Refresh resources cache when the file changed

Author: hishamco

src/My.Extensions.Localization.Json/Internal/JsonFileWatcher.cs

@@ -0,0 +1,52 @@
+using System;
+using System.IO;
+
+namespace My.Extensions.Localization.Json.Internal;
+
+public class JsonFileWatcher : IDisposable
+{
+    private const string JsonExtension = "*.json";
+
+    private bool _disposed;
+    
+    private readonly FileSystemWatcher _filesWatcher;
+
+    public event FileSystemEventHandler Changed;
+
+    public JsonFileWatcher(string rootDirectory)
+    {
+        _filesWatcher = new(rootDirectory)
+        {
+            Filter = JsonExtension,
+            NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.Size,
+            EnableRaisingEvents = true
+        };
+        _filesWatcher.Changed += (s, e) => Changed?.Invoke(s, e);
+    }
+
+    ~JsonFileWatcher()
+    {
+        Dispose(false);
+    }
+
+    public void Dispose()
+    {
+        Dispose(true);
+        GC.SuppressFinalize(true);
+    }
+
+    public virtual void Dispose(bool disposing)
+    {
+        if (_disposed)
+        {
+            return;
+        }
+
+        if (disposing)
+        {
+            _filesWatcher.Dispose();
+        }
+
+        _disposed = true;
+    }
+}

src/My.Extensions.Localization.Json/Internal/JsonResourceManager.cs

@@ -6,21 +6,33 @@
 
 namespace My.Extensions.Localization.Json.Internal;
 
-public class JsonResourceManager(string resourcesPath, string resourceName = null)
+public class JsonResourceManager
 {
+    private readonly JsonFileWatcher _jsonFileWatcher;
     private readonly ConcurrentDictionary<string, ConcurrentDictionary<string, string>> _resourcesCache = new();
 
-    public string ResourceName { get; } = resourceName;
 
-    public string ResourcesPath { get; } = resourcesPath;
+    public JsonResourceManager(string resourcesPath, string resourceName = null)
+    {
+        ResourcesPath = resourcesPath;
+        ResourceName = resourceName;
+        
+        _jsonFileWatcher = new(resourcesPath);
+        _jsonFileWatcher.Changed += RefreshResourcesCache;
+    }
+
+    public string ResourceName { get; }
+
+    public string ResourcesPath { get; }
 
     public string ResourcesFilePath { get; private set; }
 
     public virtual ConcurrentDictionary<string, string> GetResourceSet(CultureInfo culture, bool tryParents)
     {
         TryLoadResourceSet(culture);
 
-        if (!_resourcesCache.ContainsKey(culture.Name))
+        var key = $"{ResourceName}.{culture.Name}";
+        if (!_resourcesCache.ContainsKey(key))
         {
             return null;
         }
@@ -30,7 +42,7 @@ public virtual ConcurrentDictionary<string, string> GetResourceSet(CultureInfo c
             var allResources = new ConcurrentDictionary<string, string>();
             do
             {
-                if (_resourcesCache.TryGetValue(culture.Name, out var resources))
+                if (_resourcesCache.TryGetValue(key, out var resources))
                 {
                     foreach (var entry in resources)
                     {
@@ -45,7 +57,7 @@ public virtual ConcurrentDictionary<string, string> GetResourceSet(CultureInfo c
         }
         else
         {
-            _resourcesCache.TryGetValue(culture.Name, out var resources);
+            _resourcesCache.TryGetValue(key, out var resources);
 
             return resources;
         }
@@ -63,7 +75,8 @@ public virtual string GetString(string name)
 
         do
         {
-            if (_resourcesCache.TryGetValue(culture.Name, out var resources))
+            var key = $"{ResourceName}.{culture.Name}";
+            if (_resourcesCache.TryGetValue(key, out var resources))
             {
                 if (resources.TryGetValue(name, out var value))
                 {
@@ -86,7 +99,8 @@ public virtual string GetString(string name, CultureInfo culture)
             return null;
         }
 
-        if (!_resourcesCache.TryGetValue(culture.Name, out var resources))
+        var key = $"{ResourceName}.{culture.Name}";
+        if (!_resourcesCache.TryGetValue(key, out var resources))
         {
             return null;
         }
@@ -102,7 +116,7 @@ private void TryLoadResourceSet(CultureInfo culture)
         {
             var file = Path.Combine(ResourcesPath, $"{culture.Name}.json");
 
-            GetOrAddResourceCache(file);
+            TryAddResources(file);
         }
         else
         {
@@ -129,7 +143,7 @@ private void TryLoadResourceSet(CultureInfo culture)
 
                 culture = CultureInfo.GetCultureInfo(cultureName);
 
-                GetOrAddResourceCache(file);
+                TryAddResources(file);
             }
         }
 
@@ -147,14 +161,34 @@ IEnumerable<string> GetResourceFiles(string culture)
                 : [];
         }
 
-        ConcurrentDictionary<string, string> GetOrAddResourceCache(string resourceFile)
+        void TryAddResources(string resourceFile)
         {
-            return _resourcesCache.GetOrAdd(culture.Name, _ =>
+            var key = $"{ResourceName}.{culture.Name}";
+            if (!_resourcesCache.ContainsKey(key))
             {
                 var resources = JsonResourceLoader.Load(resourceFile);
 
-                return new ConcurrentDictionary<string, string>(resources.ToDictionary(r => r.Key, r => r.Value));
-            });
+                _resourcesCache.TryAdd(key, new ConcurrentDictionary<string, string>(resources));
+            }
+        }
+    }
+
+    private void RefreshResourcesCache(object sender, FileSystemEventArgs e)
+    {
+        var key = Path.GetFileNameWithoutExtension(e.FullPath);
+        if (_resourcesCache.TryGetValue(key, out var resources))
+        {
+            if (!resources.IsEmpty)
+            {
+                resources.Clear();
+
+                var freshResources = JsonResourceLoader.Load(e.FullPath);
+
+                foreach (var item in freshResources)
+                {
+                    _resourcesCache[key].TryAdd(item.Key, item.Value);
+                }
+            }
         }
     }
 }

test/My.Extensions.Localization.Json.Benchmarks/JsonResourceManagerBenchmark.cs

@@ -1,6 +1,7 @@
 using BenchmarkDotNet.Attributes;
 using My.Extensions.Localization.Json.Internal;
 using System.Globalization;
+using System.IO;
 
 namespace My.Extensions.Localization.Json.Benchmarks;
 
@@ -12,19 +13,16 @@ public class JsonResourceManagerBenchmark
 
     static JsonResourceManagerBenchmark()
     {
-        _jsonResourceManager = new JsonResourceManager("Resources\\fr-FR.json");
+        var resources = "Resources";
+        _jsonResourceManager = new JsonResourceManager(resources, Path.Combine("fr-FR.json"));
         _frenchCulture = CultureInfo.GetCultureInfo("fr-FR");
     }
 
     [Benchmark]
     public void EvaluateGetResourceSetWithoutCultureFallback()
-    {
-        _jsonResourceManager.GetResourceSet(_frenchCulture, tryParents: false);
-    }
+        => _jsonResourceManager.GetResourceSet(_frenchCulture, tryParents: false);
 
     [Benchmark]
     public void EvaluateGetResourceSetWithCultureFallback()
-    {
-        _jsonResourceManager.GetResourceSet(_frenchCulture, tryParents: true);
-    }
+        => _jsonResourceManager.GetResourceSet(_frenchCulture, tryParents: true);
 }