1 Commits (36f3e3b28c82611c72a867cdc1f5ddc8bd9325e9)

Author	SHA1	Message	Date
David Wilson	d4c0250083	issue #532: PushFileService race. ... There has always been a race in PushFileService since given a parent asked to forward modules to two children via some intermediary: interm = router.local() c1 = router.local(via=interm) c2 = router.local(via=interm) service.propagate_to(c1, 'foo/bar.py') service.propagate_to(c2, 'foo/bar.py') Two calls will be emitted to 'interm': PushFileService.store_and_forward(c1, 'foo/bar.py', [blob]) PushFileService.store(c2, 'foo/bar.py') Which will be processed in-order up to the point where service pool threads in 'interm' are woken to process the message. While it is guaranteed store_and_forward() will be processed first, no guarantee existed that its assigned pool thread would wake and take _lock first, thus it was possible for forward() to win the race, and for a request to arrive to forward a file that had not been placed in local cache yet. Here we get rid of SerializedInvoker entirely, as it is partially to blame for hiding the race: SerializedInvoker can only ensure no two messages are processed simultaneously, it cannot ensure the messages are processed in their intended order. Instead, teach forward() that it may be called before store_and_forward(), and if that is the case, to place the forward request on to _waiters alongside any local threads blocked in get().	7 years ago