From ddd99ec70324467406775165653f26e248d12377 Mon Sep 17 00:00:00 2001
From: Jose Henrique <jose.henrique.ivan@gmail.com>
Date: Thu, 11 Sep 2025 20:44:57 -0300
Subject: [PATCH] #34 add size based cache

---
 OpenCand.API/Program.cs                   | 18 +++++++++++----
 OpenCand.API/Repository/BaseRepository.cs | 28 +++++++++++++++++++++--
 OpenCand.API/appsettings.json             |  3 +++
 3 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/OpenCand.API/Program.cs b/OpenCand.API/Program.cs
index 1b726f3..700eb4a 100644
--- a/OpenCand.API/Program.cs
+++ b/OpenCand.API/Program.cs
@@ -36,7 +36,8 @@ namespace OpenCand.API
             {
                 FileProvider = new PhysicalFileProvider(Path.Combine(workingDir, "fotos_cand")),
                 RequestPath = "/assets/fotos"
-            });            app.UseHttpsRedirection();
+            });
+            app.UseHttpsRedirection();
 
             // Use rate limiting middleware
             app.UseRateLimiter();
@@ -53,11 +54,18 @@ namespace OpenCand.API
 
             app.Run();
         }
-          private static void SetupServices(WebApplicationBuilder builder)
+
+        private static void SetupServices(WebApplicationBuilder builder)
         {
             builder.Services.Configure<FotosSettings>(builder.Configuration.GetSection("FotosSettings"));
-            builder.Services.AddMemoryCache();
-            
+
+            // Configure memory cache with size limit from appsettings
+            var sizeLimitMB = builder.Configuration.GetValue<int>("CacheSettings:SizeLimitMB", 15);
+            builder.Services.AddMemoryCache(options =>
+            {
+                options.SizeLimit = sizeLimitMB * 1024L * 1024L; // Convert MB to bytes
+            });
+
             builder.Services.AddScoped(provider => new OpenCandRepository(provider.GetRequiredService<IConfiguration>(), provider.GetService<IMemoryCache>()));
             builder.Services.AddScoped(provider => new CandidatoRepository(provider.GetRequiredService<IConfiguration>(), provider.GetService<IMemoryCache>()));
             builder.Services.AddScoped(provider => new BemCandidatoRepository(provider.GetRequiredService<IConfiguration>(), provider.GetService<IMemoryCache>()));
@@ -66,7 +74,7 @@ namespace OpenCand.API
 
             builder.Services.AddScoped<OpenCandService>();
             builder.Services.AddScoped<EstatisticaService>();
-            
+
             // Add cache preload background service
             builder.Services.AddHostedService<CachePreloadService>();
         }
diff --git a/OpenCand.API/Repository/BaseRepository.cs b/OpenCand.API/Repository/BaseRepository.cs
index 1a65ca5..84a85d1 100644
--- a/OpenCand.API/Repository/BaseRepository.cs
+++ b/OpenCand.API/Repository/BaseRepository.cs
@@ -1,5 +1,7 @@
 using Microsoft.Extensions.Caching.Memory;
 using Npgsql;
+using System.Text.Json;
+using System.Text;
 
 namespace OpenCand.Repository
 {
@@ -56,7 +58,8 @@ namespace OpenCand.Repository
                 _cache.Set(cacheKey, result, new MemoryCacheEntryOptions
                 {
                     SlidingExpiration = expiration ?? DefaultCacheExpiration,
-                    Priority = priority ?? DefaultCachePriority
+                    Priority = priority ?? DefaultCachePriority,
+                    Size = EstimateSize(result)
                 });
             }
 
@@ -99,7 +102,8 @@ namespace OpenCand.Repository
                 _cache.Set(cacheKey, result, new MemoryCacheEntryOptions
                 {
                     SlidingExpiration = expiration ?? DefaultCacheExpiration,
-                    Priority = priority ?? DefaultCachePriority
+                    Priority = priority ?? DefaultCachePriority,
+                    Size = EstimateSize(result)
                 });
             }
 
@@ -133,5 +137,25 @@ namespace OpenCand.Repository
         {
             return identifier != null ? $"{entityName}_{identifier}" : entityName;
         }
+
+        /// <summary>
+        /// Estimates the memory size of an object by serializing it to JSON
+        /// </summary>
+        /// <typeparam name="T">Type of the object</typeparam>
+        /// <param name="obj">The object to estimate size for</param>
+        /// <returns>Estimated size in bytes</returns>
+        private static long EstimateSize<T>(T obj)
+        {
+            if (obj == null) return 0;
+            try
+            {
+                var json = JsonSerializer.Serialize(obj);
+                return Encoding.UTF8.GetByteCount(json);
+            }
+            catch
+            {
+                return 1024; // Default estimate if serialization fails
+            }
+        }
     }
 }
diff --git a/OpenCand.API/appsettings.json b/OpenCand.API/appsettings.json
index af09ff0..99ac803 100644
--- a/OpenCand.API/appsettings.json
+++ b/OpenCand.API/appsettings.json
@@ -12,5 +12,8 @@
         "Path": "./fotos_cand",
         "ApiBasePath": "http://localhost:5299/assets/fotos"
     },
+    "CacheSettings": {
+        "SizeLimitMB": 15
+    },
     "AllowedHosts": "*"
 }