Details
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Bug
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Resolution: Unresolved
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P2: Important
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None
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5.15.3
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None
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iOS/tvOS/watchOS
Description
Hi i have a Critical race conditions on iOS bluetooth peripheral.
This is the scenario. I have my app that acts like a peripheral. Everything works fine, the central side read and write data continuosly.
When a disconnection happen, it can occurs this race:
- central disconnects itself
- my app get it and start to advertise again
- central sees the advertisment and try to connect to it immediately
- connection restabilished, but i had a crash sometimes, check this backtrace
Thread 6 name: Thread 6 Crashed: 0 libobjc.A.dylib 0x0000000196208110 objc_msgSend + 48 1 app 0x0000000102eb1548 0x102c4c000 + 2512200 addCharacteristicsAndDescriptors 2 app 0x0000000102eaff90 0x102c4c000 + 2506640 didReceiveWriteRequests 3 app 0x0000000102eb07e8 0x102c4c000 + 2508776 addConnectedCentral 4 libdispatch.dylib 0x0000000180de424c _dispatch_call_block_and_release + 32 (init.c:1454) 5 libdispatch.dylib 0x0000000180de5db0 _dispatch_client_callout + 20 (object.m:559) 6 libdispatch.dylib 0x0000000180ded10c _dispatch_lane_serial_drain + 580 (inline_internal.h:2548) 7 libdispatch.dylib 0x0000000180dedc5c _dispatch_lane_invoke + 408 (queue.c:3862) 8 libdispatch.dylib 0x0000000180df7d78 _dispatch_workloop_worker_thread + 708 (queue.c:6601) 9 libsystem_pthread.dylib 0x00000001ccca1814 _pthread_wqthread + 276 (pthread.c:2210) 10 libsystem_pthread.dylib 0x00000001ccca876c start_wqthread + 8
The strange thing, is that when a peripheral qt app on iOS disconnects from the central side, there is no need to put again the services: infact, if you did, you will have dupliace services.
This is my reconnect code
void v::reconnect()
{
qDebug() << "v::reconnect";
leController->disconnectFromDevice();
#ifndef Q_OS_IOS
service = leController->addService(serviceData);
#endif
QLowEnergyAdvertisingParameters pars;
pars.setInterval(100, 100);
leController->startAdvertising(pars, advertisingData, advertisingData);
}
as you can see i removed the addService from the iOS build because it caused duplicate services.