Added optional `IProgress` parameter to `LoadFromFileAsync`

LLama/LLamaWeights.cs

@@ -92,10 +92,11 @@ namespace LLama
         /// </summary>
         /// <param name="params">Parameters to use to load the model</param>
         /// <param name="token">A cancellation token that can interrupt model loading</param>
+        /// <param name="progressReporter">Receives progress updates as the model loads (0 to 1)</param>
         /// <returns></returns>
         /// <exception cref="LoadWeightsFailedException">Thrown if weights failed to load for any reason. e.g. Invalid file format or loading cancelled.</exception>
         /// <exception cref="OperationCanceledException">Thrown if the cancellation token is cancelled.</exception>
-        public static async Task<LLamaWeights> LoadFromFileAsync(IModelParams @params, CancellationToken token = default)
+        public static async Task<LLamaWeights> LoadFromFileAsync(IModelParams @params, CancellationToken token = default, IProgress<float>? progressReporter = null)
         {
             // don't touch the @params object inside the task, it might be changed
             // externally! Save a copy of everything that we need later.
@@ -103,16 +104,25 @@ namespace LLama
             var loraBase = @params.LoraBase;
             var loraAdapters = @params.LoraAdapters.ToArray();
 
+            // Determine the range to report for model loading. llama.cpp reports 0-1, but we'll remap that into a
+            // slightly smaller range to allow some space for reporting LoRA loading too.
+            var modelLoadProgressRange = 1f;
+            if (loraAdapters.Length > 0)
+                modelLoadProgressRange = 0.9f;
+
             using (@params.ToLlamaModelParams(out var lparams))
             {
 #if !NETSTANDARD2_0
-                // Overwrite the progress callback with one which polls the cancellation token
-                if (token.CanBeCanceled)
+                // Overwrite the progress callback with one which polls the cancellation token and updates the progress object
+                if (token.CanBeCanceled || progressReporter != null)
                 {
                     var internalCallback = lparams.progress_callback;
                     lparams.progress_callback = (progress, ctx) =>
                     {
-                        // If the user set a call in the model params, first call that and see if we should cancel
+                        // Update the progress reporter (remapping the value into the smaller range).
+                        progressReporter?.Report(Math.Clamp(progress, 0, 1) * modelLoadProgressRange);
+
+                        // If the user set a callback in the model params, call that and see if we should cancel
                         if (internalCallback != null && !internalCallback(progress, ctx))
                             return false;
 
@@ -129,8 +139,11 @@ namespace LLama
                 {
                     try
                     {
+                        // Load the model
                         var weights = SafeLlamaModelHandle.LoadFromFile(modelPath, lparams);
-                        foreach (var adapter in loraAdapters)
+
+                        // Apply the LoRA adapters
+                        for (var i = 0; i < loraAdapters.Length; i++)
                         {
                             // Interrupt applying LoRAs if the token is cancelled
                             if (token.IsCancellationRequested)
@@ -140,14 +153,22 @@ namespace LLama
                             }
 
                             // Don't apply invalid adapters
+                            var adapter = loraAdapters[i];
                             if (string.IsNullOrEmpty(adapter.Path))
                                 continue;
                             if (adapter.Scale <= 0)
                                 continue;
 
                             weights.ApplyLoraFromFile(adapter.Path, adapter.Scale, loraBase);
+
+                            // Report progress. Model loading reported progress from 0 -> 0.9, use
+                            // the last 0.1 to represent all of the LoRA adapters being applied.
+                            progressReporter?.Report(0.9f + (0.1f / loraAdapters.Length) * (i + 1));
                         }
 
+                        // Update progress reporter to indicate completion
+                        progressReporter?.Report(1);
+
                         return new LLamaWeights(weights);
                     }
                     catch (LoadWeightsFailedException)