Original commit message from CVS:
2004-02-24  Andy Wingo  <wingo@pobox.com>

* gst/gstelement.c (gst_element_dispose): Protect against multiple
invocations.

* gst/schedulers/gstoptimalscheduler.c
I added a mess of prototypes at the top of the file by way of
documentation. Some of the operations on chains and groups were
re-organized.

(create_group): Added a type argument so if the group is enabled,
the setup_group_scheduler knows what to do.
(group_elements): Added a type argument here, too, to be passed on
to create_group.
(group_element_set_enabled): If an unlinked PLAYING element is
added to a bin, we have to create a new group to hold the element,
and this function will be called before the group is added to the
chain. Thus we have a valid case for group->chain==NULL. Instead
of calling chain_group_set_enabled, just set the flag on the group
(the chain's status will be set when the group is added to it).
(gst_opt_scheduler_state_transition, chain_group_set_enabled):
Setup the group scheduler when the group is enabled, not
specifically when an element goes PAUSED->PLAYING. This means
PLAYING elements can be added, linked, and scheduled into a
PLAYING pipeline, as was intended.
(add_to_group): Don't ref the group twice. I don't know when this
double-ref got in here. Removing it has the potential to cause
segfaults if other parts of the scheduler are buggy. If you find
that the scheduler is segfaulting for you, put in an extra ref
here and see if that hacks over the underlying issue. Of course,
then find out what code is unreffing a group it doesn't own...
(create_group): Make the extra refcount floating, and remove it
after adding the element. This means that...
(unref_group): Destroy when the refcount reaches 0, not 1, like
every other refcounted object in the known universe.
(remove_from_group): When a group becomes empty, set it to be not
active, and remove it from its chain. Don't unref it again,
there's no floating reference any more.
(destroy_group): We have to remove the group from the chain in
remove_from_group (rather than here) to break refcounting cycles
(the chain always has a ref on the group). So assert that
group->chain==NULL.
(ref_group_by_count): Removed, it was commented out anyway.
(merge_chains): Use the remove_from_chain and add_to_chain
primitives to do the reparenting, instead of rolling our own
implementation.
(add_to_chain): The first non-disabled group in the chain's group
list will be the entry point for the chain. Because buffers can
accumulate in loop elements' peer bufpens, we preferentially
schedule loop groups before get groups to avoid unnecessary
execution of get-based groups when the bufpens are already full.
(gst_opt_scheduler_schedule_run_queue): Debug fixes.
(get_group_schedule_function): Ditto.
(loop_group_schedule_function): Ditto.
(gst_opt_scheduler_loop_wrapper): Ditto.
(gst_opt_scheduler_iterate): Ditto.

I understand the opt scheduler now, yippee!

* gst/gstpad.c: All throughout, added FIXMEs to look at for 0.9.
(gst_pad_get_name, gst_pad_set_chain_function)
(gst_pad_set_get_function, gst_pad_set_event_function)
(gst_pad_set_event_mask_function, gst_pad_get_event_masks)
(gst_pad_get_event_masks_default, gst_pad_set_convert_function)
(gst_pad_set_query_function, gst_pad_get_query_types)
(gst_pad_get_query_types_default)
(gst_pad_set_internal_link_function)
(gst_pad_set_formats_function, gst_pad_set_link_function)
(gst_pad_set_fixate_function, gst_pad_set_getcaps_function)
(gst_pad_set_bufferalloc_function, gst_pad_unlink)
(gst_pad_renegotiate, gst_pad_set_parent, gst_pad_get_parent)
(gst_pad_add_ghost_pad, gst_pad_proxy_getcaps)
(gst_pad_proxy_pad_link, gst_pad_proxy_fixate)
(gst_pad_get_pad_template_caps, gst_pad_check_compatibility)
(gst_pad_get_peer, gst_pad_get_allowed_caps)
(gst_pad_alloc_buffer, gst_pad_push, gst_pad_pull)
(gst_pad_selectv, gst_pad_select, gst_pad_template_get_caps)
(gst_pad_event_default_dispatch, gst_pad_event_default)
(gst_pad_dispatcher, gst_pad_send_event, gst_pad_convert_default)
(gst_pad_convert, gst_pad_query_default, gst_pad_query)
(gst_pad_get_formats_default, gst_pad_get_formats): Better
argument checks, and some doc fixes.

(gst_pad_custom_new_from_template): Um, does anyone
use these functions? Actually make a custom pad instead of a
normal one.
(gst_pad_try_set_caps): Transpose some checks.
(gst_pad_try_set_caps_nonfixed): Same, and use a macro to check if
the pad is in negotiation.
(gst_pad_try_relink_filtered): Use pad_link_prepare.

* gst/gstelement.c: Remove prototypes also defined in gstclock.h.

* gst/gstelement.h:
* gst/gstclock.h: Un-deprecate the old clocking API, as discussed
on the list.