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Original commit message from CVS: * docs/design/part-MT-refcounting.txt: * docs/design/part-clocks.txt: * docs/design/part-gstelement.txt: * docs/design/part-gstobject.txt: * docs/design/part-standards.txt: * gst/gstbin.c: (gst_bin_add_func), (gst_bin_add), (gst_bin_remove_func), (gst_bin_remove): * gst/gstbin.h: * gst/gstbuffer.c: * gst/gstcaps.h: * testsuite/clock/clock1.c: (main): * testsuite/clock/clock2.c: (gst_clock_debug), (element_wait), (main): * testsuite/dlopen/loadgst.c: (do_test): * testsuite/refcounting/bin.c: (add_remove_test1), (add_remove_test2), (main): * testsuite/refcounting/element.c: (main): * testsuite/refcounting/element_pad.c: (main): * testsuite/refcounting/pad.c: (main): * tools/gst-launch.c: (sigint_handler_sighandler): * tools/gst-typefind.c: (main): Doc updates. Added doc about clock. removed gst_bin_iterate_recurse_up(), marked methods for removal. Fix more testsuites.
54 lines
1.6 KiB
Text
54 lines
1.6 KiB
Text
Ownership of dynamic objects
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----------------------------
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Any object-oriented system or language that doesn't have automatic garbage
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collection has many potential pitfalls as far as the pointers go. Therefore,
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some standards must be adhered to as far as who owns what.
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Strings
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-------
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Arguments passed into a function are owned by the caller, and the function
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will make a copy of the string for its own internal use. The string should
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be const gchar *. Strings returned from a function are always a copy of the
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original and should be freed after usage by the caller.
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ex:
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name = gst_element_get_name (element); /* copy of name is made */
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.. use name ..
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g_free (name); /* free after usage */
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Objects
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-------
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Objects passed into a function are owned by the caller, any additional
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reference held to the object after leaving the function should increase the
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refcount of that object.
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Objects returned from a function are owned by the caller. This means that the
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called should _free() or _unref() the object after usage.
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ex:
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peer = gst_pad_get_peer (pad); /* peer with increased refcount */
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if (peer) {
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.. use peer ..
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gst_object_unref (GST_OBJECT (peer)); /* unref peer after usage */
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}
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Iterators
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---------
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When retrieving multiple objects from an object an iterator should be used.
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The iterator allows you to access the objects one after another while making
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sure that the set of objects retrieved remains consistent.
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Each object retrieved from an iterator has its refcount increased or is a
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copy of the original. In any case the object should be unreffed or freed
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after usage.
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