Previously, we were sending Buffers to the server whenever we had new
audio data for it. This meant that for every audio enqueue action, we
needed to create a new shared memory anonymous buffer, send that
buffer's file descriptor over IPC (+recfd on the other side) and then
map the buffer into the audio server's memory to be able to play it.
This was fine for sending large chunks of audio data, like when playing
existing audio files. However, in the future we want to move to
real-time audio in some applications like Piano. This means that the
size of buffers that are sent need to be very small, as just the size of
a buffer itself is part of the audio latency. If we were to try
real-time audio with the existing system, we would run into problems
really quickly. Dealing with a continuous stream of new anonymous files
like the current audio system is rather expensive, as we need Kernel
help in multiple places. Additionally, every enqueue incurs an IPC call,
which are not optimized for >1000 calls/second (which would be needed
for real-time audio with buffer sizes of ~40 samples). So a fundamental
change in how we handle audio sending in userspace is necessary.
This commit moves the audio sending system onto a shared single producer
circular queue (SSPCQ) (introduced with one of the previous commits).
This queue is intended to live in shared memory and be accessed by
multiple processes at the same time. It was specifically written to
support the audio sending case, so e.g. it only supports a single
producer (the audio client). Now, audio sending follows these general
steps:
- The audio client connects to the audio server.
- The audio client creates a SSPCQ in shared memory.
- The audio client sends the SSPCQ's file descriptor to the audio server
with the set_buffer() IPC call.
- The audio server receives the SSPCQ and maps it.
- The audio client signals start of playback with start_playback().
- At the same time:
- The audio client writes its audio data into the shared-memory queue.
- The audio server reads audio data from the shared-memory queue(s).
Both sides have additional before-queue/after-queue buffers, depending
on the exact application.
- Pausing playback is just an IPC call, nothing happens to the buffer
except that the server stops reading from it until playback is
resumed.
- Muting has nothing to do with whether audio data is read or not.
- When the connection closes, the queues are unmapped on both sides.
This should already improve audio playback performance in a bunch of
places.
Implementation & commit notes:
- Audio loaders don't create LegacyBuffers anymore. LegacyBuffer is kept
for WavLoader, see previous commit message.
- Most intra-process audio data passing is done with FixedArray<Sample>
or Vector<Sample>.
- Improvements to most audio-enqueuing applications. (If necessary I can
try to extract some of the aplay improvements.)
- New APIs on LibAudio/ClientConnection which allows non-realtime
applications to enqueue audio in big chunks like before.
- Removal of status APIs from the audio server connection for
information that can be directly obtained from the shared queue.
- Split the pause playback API into two APIs with more intuitive names.
I know this is a large commit, and you can kinda tell from the commit
message. It's basically impossible to break this up without hacks, so
please forgive me. These are some of the best changes to the audio
subsystem and I hope that that makes up for this :yaktangle: commit.
:yakring:
With the following change in how we send audio, the old Buffer type is
not really needed anymore. However, moving WavLoader to the new system
is a bit more involved and out of the scope of this PR. Therefore, we
need to keep Buffer around, but to make it clear that it's the old
buffer type which will be removed soon, we rename it to LegacyBuffer.
Most of the users will be gone after the next commit anyways.
SystemServer had safety fallbacks to boot into text mode if the user
errorneously specified graphical mode but no video hardware was present.
As it's now possible to do exactly this intentionally, we should allow
it. This would of course make WindowServer fall over and die if
configured improperly, but if you're messing with the kernel command
line in strange ways, you should be able to fix that.
This screen backend is just memory-backed and doesn't connect to any
screen hardware. That way, we can boot Serenity without video hardware
but in full graphical mode :^)
To create a virtual screen, put something like this in your
WindowServer.ini. There's no way yet to do this through Display
Settings, though an existing virtual screen's settings can be changed
there.
```ini
[Screen0]
Mode=Virtual
Left=1024
Top=0
Width=1920
Height=1080
ScaleFactor=1
```
This will allow us to change between a couple of properties, for now
it's only Device and Virtual. (How about Remote :^) ) These get handled
by a different screen backend in the Screen.
The ScreenBackend is a thin wrapper around the actual screen hardware
connection. It contains all the variables specific to that hardware and
abstracts away operations that deal with controlling the hardware. The
standard ScreenBackend implementor is HardwareScreenBackend, which
contains all the existing frame buffer & ioctl handling code of Screen.
I took this opportunity to introduce ErrorOr wherever sensible.
This was very badly named. All that the "FBData" struct contains is the
currently to-be-flushed rectangles plus a fullness flag, so it should
better be called FlushRectData. This rename is similarly applied to all
variable names.
A mistake I've repeatedly made is along these lines:
```c++
auto nread = TRY(source_file->read(buffer));
TRY(destination_file->write(buffer));
```
It's a little clunky to have to create a Bytes or StringView from the
buffer's data pointer and the nread, and easy to forget and just use
the buffer. So, this patch changes the read() function to return a
Bytes of the data that were just read.
The other read_foo() methods will be modified in the same way in
subsequent commits.
Fixes#13687
This fixes issues with carriage return sequences.
Before, using <CR><NUL> as the return sequence wouldn't work at all,
and when using <CR><LF> there was an extra newline after every newline.
After this patch, the behaviour should be closer to the Telnet RFC.
If the .config directory (or its children, like lib) was deleted,
ConfigFile would crash because it would try to open or create a file in
a directory that didn't exist. Therefore, for user and library configs
(but not system configs), ensure that the parent directories exist. This
allows the user to delete the entire .config folder and all apps still
work. (Except those which can't handle missing config. That's a separate
issue though.)
Fixes#13555
Note: Some changes to pledges and unveils are necessary for this to
work. The only one who can recreate .config at the moment is
ConfigServer, as others probably don't pledge the user home directory.
This prevents a crash when the inspected process closes the socket (i.e.
when the app is exited). This crash was caused by the InspectableProcess
removing itself from the global process table within a callback Function
that is stored as part of the InspectableProcess.
Previously, GUI::Window::is_maximized() had to make a synchronous IPC
request to WindowServer in order to find out if the window was indeed
maximized.
This patch removes the need for synchronous IPC by instead pushing the
maximization state to clients when it changes.
The motivation for this change was that GUI::Statusbar was checking
if the containing window was maximized in its resize_event(), causing
all windows with a statusbar to block on sync IPC *during* resize.
Browser would typically block for ~15 milliseconds here every time
on my machine, continuously during live resize.
If there are pending paint requests waiting to be processed when the
client asks us to remove a backing store, we now prune them from the
request queue.
This avoids doing completely wasted painting work while resizing the
browser window. :^)
The storage inspector now has a new tab for local storage. The next step
would be to persist local storage and receive real-time notifications
for changes to update the table view.
With this change you can now set the theme and background color at the
same time in the Display Settings. Before if both were changed
before hitting 'apply' the theme background color would overwrite
the custom background.
Some ISPs may MITM DNS requests coming from clients, changing the case
of domain name in response. LookupServer will refuse responses from
any DNS server in that case. This commit changes the behaviour to
perform a case-insensitive equality check.
This is useful, for instance, in games in which you can switch held
items using the scroll wheel. In order to implement this, they
previously would have to either add a hard-coded division by 4, or look
up your mouse settings to adjust correctly.
This commit adds an MouseEvent.wheel_raw_delta_x() and
MouseEvent.wheel_raw_delta_y().
We now distribute the line-height evenly between the space above and
below inline-level boxes. This noticeably improves our baseline
alignment in many cases.
Note that the "vertical-align: <length>" case is quite awkward, as the
extra height added by the offset baseline must count towards the line
box height.
There's a lot of room for improvement here, but this makes the buckets
container on Acid3 show up in the right place, with the right size.
This converts the return value of File::read_link() from String to
ErrorOr<String>.
The rest of the change is to support the potential of an Error being
returned and subsequent release of the value when no Error is returned.
Unfortunately at this stage none of the places affected can utililize
our TRY() macro.
