFactory<BlogContext> _dbContextFactory;
+    private readonly ConcurrentDictionary<Guid, IUser> _userCache = new();
 
     /// <summary>
     ///     Initializes a new instance of the <see cref="BlogUserService" /> class.
@@ -25,8 +27,12 @@ internal sealed class BlogUserService : IBlogUserService
     /// <inheritdoc />
     public bool TryGetUser(Guid id, [NotNullWhen(true)] out IUser? user)
     {
+        if (_userCache.TryGetValue(id, out user)) return true;
+
         using BlogContext context = _dbContextFactory.CreateDbContext();
         user = context.Users.Find(id);
+
+        if (user is not null) _userCache.TryAdd(id, user);
         return user is not null;
     }
 }