Button example crashes when terminal window is resized

[jaysonsantos]

It seems that the events are coming from the same thread where the loop happens and mutexes have undefined behavior when lock is called from the same thread. To reproduce:

• Run zig build example -Dexample=counter
• Resize terminal window, tested in Alacritty and Ghostty

The following stack trace can be capture as long you attach to it in another terminal.

Target 0: (example) stopped.
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGABRT
  * frame #0: 0x000000018f129388 libsystem_kernel.dylib`__pthread_kill + 8
    frame #1: 0x000000018f16288c libsystem_pthread.dylib`pthread_kill + 296
    frame #2: 0x000000018f06bc60 libsystem_c.dylib`abort + 124
    frame #3: 0x0000000100e59d00 example`posix.abort at posix.zig:710:29
    frame #4: 0x0000000100e55a40 example`debug.defaultPanic(msg=(ptr = "Deadlock detected", len = 17), first_trace_addr=(data = 0, some = '\0')) at debug.zig:704:16
    frame #5: 0x0000000100e90fa0 example`Thread.Mutex.DebugImpl.lock at Mutex.zig:72:13
    frame #6: 0x0000000100e90f08 example`Thread.Mutex.lock(self=0x000000016efada88) at Mutex.zig:34:19
    frame #7: 0x0000000100f10ee4 example`queue.Queue(self=0x000000016efa7a78, item=<unavailable>).push at queue.zig:45:28
    frame #8: 0x0000000100f07338 example`Loop.Loop(self=0x000000016efa7a68, event=<unavailable>).postEvent at Loop.zig:89:28
    frame #9: 0x0000000100ef8520 example`Loop.Loop(ptr=0x000000016efa7a68).winsizeCallback at Loop.zig:103:31
    frame #10: 0x0000000100eef58c example`tty.PosixTty.handleWinch at tty.zig:152:29
    frame #11: 0x000000018f19c624 libsystem_platform.dylib`_sigtramp + 56
    frame #12: 0x0000000100e91138 example`heap.arena_allocator.ArenaAllocator.alloc(ctx=0x00000001010c0080, n=1, alignment=1, ra=4310651692) at arena_allocator.zig:181:48
    frame #13: 0x0000000100e9e7e8 example`mem.Allocator.rawAlloc at Allocator.zig:129:26
    frame #14: 0x0000000100e9e7c0 example`mem.Allocator.allocBytesWithAlignment__anon_12438(self=<unavailable>, byte_count=1, return_address=4310651692) at Allocator.zig:272:35
    frame #15: 0x0000000100e8c9ec example`mem.Allocator.allocWithSizeAndAlignment__anon_10511(self=<unavailable>, n=1, return_address=4310651692) at Allocator.zig:263:40
    frame #16: 0x0000000100f0c598 example`mem.Allocator.allocAdvancedWithRetAddr at Allocator.zig:257:75
    frame #17: 0x0000000100f0c57c example`mem.Allocator.alignedAlloc__anon_23988(self=<unavailable>, n=1) at Allocator.zig:245:41
    frame #18: 0x0000000100ef532c example`array_list.ArrayListAlignedUnmanaged(self=0x000000016efa72e0, allocator=<unavailable>, new_capacity=1).ensureTotalCapacityPrecise at array_list.zig:1094:62
    frame #19: 0x0000000100eefd54 example`array_list.ArrayListAlignedUnmanaged(allocator=<unavailable>, num=1).initCapacity at array_list.zig:651:48
    frame #20: 0x0000000100eef92c example`InternalScreen.init(alloc=mem.Allocator @ 0x000000016efaddd0, w=258, h=60) at InternalScreen.zig:62:64
    frame #21: 0x0000000100ef88e0 example`Vaxis.resize(self=0x000000016efae148, alloc=mem.Allocator @ 0x000000016efaddd0, tty=<unavailable>, winsize=(rows = 60, cols = 258, x_pixel = 3354, y_pixel = 1800)) at Vaxis.zig:202:47
    frame #22: 0x0000000100ef194c example`vxfw.App.run(self=0x000000016efae0e8, widget=(userdata = 0x00000001011a0000, captureHandler = 0x0000000000000000, eventHandler = 0x0000000100ef6dd0, drawFn = 0x0000000100ef70c0), opts=(framerate = '<')) at App.zig:147:38
    frame #23: 0x0000000100ef0970 example`counter.main at counter.zig:138:16
    frame #24: 0x0000000100ef2f3c example`start.callMain at start.zig:660:37 [inlined]
    frame #25: 0x0000000100ef2f30 example`start.callMainWithArgs at start.zig:620:20
    frame #26: 0x0000000100ef2eb8 example`start.main(c_argc=1, c_argv=0x000000016efaed20, c_envp=0x000000016efaed30) at start.zig:635:28
    frame #27: 0x000000018edc2b98 dyld`start + 6076
(lldb) f 6

[ShuP1]

Root cause is than winsizeCallback runs in the main thread and calls self.postEvent(.{ .winsize = winsize });. But this thread also locks the queue to pull events.

I don't known if it is possible but... running winsizeCallback on the reader thread would fix it