From 714fdc7ced770c16126fadec2b0bf314e9b4a622 Mon Sep 17 00:00:00 2001
From: Dirk Hohndel <dirk@hohndel.org>
Date: Wed, 4 Jun 2014 13:41:50 -0700
Subject: [PATCH] Force TTS/NDL calculation off if things take too long

This is kind of a random cut off, but if plotting the dive takes more than
a second and TTS/NDL is on, we force it off. Because the algorithm for
that is fundamentally quadratic in nature it can take a VERY long time -
getting users to think something is broken.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
---
 qt-ui/mainwindow.cpp             | 6 ++++++
 qt-ui/mainwindow.h               | 1 +
 qt-ui/profile/profilewidget2.cpp | 8 ++++++++
 3 files changed, 15 insertions(+)

diff --git a/qt-ui/mainwindow.cpp b/qt-ui/mainwindow.cpp
index f6dd1b37f..ee0e6f090 100644
--- a/qt-ui/mainwindow.cpp
+++ b/qt-ui/mainwindow.cpp
@@ -1226,6 +1226,12 @@ void MainWindow::on_profNdl_tts_clicked(bool triggered)
 	prefs.calcndltts = triggered;
 	TOOLBOX_PREF_PROFILE(calcndltts);
 }
+void MainWindow::turnOffNdlTts()
+{
+	const bool triggered = prefs.calcndltts = false;
+	TOOLBOX_PREF_PROFILE(calcndltts);
+}
+
 void MainWindow::on_profPhe_clicked(bool triggered)
 {
 	prefs.pp_graphs.phe = triggered;
diff --git a/qt-ui/mainwindow.h b/qt-ui/mainwindow.h
index 6f352cc74..46f685f1f 100644
--- a/qt-ui/mainwindow.h
+++ b/qt-ui/mainwindow.h
@@ -148,6 +148,7 @@ protected:
 
 public
 slots:
+	void turnOffNdlTts();
 	void readSettings();
 	void refreshDisplay(bool doRecreateDiveList = true);
 	void recreateDiveList();
diff --git a/qt-ui/profile/profilewidget2.cpp b/qt-ui/profile/profilewidget2.cpp
index 67b0c4b9f..92c368cb8 100644
--- a/qt-ui/profile/profilewidget2.cpp
+++ b/qt-ui/profile/profilewidget2.cpp
@@ -355,6 +355,8 @@ void ProfileWidget2::setupSceneAndFlags()
 void ProfileWidget2::plotDives(QList<dive *> dives)
 {
 	static bool firstCall = true;
+	QTime measureDuration; // let's measure how long this takes us (maybe we'll turn of TTL calculation later
+	measureDuration.start();
 
 	// I Know that it's a list, but currently we are
 	// using just the first.
@@ -517,6 +519,12 @@ void ProfileWidget2::plotDives(QList<dive *> dives)
 		DivePlannerPointsModel *model = DivePlannerPointsModel::instance();
 		model->deleteTemporaryPlan();
 	}
+	// OK, how long did this take us? Anything above the second is way too long,
+	// so if we are calculation TTS / NDL then let's force that off.
+	if (measureDuration.elapsed() > 1000 && prefs.calcndltts) {
+		MainWindow::instance()->turnOffNdlTts();
+		MainWindow::instance()->showError("Show NDL / TTS was disabled because of excessive processing time");
+	}
 }
 
 void ProfileWidget2::settingsChanged()