fix for delete/open race #4768
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fix for delete/open race #4768
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tgoyne
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DominicFrei
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Proposed fix for #4762
A call to realm::delete_files concurrently with opening the same realm file had a race, where the management directory could be removed from under the feet of DB::do_open. This could happen both before do_open acquires the exclusive lock and after, right before acquiring a shared lock.
The fix moves creation/deletion of the management directory such that it is protected by the exclusive lock.
It is still possible (but a different problem) for realm::delete_files() to interfere with do_open() such that the lock file is not re-initialized. However, this is highly unlikely to have any impact, since it can only happen when cleaning up after previous use of the realm file, and in that case re-initialization of the lock file should not be needed, assuming that the cleanup occurs as part of an orderly shutdown.
☑️ ToDos