Change: base autosaves intervals on real time (instead of game time) (#10655)

There are two fundamental issues with autosave:
- When fast-forwarding, it saves way too often
- When paused, it never saves

Both makes no sense. Autosaves are meant to prevent you from
accidentally losing your work. The emphasis on "your" work.

To solve both issues, the autosave now works on real time. You
can select every 10 / 30 / 60 / 120 minutes, which are similar to
what the setting was in game-months.

When you pause, autosaving will stop. Unless you make any change
to the game; then it will continue to make autosaves, even so
the game is paused. Unpausing / pausing resets this mechanism.

(cherry picked from commit f5fad88723)

src/command.cpp

@@ -1269,6 +1269,9 @@ CommandCost DoCommandPInternal(TileIndex tile, uint32 p1, uint32 p2, uint64 p3,
 	UpdateSignalsInBuffer();
 	if (_extra_aspects > 0) FlushDeferredAspectUpdates();
 
+	/* Record if there was a command issues during pause; ignore pause/other setting related changes. */
+	if (_pause_mode != PM_UNPAUSED && command.type != CMDT_SERVER_SETTING) _pause_mode |= PM_COMMAND_DURING_PAUSE;
+
 	return_dcpi(res2);
 }
 #undef return_dcpi

src/openttd.cpp

@@ -90,6 +90,7 @@
 #include "scope_info.h"
 #include "network/network_survey.h"
 #include "timer/timer.h"
+#include "timer/timer_game_realtime.h"
 #include "timer/timer_game_tick.h"
 #include "network/network_sync.h"
 
@@ -1330,6 +1331,9 @@ void SwitchToMode(SwitchMode new_mode)
 	/* Make sure all AI controllers are gone at quitting game */
 	if (new_mode != SM_SAVE_GAME) AI::KillAll();
 
+	/* When we change mode, reset the autosave. */
+	if (new_mode != SM_SAVE_GAME) ChangeAutosaveFrequency(true);
+
 	/* Transmit the survey if we were in normal-mode and not saving. It always means we leaving the current game. */
 	if (_game_mode == GM_NORMAL && new_mode != SM_SAVE_GAME) _survey.Transmit(NetworkSurveyHandler::Reason::LEAVE);
 
@@ -2200,6 +2204,33 @@ static void DoAutosave()
 	DoAutoOrNetsave(GetAutoSaveFiosNumberedSaveName(), true, lt_counter);
 }
 
+/** Interval for regular autosaves. Initialized at zero to disable till settings are loaded. */
+static IntervalTimer<TimerGameRealtime> _autosave_interval({std::chrono::milliseconds::zero(), TimerGameRealtime::AUTOSAVE}, [](auto)
+{
+	/* We reset the command-during-pause mode here, so we don't continue
+	 * to make auto-saves when nothing more is changing. */
+	_pause_mode &= ~PM_COMMAND_DURING_PAUSE;
+
+	_do_autosave = true;
+	DoAutosave();
+	_do_autosave = false;
+	SetWindowDirty(WC_STATUS_BAR, 0);
+});
+
+/**
+ * Reset the interval of the autosave.
+ *
+ * If reset is not set, this does not set the elapsed time on the timer,
+ * so if the interval is smaller, it might result in an autosave being done
+ * immediately.
+ *
+ * @param reset Whether to reset the timer back to zero, or to continue.
+ */
+void ChangeAutosaveFrequency(bool reset)
+{
+	_autosave_interval.SetInterval({_settings_client.gui.autosave_realtime, TimerGameRealtime::AUTOSAVE}, reset);
+}
+
 /**
  * Request a new NewGRF scan. This will be executed on the next game-tick.
  * This is mostly needed to ensure NewGRF scans (which are blocking) are
@@ -2259,6 +2290,16 @@ void GameLoop()
 
 	if (unlikely(_check_special_modes)) GameLoopSpecial();
 
+	if (_game_mode == GM_NORMAL) {
+		static auto last_time = std::chrono::steady_clock::now();
+		auto now = std::chrono::steady_clock::now();
+		auto delta_ms = std::chrono::duration_cast<std::chrono::milliseconds>(now - last_time);
+		if (delta_ms.count() != 0) {
+			TimerManager<TimerGameRealtime>::Elapsed(delta_ms);
+			last_time = now;
+		}
+	}
+
 	/* switch game mode? */
 	if (_switch_mode != SM_NONE && !HasModalProgress()) {
 		SwitchToMode(_switch_mode);

src/openttd.h

@@ -100,5 +100,6 @@ bool RequestNewGRFScan(struct NewGRFScanCallback *callback = nullptr);
 void GenerateSavegameId();
 
 void OpenBrowser(const char *url);
+void ChangeAutosaveFrequency(bool reset);
 
 #endif /* OPENTTD_H */

src/settings.cpp

@@ -1495,6 +1495,8 @@ static void TrainSpeedAdaptationChanged(int32 new_value) {
 }
 
 static void AutosaveModeChanged(int32 new_value) {
+	extern void ChangeAutosaveFrequency(bool reset);
+	ChangeAutosaveFrequency(false);
 	InvalidateWindowClassesData(WC_GAME_OPTIONS);
 }
 

src/settings_gui.cpp

@@ -719,6 +719,7 @@ struct GameOptionsWindow : Window {
 					ShowQueryString(STR_JUST_INT, STR_GAME_OPTIONS_AUTOSAVE_MINUTES_QUERY_CAPT, 4, this, CS_NUMERAL, QSF_ACCEPT_UNCHANGED);
 				} else {
 					_settings_client.gui.autosave_interval = _autosave_dropdown_to_minutes[index];
+					ChangeAutosaveFrequency(false);
 					this->SetDirty();
 				}
 				break;
@@ -781,6 +782,7 @@ struct GameOptionsWindow : Window {
 
 				case QueryTextItem::AutosaveCustomRealTimeMinutes:
 					_settings_client.gui.autosave_interval = Clamp(value, 1, 8000);
+					ChangeAutosaveFrequency(false);
 					this->SetDirty();
 					break;
 			}

src/timer/CMakeLists.txt

@@ -1,4 +1,6 @@
 add_files(
+    timer_game_realtime.cpp
+    timer_game_realtime.h
     timer_game_tick.cpp
     timer_game_tick.h
     timer_manager.h

src/timer/timer_game_realtime.cpp

@@ -0,0 +1,69 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * @file timer_game_realtime.cpp
+ * This file implements the timer logic for the real time game-timer.
+ */
+
+#include "../stdafx.h"
+#include "../openttd.h"
+#include "timer.h"
+#include "timer_game_realtime.h"
+
+#include "../safeguards.h"
+
+template<>
+void IntervalTimer<TimerGameRealtime>::Elapsed(TimerGameRealtime::TElapsed delta)
+{
+	if (this->period.period == std::chrono::milliseconds::zero()) return;
+	if (this->period.flag == TimerGameRealtime::PeriodFlags::AUTOSAVE && _pause_mode != PM_UNPAUSED && (_pause_mode & PM_COMMAND_DURING_PAUSE) == 0) return;
+	if (this->period.flag == TimerGameRealtime::PeriodFlags::UNPAUSED && _pause_mode != PM_UNPAUSED) return;
+
+	this->storage.elapsed += delta;
+
+	uint count = 0;
+	while (this->storage.elapsed >= this->period.period) {
+		this->storage.elapsed -= this->period.period;
+		count++;
+	}
+
+	if (count > 0) {
+		this->callback(count);
+	}
+}
+
+template<>
+void TimeoutTimer<TimerGameRealtime>::Elapsed(TimerGameRealtime::TElapsed delta)
+{
+	if (this->fired) return;
+	if (this->period.period == std::chrono::milliseconds::zero()) return;
+	if (this->period.flag == TimerGameRealtime::PeriodFlags::AUTOSAVE && _pause_mode != PM_UNPAUSED && (_pause_mode & PM_COMMAND_DURING_PAUSE) == 0) return;
+	if (this->period.flag == TimerGameRealtime::PeriodFlags::UNPAUSED && _pause_mode != PM_UNPAUSED) return;
+
+	this->storage.elapsed += delta;
+
+	if (this->storage.elapsed >= this->period.period) {
+		this->callback();
+		this->fired = true;
+	}
+}
+
+template<>
+void TimerManager<TimerGameRealtime>::Elapsed(TimerGameRealtime::TElapsed delta)
+{
+	for (auto timer : TimerManager<TimerGameRealtime>::GetTimers()) {
+		timer->Elapsed(delta);
+	}
+}
+
+#ifdef WITH_ASSERT
+template<>
+void TimerManager<TimerGameRealtime>::Validate(TimerGameRealtime::TPeriod)
+{
+}
+#endif /* WITH_ASSERT */

src/timer/timer_game_realtime.h

@@ -0,0 +1,59 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file timer_game_realtime.h Definition of the real time game-timer */
+
+#ifndef TIMER_GAME_REALTIME_H
+#define TIMER_GAME_REALTIME_H
+
+#include <chrono>
+
+/**
+ * Timer that represents real time for game-related purposes.
+ *
+ * For pausing, there are several modes:
+ * - Continue to tick during pause (PeriodFlags::ALWAYS).
+ * - Stop ticking when paused (PeriodFlags::UNPAUSED).
+ * - Only tick when unpaused or when there was a Command executed recently (recently: since last autosave) (PeriodFlags::AUTOSAVE).
+ *
+ * @note The lowest possible interval is 1ms, although realistic the lowest
+ * interval is 27ms. This timer is only updated when the game-thread makes
+ * a tick, which happens every 27ms.
+ * @note Callbacks are executed in the game-thread.
+ */
+class TimerGameRealtime {
+public:
+	enum PeriodFlags {
+		ALWAYS, ///< Always run, even when paused.
+		UNPAUSED, ///< Only run when not paused.
+		AUTOSAVE, ///< Only run when not paused or there was a Command executed recently.
+	};
+
+	struct TPeriod {
+		std::chrono::milliseconds period;
+		PeriodFlags flag;
+
+		TPeriod(std::chrono::milliseconds period, PeriodFlags flag) : period(period), flag(flag) {}
+
+		bool operator < (const TPeriod &other) const
+		{
+			if (this->flag != other.flag) return this->flag < other.flag;
+			return this->period < other.period;
+		}
+
+		bool operator == (const TPeriod &other) const
+		{
+			return this->flag == other.flag && this->period == other.period;
+		}
+	};
+	using TElapsed = std::chrono::milliseconds;
+	struct TStorage {
+		std::chrono::milliseconds elapsed;
+	};
+};
+
+#endif /* TIMER_GAME_REALTIME_H */