If this is not done, the event loop pointer will be initialized to
exploded MALLOC_SCRUB_BYTEs and the null pointer check at destruction
time will fail, causing a crash any time an audio client without a
started enqueuer thread exits. With this change, we correctly skip
quitting the event loop both when it was never started (if the enqueuer
thread never ran) as well as if it already exited (if the enqueuer
thread exited fast enough) without additional logic for the two very
different cases.
This commit does three things atomically:
- switch over Core::Account+SystemServer+LoginServer to sid based socket
names.
- change socket names with %uid to %sid.
- add/update necessary pledges and unveils.
Userland: Switch over servers to sid based sockets
Userland: Properly pledge and unveil for sid based sockets
This patch allows to insert "%uid" in `IPC_CLIENT_CONNECTION`
declaration and in SystemServer's ini files. This pattern is replaced
then replaced by the UID of the owner of the service. It opens a path
for seamlessly managed, per-user portal.
The audio enqueuer thread goes to sleep when there is no more audio data
present, and through normal Core::EventLoop events it can be woken up.
However, that waking up only happens when the thread is not currently
running, so that the wake-up events don't queue up and cause weirdness.
The atomic variable responsible for keeping track of whether the thread
is active can lead to a racy deadlock however, where the audio enqueuer
thread will never wake up again despite there being audio data to
enqueue. Consider this scenario:
- Main thread calls into async_enqueue. It detects that according to the
atomic variable, the other thread is still running, skipping the event
queue wake.
- Enqueuer thread has just finished playing the last chunk of audio and
detects that there is no audio left. It enters the if block with the
dbgln "Reached end of provided audio data..."
- Main thread enqueues audio, making the user sample queue non-empty.
- Enqueuer thread does not check this condition again, instead setting
the atomic variable to indicate that it is not running. It exits into
an event loop sleep.
- Main thread exits async_enqueue. The calling audio enqueuing system
(see e.g. Piano, but all of them function similarly) will wait until
the enqueuer thread has played enough samples before async_enqueue is
called again. However, since the enqueuer thread will never play any
audio, this condition is never fulfilled and audio playback deadlocks
This commit fixes that by allowing the event loop to not enqueue an
event that already exists, therefore overloading the audio enqueuer
event loop by at maximum one message in weird situations. We entirely
get rid of the atomic variable and the race condition is prevented.
