The time driver for the threadshare runtime assigns the timer
entries to the nearest throttling time frame so that the timer
fires as close as possible to the expected instant. This means
that the timer might fire before or after the expected instant
(at most `wait / 2` away).
In some cases, we don't want the timer to fire early. The new
function `delay_for_at_least` ensures that the timer is assigned
to the time frame after the expected instant.
Only two uses of unsafely setting the pad functions is left:
- fallbacksrc for overriding the chain function of the proxy pad of a
ghost pad
- threadshare for overriding the pad functions after creationg, which
probably needs some fixing at some point
Pad{Src,Sink}[Ref] delegate some functions to their respective
Pad{Src,Sink}Inner. Since they act as smart pointers, we can
safely implement the Deref trait to simplify the implementations.
StateMachines are spawned on a runtime::Context which uses a tokio
runtime. The StateMachine doesn't need all the features from tokio
such as the IO and timers drivers.
This commit makes use of a light-weight futures executor to spawn
the StateMachines.
When initializing Pad functions in `Pad{Src,Sink}`, we downgrade the
`Pad{Src,Sink}` and upgrade it when necessary. This was implemented
to avoid reference cycles:
`gst::Pad` -> pad function -> `Pad{Src,Sink}` -> `gst::Pad`.
Since `Pad{Src,Sink}` reset the pad functions when dropping, there is
no cycles, so we can use an `Arc<Pad{Src,Sink}>` in the pad functions,
thus saving an `upgrade`.
