Recently I have started getting crash when trying to resolve an object. Following is the crash logs. I can see that in Container.swift at line 299 guard let currentObjectGraph = currentObjectGraph else { fatalError() } the application is not getting currentObjectGraph and it fails. What can be the probable cause?
In my project, I have a global level assembler which adds all the Assembly from different frameworks. But when I am trying to resolve an object it's giving the crash. This is an intermediate issue:-
#15. Crashed: com.apple.NSURLSession-work
0 libswiftCore.dylib 0x109a1b95c specialized _assertionFailure(_:_:file:line:flags:) + 97848
1 Swinject 0x1096d4994 Container.resolve<A, B> (entry : ServiceEntryProtocol, invoker : (B) -> Any) -> A? (Container.swift:299)
2 Swinject 0x1096d2e54 Container._resolve<A, B> (name : String?, option : ServiceKeyOption?, invoker : ((B) -> Any) -> Any) -> A? (Container.swift:192)
3 Swinject 0x1096d582c Container.resolve<A> (A.Type, name : String?) -> A? (Container.swift:281)
4 Swinject 0x1096d5918 ContainerSwinjectResolver (Container.swift)
5 Commons 0x10661e268 specialized static NetworkInterceptor.canInit(with : URLRequest) -> Bool (NetworkInterceptor.swift:67)
6 Commons 0x10661c084 @objc static NetworkInterceptor.canInit(with : URLRequest) -> Bool (NetworkInterceptor.swift)
7 CFNetwork 0x1822ec64c -[__NSURLSessionLocal _protocolClassForRequest:] + 188
8 CFNetwork 0x1822ec7f4 -[__NSURLSessionLocal _request:isCacheEquivalentTo:] + 64
9 CFNetwork 0x1822ec9c8 -[__NSURLSessionLocal _cfurlRequest:isCacheEquivalentTo:] + 172
10 CFNetwork 0x18234fcc8 __CFURLCache::checkMemoryCache(__CFString const*, _CFURLRequest const*, NSURLSession const*) + 188
11 CFNetwork 0x18234bfd0 __CFURLCache::CopyResponseForRequestWithCompletionHandler(_CFURLRequest const*, bool, NSURLSession const*, void (_CFCachedURLResponse const*) block_pointer) + 316
12 CFNetwork 0x1824e4020 CFXURLCache::getResponseForTask(NSURLSessionTask const*, unsigned char, void (_CFCachedURLResponse const*) block_pointer) const + 84
13 CFNetwork 0x18244a578 URLConnectionLoader::_loaderEvent_StartLoad(NSURLSessionTask const*) + 1116
14 CFNetwork 0x18238007c -[__NSCFURLLocalSessionConnection withLoaderOnQueue:] + 72
15 CFNetwork 0x1823806a4 -[__NSCFURLLocalSessionConnection _tick_initialize] + 92
16 CFNetwork 0x18237fc24 __71-[__NSCFURLLocalSessionConnection initWithTask:delegate:delegateQueue:]_block_invoke + 40
17 libdispatch.dylib 0x1816dea54 _dispatch_call_block_and_release + 24
18 libdispatch.dylib 0x1816dea14 _dispatch_client_callout + 16
19 libdispatch.dylib 0x1816e896c _dispatch_queue_serial_drain$VARIANT$mp + 528
20 libdispatch.dylib 0x1816e92fc _dispatch_queue_invoke$VARIANT$mp + 340
21 libdispatch.dylib 0x1816e9d20 _dispatch_root_queue_drain_deferred_wlh$VARIANT$mp + 404
22 libdispatch.dylib 0x1816f203c _dispatch_workloop_worker_thread$VARIANT$mp + 644
23 libsystem_pthread.dylib 0x181986f1c _pthread_wqthread + 932
24 libsystem_pthread.dylib 0x181986b6c start_wqthread + 4
To summarise the solution we converged to in the github issue:
When resolving services on multiple threads, you need to use the synchronised resolver, which provides the thread safety. Assembler doesn't quite support this yet (Swijnject#221) but you can work around this by
let synchronizedResolver = (assembler.resolver as! Container).synchronized()
and use this instance of Resolver every time you resolve() a service on all the threads.