Logging callback exposed

LiteDB/Engine/EngineState.cs

@@ -36,7 +36,7 @@ public void Validate()
 
         public bool Handle(Exception ex)
         {
-            LOG(ex.Message, "ERROR");
+            LOG(ex, "ERROR");
 
             if (ex is IOException ||
                 (ex is LiteException lex && lex.ErrorCode == LiteException.INVALID_DATAFILE_STATE))

LiteDB/Engine/LiteEngine.cs

@@ -160,7 +160,7 @@ internal bool Open()
             }
             catch (Exception ex)
             {
-                LOG(ex.Message, "ERROR");
+                LOG(ex, "ERROR");
 
                 this.Close(ex);
                 throw;

LiteDB/Engine/Pages/CollectionPage.cs

@@ -39,7 +39,7 @@ public CollectionPage(PageBuffer buffer, uint pageID)
         public CollectionPage(PageBuffer buffer)
             : base(buffer)
         {
-            ENSURE(this.PageType == PageType.Collection, "page type must be collection page");
+            ENSURE(this.PageType == PageType.Collection, "page type must be collection page, but it is {0}", PageType);
 
             if (this.PageType != PageType.Collection) throw LiteException.InvalidPageType(PageType.Collection, this);
 

LiteDB/Engine/Pages/IndexPage.cs

@@ -16,7 +16,7 @@ internal class IndexPage : BasePage
         public IndexPage(PageBuffer buffer)
             : base(buffer)
         {
-            ENSURE(this.PageType == PageType.Index, "page type must be index page");
+            ENSURE(this.PageType == PageType.Index, "page type must be index page, but it is {0}", PageType);
 
             if (this.PageType != PageType.Index) throw LiteException.InvalidPageType(PageType.Index, this);
         }

LiteDB/Utils/Constants.cs

@@ -108,28 +108,6 @@ internal class Constants
         public const int RANDOMIZER_SEED = 0;
 #endif
 
-        /// <summary>
-        /// Log a message using Debug.WriteLine
-        /// </summary>
-        [DebuggerHidden]
-        [Conditional("DEBUG")]
-        public static void LOG(string message, string category)
-        {
-            //Debug.WriteLine is too slow in multi-threads
-            //var threadID = Environment.CurrentManagedThreadId;
-            //Debug.WriteLine(message, threadID + "|" + category);
-        }
-
-        /// <summary>
-        /// Log a message using Debug.WriteLine only if conditional = true
-        /// </summary>
-        [DebuggerHidden]
-        [Conditional("DEBUG")]
-        public static void LOG(bool conditional, string message, string category)
-        {
-            if (conditional) LOG(message, category);
-        }
-
         /// <summary>
         /// Ensure condition is true, otherwise throw exception (check contract)
         /// </summary>

LiteDB/Utils/Logging.cs

@@ -0,0 +1,44 @@
+global using static LiteDB.Logging; // make LOG method available globally
+using System;
+using System.Diagnostics;
+
+namespace LiteDB;
+
+public static class Logging
+{
+    public static event Action<LogEventArgs> LogCallback;
+
+    /// <summary>
+    /// Log a message using LogCallback event
+    /// </summary>
+    [DebuggerHidden]
+    internal static void LOG(string message, string category)
+    {
+        LogCallback?.Invoke(new LogEventArgs() { Message = message, Category = category });
+    }
+
+    /// <summary>
+    /// Log a message using LogCallback event only if conditional = true
+    /// </summary>
+    [DebuggerHidden]
+    internal static void LOG(bool conditional, string message, string category)
+    {
+        if (conditional) LOG(message, category);
+    }
+
+    /// <summary>
+    /// Log an exception using LogCallback event only if conditional = true
+    /// </summary>
+    [DebuggerHidden]
+    internal static void LOG(Exception exception, string category)
+    {
+        LogCallback?.Invoke(new LogEventArgs() { Exception = exception, Category = category });
+    }
+}
+
+public class LogEventArgs
+{
+    public string Category { get; set; }
+    public string Message { get; set; }
+    public Exception Exception { get; set; }
+}