'Twas brillig, and Lennart Poettering at 01/03/09 09:40 did gyre and gimble: > On Sun, 01.03.09 02:27, Colin Guthrie (gmane at colin.guthr.ie) wrote: > >> Hi, >> >> I was trying to debug a deadlock while using gvim (with >> libcanberra+pulse output: https://qa.mandriva.com/show_bug.cgi?id=44925) >> I had reason to read the threaded loop docs. >> >> The reference implementation shown here: >> http://0pointer.de/lennart/projects/pulseaudio/doxygen/threaded_mainloop.html#basic_subsec >> >> In my mind, the operation could theoretically be cancelled and this the >> _get_state() will return PA_OPERATION_CANCELLED. >> >> In the example code, if this happens, the loop will spin and the main >> loop will never be unlocked. >> >> This could be fixed by spinning when the state is PA_OPERATION_RUNNING >> rather when it is not PA_OPERATION_DONE (incidentally, there is a typo >> in the docs... it says OPERATION_RUNNING without the PA_ prefix...). >> >> Anyway, any comments on this observation would be appreciated. > > PA_OPERATION_CANCELLED is a state that is only entered after the > *client* called pa_operation_cancel(), i.e. it needs to be triggered > from the same code that waits for pa_operation_get_state() becoming > PA_OPERATION_DONE. Hence waiting for _DONE is actually safe. > > That said it is probably still more robust if we'd only loop as long > as _RUNNING is the current state so that this loop properly exits > should the client code be eventullay changed to call _cancel > somewhere. I have now changed this in my local git tree here. Ahh cool. Well that's reassuring to hear as there is a fair bit of code that uses this approach from what I can tell. Incidentally, can you have a quick glance over this bug for me? https://qa.mandriva.com/show_bug.cgi?id=44925 As I said in my last comment, I'm pretty sure the problem is the abuse of the gtk main loop (which they exit and restart) but as I'm not really a gtk hacker I'm not too sure. Col -- Colin Guthrie gmane(at)colin.guthr.ie http://colin.guthr.ie/ Day Job: Tribalogic Limited [http://www.tribalogic.net/] Open Source: Mandriva Linux Contributor [http://www.mandriva.com/] PulseAudio Hacker [http://www.pulseaudio.org/] Trac Hacker [http://trac.edgewall.org/]
