Initial commit

DynamicFieldRegistry.cs

@@ -0,0 +1,163 @@
+using System.Text.Json;
+using Google.Protobuf;
+
+namespace DynamicProtobuf.Runtime;
+
+public static class DynamicFieldRegistry
+{
+    #region Local State
+    private static FileSystemWatcher? _fsWatcher;
+
+    private static ProtoJsonRegistry Registry { get; set; } = new();
+
+    private static HashSet<(string, string)> MissingFieldSet { get; set; } = [];
+
+    private static Timer? _reloadTimer;
+
+    private static readonly Lock _reloadLock = new();
+
+    #endregion Local State
+
+    #region Actions
+    public static Action<string> OnMissingField { get; set; } = msg => Console.Error.WriteLine("[DynamicProtobuf] [WARN]: " + msg);
+
+    public static Action<string> OnError { get; set; } = msg => Console.Error.WriteLine("[DynamicProtobuf] [ERROR]: " + msg);
+
+    public static event Action<ProtoJsonRegistry>? OnHotReloaded;
+
+    #endregion Actions
+
+    #region Codegen Helper
+
+    public static uint GetXorConst(string fullName, string fieldName)
+    {
+        return GetField(fullName, fieldName)?.XorConst ?? 0;
+    }
+
+    public static bool HasField(string fullName, string fieldName)
+    {
+        return GetField(fullName, fieldName) != null;
+    }
+
+    public static int GetFieldNumber(string fullName, string fieldName)
+    {
+        return GetField(fullName, fieldName)?.FieldNumber ?? 0;
+    }
+
+    public static uint GetTag(string fullName, string fieldName, bool packed = false)
+    {
+        MessageField? field = GetField(fullName, fieldName);
+        if (field == null)
+            return 0;
+        return (uint)((field.FieldNumber << 3) | (int)field.WireType);
+    }
+
+    public static int GetTagSize(string fullName, string fieldName)
+    {
+        return CodedOutputStream.ComputeTagSize(GetFieldNumber(fullName, fieldName));
+    }
+
+    private static MessageField? GetField(string fullName, string fieldName)
+    {
+        if (Registry.Messages.TryGetValue(fullName, out var fields) && fields.TryGetValue(fieldName, out var field))
+        {
+            return field;
+        }
+
+        if (MissingFieldSet.Add((fullName, fieldName)))
+        {
+            OnMissingField?.Invoke($"no such field \"{fieldName}\" at message \"{fullName}\"");
+        }
+
+        return null;
+    }
+
+    #endregion Codegen Helper
+
+    public static void ListenFromFile(string path)
+    {
+        LoadFromFile(path);
+
+        var directory = Path.GetDirectoryName(path);
+        if (string.IsNullOrEmpty(directory)) directory = ".";
+        var fileName = Path.GetFileName(path);
+
+        _fsWatcher = new FileSystemWatcher(directory, Path.GetFileName(path))
+        {
+            NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.Size,
+            EnableRaisingEvents = true
+        };
+
+        _fsWatcher.Error += (sender, e) =>
+        {
+            OnError?.Invoke(e.GetException().Message);
+        };
+
+        _fsWatcher.Changed += (sender, e) =>
+        {
+            if (e.ChangeType != WatcherChangeTypes.Changed)
+                return;
+
+            lock (_reloadLock)
+            {
+                _reloadTimer?.Dispose();
+
+                _reloadTimer = new Timer(_ =>
+                {
+                    try
+                    {
+                        while (IsFileLocked(path))
+                            Thread.Sleep(50);
+
+                        LoadFromFile(path);
+                    }
+                    catch (Exception ex)
+                    {
+                        OnError?.Invoke(ex.Message);
+                    }
+                }, null, 250, Timeout.Infinite);
+            }
+        };
+    }
+
+    public static void LoadFromFile(string path)
+    {
+        if (!File.Exists(path))
+        {
+            OnError?.Invoke($"proto json registry file not found: {path}");
+            return;
+        }
+
+        try
+        {
+            MissingFieldSet.Clear();
+
+            var json = File.ReadAllText(path);
+            var reg = JsonSerializer.Deserialize<ProtoJsonRegistry>(json);
+
+            if (reg != null)
+            {
+                Registry = reg;
+                OnHotReloaded?.Invoke(Registry);
+            }
+        }
+        catch (Exception ex)
+        {
+            OnError?.Invoke($"failed to load proto json registry: {ex.Message}");
+        }
+    }
+
+    private static bool IsFileLocked(string path)
+    {
+        try
+        {
+            using FileStream file = File.Open(path, FileMode.Open, FileAccess.ReadWrite, FileShare.None);
+            return false;
+        }
+        catch (Exception)
+        {
+            return true;
+        }
+    }
+
+}