[cppia] Crashes when executing callables

[tobil4sk]

I have a pending PR to enable thread and eventloop tests for cppia: HaxeFoundation/haxe#12820

By reverting back to these commits before the callable rework, both of them run fine:
HaxeFoundation/haxe@add3235
14133db

However, the next commits after those break both tests:
HaxeFoundation/haxe@e4c2369
a20c1cc

Threads:

$ haxe --main Main --dce full --cppia bin/threads.cppia
$ haxelib run hxcpp bin/threads.cppia
Running cases.TestEvents...
    testRun
    testRepeat
    testIssue10567_runEventsInOrderByTime
Running cases.TestTimer...
    testCorrectInterval
terminate called after throwing an instance of 'Dynamic'

eventLoop:

$ haxe --main Main --dce full --cppia bin/Main.cppia
$ haxelib run hxcpp bin/Main.cppia                  
Main.hx:7: 0
terminate called after throwing an instance of 'Dynamic'

[tobil4sk]

@Aidan63 it looks like maybe some part of client/host interop was overlooked in the typed callable PR. Any ideas what might be missing here?

[Aidan63]

Seems like it's related to atomic ints, there was some shuffling of these atomics recently, right? Are they now missing some cppia guard or no longer forced to be in the host (can't remember where that file is kept)?

[Simn]

That was HaxeFoundation/haxe@b19f2d8#diff-85ecb7e473c06e2cf70878b33f3026f2c2ba32ac9ed0c840dab5764a1596c88f, but they were an abstract in the same place before that change too, so I'm not sure if that's the cause.

[tobil4sk]

I think errors like that happen sometimes when the host and client are out of sync. I don't think it's what's causing my crash, from what I can tell the issue I'm experiencing is usually a seg fault that occurs when a callable is executed.

Here is an example of the backtraces I'm seeing:

threads:

Running cases.TestTimer...
    testCorrectInterval

Program received signal SIGSEGV, Segmentation fault.
0x0000555556539130 in typeinfo for hx::ScriptCallable ()
(gdb) bt
#0  0x0000555556539130 in typeinfo for hx::ScriptCallable ()
#1  0x0000555555990871 in hx::Callable<void()>::operator() (this=0x7ffff7823a18) at /home/tobil/Dev/haxe/hxcpp/include/hx/Functions.h:410
#2  0x0000555555a2d51f in _hx_Closure_0::_hx_run (this=0x7ffff7823a40) at ./src/haxe/Timer.cpp:132
#3  0x0000555555990871 in hx::Callable<void()>::operator() (this=0x7ffff7823ac8) at /home/tobil/Dev/haxe/hxcpp/include/hx/Functions.h:410
#4  0x0000555555b823f5 in _hx_Closure_0::_hx_run (this=0x7ffff7823ab0) at ./src/haxe/EventLoop.cpp:907
#5  0x0000555555990871 in hx::Callable<void()>::operator() (this=0x7ffff7823a70) at /home/tobil/Dev/haxe/hxcpp/include/hx/Functions.h:410
#6  0x0000555555b81af1 in haxe::EventLoop_obj::loopOnce (this=0x7ffff77f8408, __o_threadCheck=...) at ./src/haxe/EventLoop.cpp:856
#7  0x0000555555b807a2 in haxe::EventLoop_obj::loop (this=0x7ffff77f8408) at ./src/haxe/EventLoop.cpp:707
#8  0x0000555555c2ea7e in haxe::EntryPoint_obj::run () at ./src/haxe/EntryPoint.cpp:53
#9  0x0000555555c2ec0a in haxe::__s_run (ctx=0x5555565b1c80) at ./src/haxe/EntryPoint.cpp:90
#10 0x0000555555ef228d in hx::CallHaxe::run<null> (this=0x555556794ff0, ctx=0x5555565b1c80, outValue=...) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/Cppia.cpp:1789
#11 0x0000555555edd0fe in hx::CallHaxe::runVoid (this=0x555556794ff0, ctx=0x5555565b1c80) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/Cppia.cpp:1810
#12 0x0000555555ed7f98 in hx::BlockExpr::runVoid (this=0x555556769860, ctx=0x5555565b1c80) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/Cppia.cpp:445
#13 0x0000555555ebd20c in hx::ScriptCallable::runFunction (this=0x555556769720, ctx=0x5555565b1c80) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/CppiaFunction.cpp:534
#14 0x0000555555db26e0 in hx::StackContext::runVoid (this=0x5555565b1c80, vtable=0x555556769720) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/CppiaCtx.cpp:32
#15 0x0000555555dae7f3 in hx::CppiaObject::run (this=0x7ffff77f96c0) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/CppiaModule.cpp:331
#16 0x0000555555c3b054 in cpp::cppia::Host_obj::runFile (filename=...) at ./src/cpp/cppia/Host.cpp:103
#17 0x0000555555c3b212 in cpp::cppia::Host_obj::main () at ./src/cpp/cppia/Host.cpp:120
#18 0x0000555555cc293e in __hxcpp_main () at ./src/__main__.cpp:25
#19 0x0000555555cc2749 in main (argc=2, argv=0x7fffffffdff8) at /home/tobil/Dev/haxe/hxcpp/include/hx/HxcppMain.h:93

eventloop:

[New Thread 0x7ffff77ef6c0 (LWP 85505)]
Main.hx:7: 0
[Thread 0x7ffff77ef6c0 (LWP 85505) exited]

Thread 1 "Cppia" received signal SIGSEGV, Segmentation fault.
0x0000555556539130 in typeinfo for hx::ScriptCallable ()
(gdb) bt
#0  0x0000555556539130 in typeinfo for hx::ScriptCallable ()
#1  0x0000555555990871 in hx::Callable<void()>::operator() (this=0x7ffff7801140) at /home/tobil/Dev/haxe/hxcpp/include/hx/Functions.h:410
#2  0x0000555555a2d51f in _hx_Closure_0::_hx_run (this=0x7ffff7801168) at ./src/haxe/Timer.cpp:132
#3  0x0000555555990871 in hx::Callable<void()>::operator() (this=0x7ffff78011f0) at /home/tobil/Dev/haxe/hxcpp/include/hx/Functions.h:410
#4  0x0000555555b823f5 in _hx_Closure_0::_hx_run (this=0x7ffff78011d8) at ./src/haxe/EventLoop.cpp:907
#5  0x0000555555990871 in hx::Callable<void()>::operator() (this=0x7ffff7801198) at /home/tobil/Dev/haxe/hxcpp/include/hx/Functions.h:410
#6  0x0000555555b81af1 in haxe::EventLoop_obj::loopOnce (this=0x7ffff77f8408, __o_threadCheck=...) at ./src/haxe/EventLoop.cpp:856
#7  0x0000555555b807a2 in haxe::EventLoop_obj::loop (this=0x7ffff77f8408) at ./src/haxe/EventLoop.cpp:707
#8  0x0000555555c2ea7e in haxe::EntryPoint_obj::run () at ./src/haxe/EntryPoint.cpp:53
#9  0x0000555555c2ec0a in haxe::__s_run (ctx=0x5555565b1c80) at ./src/haxe/EntryPoint.cpp:90
#10 0x0000555555ef228d in hx::CallHaxe::run<null> (this=0x55555660dad0, ctx=0x5555565b1c80, outValue=...) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/Cppia.cpp:1789
#11 0x0000555555edd0fe in hx::CallHaxe::runVoid (this=0x55555660dad0, ctx=0x5555565b1c80) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/Cppia.cpp:1810
#12 0x0000555555ed7f98 in hx::BlockExpr::runVoid (this=0x55555660b4f0, ctx=0x5555565b1c80) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/Cppia.cpp:445
#13 0x0000555555ebd20c in hx::ScriptCallable::runFunction (this=0x55555660b3b0, ctx=0x5555565b1c80) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/CppiaFunction.cpp:534
#14 0x0000555555db26e0 in hx::StackContext::runVoid (this=0x5555565b1c80, vtable=0x55555660b3b0) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/CppiaCtx.cpp:32
#15 0x0000555555dae7f3 in hx::CppiaObject::run (this=0x7ffff77f96c0) at /home/tobil/Dev/haxe/hxcpp/src/hx/cppia/CppiaModule.cpp:331
#16 0x0000555555c3b054 in cpp::cppia::Host_obj::runFile (filename=...) at ./src/cpp/cppia/Host.cpp:103
#17 0x0000555555c3b212 in cpp::cppia::Host_obj::main () at ./src/cpp/cppia/Host.cpp:120
#18 0x0000555555cc293e in __hxcpp_main () at ./src/__main__.cpp:25
#19 0x0000555555cc2749 in main (argc=2, argv=0x7fffffffdfe8) at /home/tobil/Dev/haxe/hxcpp/include/hx/HxcppMain.h:93
(gdb) 

[Aidan63]

Yes, I had an out of date cppia runtime.

The problem seems to be is that a Callable which should only ever hold pointers to a Callable_obj seems to have a pointer to a hx::CppiaClosure which does not have a _hx_run function. This class is still all dynamic, so what I assume is happening is that when the cppia closure is passed back into the native world it's pointer is blindly reinterpreted to a callable instead of going through the dynamic -> callable conversion.
I remember coming across a similar issue when first getting this all running on cppia.

[Aidan63]

I'm having a proper look at this now and the issue seems to be related to dynamic functions, specifically setting dynamic function in a host class from a script. E.g. the following is enough to reproduce the error.

function main() {
	var t = new haxe.Timer(1000);

	Reflect.setField(t, 'run', () -> {
		trace('done');

		t.stop();
	});
}

I think my guess of the dynamic callable conversion not happening is correct as if you replace that with a reflection version

function main() {
	var t = new haxe.Timer(1000);

	Reflect.setField(t, 'run', () -> {
		trace('done');

		t.stop();
	});
}

it works fine, just need to to find out where / how this dynamic function setting takes place in cppia.

[Aidan63]

#1324 Changes in that PR get the thread tests passing on cppia