V13: Clear Member Username Cache in Load Balanced Environments (#19191)

* Clear usernamekey

* Odd explaining comment

* Update src/Umbraco.Core/Cache/Refreshers/Implement/MemberCacheRefresher.cs

Co-authored-by: Copilot <[email protected]>

* Make UserNameCachePrefix readonly for better immutabilityly

* Move prefix to CacheKeys constants

---------

Co-authored-by: Copilot <[email protected]>
# Conflicts:
#	src/Umbraco.Core/Cache/CacheKeys.cs

Author: AndyButland

src/Umbraco.Core/Cache/CacheKeys.cs

@@ -22,4 +22,6 @@ public static class CacheKeys
 
     public const string PreviewPropertyCacheKeyPrefix = "Cache.Property.CacheValues[D:";
     public const string PropertyCacheKeyPrefix = "Cache.Property.CacheValues[P:";
+
+    public const string MemberUserNameCachePrefix = "uRepo_userNameKey+";
 }

src/Umbraco.Core/Cache/Refreshers/Implement/MemberCacheRefresher.cs

@@ -71,11 +71,22 @@ private void ClearCache(params JsonPayload[] payloads)
         foreach (JsonPayload p in payloads)
         {
             _idKeyMap.ClearCache(p.Id);
-            if (memberCache.Success)
+            if (memberCache.Success is false)
             {
-                memberCache.Result?.Clear(RepositoryCacheKeys.GetKey<IMember, int>(p.Id));
-                memberCache.Result?.Clear(RepositoryCacheKeys.GetKey<IMember, string>(p.Username));
+                continue;
             }
+
+            memberCache.Result?.Clear(RepositoryCacheKeys.GetKey<IMember, int>(p.Id));
+            memberCache.Result?.Clear(RepositoryCacheKeys.GetKey<IMember, string>(p.Username));
+
+            // This specific cache key was introduced to fix an issue where the member username could not be the same as the member id, because the cache keys collided.
+            // This is done in a bit of a hacky way, because the cache key is created internally in the repository, but we need to clear it here.
+            // Ideally, we want to use a shared way of generating the key between this and the repository.
+            // Additionally, the RepositoryCacheKeys actually caches the string to avoid re-allocating memory; we would like to also use this in the repository
+            // See:
+            // https://github.com/umbraco/Umbraco-CMS/pull/17350
+            // https://github.com/umbraco/Umbraco-CMS/pull/17815
+            memberCache.Result?.Clear(RepositoryCacheKeys.GetKey<IMember, string>(CacheKeys.MemberUserNameCachePrefix + p.Username));
         }
     }
 }

src/Umbraco.Infrastructure/Persistence/Repositories/Implement/MemberRepository.cs

@@ -39,7 +39,6 @@ public class MemberRepository : ContentRepositoryBase<int, IMember, MemberReposi
     private readonly ITagRepository _tagRepository;
     private bool _passwordConfigInitialized;
     private string? _passwordConfigJson;
-    private const string UsernameCacheKey = "uRepo_userNameKey+";
 
     public MemberRepository(
         IScopeAccessor scopeAccessor,
@@ -327,7 +326,7 @@ public override IEnumerable<IMember> GetPage(
     }
 
     public IMember? GetByUsername(string? username) =>
-        _memberByUsernameCachePolicy.GetByUserName(UsernameCacheKey, username, PerformGetByUsername, PerformGetAllByUsername);
+        _memberByUsernameCachePolicy.GetByUserName(CacheKeys.MemberUserNameCachePrefix, username, PerformGetByUsername, PerformGetAllByUsername);
 
     public int[] GetMemberIds(string[] usernames)
     {
@@ -609,7 +608,7 @@ protected virtual Sql<ISqlContext> GetBaseQuery(QueryType queryType, bool curren
 
     protected override void PersistDeletedItem(IMember entity)
     {
-        _memberByUsernameCachePolicy.DeleteByUserName(UsernameCacheKey, entity.Username);
+        _memberByUsernameCachePolicy.DeleteByUserName(CacheKeys.MemberUserNameCachePrefix, entity.Username);
         base.PersistDeletedItem(entity);
     }
 
@@ -943,7 +942,7 @@ protected override void PersistUpdatedItem(IMember entity)
 
         OnUowRefreshedEntity(new MemberRefreshNotification(entity, new EventMessages()));
 
-        _memberByUsernameCachePolicy.DeleteByUserName(UsernameCacheKey, entity.Username);
+        _memberByUsernameCachePolicy.DeleteByUserName(CacheKeys.MemberUserNameCachePrefix, entity.Username);
 
         entity.ResetDirtyProperties();
     }