Every std::mutex, lock_guard, unique_lock, scoped_lock,
condition_variable, call_once and semaphore left in Source/Core is
replaced by a lock-free design:
- Input: the device list, control bindings, stick calibration and
default device are published snapshots read under a quiesce; a
rebind requested while another thread is rebinding is handed to
that thread instead of waited for.
- WiimoteReal: the pool thread owns the slots and runs commands from
an MPSC queue; the active Wiimotes are atomic slots.
- EXI/SI/IOS devices: socket and packet traffic goes through SPSC
rings or MPSC handoffs owned by one thread; USB scanning publishes
its device list, and libusb transfers drain through a CallGate.
- Memory cards: the flush thread applies change records queued by
the CPU thread.
- Custom assets: loads are scheduled as a published batch with an
atomic cursor, results come back over an MPSC stack, and busy
assets are skipped and retried.
- D3D state and GL program caches use insert-only atomic maps
(Common/AtomicHashMap.h).
- Logging appends with O_APPEND / FILE_APPEND_DATA; FatFs reports
busy instead of waiting; per-socket WSAStartup/WSACleanup.
Deleted as unused by the libretro core: the profiler, the FIFO
recorder, the volume verifier, the touch InputOverrider and the
GameCube adapter's libusb path.
With 12 uses of `JoinStrings` in the codebase vs 36 uses of `fmt::join`, fmtlib's range adapter for string concatenation with delimiters is clearly the preferred option.
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
This is useful in far out-of-calibration controllers, such as the
Switch Pro controller. This also adds support for configuring the center
in the Mapping widget.
LibretroAdmin