@Jie, if the target processes in “.onAny(defer())” are the same, is it still un-ordered?
> On Mar 29, 2016, at 09:19, Qian Zhang <zhq527...@gmail.com> wrote: > > So the point is, if the state of the future is set to READY between > .onAny(callback_A) and .onAny(callback_B) and before callback_A is executed > in this thread, another thread comes in and does onAny(callback_B), then > callback_B will be executed immediately in this thread, and callback_A will > only be executed when the previous thread comes in again, right? > > > Thanks, > Qian Zhang > > On Tue, Mar 29, 2016 at 8:50 AM, Jie Yu <yujie....@gmail.com> wrote: > >> Hi, >> >> While digging a bug reported in, I realized an assumption we shouldn't make >> in our code. >> https://issues.apache.org/jira/browse/MESOS-5023 >> >> Say you have the following code: >> >> void some_func() >> { >> future >> .onAny(callback_A) >> .onAny(callback_B); >> } >> >> Question: will callback_A already be executed before callback_B? >> >> The answer is NO. We should never assume that. Under the following >> interleaving, callback_B can be invoked first: >> >> Thread-1 Thread-2 >> >> onAny(callback_A) { >> onAnyCallbacks.push_back(callback_A); >> } >> set() { >> lock() >> if (state == >> PENDING) { >> state = READY; >> result = true; >> } >> unlock(); >> >> onAny(callback_B) { >> lock() >> if (state != PENDING) { >> run = true >> } >> unlock() >> >> if (run) { >> callback_B() >> } >> >> if (result) { >> >> internal::run(data->onAnyCallbacks, >> *this); >> } >> >> - Jie >>
