Crash on iOS when swiping app out

[sdelaysam]

Hi, @frankinshtein !

There is a crash on iOS when using OXYGINE_DEBUG_TRACE_LEAKS.
It occurs each time when app is swiped out from tasks.

4  game                           0x1013d4ea8 oxygine::ObjectBase::__removeFromDebugList(oxygine::ObjectBase*) + 932
5  game                           0x1013d54c0 oxygine::ObjectBase::~ObjectBase() + 216
6  game                           0x10129c2f0 oxygine::Object::~Object() + 40
7  game                           0x1015a184c oxygine::ShaderProgram::~ShaderProgram() + 36
8  game                           0x1015a1938 oxygine::ShaderProgramGL::~ShaderProgramGL() + 136
9  game                           0x1015a1974 oxygine::ShaderProgramGL::~ShaderProgramGL() + 28
10 game                           0x1015a19dc oxygine::ShaderProgramGL::~ShaderProgramGL() + 28

I've managed to catch it in Xcode debugger

if (_tracingLeaks)
{
    MutexAutoLock m_(getMutex());
    if (base->__traceLeak)
    {
        base->__traceLeak = false;
        __createdObjects& objs = __getCreatedObjects();
        __createdObjects::iterator i = std::find(objs.begin(), objs.end(), base);
        OX_ASSERT(i != objs.end());  // <-- That line
        objs.erase(i);
    }
}

UPD: maybe its on my side, didn't notice it on example projects..

[frankinshtein]

yes, it is on your side
same object was deleted twice or was deleted previously

[sdelaysam]

No, having the same issue with HelloWorld example

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   libsystem_kernel.dylib        	0x00000001836c5348 __pthread_kill + 8
1   libsystem_pthread.dylib       	0x00000001837d9354 pthread_kill$VARIANT$mp + 396
2   libsystem_c.dylib             	0x0000000183634fd8 abort + 140
3   libsystem_c.dylib             	0x0000000183608abc basename_r + 0
4   HelloWorld_ios                	0x00000001011c4ab0 oxygine::ObjectBase::__removeFromDebugList(oxygine::ObjectBase*) + 264880 (Object.cpp:226)
5   HelloWorld_ios                	0x00000001011c5048 oxygine::ObjectBase::~ObjectBase() + 266312 (Object.cpp:187)
6   HelloWorld_ios                	0x00000001011c68e8 oxygine::Object::~Object() + 272616 (Object.h:83)
7   HelloWorld_ios                	0x00000001011db224 oxygine::EventDispatcher::~EventDispatcher() + 356900 (EventDispatcher.cpp:20)
8   HelloWorld_ios                	0x0000000101190864 oxygine::Actor::~Actor() + 51300 (Actor.cpp:96)
9   HelloWorld_ios                	0x0000000101236b64 oxygine::VStyleActor::~VStyleActor() + 732004 (VisualStyle.h:29)
10  HelloWorld_ios                	0x000000010123b7ac oxygine::TextField::~TextField() + 751532 (TextField.cpp:43)
11  HelloWorld_ios                	0x000000010123b7e0 oxygine::TextField::~TextField() + 751584 (TextField.cpp:43)
12  HelloWorld_ios                	0x000000010123b848 oxygine::TextField::~TextField() + 751688 (TextField.cpp:40)

[frankinshtein]

how to reproduce it in HelloWorld then?

[sdelaysam]

Just try launch it on device, then put to background, then swipe out from recent tasks.
I did it like 10 times and found 3 crashes in device logs (Xcode -> Devices & Simulators -> View Device Logs)

[frankinshtein]

but without crash in xcode?

[sdelaysam]

Hmm, what do you mean?

[frankinshtein]

breakpoint stop when error occurs

[sdelaysam]

Ahh, yep, I could catch it that way, but only once. Steps are the same.

[sdelaysam]

After some investigation, I think that it might be SDL issue. Looks like there is a problem with app termination on iOS. Just give you an idea of what I did.

1. In SDL_video.c

void SDL_OnApplicationWillTerminate(void)
{
    SDL_SendQuit(); // <-- add this line
    SDL_SendAppEvent(SDL_APP_TERMINATING);
}

2. In SDL_main.h add these lines

#define SDLEXIT_DECLSPEC
#define exit    SDL_exit
extern C_LINKAGE SDLEXIT_DECLSPEC void SDL_exit();

3. In main.cpp defined exit() function, which do regular destroy logic.

4. In SDL_uikitappdelegate.m

- (void)applicationWillTerminate:(UIApplication *)application
{
    SDL_OnApplicationWillTerminate();
    SDL_exit(); // <-- add this line
}

Note: I'm using CADisplayLink for game loop update.

[frankinshtein]

hmm, oxygine examples doesnt use CADisplayLink
in this case you just have to destroy everything in applicationWillTerminate

/*
     If we get here, the user has requested the Application to terminate.
     We dump and log all our created objects that have not been freed yet
    */
    ObjectBase::dumpCreatedObjects();

    /*
    Let's clean up everything right now and call ObjectBase::dumpObjects() again.
    We need to free all allocated resources and delete all created actors.
    All actors/sprites are smart-pointer objects and don't need to be removed by hand.
    But now we want to delete it by hand.
    */

    // See example.cpp for the shutdown function implementation
    example_destroy();


    //renderer.cleanup();

    // Releases all internal components and the stage
    core::release();

    // The dump list should be empty by now,
    // we want to make sure that there aren't any memory leaks, so we call it again.
    ObjectBase::dumpCreatedObjects();

    ObjectBase::__stopTracingLeaks();

[sdelaysam]

Yes, exactly! Release logic need to be called synchronously in applicationWillTerminate.