diff --git a/LLama/Logger.cs b/LLama/Common/Logger.cs
similarity index 58%
rename from LLama/Logger.cs
rename to LLama/Common/Logger.cs
index 80fdc4bc..9bcd927e 100644
--- a/LLama/Logger.cs
+++ b/LLama/Common/Logger.cs
@@ -1,15 +1,35 @@
 using System;
 using System.Diagnostics;
 using System.IO;
+using static LLama.Common.ILLamaLogger;
 
-namespace LLama.Types;
+namespace LLama.Common;
+
+public interface ILLamaLogger
+{
+    public enum LogLevel
+    {
+        Info,
+        Debug,
+        Warning,
+        Error
+    }
+    /// <summary>
+    /// Write the log in cosutomized way
+    /// </summary>
+    /// <param name="source">The source of the log. It may be a method name or class name.</param>
+    /// <param name="message">The message.</param>
+    /// <param name="level">The log level.</param>
+    void Log(string source, string message, LogLevel level);
+}
 
 /// <summary>
-/// The logger of LLamaSharp. On default it write to console. User methods of `LLamaLogger.Default` to change the behavior.
+/// The default logger of LLamaSharp. On default it write to console. User methods of `LLamaLogger.Default` to change the behavior.
+/// It's more recommended to inherit `ILLamaLogger` to cosutomize the behavior.
 /// </summary>
-public sealed class LLamaLogger
+public sealed class LLamaDefaultLogger : ILLamaLogger
 {
-    private static readonly Lazy<LLamaLogger> _instance = new Lazy<LLamaLogger>(() => new LLamaLogger());
+    private static readonly Lazy<LLamaDefaultLogger> _instance = new Lazy<LLamaDefaultLogger>(() => new LLamaDefaultLogger());
 
     private bool _toConsole = true;
     private bool _toFile = false;
@@ -17,26 +37,26 @@ public sealed class LLamaLogger
     private FileStream? _fileStream = null;
     private StreamWriter _fileWriter = null;
 
-    public static LLamaLogger Default => _instance.Value;
+    public static LLamaDefaultLogger Default => _instance.Value;
 
-    private LLamaLogger()
+    private LLamaDefaultLogger()
     {
-        
+
     }
 
-    public LLamaLogger EnableConsole()
+    public LLamaDefaultLogger EnableConsole()
     {
         _toConsole = true;
         return this;
     }
 
-    public LLamaLogger DisableConsole()
+    public LLamaDefaultLogger DisableConsole()
     {
         _toConsole = false;
         return this;
     }
 
-    public LLamaLogger EnableFile(string filename, FileMode mode = FileMode.Append)
+    public LLamaDefaultLogger EnableFile(string filename, FileMode mode = FileMode.Append)
     {
         _fileStream = new FileStream(filename, mode, FileAccess.Write);
         _fileWriter = new StreamWriter(_fileStream);
@@ -44,14 +64,14 @@ public sealed class LLamaLogger
         return this;
     }
 
-    public LLamaLogger DisableFile(string filename)
+    public LLamaDefaultLogger DisableFile(string filename)
     {
-        if(_fileWriter is not null)
+        if (_fileWriter is not null)
         {
             _fileWriter.Close();
             _fileWriter = null;
         }
-        if(_fileStream is not null)
+        if (_fileStream is not null)
         {
             _fileStream.Close();
             _fileStream = null;
@@ -60,6 +80,26 @@ public sealed class LLamaLogger
         return this;
     }
 
+    public void Log(string source, string message, LogLevel level)
+    {
+        if (level == LogLevel.Info)
+        {
+            Info(message);
+        }
+        else if (level == LogLevel.Debug)
+        {
+
+        }
+        else if (level == LogLevel.Warning)
+        {
+            Warn(message);
+        }
+        else if (level == LogLevel.Error)
+        {
+            Error(message);
+        }
+    }
+
     public void Info(string message)
     {
         message = MessageFormat("info", message);
diff --git a/LLama/LLamaExecutorBase.cs b/LLama/LLamaExecutorBase.cs
index d8f5eb4a..18ebd6e1 100644
--- a/LLama/LLamaExecutorBase.cs
+++ b/LLama/LLamaExecutorBase.cs
@@ -6,30 +6,30 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Runtime.CompilerServices;
-using System.Text;
 using System.Text.Json.Serialization;
 using System.Threading;
-using System.Threading.Tasks;
 
 namespace LLama
 {
     using llama_token = Int32;
-    public abstract class ChatExecutorBase: ILLamaExecutor
+    public abstract class ChatExecutorBase : ILLamaExecutor
     {
         protected readonly LLamaModel _model;
+        protected ILLamaLogger? _logger;
         protected int _pastTokensCount; // n_past
         protected int _consumedTokensCount; // n_consume
         protected int _n_session_consumed;
         protected int _n_matching_session_tokens;
-        protected string _pathSession;
+        protected string? _pathSession;
         protected List<llama_token> _embeds = new(); // embd
         protected List<llama_token> _embed_inps = new();
         protected List<llama_token> _session_tokens = new();
         protected FixedSizeQuene<llama_token> _last_n_tokens;
         public LLamaModel Model => _model;
-        protected ChatExecutorBase(LLamaModel model)
+        protected ChatExecutorBase(LLamaModel model, ILLamaLogger? logger = null)
         {
             _model = model;
+            _logger = logger;
             _pastTokensCount = 0;
             _consumedTokensCount = 0;
             _n_session_consumed = 0;
@@ -47,14 +47,49 @@ namespace LLama
             }
             if (File.Exists(filename))
             {
+                _logger?.Log("LLamaExecutor", $"Attempting to load saved session from {filename}", ILLamaLogger.LogLevel.Info);
                 llama_token[] session_tokens = new llama_token[_model.ContextSize];
                 ulong n_token_count_out = 0;
                 if (!NativeApi.llama_load_session_file(_model.NativeHandle, _pathSession, session_tokens, (ulong)_model.ContextSize, &n_token_count_out))
                 {
+                    _logger?.Log("LLamaExecutor", $"Failed to load session file {filename}", ILLamaLogger.LogLevel.Error);
                     throw new RuntimeError($"Failed to load session file {_pathSession}");
                 }
                 _session_tokens = session_tokens.Take((int)n_token_count_out).ToList();
+                _logger?.Log("LLamaExecutor", $"Loaded a session with prompt size of {session_tokens.Length} tokens", ILLamaLogger.LogLevel.Info);
             }
+            else
+            {
+                _logger?.Log("LLamaExecutor", $"Session file does not exist, will create", ILLamaLogger.LogLevel.Warning);
+            }
+
+            _n_matching_session_tokens = 0;
+            if (_session_tokens.Count > 0)
+            {
+                foreach (var id in _session_tokens)
+                {
+                    if (_n_matching_session_tokens >= _embed_inps.Count || id != _embed_inps[_n_matching_session_tokens])
+                    {
+                        break;
+                    }
+                    _n_matching_session_tokens++;
+                }
+                if (_n_matching_session_tokens >= _embed_inps.Count)
+                {
+                    _logger?.Log("LLamaExecutor", $"Session file has exact match for prompt!", ILLamaLogger.LogLevel.Info);
+                }
+                else if (_n_matching_session_tokens < _embed_inps.Count / 2)
+                {
+                    _logger?.Log("LLamaExecutor", $"session file has low similarity to prompt ({_n_matching_session_tokens}" +
+                        $" / {_embed_inps.Count} tokens); will mostly be reevaluated", ILLamaLogger.LogLevel.Warning);
+                }
+                else
+                {
+                    _logger?.Log("LLamaExecutor", $"Session file matches {_n_matching_session_tokens} / " +
+                        $"{_embed_inps.Count} tokens of prompt", ILLamaLogger.LogLevel.Info);
+                }
+            }
+
             return this;
         }
 
@@ -169,7 +204,7 @@ namespace LLama
         }
         public virtual async IAsyncEnumerable<string> InferAsync(string text, InferenceParams? inferenceParams = null, [EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
-            foreach(var result in Infer(text, inferenceParams, cancellationToken))
+            foreach (var result in Infer(text, inferenceParams, cancellationToken))
             {
                 yield return result;
             }
diff --git a/LLama/LLamaModel.cs b/LLama/LLamaModel.cs
index 19db1954..23982680 100644
--- a/LLama/LLamaModel.cs
+++ b/LLama/LLamaModel.cs
@@ -1,7 +1,6 @@
 using LLama.Exceptions;
 using LLama.Native;
 using LLama.OldVersion;
-using LLama.Types;
 using LLama.Extensions;
 using System;
 using System.Collections.Generic;
@@ -17,7 +16,7 @@ namespace LLama
     public class LLamaModel: IDisposable
     {
         // TODO: expose more properties.
-        LLamaLogger _logger;
+        ILLamaLogger? _logger;
         Encoding _encoding;
         SafeLLamaContextHandle _ctx;
         public int ContextSize { get; }
@@ -25,12 +24,12 @@ namespace LLama
         public SafeLLamaContextHandle NativeHandle => _ctx;
         public Encoding Encoding => _encoding;
 
-        public LLamaModel(ModelParams Params, string encoding = "UTF-8")
+        public LLamaModel(ModelParams Params, string encoding = "UTF-8", ILLamaLogger? logger = null)
         {
-            _logger = LLamaLogger.Default;
+            _logger = logger;
             this.Params = Params;
             _encoding = Encoding.GetEncoding(encoding);
-            _logger.Info($"Initializing LLama model with params: {this.Params}");
+            _logger?.Log(nameof(LLamaModel), $"Initializing LLama model with params: {this.Params}", ILLamaLogger.LogLevel.Info);
             _ctx = Utils.InitLLamaContextFromModelParams(this.Params);
             ContextSize = NativeApi.llama_n_ctx(_ctx);
         }
@@ -210,7 +209,7 @@ namespace LLama
 
                 if(Utils.Eval(_ctx, tokens, i, n_eval, pastTokensCount, Params.Threads) != 0)
                 {
-                    _logger.Error($"Failed to eval.");
+                    _logger?.Log(nameof(LLamaModel), "Failed to eval.", ILLamaLogger.LogLevel.Error);
                     throw new RuntimeError("Failed to eval.");
                 }
 
diff --git a/LLama/OldVersion/LLamaModel.cs b/LLama/OldVersion/LLamaModel.cs
index 55ecc843..41986954 100644
--- a/LLama/OldVersion/LLamaModel.cs
+++ b/LLama/OldVersion/LLamaModel.cs
@@ -1,5 +1,4 @@
 using LLama.Exceptions;
-using LLama.Types;
 using LLama.Extensions;
 using LLama.Native;
 using System;
@@ -8,6 +7,7 @@ using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Text;
+using LLama.Common;
 
 namespace LLama.OldVersion
 {
@@ -184,12 +184,12 @@ namespace LLama.OldVersion
             {
                 if (verbose)
                 {
-                    LLamaLogger.Default.Info($"Attempting to load saved session from '{_path_session}'");
+                    LLamaDefaultLogger.Default.Info($"Attempting to load saved session from '{_path_session}'");
                 }
 
                 if (!File.Exists(_path_session))
                 {
-                    LLamaLogger.Default.Warn("Session file does not exist, will create.");
+                    LLamaDefaultLogger.Default.Warn("Session file does not exist, will create.");
                 }
 
                 llama_token[] session_tokens = new llama_token[@params.n_ctx];
@@ -201,7 +201,7 @@ namespace LLama.OldVersion
                 _session_tokens = session_tokens.Take((int)n_token_count_out).ToList();
                 if (verbose)
                 {
-                    LLamaLogger.Default.Info($"Loaded a session with prompt size of {_session_tokens.Count} tokens");
+                    LLamaDefaultLogger.Default.Info($"Loaded a session with prompt size of {_session_tokens.Count} tokens");
                 }
             }
 
@@ -231,39 +231,39 @@ namespace LLama.OldVersion
 
             if (_params.verbose_prompt)
             {
-                LLamaLogger.Default.Info("\n");
-                LLamaLogger.Default.Info($"prompt: '{_params.prompt}'");
-                LLamaLogger.Default.Info($"number of tokens in prompt = {_embed_inp.Count}");
+                LLamaDefaultLogger.Default.Info("\n");
+                LLamaDefaultLogger.Default.Info($"prompt: '{_params.prompt}'");
+                LLamaDefaultLogger.Default.Info($"number of tokens in prompt = {_embed_inp.Count}");
                 for (int i = 0; i < _embed_inp.Count; i++)
                 {
-                    LLamaLogger.Default.Info($"{_embed_inp[i]} -> '{NativeApi.llama_token_to_str(_ctx, _embed_inp[i])}'");
+                    LLamaDefaultLogger.Default.Info($"{_embed_inp[i]} -> '{NativeApi.llama_token_to_str(_ctx, _embed_inp[i])}'");
                 }
                 if (_params.n_keep > 0)
                 {
-                    LLamaLogger.Default.Info($"static prompt based on n_keep: '");
+                    LLamaDefaultLogger.Default.Info($"static prompt based on n_keep: '");
                     for (int i = 0; i < _params.n_keep; i++)
                     {
-                        LLamaLogger.Default.Info($"{NativeApi.llama_token_to_str(_ctx, _embed_inp[i])}");
+                        LLamaDefaultLogger.Default.Info($"{NativeApi.llama_token_to_str(_ctx, _embed_inp[i])}");
                     }
-                    LLamaLogger.Default.Info("\n");
+                    LLamaDefaultLogger.Default.Info("\n");
                 }
-                LLamaLogger.Default.Info("\n");
+                LLamaDefaultLogger.Default.Info("\n");
             }
 
             if (_params.interactive && verbose)
             {
-                LLamaLogger.Default.Info("interactive mode on.");
+                LLamaDefaultLogger.Default.Info("interactive mode on.");
             }
             if (verbose)
             {
-                LLamaLogger.Default.Info($"sampling: repeat_last_n = {_params.repeat_last_n}, " +
+                LLamaDefaultLogger.Default.Info($"sampling: repeat_last_n = {_params.repeat_last_n}, " +
                     $"repeat_penalty = {_params.repeat_penalty}, presence_penalty = {_params.presence_penalty}, " +
                     $"frequency_penalty = {_params.frequency_penalty}, top_k = {_params.top_k}, tfs_z = {_params.tfs_z}," +
                     $" top_p = {_params.top_p}, typical_p = {_params.typical_p}, temp = {_params.temp}, mirostat = {_params.mirostat}," +
                     $" mirostat_lr = {_params.mirostat_eta}, mirostat_ent = {_params.mirostat_tau}");
-                LLamaLogger.Default.Info($"generate: n_ctx = {_n_ctx}, n_batch = {_params.n_batch}, n_predict = {_params.n_predict}, " +
+                LLamaDefaultLogger.Default.Info($"generate: n_ctx = {_n_ctx}, n_batch = {_params.n_batch}, n_predict = {_params.n_predict}, " +
                     $"n_keep = {_params.n_keep}");
-                LLamaLogger.Default.Info("\n");
+                LLamaDefaultLogger.Default.Info("\n");
             }
 
             _last_n_tokens = Enumerable.Repeat(0, _n_ctx).ToList();
@@ -272,7 +272,7 @@ namespace LLama.OldVersion
             {
                 if (verbose)
                 {
-                    LLamaLogger.Default.Info("== Running in interactive mode. ==");
+                    LLamaDefaultLogger.Default.Info("== Running in interactive mode. ==");
                 }
                 _is_interacting = _params.interactive_first;
             }
@@ -316,16 +316,16 @@ namespace LLama.OldVersion
                 }
                 if (n_matching_session_tokens >= (ulong)_embed_inp.Count)
                 {
-                    LLamaLogger.Default.Info("Session file has exact match for prompt!");
+                    LLamaDefaultLogger.Default.Info("Session file has exact match for prompt!");
                 }
                 else if (n_matching_session_tokens < (ulong)(_embed_inp.Count / 2))
                 {
-                    LLamaLogger.Default.Warn($"session file has low similarity to prompt ({n_matching_session_tokens} " +
+                    LLamaDefaultLogger.Default.Warn($"session file has low similarity to prompt ({n_matching_session_tokens} " +
                         $"/ {_embed_inp.Count} tokens); will mostly be reevaluated.");
                 }
                 else
                 {
-                    LLamaLogger.Default.Info($"Session file matches {n_matching_session_tokens} / {_embed_inp.Count} " +
+                    LLamaDefaultLogger.Default.Info($"Session file matches {n_matching_session_tokens} / {_embed_inp.Count} " +
                         $"tokens of prompt.");
                 }
             }
@@ -511,7 +511,7 @@ namespace LLama.OldVersion
             {
                 if (_verbose)
                 {
-                    LLamaLogger.Default.Warn("In interacting when calling the model, automatically changed it.");
+                    LLamaDefaultLogger.Default.Warn("In interacting when calling the model, automatically changed it.");
                 }
                 _is_interacting = false;
             }
@@ -581,7 +581,7 @@ namespace LLama.OldVersion
                         var array = _embed.Skip(i).ToArray();
                         if (NativeApi.llama_eval(_ctx, array, n_eval, _n_past, _params.n_threads) != 0)
                         {
-                            LLamaLogger.Default.Error($"Failed to eval.");
+                            LLamaDefaultLogger.Default.Error($"Failed to eval.");
                             throw new RuntimeError("Failed to eval.");
                         }
 
@@ -776,7 +776,7 @@ namespace LLama.OldVersion
                         }
                         else
                         {
-                            LLamaLogger.Default.Info(" [end of text]");
+                            LLamaDefaultLogger.Default.Info(" [end of text]");
                         }
                     }
 
@@ -790,7 +790,7 @@ namespace LLama.OldVersion
 
             if (!string.IsNullOrEmpty(_path_session) && _params.prompt_cache_all)
             {
-                LLamaLogger.Default.Info($"saving final output to session file {_path_session}");
+                LLamaDefaultLogger.Default.Info($"saving final output to session file {_path_session}");
                 var session_token_array = _session_tokens.ToArray();
                 NativeApi.llama_save_session_file(_ctx, _path_session, session_token_array, (ulong)session_token_array.Length);
             }