[gstreamer-bugs] [Bug 575406] New: [collectpads] Race condition if collected function returns an error

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gstreamer (core) | Ver: git
           Summary: [collectpads] Race condition if collected function
                    returns an error
           Product: GStreamer
           Version: git
          Platform: Other
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: major
          Priority: Normal
         Component: gstreamer (core)
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: slomo at circular-chaos.org
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


Hi,
there's a race condition in collectpads. If the collected function returns an
error, i.e. not GST_FLOW_OK, this will be forwarded upstream. Now upstream
probably will post an error message on the bus and sends EOS downstream. If
this error message is not handled yet and the pipeline stopped, collectpads
will call the collected function again for the EOS for all remaining buffers on
some pads. This is absolutely unexpected and will most probably result in weird
errors inside the element that uses collectpads (like mine).
This is of course less likely to happen if the element that uses collectpads
posts an error message on the bus before returning a non-GST_FLOW_OK flowreturn
but it can still happen.

Solution would be to set collectpads into an error state and not call the
collected function again. I'll make a patch later...

Any comments on this?


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