cache only the first datasource instead of all

leaderboardsgg · Oct 20, 2023 · 3f8cfde · 3f8cfde
1 parent 6cc9feb
commit 3f8cfde
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Showing 2 changed files with 44 additions and 29 deletions.
diff --git a/LeaderboardBackend/Models/Entities/ApplicationContext.cs b/LeaderboardBackend/Models/Entities/ApplicationContext.cs
@@ -1,4 +1,3 @@
-using System.Collections.Concurrent;
 using System.Reflection;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Options;
@@ -10,15 +9,12 @@ public class ApplicationContext : DbContext
 {
     public const string CASE_INSENSITIVE_COLLATION = "case_insensitive";
 
-    // the HashCode is calculated with all of the config's property because PostgresConfig is a record
-    private static readonly ConcurrentDictionary<PostgresConfig, NpgsqlDataSource> _dataSourceCache = new();
+    private readonly AppContextDataSourceProvider _dataSourceProvider;
 
-    private readonly NpgsqlDataSource _dataSource;
-
-    public ApplicationContext(DbContextOptions<ApplicationContext> options, IOptions<ApplicationContextConfig> config)
+    public ApplicationContext(DbContextOptions<ApplicationContext> options, AppContextDataSourceProvider dataSourceProvider)
         : base(options)
     {
-        _dataSource = CreateDataSource(config.Value.Pg);
+        _dataSourceProvider = dataSourceProvider;
     }
 
     public DbSet<AccountRecovery> AccountRecoveries { get; set; } = null!;
@@ -28,6 +24,28 @@ public ApplicationContext(DbContextOptions<ApplicationContext> options, IOptions
     public DbSet<Run> Runs { get; set; } = null!;
     public DbSet<User> Users { get; set; } = null!;
 
+    public static NpgsqlDataSource CreateDataSource(PostgresConfig config)
+    {
+        NpgsqlConnectionStringBuilder connectionBuilder = new()
+        {
+            Host = config.Host,
+            Username = config.User,
+            Password = config.Password,
+            Database = config.Db,
+            IncludeErrorDetail = true,
+        };
+
+        if (config.Port is not null)
+        {
+            connectionBuilder.Port = config.Port.Value;
+        }
+
+        NpgsqlDataSourceBuilder dataSourceBuilder = new(connectionBuilder.ConnectionString);
+        dataSourceBuilder.UseNodaTime().MapEnum<UserRole>();
+
+        return dataSourceBuilder.Build();
+    }
+
     public void MigrateDatabase()
     {
         Database.Migrate();
@@ -75,32 +93,28 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
 
     protected override void OnConfiguring(DbContextOptionsBuilder opt)
     {
-        opt.UseNpgsql(_dataSource, o => o.UseNodaTime());
+        opt.UseNpgsql(_dataSourceProvider.Value, o => o.UseNodaTime());
         opt.UseSnakeCaseNamingConvention();
     }
+}
+
+public class AppContextDataSourceProvider
+{
+    private static int _cacheKey;
+    private static NpgsqlDataSource? _cachedDataSource;
 
-    private static NpgsqlDataSource CreateDataSource(PostgresConfig c)
+    public NpgsqlDataSource Value => _cachedDataSource!;
+
+    public AppContextDataSourceProvider(IOptions<ApplicationContextConfig> appContextConfig)
     {
-        return _dataSourceCache.GetOrAdd(c, config =>
+        PostgresConfig config = appContextConfig.Value.Pg;
+
+        int key = config.GetHashCode(); // a record's HashCode is calculated with all its properties values
+        if (_cacheKey != key)
         {
-            NpgsqlConnectionStringBuilder connectionBuilder = new()
-            {
-                Host = config.Host,
-                Username = config.User,
-                Password = config.Password,
-                Database = config.Db,
-                IncludeErrorDetail = true,
-            };
-
-            if (config.Port is not null)
-            {
-                connectionBuilder.Port = config.Port.Value;
-            }
-
-            NpgsqlDataSourceBuilder dataSourceBuilder = new(connectionBuilder.ConnectionString);
-            dataSourceBuilder.UseNodaTime().MapEnum<UserRole>();
-
-            return dataSourceBuilder.Build();
-        });
+            // if we ever want to parallelize tests, this code will need to be made thread-safe
+            _cacheKey = key;
+            _cachedDataSource = ApplicationContext.CreateDataSource(config);
+        }
     }
 }
diff --git a/LeaderboardBackend/Program.cs b/LeaderboardBackend/Program.cs
@@ -59,6 +59,7 @@
     .ValidateDataAnnotationsRecursively()
     .ValidateOnStart();
 
+builder.Services.AddSingleton<AppContextDataSourceProvider>();
 builder.Services.AddDbContext<ApplicationContext>();
 
 // Add services to the container.