jack2 can process in parallel with calling a graph-order or
latency-callback, so Ardour takes a lock to update those in sync.
Yet jack2 can also block while port-registrations happen,
and concurrently emit latency-callback from another thread..
Port and connection changes always imply a latency_callback from
the engine. Worst I/O latency is updated directly in
Session::update_latency() which is called from
AudioEngine::latency_callback.
Explicit subscriptions to route->output()->changed() is not needed
to update the worst I/O latency.
Only set_block_size() needs to to update the I/O latency when
the buffer-size changes.
The backend may call update_latency() while at the same time
the auto-connect-port calls set_worst_io_latencies().
The latter already holds the process-lock, so update_latency()
first needs to acquire it, as well. If one already holds the
_update_latency_lock, one must not ask for the process-lock.
---
Previously Ardour's connection manager first took the process_lock
and then waited to the _update_latency_lock.
Meanwhile jack calls latency_callback(), takes the
_update_latency_lock and waits for the process_lock.
Classic deadlock.
LV2 plugins may add a MIDNAM file when they're loaded.
This can be happen concurrently with the MidiPatchManager,
loading the system-wide patch files.
Session load should not be interrupted by the initial
background scan of patch files, which can take a very long time.
We need to allow update_custom_midnam() to grab the _lock.
Previously, `dist` had to be the first argument to waf. If it came in a
different position (e.g. `APPNAME=Ardour ./waf tarball dist`) or
`distcheck` was used instead of `dist`, the resulting archive was named
`noname-....tar.bz2`.
Signed-off-by: Nils Philippsen <nils@tiptoe.de>
Various backends have different strategies for updating latencies,
and different thread semantics for latency update callbacks.
With jack2 it is possible that processing happens concurrently
while port latencies are being changed.
Ardour internal backends emit the latency callback from the
main process thread, serializing latency changes with processing.
Various user actions can also trigger latency changes. e.g.
with a stopped engine it is possible to re-order plugins.
When editing a sends, this allows to unlink send panner via
the panner's context menu.
NB. After 6.0-rc string freeze the context menu needs an update.
So far the text from the Processor Box context menu is reused.
The semantics are that if the user configures things to allow transport commands while
using a transport master, issuing such commands first stops using the master
Auditioner seek calls are explicitly handled by the butler,
and DR:overwrite_existing_buffers() is called explicitly
to read MIDI data for audition.
Session::non_realtime_overwrite is no longer required.
This reverts commit 6fbcf83779
and parts of 2d11667ce3.
The options ForwardSlow, Forward and ForwardFast and their
respective Rewind options were not honoured in the execution
of forward/rewind operations when the transport was already
rolling at a slower speed than the forward or rewind option's
speed with same direction as the requested direction.
The Auditioner is not part of the session route-list and the
auditioner route's I/O latency is never updated.
Session::process_audition() does not handle pre-roll either,
so it need to be zeroed, otherwise Route::roll skips samples.
This has lead to initial samples being skipped, IFF the
auditioner's output-port had non-zero latency.
Since private port-latencies are usually only set for routes
in the route-list, and _remaining_latency_preroll is reset
at transport-stop, this *usually* worked...
Last but not least, MIDI notes need to be resolved when seeking.
