<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML dir=ltr><HEAD><TITLE>[gst-devel] Why do we call gst_object_unref() ?</TITLE> <META content="text/html; charset=unicode" http-equiv=Content-Type> <META name=GENERATOR content="MSHTML 8.00.6001.18999"></HEAD> <BODY> <DIV dir=ltr id=idOWAReplyText52179> <DIV dir=ltr><FONT color=#000000 size=2 face=Arial>It's used to perform reference counting.  Each use or user of an object should be counted.  When that count goes to 0, then it means the object is no longer needed and the resources it occupies can be reclaimed.  If you see an object being unref'd that should continue to exist, then you should check up on who is resposible for keeping a count on it, after the unref in question.</FONT></DIV> <DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV> <DIV dir=ltr><FONT size=2 face=Arial>The reason this is necessary during program execution is that numerous short-lived objects are created.  If these are never deallocated, then a program's memory usage would continually grow.  Ref-counting is sometimes described as a lesser form of garbage collection, and is commonly used in cases where there's not necessarilly a clear relationship between consumers and producers of objects.  Be warned that ref counting fails in the case of circular references (weak refs can sometimes be used to avoid these scenarios).</FONT></DIV> <DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV> <DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV> <DIV dir=ltr><FONT size=2 face=Arial>BTW, this is complicated by the concept of "parenting", where exclusive ownership of an object is asserted.  I encourage you to look for details about all of this in the GLib docs, as I'm sure it must be described in there at length.</FONT></DIV> <DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV> <DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV> <DIV dir=ltr><FONT size=2 face=Arial>Matt</FONT></DIV> <DIV dir=ltr><FONT size=2 face=Arial></FONT> </DIV></DIV> <DIV dir=ltr><BR> <HR tabIndex=-1> <FONT size=2 face=Tahoma><B>From:</B> gst_call_me_newbie() [mailto:21stninjagod@gmail.com]<BR><B>Sent:</B> Sun 1/2/2011 1:43 AM<BR><B>To:</B> gstreamer-devel@lists.sourceforge.net<BR><B>Subject:</B> [gst-devel] Why do we call gst_object_unref() ?<BR></FONT><BR></DIV> <DIV><BR> <P><FONT size=2>hi all,<BR><BR>I checked the meaning of the function gst_object_unref() and got what it<BR>does but I could not get why do we call it while the program is in<BR>execution.<BR><BR>for e.g this is a code snippet from the application developer manual<BR>provided at the gstreamer's site.<BR><BR>[some code here.....]<BR>bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));<BR>gst_bus_add_watch (bus, my_bus_callback, loop);<BR>gst_object_unref (bus);<BR>[some other code here.....]<BR><BR>so why would someone want to unref the bus when we still need it in our<BR>program. If I unref it and if somehow that would have been the last<BR>reference to the object than object would surely be destroyed.<BR>so why should I call it. Please enlighten me.<BR>Thanks<BR><BR><BR>--<BR>View this message in context: <A href="http://gstreamer-devel.966125.n4.nabble.com/Why-do-we-call-gst-object-unref-tp3170699p3170699.html">http://gstreamer-devel.966125.n4.nabble.com/Why-do-we-call-gst-object-unref-tp3170699p3170699.html</A><BR>Sent from the GStreamer-devel mailing list archive at Nabble.com.<BR><BR>------------------------------------------------------------------------------<BR>Learn how Oracle Real Application Clusters (RAC) One Node allows customers<BR>to consolidate database storage, standardize their database environment, and,<BR>should the need arise, upgrade to a full multi-node Oracle RAC database<BR>without downtime or disruption<BR><A href="http://p.sf.net/sfu/oracle-sfdevnl">http://p.sf.net/sfu/oracle-sfdevnl</A><BR>_______________________________________________<BR>gstreamer-devel mailing list<BR>gstreamer-devel@lists.sourceforge.net<BR><A href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel">https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</A><BR></FONT></P></DIV></BODY></HTML>