From ebc6ad0eaecc9cf0a18e1bca96ba2abf9ba9e9e3 Mon Sep 17 00:00:00 2001
From: Vincent Velociter <vincent.velociter@gmail.com>
Date: Mon, 15 Apr 2024 09:19:22 +0200
Subject: [PATCH] Set default engine cores as half of nb of processors

---
 lib/src/model/analysis/analysis_preferences.dart | 6 ++----
 lib/src/model/engine/evaluation_service.dart     | 7 +++++--
 lib/src/view/analysis/analysis_settings.dart     | 1 +
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/lib/src/model/analysis/analysis_preferences.dart b/lib/src/model/analysis/analysis_preferences.dart
index 621b7ad4cd..45d615baef 100644
--- a/lib/src/model/analysis/analysis_preferences.dart
+++ b/lib/src/model/analysis/analysis_preferences.dart
@@ -1,15 +1,13 @@
 import 'dart:convert';
-import 'dart:io';
 
 import 'package:freezed_annotation/freezed_annotation.dart';
 import 'package:lichess_mobile/src/db/shared_preferences.dart';
+import 'package:lichess_mobile/src/model/engine/evaluation_service.dart';
 import 'package:riverpod_annotation/riverpod_annotation.dart';
 
 part 'analysis_preferences.freezed.dart';
 part 'analysis_preferences.g.dart';
 
-final maxEngineCores = Platform.numberOfProcessors - 1;
-
 @Riverpod(keepAlive: true)
 class AnalysisPreferences extends _$AnalysisPreferences {
   static const prefKey = 'preferences.analysis';
@@ -106,7 +104,7 @@ class AnalysisPrefState with _$AnalysisPrefState {
     showBestMoveArrow: true,
     showPgnComments: true,
     numEvalLines: 2,
-    numEngineCores: maxEngineCores,
+    numEngineCores: defaultEngineCores,
   );
 
   factory AnalysisPrefState.fromJson(Map<String, dynamic> json) {
diff --git a/lib/src/model/engine/evaluation_service.dart b/lib/src/model/engine/evaluation_service.dart
index 206752b04a..95d6e854c2 100644
--- a/lib/src/model/engine/evaluation_service.dart
+++ b/lib/src/model/engine/evaluation_service.dart
@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:io';
+import 'dart:math';
 
 import 'package:dartchess/dartchess.dart';
 import 'package:fast_immutable_collections/fast_immutable_collections.dart';
@@ -19,7 +20,9 @@ part 'evaluation_service.g.dart';
 part 'evaluation_service.freezed.dart';
 
 const kMaxEngineDepth = 22;
-final maxEngineCores = Platform.numberOfProcessors - 1;
+final maxEngineCores = max(Platform.numberOfProcessors - 1, 1);
+final defaultEngineCores =
+    min((Platform.numberOfProcessors / 2).ceil(), maxEngineCores);
 
 const engineSupportedVariants = {
   Variant.standard,
@@ -38,7 +41,7 @@ class EvaluationService {
   EvaluationContext? _context;
   EvaluationOptions _options = EvaluationOptions(
     multiPv: 1,
-    cores: maxEngineCores,
+    cores: defaultEngineCores,
   );
 
   /// Initialize the engine with the given context and options.
diff --git a/lib/src/view/analysis/analysis_settings.dart b/lib/src/view/analysis/analysis_settings.dart
index 53f27a794f..0df8b75992 100644
--- a/lib/src/view/analysis/analysis_settings.dart
+++ b/lib/src/view/analysis/analysis_settings.dart
@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:lichess_mobile/src/model/analysis/analysis_controller.dart';
 import 'package:lichess_mobile/src/model/analysis/analysis_preferences.dart';
+import 'package:lichess_mobile/src/model/engine/evaluation_service.dart';
 import 'package:lichess_mobile/src/model/settings/general_preferences.dart';
 import 'package:lichess_mobile/src/utils/l10n_context.dart';
 import 'package:lichess_mobile/src/widgets/adaptive_bottom_sheet.dart';