-[SPExportController cancelExport:] does not wait until queue is actually empty

[dmoagx]

Code in question:

    // Cancel all of the currently running operations
    [operationQueue cancelAllOperations];

    // Loop the cached export file paths and remove them from disk if they exist
    for (SPExportFile *file in exportFiles)
    {
        [file delete];
    }

cancelAllOperations is async and whether an operation actually reacts to cancellation is still up to the operation. This means while [file delete] is running another thread could still be writing to that file.

Reports:
(all erroneously grouped with other issues – feedback reporter causes a crash and hides the real issue ;see console log)
http://log.sequelpro.com/view/4878
http://log.sequelpro.com/view/4400
http://log.sequelpro.com/view/2036

Exception:

Cannot write to a file handle after it has been closed
(
    0   CoreFoundation                      0x00007fff8629f25c __exceptionPreprocess + 172
    1   libobjc.A.dylib                     0x00007fff836b2e75 objc_exception_throw + 43
    2   CoreFoundation                      0x00007fff8629f10c +[NSException raise:format:] + 204
    3   Sequel Pro                          0x00000001000f7dc9 -[SPFileHandle writeData:] + 70
    4   Sequel Pro                          0x00000001000d0971 -[SPSQLExporter main] + 5468
    5   Foundation                          0x00007fff8a7788a1 -[__NSOperationInternal _start:] + 631
    6   Foundation                          0x00007fff8a77854b __NSOQSchedule_f + 64
    7   libdispatch.dylib                   0x00007fff8a0ff28d _dispatch_client_callout + 8
    8   libdispatch.dylib                   0x00007fff8a1037e3 _dispatch_async_redirect_invoke + 154
    9   libdispatch.dylib                   0x00007fff8a0ff28d _dispatch_client_callout + 8
    10  libdispatch.dylib                   0x00007fff8a101082 _dispatch_root_queue_drain + 326
    11  libdispatch.dylib                   0x00007fff8a102177 _dispatch_worker_thread2 + 40
    12  libsystem_pthread.dylib             0x00007fff8e087ef8 _pthread_wqthread + 314
    13  libsystem_pthread.dylib             0x00007fff8e08afb9 start_wqthread + 13
)