I'm not sure what you mean when you refer to tag->status and tag->reply. The gRPC API does not define a particular API for the tag; that's entirely up to your application code, so I have no idea what those fields represent or how they are being set.
Yang's earlier description is correct: the ok parameter is an indication of whether the operation corresponding to the returned tag was successful. What a failure means depends on what the operation was. If it was a RequestCall(), then it means that the completion queue is shutting down and you can stop listening for new calls. For any request as part of a call (e.g., a read or a write), it means that there was a problem with the operation and you should call Finish() to get the call's final status. On Thu, Aug 31, 2017 at 11:30 PM, 谭锦彪 <[email protected]> wrote: > Hi > > I meet the situation that the Next return true, but ok==false, howerer, > the content of the tag is right, tag->status.ok() return true, tag->reply > is right too, That confuse me, > why would this situation happen? Could I ignore the check of ok? > > 在 2017年8月2日星期三 UTC+8上午6:57:16，Yang Gao写道： > >> Usually we have a loop calling Next and when we are sure there will be no >> more work adding to the completion queue we call completion queue's >> Shutdown method to shutdown the queue. >> It will in turn cause the Next to return false and it can be used to >> break out of the loop. >> >> The ok parameter is an indication of the success of that particular >> operation and usually is not related to the cq life time management. >> >> >> On Monday, July 10, 2017 at 2:32:37 AM UTC-7, Przemysław Sobala wrote: >>> >>> Hello >>> What is the difference between method's >>> bool CompletionQueue::Next(void** tag, bool* ok) >>> return value and 2nd parameter's value? >>> >>> Reading docs, it says: >>> /// \param ok[out] true if read a regular event, false otherwise. >>> /// \return true if read a regular event, false if the queue is shutting >>> down >>> >>> Following the example: >>> while (true) { >>> // Block waiting to read the next event from the completion queue. >>> The >>> // event is uniquely identified by its tag, which in this case is >>> the >>> // memory address of a CallData instance. >>> // The return value of Next should always be checked. This return >>> value >>> // tells us whether there is any kind of event or cq_ is shutting >>> down. >>> GPR_ASSERT(cq_->Next(&tag, &ok)); >>> GPR_ASSERT(ok); >>> static_cast<CallData*>(tag)->Proceed(); >>> } >>> it breaks whether the return value or ok parameter is false. >>> But in the production environment maybe I can break the loop when the >>> queue is shutting down (based on return value) and continue when ok >>> parameter's value is false? >>> What is the most preferable approach? Should I consider both of them as >>> the same and break on false as in the example? >>> >>> -- >>> regards >>> Przemysław Sobala >>> >> -- > You received this message because you are subscribed to the Google Groups " > grpc.io" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/grpc-io. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/grpc-io/35ece217-c182-4dd9-b779-bbe8bf6b58d3%40googlegroups.com > <https://groups.google.com/d/msgid/grpc-io/35ece217-c182-4dd9-b779-bbe8bf6b58d3%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- Mark D. Roth <[email protected]> Software Engineer Google, Inc. -- You received this message because you are subscribed to the Google Groups "grpc.io" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/grpc-io. To view this discussion on the web visit https://groups.google.com/d/msgid/grpc-io/CAJgPXp6O8y6o%2ByPnU-%3DiBRSAOgFU7hodNA8xFfrCkdDYLXVbyA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
