apitrace and RenderDoc cause a failure during initialization.

[mcourteaux]

I tried both RenderDoc and apitrace, and they both yield the same behavior:

tracy/public/client/TracyProfiler.cpp

Lines 3827 to 3835 in 0c22853

	moodycamel::ConsumerToken token( GetQueue() );
	int left = Events;
	while( left != 0 )
	{
	const auto sz = GetQueue().try_dequeue_bulk_single( token, [](const uint64_t&){}, [](QueueItem* item, size_t sz){} );
	assert( sz > 0 );
	left -= (int)sz;
	}
	assert( GetQueue().size_approx() == 0 );

Asserts on the sz being 0. Simple steps to reproduce (on Unix-like systems):

1. Download apitrace binary and extract with tar xvf
2. Compile some application that uses Tracy in Debug mode.
3. ./apitrace trace --api gl --debug <some-app-using-tracy>
4. GDB starts (thanks to the --debug flag), enter run.
5. You are now in the assert(sz > 0).

I observed that not a single event got popped from the queue:

(gdb) f 5
#5  0x0000000000d4514f in tracy::Profiler::CalibrateDelay (this=0x1dde740 <tracy::s_profiler>) at /home/martijn/zec/3rd/tracy/public/client/TracyProfiler.cpp:3846
3846	       assert( sz > 0 );
(gdb) p sz
$1 = 0
(gdb) l
3841	   moodycamel::ConsumerToken token( GetQueue() );
3842	   int left = Events;
3843	   while( left != 0 )
3844	   {
3845	       const auto sz = GetQueue().try_dequeue_bulk_single( token, [](const uint64_t&){}, [](QueueItem* item, size_t sz){} );
3846	       assert( sz > 0 );
3847	       left -= (int)sz;
3848	   }
3849	   assert( GetQueue().size_approx() == 0 );
3850	#endif
(gdb) p Events
$2 = 100000
(gdb) p left
$3 = 100000
(gdb) p token
$4 = {initialOffset = 0, lastKnownGlobalOffset = 4294967295, itemsConsumedFromCurrent = 0, currentProducer = 0x0, desiredProducer = 0x0}
(gdb) p s_queue
$5 = {static BLOCK_SIZE = 65536, static EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD = 32, static EXPLICIT_INITIAL_INDEX_SIZE = 32, producerListTail = std::atomic<tracy::moodycamel::ConcurrentQueue<tracy::QueueItem, tracy::moodycamel::ConcurrentQueueDefaultTraits>::ProducerBase *> = { 0x0 }, producerCount = std::atomic<unsigned int> = { 0 }, initialBlockPoolIndex = std::atomic<unsigned long> = { 1 }, 
  initialBlockPool = 0x7ffff6010080, initialBlockPoolSize = 4, freeList = {freeListHead = std::atomic<tracy::moodycamel::ConcurrentQueue<tracy::QueueItem, tracy::moodycamel::ConcurrentQueueDefaultTraits>::Block *> = { 0x0 }, static REFS_MASK = 2147483647, static SHOULD_BE_ON_FREELIST = 2147483648}, nextExplicitConsumerId = std::atomic<unsigned int> = { 1 }, 
  globalExplicitConsumerOffset = std::atomic<unsigned int> = { 0 }}