Android: Make ALooper_pollAll call always non-blocking

[srifqi]

This PR tries to fix minetest/minetest#10842. See there for further discussion.

Implementation details

Original:

((Focused && !Paused) || !Initialized) ? 0 : -1

Since we want Minetest to still run when the text box shows up (Focused is false) and when Minetest is minimised (Paused is true), we remove both variables from the formula.

!Initialized ? 0 : -1

Because of this:

irrlicht/source/Irrlicht/Android/CIrrDeviceAndroid.cpp

Lines 100 to 101 in 85081d6

	if (!Initialized)
	return false;

we need to remove Initialized from the formula to prevent it from making Minetest freeze/stuck waiting a (blocking) ALooper_pollAll call.

0

---

EDIT: The Visual Studio builds failed due to vcpkg errors.

[grorp]

Pausing Minetest completely when the app is paused doesn't make sense in multiplayer. It's also problematic in the mainmenu if the user is currently downloading a package from CDB. So +1 for the concept.

What about line 67 in the same file?

irrlicht/source/Irrlicht/Android/CIrrDeviceAndroid.cpp

Line 67 in b15dabe

while ((ALooper_pollAll(((Focused && !Paused) || !Initialized) ? 0 : -1, 0, &Events, (void**)&Source)) >= 0)

---

To avoid an unnecessarily big increase in battery usage from this PR, maybe we could add code to Minetest to stop rendering while the app is paused? Something like this:

diff --git a/include/IrrlichtDevice.h b/include/IrrlichtDevice.h
index 6dcdb49..98c21f7 100644
--- a/include/IrrlichtDevice.h
+++ b/include/IrrlichtDevice.h
@@ -173,6 +173,8 @@ namespace irr
 		/** \return True if window is maximized. */
 		virtual bool isWindowMaximized() const = 0;
 
+		virtual bool isAppPaused() const { return false; };
+
 		//! Checks if the Irrlicht window is running in fullscreen mode
 		/** \return True if window is fullscreen. */
 		virtual bool isFullscreen() const = 0;
diff --git a/source/Irrlicht/Android/CIrrDeviceAndroid.cpp b/source/Irrlicht/Android/CIrrDeviceAndroid.cpp
index b1df885..745ed4f 100644
--- a/source/Irrlicht/Android/CIrrDeviceAndroid.cpp
+++ b/source/Irrlicht/Android/CIrrDeviceAndroid.cpp
@@ -193,6 +193,10 @@ bool CIrrDeviceAndroid::isWindowMinimized() const
 	return !Focused;
 }
 
+bool CIrrDeviceAndroid::isAppPaused() const {
+	return Paused;
+}
+
 void CIrrDeviceAndroid::closeDevice()
 {
 	ANativeActivity_finish(Android->activity);
diff --git a/source/Irrlicht/Android/CIrrDeviceAndroid.h b/source/Irrlicht/Android/CIrrDeviceAndroid.h
index 656c456..f5a88a5 100644
--- a/source/Irrlicht/Android/CIrrDeviceAndroid.h
+++ b/source/Irrlicht/Android/CIrrDeviceAndroid.h
@@ -36,6 +36,8 @@ namespace irr
 
 		virtual bool isWindowMinimized() const;
 
+		virtual bool isAppPaused() const;
+
 		virtual void closeDevice();
 
 		virtual void setResizable(bool resize = false);

diff --git a/src/client/game.cpp b/src/client/game.cpp
index cc88915474..4c9a8ae0bc 100644
--- a/src/client/game.cpp
+++ b/src/client/game.cpp
@@ -1251,7 +1251,8 @@ void Game::run()
 		updateCamera(dtime);
 		updateSound(dtime);
 		processPlayerInteraction(dtime, m_game_ui->m_flags.show_hud);
-		updateFrame(&graph, &stats, dtime, cam_view);
+		if (!device->isAppPaused())
+			updateFrame(&graph, &stats, dtime, cam_view);
 		updateProfilerGraphs(&graph);
 
 		// Update if minimap has been disabled by the server

[srifqi]

What about line 67 in the same file?

I am not sure about that line. I have not tested it. Since that is run in initialisation step, it is probably fine to not change it.

---

To avoid an unnecessarily big increase in battery usage from this PR, maybe we could add code to Minetest to stop rendering while the app is paused? Something like this:

That looks good. The frame/window would not be shown anyway, but we still need the engine to run for other background tasks. It is probably better to also use conditional inclusion (#ifdef directive) since it is only used for Android devices.

[sfan5]

To avoid an unnecessarily big increase in battery usage from this PR, maybe we could add code to Minetest to stop rendering while the app is paused?

take a look at isWindowActive, it already enables exactly this

[grorp]

LGTM

I think it would be good to merge this together with minetest/minetest#14058.

[sfan5]

I think that change in MT is a bit risky to pull in last minute.