(#1332) Fix crashes in test case PushTests.test__008__LocalDevice__has_a_device_method_that_returns_a_LocalDevice (4f837671-6233-41f1-94e8-01174d1da7b8)
#1392
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We currently read / write the variable that stores the shared ARTLocalDevice variable from the internal queue of the ARTRest instance through which the device is being accessed. But, since each ARTRest instance has its own queue, this means that access to this variable isn’t currently synchronised between multiple ARTRest instances. So, here we do that. This also allows us to remove our usage of dispatch_once. This is a good thing, because we were using it incorrectly before. From an Apple engineer on https://stackoverflow.com/a/19845164: > The implementation of dispatch_once() requires that the > dispatch_once_t is zero, and has never been non-zero. That is, you can’t reset a dispatch_once_t variable and expect dispatch_once to still work with it, which is what we were doing.
This doesn’t change anything, it just explains the current behaviour of the code. ARTLocalDeviceStorage already conforms to these requirements, since it uses the (already thread-safe) user defaults / keychain. However, MockDeviceStorage does need some synchronisation. I’ll do that next.
As promised in e0ff029. Together with de281bd and fbd5645, I believe this closes #1332 (various crashes in PushTests.test__008__LocalDevice__has_a_device_method_that_returns_a_LocalDevice, which seemed to be related to threading). Test case: https://test-observability.herokuapp.com/repos/ably/ably-cocoa/test_cases/4f837671-6233-41f1-94e8-01174d1da7b8
lawrence-forooghian
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lukasz-szyszkowski,
maratal and
QuintinWillison
maratal
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maratal
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May 9, 2022
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[EDX-75] Move raw REST API ref
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What does this do?
Introduces various concurrency-related fixes related to the local device. Together, I believe these fix various crashes that we've observed in the test mentioned in the title (#1332). See commit messages for more details.
How do I know it's fixed the test?
These are the results of the tests running continuously with these fixes applied. At time of writing, there are 97 test runs with no failures in this test, but I'll keep it running for a while more before merging.