On 21.02.2018 21:02, Georg Chini wrote: > On 21.02.2018 20:15, Raman Shishniou wrote: >> On 02/21/2018 09:41 PM, Raman Shuishniou wrote: >>> 21.02.2018 20:07, Georg Chini пиÑ?еÑ?: >>>> Maybe you misunderstood me. What I mean, is that the pipe can be >>>> opened for writing as long as we are suspended. So it open when >>>> we see that the source is suspended or when we auto suspend. Close >>>> it as soon as the source gets unsuspended. This will avoid POLLHUP >>>> during suspend completely. While auto suspended, we additionally have >>>> to listen for POLLIN. >>>> This way we can only get POLLHUP (or POLLIN with no data) when the >>>> source is running. >>>> >>> I think I understand. We need to keep our writer opened while >>> transition >>> from autosuspended to opened state and just set events = 0. > > Exactly. I was also thinking about how to decide if data can be discarded > or needs to be posted. On resume, the SET_STATE handler could set a > just_unsuspended flag and when we know auto suspend is the only > suspend cause, we can additionally set a resume_from_auto_suspend > flag when we send the unsuspend message. In the thread function we > could then check if > > just_unsuspended && resume_from_autosuspend -> post pending data, > reset flags > just_unsuspended && !resume_from_auto_suspend -> discard data, reset > flags > !just_unsuspended -> post data > > But that's only an idea. It's even simpler, because the old and new suspend cause are available in the SET_STATE handler (or in the set_state_in_io_thread() callback). So there we can do: if (old_cause == AUTO_SUSPEND && new_cause == 0) -> resume_from_auto_suspend = true else if (old_caue != 0 && new_cause == 0) -> resume_from_user_suspend = true BTW, maybe we should have a new suspend cause for that. Currently, the best suspend cause we could use is PA_SUSPEND_UNAVAILABLE. In the future however, it is planned, that streams get rescued when the suspend cause is PA_SUSPEND_UNAVAILABLE and I guess that is not what you want in your case.
