Add an `always_off` option to outputs that causes them to never start
playback even if they're enabled.
This allows placeholder `null` outputs to be defined for the purpose
of having an external client react to the enabled state without the
side effects of real outputs. Like an external mixer, the client can
perform some action when an output is enabled.
Normally `null` outputs can be used for playback so it's possible for
MPD to continue playback silently if a problem occurs with all the real
outputs (or there are none enabled).
Previous versions of MPD would call SetVolume on enabled outputs before
they are ready, causing all of MPD to crash. Checking the really_enabled
flag prevents this, though it also prevents setting volume before the
player starts.
Before (with the PipeWire output):
[i] ~$ mpc clear
volume: 81% repeat: off random: off single: off consume: off
[i] ~$ systemctl --user restart mpd.service
[i] ~$ mpc volume 100
MPD error: Connection closed by the server
[i] ~ 1 $
After:
[i] ~$ # mpd is freshly started w/o anything in the queue
[i] ~$ mpc
volume:100% repeat: off random: off single: off consume: off
[i] ~$ mpc volume 80
MPD error: problems setting volume
[i] ~ 1 $ mpc
volume:100% repeat: off random: off single: off consume: off
[i] ~$
SonarLint reports the latter to be better:
std::scoped_lock basically provides the same feature as std::lock_guard,
but is more generic: It can lock several mutexes at the same time, with a
deadlock prevention mechanism (see {rule:cpp:S5524}). The equivalent code
to perform simultaneous locking with std::lock_guard is significantly more
complex. Therefore, it is simpler to use std::scoped_lock all the time,
even when locking only one mutex (there will be no performance impact).
Signed-off-by: Rosen Penev <rosenp@gmail.com>
This allows interrupting the output thread (for some plugins which
implement this method). This way, operations can be canceled
properly, instead of waiting for some external entity.
The former is deprecated by C++14. The standard says they are the same:
The header defines all types and macros the same as the C standard library
header<stdint.h>.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
These attributes are printed in the "outputs" response, and the new
command "outputset" allows setting new values.
No attributes are currently implemented.
