SDL_HashTable uses callbacks to calculate hash, compare keys and destroy items. Compiler doesn't know anything about functions that hashtable is going to call, so some optimizations can't be applied. But in almost all cases we know the functions to be called at compile time.
Generic hashtable is a reusable header that generates hashtable implementation for concrete hash, compare and destroy functions. It allows them to be inlined by the compiler, resulting in 1.5-4x performance boost compared to SDL_HashTable. The implementation is taken from SDL_HashTable, with a few improvements:
- Lowered max load factor to 128 (50%). Seems to be a good default value, as find is unlikely to load more than one cache line. The value also can be overriden by setting SDL_HASHTABLE_MAX_LOAD_FACTOR.
- Removed live bit field, using probe_len = 0 to indicate whether the item is live instead. Seems to be a bit faster, as CPU doesn't need to reset live bit each time probe_len is accessed.
- Removed max_probe_len. Unneeded, as we compare to probe_len of each item we visit, which is a stronger break condition.
From @AntTheAlchemist:
This is an interesting one, on a Xiaomi MiTV. Caused by a camera device, full stack:
android.app.LoadedApk$ReceiverDispatcher$Args.lambda$getRunnable$0$LoadedApk$ReceiverDispatcher$Args -> org.libsdl.app.HIDDeviceManager$1.onReceive -> handleUsbDeviceAttached -> connectHIDDeviceUSB -> getSerialNumber -> android.hardware.usb.UsbDevice.getSerialNumber -> android.hardware.usb.IUsbSerialReader$Stub.onTransact -> com.android.server.usb.UsbSerialReader.getSerial -> UsbUserPermissionManager.checkPermission -> hasPermission -> isCameraDevicePresent
This prevents ABBA deadlocks caused by taking a hardware resource lock then delivering events at the same time another thread is taking a hardware resource lock from an event watch callback.
Fixes https://github.com/libsdl-org/SDL/issues/15709
We're still seeing this frequently when unregistering PlayStation controller sensors. We don't know what else is modifying the sensor list, but if we end up getting this exception we'll retry after a short sleep.
Otherwise, it might cause a deadlock, if the output_callback runs in another
thread while the guaranteed initial hint callback fires. One will wait for the
SDL device lock, the other the pipewire thread loop lock, each already holding
what the other needs.
This way, the hint callback fires and we ignore it, since the stream isn't
set up yet...which is good, because we're about to create the stream and set
that exact same state on it directly anyhow. Now there's no chance of this
deadlock happening.
Reference Issue #15075.
This reverts commit 91173aba25.
As @icculus mentioned: I'd rather we not get into the business of making fixes by tweaking values in the Preseed files. Were there no preseed file, CMake would correctly record that the vfork function exists, so if we're really hitting the vfork() codepath on DOS, we should stop that in either CMakeLists.txt itself, or in src/process.
The experimental Steam Linux Runtime 3.0 (arm64) container is being
phased out, so games that want native arm64 binaries should upgrade to
Steam Linux Runtime 4.0.
steamrt/tasks#1032
Signed-off-by: Simon McVittie <smcv@collabora.com>
Some sensors will occasionally report two identical timestamps in a row.
This leads to the timestamp wrapping calculation to underflow, subtracting
0x80000000 from the timestamp whenever it happens. By adjusting the wrap
test, we can just directly add zero to the timestamp, fixing the underflow.
Previously something like SDL_GetCurrentDisplayMode() would have this output:
```
RETURN VALUE
*) Returns a pointer to the desktop display mode or NULL on failure; call SDL_GetError() for more information.
```
Now it doesn't have the junk at the start of the text:
```
RETURN VALUE
Returns a pointer to the desktop display mode or NULL on failure; call SDL_GetError() for more information.
```
That also covers removal of the call `SDLActivity.onNativeAccel`,
plus a change of comment under SDL_android.c.
Definitions were previously used while an accelerometer could be listed as a joystick.
