... instead of the `Pad{Src,Sink}Ref` wrappers:
- In practice, only the `gst::Pad` is useful in these functions.
Some of these which need a `Pad{Src,Sink}Ref`, but it's the one
for the opposite stream direction. In those cases, it is accessed
via the element's implementation.
- It saves a few `clone`s.
- The implementations usually use the `gst::Pad` for logging.
They no longer need to access it via `pad.gst_pad()`.
- They are either unit types or `Clone` (in which case they are implemented
as pointers).
- Internally, we already use an owned version, so there's no need to get a
reference.
- It facilitates implementation if the handler must be moved into a closure
or a `Future`.
This is a follow-up to commit 7ee4afac.
This commit cleans up the `Pad{Sink,Src}Handler` by
- Keeping arguments which are strictly necessary.
- Passing arguments by value for the trait functions which return
a `Future`. The arguments which were previously passed by reference
were `clone`d internally and then `clone`d again in most
implementations.
There are unfortunate differences in trait function signatures
between those which return a `Future` and the sync functions. This
is due to the requirement for the arguments to be moved to the
resulting `Future`, whereas sync functions can rely on references.
One particular notable difference is the use of the `imp` in sync
functions instead of the `elem` in functions returning a `Future`.
Because the `imp` is not guaranteed to implement `Clone`, we can't
move it to the resulting `Future`, so the `elem` is used.
Add a `tuning` feature which adds counters that help with performance
evaluation. The only counter added so far accumulates the duration a
Scheduler has been parked, which is pretty accurate an indication of
CPU usage of the Scheduler.
- Reworked buffer push.
- Reworked stats.
- Make first elements logs stand out. This make it possible to
follow what's going on with pipelines containing 1000s of
elements.
- Actually handle EOS.
- Use more significant defaults.
- Allow building without `clap` feature.
Implement a test that initializes pipelines with minimalistic
theadshare src and sink. This can help with the evaluation of
changes to the threadshare runtime or with element
implementation details. It makes it easy to run flamegraph or
callgrind and to focus on the threadshare runtime overhead.
